6 years with the Socata TB20

This article describes the author's 6-year experience of operation of the Socata TB20GT aircraft. It was also written to help answer frequent questions asked by prospective TB20 buyers about type conversion issues, general operation, costs, and things to look out for.

PPL Training

This is just a brief bit of history to put things in perspective.

I started PPL training in 2000. The objective was to learn to fly so I could travel to far away places around Europe, and to see Europe from the air.

The PPL training scene at my local airport was somewhat behind the times... The first training plane was the PA38 Tomahawk which is a type most charitably described as an "exciting" plane to fly, but its condition was something else. The plastic had come off the yoke (the control column) many years before and one was holding bare metal rusted through years of students' sweat. After a rainy night there would be a puddle of water on the floor and the plane smelt like an old-style public telephone kiosk. During preflight fuel drain tests following a rainy night, it was not unusual to drain out several test beakers full of water before the fuel would start to come out - presumably due to perished filler cap seals. After about 20hrs of lessons, I left this school due to this and other less mentionable maintenance issues.

The next school operated Cessna 152s, in which I finished the UK/JAA PPL in May 2001. These were decrepit too but quite pleasant to fly and very easy to land due to ground effect being nearly absent.

The first thing which became obvious during PPL training was that the entire scene was very far removed from the reason I was learning to fly. Even if the training planes had been functionally capable of going somewhere "serious" (which they weren't, due to range) convincing passengers to come along would be a challenge. They were not unsafe in the sense that the wings would not fall off but their condition was poor at best and only hardened anoraks would want to travel in them regularly. More technically, the range of a Cessna 152 or a PA28-161 means that a flight from the UK to e.g. Prague would involve one or two fuel stops which makes it a gruelling all-day exercise - in each direction! Topping off a plane is not like dropping into a petrol station; in Europe one normally has to clear Customs even just for an airside-only fuel stop, so landings are generally to be avoided unless one actually wants to do something there.

It also became obvious, after the 2nd or 3rd cancelled lesson, that flying would be all but useless without an instrument capability. During one Oct-Dec period I booked every day to fly (i.e. 90 lessons) and due to rain and low cloud I got just 3 lessons in! Unfortunately nothing available for rental was suitable for "real" instrument flight. For instrument training, we used one plane (with a working VOR but a duff ADF) for VOR work, and another plane (with a duff VOR, duff DME, but a working ADF) for NDB work.

Therefore, I started looking around for planes to "get into long-term" (in a syndicate, or to buy outright) very soon after starting PPL training. This annoyed the various instructors, most of whom were ATPL hour builders who had never flown past the nearest crease in their charts and who knew next to nothing about different aircraft types. Naturally they preferred me to carry on renting what they had on offer - self fly hire is an important source of income to a flying school.

Aircraft Choice

This was done largely through a process of elimination of everything I did not want. After the PPL which took 66 hours, I converted to and rented PA28-160s and -180s in which I accumulated about 50 hours on various local flights, while looking around at various options. By this time, the requirements had been refined:

- no high wing (cannot see properly when doing steep turns)

- no single door (hard to get in/out, and difficult emergency escape - I had one of the two PA28 door locks jam once and that was enough)

- a modern design with 2 doors which is easy for everybody to get in and out of

- IFR avionics including a large screen GPS which is good for both VFR and IFR

- suitable for both hard runways and grass, 500m tarmac or 750m grass

- long range, suitable for the 400-600nm legs (with reserves for another 200+nm) typical in European touring

- actual aircraft less than 15 years old (aluminium airframes tend to need significant airframe parts after this point)

- an RMI with ADF and VOR needles (NDB approaches are a feature of European IFR and are not going to go away anytime soon)

- 130kt+ cruise

No suitable syndicates were found. The nearest I got to was a share in a Socata TB10, but it was quickly established that some of the IFR avionics were not functioning and the VFR-only members were unwilling to pay their share of fixing them; this turned out to be a common scenario in syndicates. The aircraft was also on the Private CofA which could not be used for training for the initial award of a License or a Rating (100% owners and some other cases excepted) which was no good as my immediate objective at the time was the IMC Rating. In retrospect, I could have tried forming a syndicate around an outright purchase (new or used) but with most of the people who trained with me having left flying almost immediately there was no obvious pool of potential shareholders to tap into.

Soon I moved to various outright purchase options. I did not at that time have the budget for anything brand new. The front runner, on specification and budget, was another used Socata TB10. The TB9 was no better than the PA28-160 (Warrior) on performance and was ruled out. However, very few TB10s found for sale were in good condition. After a great initial success in the early 1980s, the sales of the TB9/TB10 models had been poor (probably due to excessive pricing) and this resulted in most for-sale specimens being around 20 years old.

In early 2002 the budget situation improved and new purchase options were considered. The planes which met the technical requirements were a suprisingly short list:

Cirrus SR20 (SR22 not yet available)
Diamond DA40-180 (Diesel engines were not available at the time)
Socata TB20 (or possibly the TB21)

The first two were very recent designs while the TB range - while "ultra modern" by normal Cessna/Piper standards - dated back to ~ 1980. The TB20 was the only retractable gear aircraft in the lineup.

It was time to check out the hardware and meet up with some dealers...

The fibreglass Cirrus' chief innovation was the whole-aircraft parachute which would offer options for some classes of emergency e.g. structural failure, or an engine failure at night or over "impossible" terrain. However, it did not have an ADF or a DME; these were (and still are) a legal requirement for IFR in controlled airspace in the UK, and a DME is required for IFR practically everywhere in Europe. When the Cirrus dealer was asked about this he replied "just ignore it; a GPS is much better" (which is true but not really the point) following which he turned around to talk to another customer who was not asking awkward questions. I did discover later that an ADF and DME could be retrofitted as a crude hack in the far right of the instrument panel, but if the dealer had this arrogant attitude before he got the money what would he be like afterwards? The build quality was not great either, with plenty of sharp edges around and poorly fitting trims. The Cirrus does not have an engine RPM lever - this was achieved with a rather crude mechanical device linking the throttle to the prop governor such that the engine runs at max RPM whenever the throttle is beyond a specific setting.

The Diamond DA40 was another very modern looking fibreglass plane but with the build quality of an IKEA kitchen with sharp edges and poorly fitting parts everywhere. It was also not capable of having the avionics I wanted; I did not consider a single Garmin 430 with its tiny screen adequate as the main GPS for VFR and IFR. The dealer didn't want to discuss avionics changes. The DA40 was an interesting aircraft which showed how the "sports VFR" future would look but it did not appear to be made for serious long range IFR.

The Socata TB20 was very different. The build quality was very good and the contrast would have been obvious to any "engineer type". Construction was mostly aluminium, with a curved composite roof and a lot of car-type plastic (a little like a 1970s Renault - apparently they designed the interior) and cloth trim inside. It met the performance requirements. It came with a full set of IFR avionics, engine instruments, a fuel flow totaliser, all in a panel which was a masterpiece of ergonomic design.

It also had TKS propeller de-ice, and a dealer who was willing to talk about options like the RMI. The above panel shows the RMI, and also a Garmin 496 which was installed in the LH yoke in later years.

The TB21 was considered too; it was another £60k or so, the delivery time was longer, but unfortunately I picked up bogus information on the operating costs which - it was claimed - included an engine fund about 3x bigger than the TB20, plus the Annual costing a lot more due to mandatory inspections on the fitted oxygen system. The actual engine fund is around 2x of the TB20 but the fuel economy is very slightly worse at low operating altitudes due to the lower engine compression ratio, but improving at higher altitudes.

Another option at the time was the Rockwell Commander 114/115 but it was way too expensive and, in retrospect, no more capable than a TB20/21 if comparing the same level of equipment e.g. full de-ice in both cases. I had also seen quite a few Commanders sitting on the ground for many months waiting for parts. Mooneys were ruled out due to being single door and with cramped cockpits even more difficult to get into than a PA28. The rather larger Bonanza A36 was ruled out on grounds of cost.

Considerable "due diligence" was done on Socata aircraft. All maintenance firms I spoke to reported no current problems with them, while warning me off many other types with recurring AD and parts availability issues. TB20 owners universally liked the aircraft - even if this is to be largely expected. Pilots with known long experience of many types also spoke very well of the TB20. Some negative views included high parts prices, long lead time on parts, and difficult access to wiring behind the car-like instrument panel.

The TB20 was available with two main avionics configurations: Garmin 430+530, or the Honeywell KLN94+KMD550. The latter option was chosen because of the much better VFR data on the KMD550 over anything from Garmin.

Today, the options (still working to the original specification) would have been suprisingly similar. The Cirrus SR22 would be most pilots' obvious choice for an IFR tourer - it is a current production aircraft with a seemingly assured future, employs very conventional technology, has no real reliability issues, and its build quality has much improved. Diamond, whose build quality has also improved since their early days, has been an extremely tempting option for anybody doing long distance European touring (avtur burning engines avoid the avgas availability problems around Europe) but sadly has just become a very questionable choice due to the bankrupcy of Thielert engines. There is also the Lancair/Cessna 400 but this is very new and they appear to have scrapped their novel electrically powered de-ice system; also its impressive headline performance figures are based on a high fuel flow and the TAS at FL250. Personally, I have recently flown the SR22 and the DA42 and would still prefer a good-condition 2002/2003 TB20GT or TB21GT for the same reasons as originally, plus I much prefer a yoke over a side- or centre-stick. The TB20 also feels a lot more solid and stable. I've also flown in the Cessna 400 which flies nicely and appears to be a solidly built aircraft, with a really well designed dual-redundant electrical system (2 alternators, 2 batteries, etc) and is quick, but the performance obviously comes only from fuel flow and its MPG turns out to be exactly identical to the TB20, at the same speed of e.g. 140kt IAS.

The TB20 - Initial Impressions

As it was the only realistic option which met the requirements, the TB20 was ordered without a test flight. I had about 120 hours total time at that point and what would a 120 hour pilot know anyway?

The aircraft was collected, with the factory pilot being the PIC, from the Socata facility at Le Bourget (this office has since been closed). A couple of obvious faults were found: the VSI was showing +400fpm on the ground, and the right-hand yoke PTT switch did not work. The VSI was adjusted by Socata but they could not fix the PTT switch, so we departed for the UK with me wondering how someone could deliver a £200k aircraft with such very obvious defects. As I was soon to learn, however, the world of aviation runs in its own parallel universe...

The aircraft flew very nicely - exactly as I had expected. 150/160kt does not feel any different to the 100kt I was used to and the great stability of the TB20 was a revelation, as was the ease of doing 60 degree turns without losing altitude. Obviously it is not anything aerobatic but is great for having fun, drilling holes in clouds, etc.

There was a suprising level of high frequency vibration in the cockpit which did not seem right but I was assured this would go away once the engine had settled down. Being a competent mechanical engineer I did not believe this - mechanical imbalance issues are not going to get better.

After landing in the UK, the aircraft was left with the dealer who was to prepare it for placing on the UK register. I did some digging and quickly found that the Socata factory outlet (not a dealership as such) in the USA routinely finds that the Hartzell 3-blade props are way out of balance and they dynamically balance them, much to the annoyance of the French factory which did not like the extra costs. I said I would not accept the aircraft until the prop had been dynamically balanced. The dealer refused but after some weeks accepted they would not get paid and we flew off to a firm at Exeter for the propeller balancing; the cost was only about £200. The prop was found to be 1.5 IPS (inches per second) out which most specialists now describe as serious enough to ground an aircraft. The balanced prop was below 0.1 IPS and the result was very noticeable. The aircraft was accepted immediately and the final payment handed over on the return flight.

Converting to the TB20

I arranged for an instructor at my old flying school to do the "differences training" with me so I could fly the TB20 on my own.

This did not start well: when taxiing out, the nosewheel went into a 5" deep pothole (hidden in the grass and thus not visible) and the prop got dinged. Only the last 10mm was damaged, but it was a clear prop strike which required a full shock load inspection on the engine. Hartzell's rules for prop repair also mandated that the hub is scrapped if more than one blade needs to be removed for repair and this "interesting" policy meant that a new prop was hardly more expensive than repairing the existing one. The insurance company (Haywards) were very good and paid out, but only after the insurance broker had passed to them the initial premium which he was hoping to keep in his bank for as long as possible. They were especially generous considering that somebody decided to source a new prop via Socata in France, with a JAR-1 form, for £11,000, when the same prop with an equally acceptable FAA 8130-3 form was listed in the USA at $10,000. Clearly, the words "insurance job" have the same effect in aviation as in the motor trade! To preserve the 2 year warranty on the engine/prop, the shock load inspection was done by a Lycoming distributor.

The prop strike adventure cost about £20,000 (effectively a few k in lost no-claim discount over the next few years), grounded me for 8 weeks, and taught me a big lesson about the bizzare world of aviation: you (not the airport) are responsible for the condition of the airport and if you are not happy about something, stop the engine, get out and have a walk around. It's suprising what you sometimes find... Actually this is not the legal position; you can sue the airfield but they will fight it all the way because of the prededent it would create. Anyway, suing the airfield where you are based is not a great idea politically! I never sued anybody and neither did the insurer.

The differences training was completed with a different school and instructor and took about 15 hours. The new instructor was one of aviation's many great bar-room story-tellers: he claimed to have an ATPL but then he said that if too many planes tune into a particuIar VOR, the VOR stops working! But he was a good instructor who taught me some important stuff (e.g. what the trim wheel actually does: it sets the aircraft's speed).

So I think 15hrs is a generous measure of how long it takes to convert to the TB20... Flying it was never a problem; it is an extremely well designed plane which does exactly what it should in all circumstances and never bites. A reasonably technically savvy pilot could easily do the ab initio PPL in a TB20 and there are some training establishments in the Far East that do that, but the UK instruction scene is not well set up for it.

There are nevertheless a few things which take a fresh PPL holder a bit longer to get his head around, than flying e.g. a Cessna 152:

One is the different way of flying at 150kt rather than 100kt, and flying at say 5000ft rather than the 2000ft which many PPLs have been trained to do. The higher speed itself is irrelevant and barely noticeable, but if you arrive overhead the airfield at 5000ft and still doing 150kt, you are going to look a right plonker doing several orbits trying to get down, in full view of the restaurant and the plane spotters, at the same time as trying to lose some speed, and doing this without cooling the engine excessively quickly! It's no rocket science at all but one needs to think ahead - the descent may start gently 30nm out. I use the simple mental formula of 200fpm for every 1000ft to lose, if starting 10nm out. So, if 10nm out and 3000ft to lose, set -600fpm. And if starting 20nm out, set -300fpm.

Another is the need to embrace modern navigation. Navigating with the map, stopwatch, and compass is a tedious and highly error prone procedure which is nevertheless popular with traditional pilots and these will find it harder to get used to something a bit faster. I had no problem with this since I discarded all PPL navigation training the day after the PPL skills test, and used GPS backed up with conventional radio navigation (VOR/NDB/DME) as the sole means of going everywhere. The benefit of this is that the workload of flying is a tiny fraction of what it is during training.

Another is the avionics... These were a mixture of standard old stuff like the ubiquitous 1982-model Bendix-King slaved HSI

the KI-229 RMI (one needle pointing to the NDB and one to the VOR)

and "late 1990s" products from Bendix/King-Honeywell e.g. the KLN94 GPS, the KMD550 multifunction display

the KX155A radios

and the KFC225 autopilot

All of it should be easy for any private pilot to learn and most of it is immediately obvious (unlike the Garmin G1000 which needs a serious ground course) but the GPS / HSI / autopilot usually involve their fair share of tricks. I did attend a Honeywell training course on the KLN94/KMD550 which was of some benefit but there are a lot of little operational details to pick up. No instructor I ever found knew much about it (the one who signed off my differences training didn't know how the HSI worked) so I worked things out while flying around the UK at 4500ft on the autopilot - not an ideal solution but the new engine (rebuilt yet again in the shock load inspection) needed many hours at high power to bed in the piston rings and other parts and this was a reasonable way to do that.

An example of a subtle operational trick is that when the KFC225 autopilot is switched from to NAV (e.g. from HDG) it will not do a clear positive intercept of the GPS track unless - at the instant NAV is pressed - the HSI bar deviation is at least 3 divisions (3nm off track in the standard 5nm full-scale HSI mode; less in the 1nm or 0.3nm modes). In other words, if you are quite close to the GPS track when you press NAV, the autopilot will not be able to intercept the GPS track, and your best bet is to hack the intercept manually, using the HDG mode, and select NAV when on the GPS track (a slicker way is to use the HSI course pointer - once you know how it works with the autopilot - to get the plane to go where you want it). This one took ages to get to the bottom of, with Honeywell UK and USA, and the product documentation, denying any knowledge of it. If you fail to satisfy this rule, the autopilot turns onto the new track (actually onto the current HSI course pointer setting) immediately and then very slowly creeps towards the track line - absolutely not what is ever wanted. The way the HSI course pointer is used in different phases of flight also needs to be understood - in essence the CP tells the AP which track to fly, while the HSI bar deflection tells the AP which correction to make to stay on track. It's all very basic stuff but there is suprisingly little operational knowledge of it on the UK training circuit.

It is sometimes debated whether a pilot should fully understand all the avionics installed. I believe he should, to the extent operationally necessary (e.g. no need to know the precise waypoint sequencing process on GPS approaches, since there aren't any of relevance in Europe). The FAA holds the same view - if you turn up for an FAA checkride, the examiner is entitled to ask you to demonstrate the operation of all installed avionics. The UK CAA doesn't do this (at PPL level) and items like the GPS get switched off, which I think is really stupid because it promotes ignorance of modern methods. You wouldn't drive a car unless you knew where all the switches are...

After another 20 hours or so I finished off the IMC Rating, which had been started in the PA28s flown previously. The full IR soon became the objective but due to the size of the JAA IR ground school (14 ATP exams, since reduced to about 8 if doing just the PPL/IR) I decided to do the FAA route. I did the FAA PPL in 2004 (UK), the FAA IR in 2006 (USA, due to lack of examiners in the UK) and the FAA CPL in 2007 (UK).

To get worldwide IFR privileges with the FAA IR, one needs a U.S. (N-reg) plane. This particular TB20 was originally built as an N-reg plane and if I had known at the outset about this stuff I would have left it on the N-reg. Unfortunately this was not discovered until years later (I was not revolving within a group of experienced pilots and nobody, least of all the flying school, ever told me why so many planes have "N" on the side) and the TB20 was transferred, at a considerable cost and hassle (but which could have been far worse had it not met FAA requirements when built) to the N-reg at the expiry of the original 3 year CAA CofA. Comparing N-reg to G-reg, there is no single huge cost saving item (except perhaps the lack of the CAA 150hr check which costs almost as much as the Annual, but very few private pilots reach the 150hr mark within a year) but you get a collection of useful concessions, particularly a more straightforward certification regime for both minor and major modifications, and a better availability of freelance maintenance and certification engineers. The principal downside of being on the N-reg is a constant cloud on the horizon of a possible action against foreign registered planes in Europe; this cloud takes various forms from one year to the next and EASA has just published a proposal (see pages 159-161) which cleverly screws FAA licensed pilots, rather than screwing N-reg airframes which previous proposals tried to do. However, there is another proposal in the pipeline which may attempt to screw airframes too.

"Living with" the TB20

The Good Stuff

1 year following the purchase I was doing well over 100 hours/year and flying long range flights into France and Spain; a year later I ventured to Sitia LGST at the far end of Crete. I did not have the IR at the time and these long trips were done under VFR; making use of "VMC on top VFR" whenever possible. Now, with an IR and always flying airways when going abroad, I shudder at some of the tricks which Italian ATCOs played on me and how I used to get around them. The aircraft performed flawlessly and has done so since - with the exception of occassional KFC225 autopilot failures.

Now I regularly do long trips across Europe and am completely satisfied with the TB20. Some trip writeups can be found here and these show the typical IFR flight planning / weather strategies applicable to non de-iced aircraft (my TB20 has propeller de-ice only) with this level of performance. The normal procedure is to climb straight up into VMC and sit there for the entire enroute section, with not getting sunburnt being a bit of a challenge at times.

I have never regretted the purchase for a single moment. The TB20 has delivered exactly what I wanted. Later, in 2007, when I did the FAA CPL in it I discovered just how well designed it is. It flies the chandelle perfectly, on the edge of the stall buffet, with all control surfaces fully working.

The TB20 was originally operated as a zero equity group with several pilots but this was terminated after a few years and many difficulties.

Every aircraft is a compromise between cockpit cross-section (occupant space), fuel flow, cruise speed, stall speed (short field capability), max certified weight, fuel capacity (range) etc etc etc. Every different aircraft has been compromised to suit a specific perceived mission requirement. As far as IFR capable tourers go, the TB20 pushes the compromise about as far as anybody else has ever managed to do, delivering highest (in the class) occupant comfort, with a good short field capability (500m hard runway), with a good cruise speed (140kt IAS at 11.2GPH, just slightly lean of peak and about 60% power) and an exceptional range of around 1100nm to zero fuel which enables nonstop flights right across most of Europe. Plus good looks which are quite rare on the GA scene where most machines are post-WW2 designs revamped with a GPS or (very recently) a glass panel. The Cirrus SR22 (a much newer composite design) does not beat the TB20 on any parameter except the high power cruise speed but this is achieved at a much higher fuel flow rate - presumably because the SR22 sacrifices a lot of power in dragging along its fixed gear.

Some experiments on this trip suggest that at FL100 and about 5% under MTOW one can achieve 140kt TAS (2200rpm, 9.0GPH) which gives an endurance of 9.5 hours and 1300nm zero-fuel range. FL200 was also easily reached, and the TAS up there is also 140kt (2575rpm, 100F ROP).

A typical TB20GT loaded up with all the possible factory fit avionics options has a 500kg payload which means ~ 240kg of passengers and junk, with full fuel. Together with the full-fuel range, this is simply amazing. In six years, I have had to depart with less than full fuel on just one occassion when I had three large male passengers.

The max demonstrated crosswind limit of 25kt is also very generous. In six years, not one flight has been cancelled due to wind over the limit, which is another amazing statistic when compared to the traditional training types.

The high wing loading results in the best ride in the class in turbulence. This is particularly important on a long range touring aircraft.

Of around 2000 TBs made, there is just one known in-flight structural failure of a TB aircraft (TB21 PH-UBG in 2001, in an embedded thunderstorm) which is probably unique and is a testimony to the wing spar which is machined from a single solid piece of aluminium (on large CNC machines used for Airbus airframe parts) and looks strong enough to hold up a brick wall.

The TB20 is certified for flight into known icing if fitted with the full TKS system - the only de-ice option - but only on a G-reg. On the N-reg it isn't, because the FAA requires additional equipment e.g. two alternators for which there is no easy approval path. This is a rare example where the UK version is more capable than the US version. Another one is a 20,000 ceiling on a G-reg which reduces to 18,000ft under N-reg... The aircraft is capable of carrying a suprising amount of ice; I have seen highly unofficial post-landing photos of TB20s with several inches of rough (the classical "horn" shape) ice on the wing leading edges. Obviously, these are emergency situations (which only a mistaken IFR strategy would get you into in the first place) and one needs to keep one's speed up. I have found the prop-only TKS to be highly effective in keeping the prop clear of ice and the spray also keeps the whole front window ice-free. This is a relatively cheap option (of the order of $4,000 whereas the full system is some $50,000) which is well worth the cost. The most ice I have had is about 8mm of mixed rime and clear and there was no noticeable impact on speed, suggesting that other owners' reports of substantial speed loss in light icing were in fact caused by an iced-up prop. The TKS fluid can be purchased (UK) from Silmid as Aeroshell 07. It is very expensive; around £150 for a 20 litre drum which is irrelevant on the prop-only system but potentially an issue on the full system which can use up the whole £150 on one flight - if one was trapped in IMC. Also, in Europe, one has the same issues as with oxygen in that hardly any airports provide a top-up facility, and most owners keep a drum back in their hangar. On the prop-only system I have, it is topped off via a cover next to the oil dipstick cover and is easily transferred using small bottles.

Despite the prop strike early on, the 3-blade prop clearance is about 8 inches (200mm); about 20mm less with the 2-blade prop, and this is as good as it gets on IFR tourers. But, the nose suspension travel is about 3 inches (75mm) which means that driving into a 5 inch (125mm) deep hole will result in a prop strike.

The TB20 is fine to operate from both grass and tarmac. The handbook contains only hard runway distances and short dry grass is perhaps another 20-30%. With long wet grass, all bets are off, of course. However, as with any aircraft, the more grass you do the more dirty it will get and this will eventually translate into a poorer general condition. Equally with any aircraft, a takeoff from grass long enough to reach the prop arc will cover the entire aircraft with fine grass cuttings which stick and are very hard to wash off. I do grass if I have to go there for a pressing reason but normally avoid it because grass airfields also tend to have poor taxiways.

The TB20 is easy to land - if the speed is right - and the trailing link gear provides lots of suspension travel. Out of hundreds of landings, I have not once had to go-around due to a botched landing and have never done a landing which was unacceptably hard. Go arounds due to traffic, etc, are not uncommon of course and the plane has loads of power to get climbing again even with landing flap down.

The Not So Good Stuff

Initially I found it difficult to plan longer trips due to regular avionics failures. These ranged from relative trivia like the RPM indicator (failed twice), the ADF display not auto dimming with ambient light, the yoke clock and the battery master relay (both changed several times) to more alarming events like the KFC225 autopilot (several failures of both the servos and the computer, with the latter suddenly deciding to climb at +2000ft/min). Apart from the KFC225 (which contains a known design defect in its servos) these failures appeared to be randomly spread among the equipment. The EDM700 engine monitor was also changed because the unit fitted was an old one with duff firmware on which the data download did not work. The RMI packed up more than once, as did the 400Hz inverter driving it. In terms of end user list prices, the value of the equipment changed under the warranty must have come to £50k-£100k which made the 2 year warranty (which was obviously heavily paid for in the price of the aircraft) seem well worthwhile.

Most of the items changed were generally good 1990's-era avionics, without a reputation for poor reliability. The only explanation I can think of is that the aircraft had been built with a pile of used avionics which had been returned from the field with non-obvious or intermittent faults and which were found to be OK when bench tested. This was apparent from the date codes on the instruments which were mostly 1999-2000 dated i.e. 2-3 years old when installed.

I think I was very unlucky because most other TB owners have not reported such a high degree of early equipment failures - even allowing for the fact that most owners don't advertise problems in case they want to sell the aircraft later! But it's easily done. In aviation, in general terms, an item can be tagged as New, Overhauled, or Unserviceable. It follows that if an item is functioning but has never been formally overhauled (and many items have no approved overhaul procedure anyway) it can be regarded as New. It is of course morally unacceptable to fit anything other than brand new unused items to a brand new aircraft, but aviation does not work like a normal business and the avionics shop procedures, operating under the company certification regime, mean that the line between "new" and "used" can be blurred. I recently purchased, for another aviation related project, a P-clip from one of UK's best known aviation outlets and when examining the sheaf of documents accompanying it, it turned out to have been made in 1968 and had worked its way around several airline parts stores!! Enquiries revealed this practice is commonplace and results from the tight certification regime under which nobody has the authority to question the status of an item which is certified as OK.

It is likely that at the time this aircraft was being built, late 2001, Socata had a good reason to recycle its stock of old parts: they had already made the decision to wind down production of the TB series.

In the end this cost Socata (France) dearly because - for the main avionics - the dealer simply bought new replacement items from a local aviation parts outlet, and billed the cost (plus labour) to Socata.

There was an irritating issue with the Shadin fuel totaliser, partly due to a firmware bug (which resulted in a couple of ineffective replacements of the instrument, until I tracked it down a year later) and partly due to an incorrectly located fuel flow transducer. It would be 6 years, and long after everybody connected with Socata washed their hands of it, before I finally managed to fix the transducer issue.

The avionics issues settled down within the first year or so - apart from the KFC225 which continued to pack up regularly and on which Honeywell offered me an indefinite warranty, valid all the time it keeps packing up. They later washed their hands of some of this warranty...

A very important point is that nothing of the slightest significance made by Socata has ever gone wrong i.e. there were no airframe issues. The avionics/electrical issues could easily have happened on e.g. a Cessna 182 from the same era. Fortunately !! there were no engine issues; the 1960s Lycoming just keeps going round and round...

Aircraft ownership involves a steep learning curve. The two major items are: learning who you can trust with regard to maintenance, and discovering the airfield political / gossip circuit in which - in the UK, anyway - malicious rumour travels faster than the aircraft.

Maintenance was an issue on occassions. Sometimes I felt that more damage was done during clumsy maintenance than through any operations. The TB20 was originally placed on the G-reg and - as with all new G-reg planes - was on the Transport CofA. This involved mandatory 50hr checks done by an approved (JAR145 in this case, company no longer trading) maintenance company which at £500-£600 each were a substantial portion of the operating cost - as much as the engine fund! They used power screwdrivers without a torque stop and regularly chewed up external screws. I used to replace the damaged screws myself, from a Socata screw kit.

Occassional lubrication issues came up. The most important aspect of maintenance by far is correct lubrication. Planes in this price range (sub turboprop) rarely use ball bearings even though sealed ballraces would do wonders for the entire maintenance process on control linkages or anything else that moves (outside the engine). One usually ends up with plain bearings. If one of these has a grease nipple, only a moron can get it wrong because you simply pump in the grease with a grease gun until it starts to ooze out at the ends. It is those without a grease nipple (the vast majority of the smaller ones) that are the problem - these must be dismantled, solvent washed, dried, packed with fresh grease and reassembled. If this is done correctly, it should last for years. This process takes time and very few UK maintenance companies do it; most preferring to use a convenient aerosol spray (not quite WD40 but not far off) which is aimed at the ends of the bearing, and with some luck some of it seeps inside the bearing where is will happily co-exist with all the grit and metal particles which have accumulated there over the years. The bearing surface may be formed with a replaceable insert but there is rarely an approved procedure for replacing just the insert so the whole part has to be replaced and £1000 for an innocent looking item is not unusual. The results of not doing this correctly range from control stiffness to having to spend a lot of money on expensive airframe parts. Or a gear-up landing (typical cost £30,000) caused by a failure of the hydraulic pump coupled with a lack of lubrication which prevented the emergency gear release working. After finding a few joints go "stiff" I started to make a fuss about it but it was only when I went N-reg after 3 years that I started operating my own progressive lubrication regime during the 50hr checks which were carried out under pilot maintenance privileges. Something similar is also possible on a G-reg if not used for training or public transport.

From users' reports it also appears that the rudder is a popular item to be missed off because one needs a ladder to reach the upper bearing, and a complete removal of the rudder is a bit of a procedure. I have seen a photo of a TB20 rudder which fell right off because the bearing had not seen any grease in around 20 years and eventually wore right through. However, to be fair, it's pretty obvious the pilot(s) never did any preflight checks on the back of that aircraft, or possibly anywhere else...

The airfield political scene is quickly enough learnt, hopefully without upsetting anybody (whose services one may need) based at one's own airfield. One soon discovers that at some airfields most of the based pilots fly away to get their maintenance done. This is not necessarily because the based company is no good - this procedure merely ensures that the based company will always be there in case you really need them because since you never used them you never acquired the opportunity to have a dispute with them!

Unfortunately, the relationship between the Socata factory and the dealer was less than close, and Socata refused to reimburse the dealer for certain items which were done by the dealer within the 2 year warranty. The dealer consequently asked the owner to cough up and some owners (myself included) understandably refused! This is an example where a warranty - even though normally hugely valuable - carries the risk of destroying your relationship with the dealer, leaving you to scrape around looking for other companies to do any required work. I am currently unable to use the original dealer for any maintenance work due to such an issue dating back to the warranty period, although I do buy parts from them. Some of the other owners did eventually pay off the £1600 in the interest of maintaining the relationship.

End of Production

Socata officially ended the manufacture of the TB range around 2005, with a public announcement saying that they would restart when market / exchange rate conditions improved, with a manufacturing facility in a lower cost location than France. This was not a clever move; a much smarter procedure would have been to build one final large batch and then quote progressively longer delivery times, which would give them time to sort out a new facility without destroying the credibility of the product line and causing many owners to overtly or covertly try to offload their plane before its market value plummets. However, I know from my own business that they are right about French labour costs and working practices. If you are going to make something in France, and make money on it, it needs to be really expensive (like the £2M TBM850).

However it appears (partly from date codes on various parts purchased from Socata) that an internal decision was made to stop TB production much earlier; most likely around 2001, and the whole operation including spare parts stock were run down after that, with extensive re-cycling of old stock. The latest TBs on the market are likely to be "2003" with an actual assembly date in 2002, and built largely from parts from 1999-2001.

Over the past few years it has emerged that Socata has been looking at alternative manufacturing locations / joint ventures. The first was to be in Romania (some kind of offset deal; this fell through c. 2006). The second was in New Zealand; this came to light when Alpha Aviation there went bust and the Socata connection became public. More recently this (local copy) has appeared; the same investor has been connected with Epic Aircraft. So the TB piston line is not dead; Socata may still be talking to people.

In late 2008 Socata as a whole (TB, TBM and all their other Airbus etc subcontract business) was sold to Daher - 1 2 3

It's obvious that with the major market being the USA, and with the most expensive bits (engine and avionics) coming from the USA, the logical place to build the aircraft would be either the USA or a low labour cost (but skilled) location that operates in US$.

However, a re-entry into the single engine piston IFR market will not be easy, with Cirrus so well established in the USA, and the European market virtually mandating an avtur burning (diesel) engine but the only remotely proven contender (Thielert) has just gone bust! Any new TB aircraft would likely be a TB20-type retractable with a glass cockpit, lots of cosmetic changes, and avgas/diesel engine options. A TB fitted with what appeared to be the SMA diesel engine was seen test flying in the UK c. 2004, and an SMA engined TB20 definitely exists in France. Severe vibration problems were encountered with the diesel engines.

A couple of visits to the factory at Tarbes reveal a bunch of people who are exceedingly polite and courteous, and always willing to discuss a TBM850 or a used TBM700 sale, but there is absolutely no sign of the dynamism which must have been present in the 1970s, and which must have returned for a brief burst of activity in the late 1990s when they were doing the "GT" upgrade. The factory is well equipped, with special tooling having been made for seemingly every last bracket. A lot of use is made of CNC facilities which are in place for machining large Airbus components; the benefit of this is clear on the solid wing spar which is machined from one piece of aluminium.

Myself, I would put the chances of TB production restarting, after the 6-year break, at around zero. This is not a problem for anybody wanting to buy a nice TB20 because there is a regular (if tight) supply of the GTs on the used market, and a hangared 2002/2003 sample should be almost as good as new. If the crank swap needs doing, this knocks £10k off the price and offers a great opportunity to open up the engine and make sure it is OK. At the other end of the scale there are some very old TB20s around for about £40k; these would make an interesting "aircraft project" where you spend perhaps £100k rebuilding from ground up, to end up with a virtually brand new aircraft.

My view is that Socata is never likely to stop making TB parts. Like most aircraft spare parts operations, it is a highly lucrative profit centre. One of the reasons that spares is such a good business is that the company is certified to generate the original aviation paperwork from nothing. In crude terms, this means they could pop along to a shop and buy a packet of 100 screws for £0.01 each, "inspect" them, and resell each of them with an 8130-3 or EASA-1 form for £5.00 each. In fact they should obtain a traceability document from the screw supplier but the principle stands - it is a very high gross margin operation. And anything manufactured in-house (true for most airframe parts) can have its paperwork generated from fresh air. This obviously means that anybody who restarts TB production will want the parts operation as part of the package. A good example of this is Piper whose piston sales are poor (14 Archers sold worldwide in 2007) and which is reduced to an extensive Spares operation servicing the enormous worldwide Piper fleet; occassionally they sell some Meridian turboprops.

High Socata parts prices, difficult maintenance, etc?

This is largely untrue, when compared to other aircraft types. However the origin of the widespread rumours (usual rubbish written on pilot forums aside) is not hard to work out.

Socata have allocated a special part number (usually starting with Z00... TB10... TB20... TB30...) to every single component on the aircraft. In the spirit of how aviation is supposed to work, your dealer is supposed to look after your every need. He in turn is supposed to source everything from the factory, using the factory part numbers.

This may be done by some maintenance firms but anybody who has been in aircraft maintenance for any time will know that e.g. the magneto gasket is actually a dead common Lycoming P/N XXXXX and if purchased from a normal aviation parts supplier may cost £5 whereas the Socata price might be £10 or more. Since Socata make only the airframe and some other oddball parts (e.g. the exhaust system) this means that very little of what is required during routine maintenance needs to be purchased from Socata! On an old aircraft (say 20+ years) significant airframe parts may be needed and the maintenance cost can then go way up; however this is the case for any aircraft as airframe parts are universally priced at silly levels. The exception to the foregoing is when a dealer is doing a warranty job; in that case, for political reasons, he may source parts from the factory even though they are massively over-priced, because the cost will be claimed back anyway, and the factory is always happy to turn over its stock which they purchased at very good prices anyway. Socata are sitting on a pile of old stock going back to 1999/2000, this would not matter on airframe parts but can matter on electrical items like starter motors - as I recently discovered to my cost.

There is no official parts cross-reference although some attempts have been made to collate cross-references which exist widely spread among Socata dealers/maintenance shops. I have accumulated a few part numbers myself.

While the small parts generally used during the Annual cost very little, some items do have eye watering prices; for example the exhaust system is well into 4 digits, though the GT range uses Inconol exhausts which last for many years. While most of the engine hoses use standard U.S. fittings and can be made up in Teflon (no life limit) and to the highest possible specs for around £40 each, some of them use rare ISO-thread fittings and cost £400 each from Socata (£180 if you can find a hose shop willing to track down the fittings). This is an area where a pro-active owner of an older aircraft can save large amounts of money, by locating the real manufacturer who will hopefully sell the part with the proper aviation paperwork.

The UK dealer (Air Touring) had a long running policy of selling Socata parts at inflated prices. This led to many owners purchasing from other Socata dealers around Europe. However, such sourcing did not have Socata (France) support because they tried to support their dealers' geographical franchises; this didn't matter on small parts but was a problem where factory help was needed. Such a "sole agent" policy has been illegal in the EU for years but this did not worry the French... Anyway, Air Touring's pricing has fallen into line in recent times and I have found that prices are now uniform across the European dealers. I buy parts from both Air Touring and Anders Nilsson in Sweden. European owners can also purchase parts from Socata USA but they have to do it covertly, fronted via a contact in the USA.

Around 2005, Socata withdrew the right to sell new aircraft from its European dealers, except Air Touring (UK) and Socata Germany. In practice this affected only TBM sales by then.

Long part lead time is largely a myth. The longest I have come across (another owner) was about 3 months and this is likely only following a major accident repair.

There are no major "tricky job" issues on TBs relative to any other common type. It is true that it takes more time to get behind the centre section of the Socata instrument panel than on a simple plane whose entire panel either comes right off or tilts forward. In this respect, one pays a slight price for the very nice cockpit layout - most modern cars are an absolute pig to work on for this reason. Access to the two left and right panels is excellent, due to the two large external inspection panels at the base of the windscreen. One tricky item are the exhaust clamps which contain an Inconol gas sealing strip whose ends need to be carefully mated up while the clamp is tightened; more info here.

The TB20 uses a very unusual variant of the IO-540 engine - the C4D5D single shaft dual magneto. It's not obvious why this is, as there is room behind the engine for two separate mags. This is not a problem except that it is nearly impossible to find an exchange engine - itself even less of a problem given that most exchange engines are around 5,000 hours old so you wouldn't actually want one! The TB21 uses an even more scarce variant of the TIO-540 engine, which I understand was used on only one other aircraft: a pilot-less target drone, and a new one is priced somewhere around $130k.

A lot of maintenance shops complain that the Socata maintenance schedule is very long, and this is true. Under G-reg, this issue can be side-stepped by either not doing the work and ticking the boxes or (legally) by doing what CAA LAMS (light aircraft maintenance schedule) says. This will be changing under EASA in 2009 though nobody knows quite how; some believe that EASA will simply mandate the manufacturer's maintenance schedule. Under N-reg, you can do something similar (legally) by working under FAR 43 appendix D. However, missing out stuff which really needs doing (e.g. lubrication, on which the Socata manual contains hugely detailed instructions) is eventually going to cost the owner serious money, by which time it will be years too late to lay the blame at the door of any particular maintenance firm. The Socata schedule of how many hours they think each service should take is here.

For European TB owners, there is an interesting aspect: the English language maintenance manual, chapter 5, contains an approved type-specific maintenance schedule/program which is also in use by French TB20 owners. It has been approved by the French GSAC and by EASA. This will smooth the transition to EASA Part M maintenance, compared with most U.S. made aircraft.

Socata have a vastly smoother customer service organisation in the USA (undoubtedly due to the large TBM sales out there) than in Europe and this accounts for the often noticed discrepancy in customer satisfaction between American and European pilots. There isn't much one can do about that - the culture is different and American consumers would never accept a lot of stuff which one can get away with in Europe. And the typical TBM owner has the financial resources to TERMINATE a dealer who upsets him.

TB20GT - Known Issues

There are only two potentially operationally significant issues: the KFC225 autopilot with its defective servos, and the Shadin fuel totaliser system with its incorrectly located transducer which can be wildly inaccurate.

The KFC225 (which only approx-2001 and later TB GTs came with) has no present economic solution other than the procurement of spare servos at $1500 each (3 of them; overhauled price by mail order from the USA) and banking on replacing one on average say every 2 years. Suprisingly, there is no recommended periodic service on the servos (e.g. motor brushes); you are supposed to fly the plane until it fails, although obviously nothing stops you doing a precautionary servo change every (say) 2 years. Autopilot failure is not normally a big issue unless one is doing long trips, and unfortunately nearly all my failures (about 10 to date, 2008) were on such long trips. As a drastic measure and one which offers no guarantee of fixing the problem, one could replace the entire KFC225 system with an STEC autopilot but all feedback suggests that the KFC225 has a much better performance than the STEC and since the STEC is far from 100% reliable this could be a hugely expensive step sideways. The KFC225 servos are very easy to replace, in minutes, due to a clever design of the mounts which enables the servo to be swapped safely without disturbing the control cables. On the STEC system, servo replacement disturbs the control cables which is dumb since servo motor brushes will eventually wear out as surely as death and taxes. The above link to the servo issues contains a discovery that most of the servo failures are caused by radio frequency interference (powerful radar signals, probably) from the ground.

The Shadin fuel totaliser issue (not all TB GTs have this factory fitted) can be corrected by implementing the Shadin U.S. STC but while the job is trivial it is legally straightforward only on an N-reg. On an EASA-reg it would probably be a Major Mod. There may well be a precedent approval floating somewhere around the EU from pre-EASA days; I do not believe that none of the many European registered owners of planes with the defective installation have done nothing about it. I did some searching but did not find any Euro-reg US-STC-based installations (that anybody was willing to own up to) which suprised me. However, the simplicity of the fix is such that it would be easy to do it "unofficially". I believe the TB21 does not have this problem due to a different layout of the fuel pipework.

Other small issues are: The electronic oil pressure indicator is affected by the aircraft's VHF transmission on certain frequencies; this is easily fixed with a cheap ferrite DB25 filter fitted in the back of the centre instrument cluster. The oil pressure transducer (in the same system) is not very reliable and suffers from moisture ingress via a tiny vent hole; Socata issued an SB (SB10-129) but this is ineffective because they didn't know about the vent hole. One can install a backup oil pressure gauge but it is probably a Major Mod under EASA.

All TB20s made from approximately 1997 (pre-2000 it was the non-GT model) up to the end of production sometime in 2002/2003 are affected by the Lycoming SB569 12 year crankshaft life limitation, which is now an AD and is thus mandatory. This costs around £10k to do but the downtime can be huge if poorly managed; I sent the engine to a specialist engine shop in the USA (details) and due to various factors including shipping delays it took 4 months.

Some TB20/TB21 aircraft were built sometime during 2000-2003 using engines that were stored (crated) for too long and were internally corroded, resulting in users discovering severe damage (barrel scoring) in later years. The damage would have been discovered much earlier if everybody was doing oil analysis but few owners do. For example, my engine was shipped by Lycoming on 24/2/2001 and didn't get installed by Socata until 8/1/2002. The first run was 7/2/2002 - nearly a year later, which is "not quite" long enough to render the engine legally unairworthy but is very careless. These dates are verified - from Lycoming and from the original French factory logbooks. Despite very regular use, the engine was found to contain widespread (but not deep) cylinder corrosion when opened up for SB569 in 2008. A borescope inspection and preferably a cylinder removal (to inspect the camshaft) is thus highly recommended on any TB2xGT purchase, unless the engine has been recently opened (or it about to be) by a trustworthy firm for e.g. the SB569 crankshaft swap and found to be OK.

The 3-blade Hartzell prop works very well but due to poor static balancing from Hartzell appears to cause excessive vibration in most installations, and dynamic propeller balancing is required. At Socata USA, and in the French factory, they do this while airborne (which is the best way because the vibration changes somewhat with the blade pitch) but very few UK outfits will do this, partly because they are afraid of the legalities and partly because it needs the accelerometer to be mounted underneath the cowling, where there isn't much room. It also takes extra work to run the wires through existing holes in the firewall, etc. I found one firm which did it for a friend of mine but they denied ever having done it. It's well worth doing even if done on the ground - I use Worldwide Aviation at Bournemouth. The TB20 is perhaps not the smoothest aircraft flying - the rubber mounted instrument panels always move about a little, which is normal - but with a well built engine and a dynamically balanced prop can be very good; more details here.

Pre-GT TBs: To ease certification issues, Socata designated the GT version "Modification 151" and kept most of the Flight Manual unchanged from its original 1988 version, but in reality there was a large number of changes. I have never found a comprehensive list. They range from the visually obvious ones like the composite roof which gives an increased headroom, to the smallest details. From contacts with pre-GT owners it appears that Socata fixed a large number of persistent small reliability issues; for example the landing gear relays were replaced with much more robust versions. However, the pre-GT TB20 was already a very good and relatively trouble-free aircraft.

Operating Costs over 6 years

As one would expect with a new plane, almost nothing was spent on unscheduled maintenance during this period. With the exception of the KFC225, the bill was probably under £1000, which is nothing short of stunning.

The direct costs are:

Fuel: 11 USG/hr (40.5 litres/hr) during normal economy lean-of-peak cruise; even less during high altitude flights
Engine fund: £10/hr - this is based on sending the engine to a specialist engine builder in the USA
50hr checks: £4/hr - based on pilot maintenance plus employing the service of an experienced freelance engineer (it's a half day 2-person job)

Fixed costs:

Annual: £2500+VAT
Insurance: £2500+IPT (no IPT if N-reg) - this is based on a 900hr CPL/IR, sole pilot, no claims in past 5 years, £195k agreed hull value
Hangarage: £5000+VAT/year - this will vary widely around the UK
Propeller overhaul: £3500 overhaul after 6 years, at 700hrs (equivalent to £5/hr)

However, around the 6.5 year point, I got caught with a couple of things: the Lycoming crankshaft replacement which cost a packet, and then the KI-256 vacuum driven horizon (which drives the KFC-225 autopilot) packed up and the cheapest option (a refurbished exchange unit from the USA) cost $3000.

Maintenance and Operational Recommendations

This is not specific to the TB20: On general maintenance, I would recommend any owner to be pro-active and either use a very good firm which is amenable to discussing with him exactly what is going to be done and not done, or use any firm for the Annual and then operate an active 50hr check regime under authorised pilot maintenance during which he can ensure that everything is lubricated properly.

The least-hassle way to work aircraft ownership is to assemble a bunch of people who one can trust - different people for different jobs. I use one company for the Annual, do the 50hr checks myself, use a small local avionics man for small avionics jobs, haven't done any major avionics work but would use a carefully chosen avionics firm for that, etc. The contrary view is that using one company (in aviation, you are "supposed" to use your dealer for everything) will result in a valuable long term relationship, and this works well for some owners, but this option is not available to many owners for geographical or political reasons. At the "cheap" (piston) end of aviation, few of the service companies (e.g. avionics shops) will travel to you; the normal line is a "bring us the plane and we will have a look at it" and straight away this is a few hundred £ in flying costs, plus trains, taxis, or hotels, and a load of hassle. Freelance engineers tend to travel and such contacts can thus be hugely valuable. Also, the freelance man knows where the buck stops whereas a large company can hide behind its certification and most of the time you have no idea who actually did the work.

The Socata user group can be a useful resource for TB owners who do not completely rely on their dealer. The mostly American site is owned and tightly controlled by a one-time Socata employee and past TB owner who lives in the USA and spends a lot of his time answering questions about TB aircraft. It is not an official Socata factory support site although it does seem to operate with their tacit approval. In the discussion forum, do stick to purely technical Q&A topics and avoid expressing opinions that might have alternative interpretations in different cultures - preferably avoid expressing any opinions whatsoever - otherwise you risk getting jumped on! A recently implemented "moderation" function enables the blocking of postings from specific people (who have upset the site owner, or one of the regulars) until the site owner has approved them. They do not like postings which are overly critical or negative - all forums have a tendency to become rather negative but in this case there are many owners whose planes are on the market and they get upset by criticism of the type, because many prospective buyers read the forum. Definitely avoid expressing opinions on how much a particular plane might sell for. I've had some "run-ins" with the site owner who eventually banned me from posting on the site, but in the process I discovered that all postings become the property of the site owner - another reason to be very careful what one writes there. The forum has an "Owners only" section to which you get access if you submit evidence of TB ownership, and contentious issues get moved into that section.

Socata also provide a factory site which carries a freely accessible list of SBs, in addition to a lot of documentation which needs to be paid for. Curiously the TB maintenance manuals are charged for, while the TBM ones are provided free of charge on the site...

The user group site also carries an official copy of the TB maintenance manual which is very rare for any aircraft; possession of up to date data is in theory a legal requirement for any maintenance whether done by a firm or by the owner. Most manufacturers, Socata included, license this information to a firm called ATP who resell it as an extremely expensive CD which can fortunately be picked up on Ebay from time to time. As TB production stopped years ago, the 2006 CD which is widely floating around is perfectly good enough and I would highly recommend it. As the online manual is a recent development, I don't know how much additional information the ATP CD contains; while the CD is certainly quicker to browse, it is not text-searchable.

Extended warranties: This is an option only on the avionics. For two years following the expiry of the original two year Socata warranty, I had a two year Honeywell warranty and made one claim under this whose value appeared to make the warranty worth having, but in reality this is a false impression and I believe these warranties offer poor value. Details here.

I have a large collection of avionics installation and operating manuals so if you need anything, drop me an email. These are priceless if you are using a small friendly avionics engineer to work on the aircraft. And if you have any (in PDF form) I would appreciate them because they can help out somebody else one day.

A useful site carrying suprisingly accurate data on TB aircraft serial and registration numbers, and where they ended up, is here (local copy).

The best single thing which can be done to make an aircraft remain in good condition (inside and outside) for a long time is hangarage. This can be very expensive and probably not worth paying for on a strict basis of rent paid versus actual aircraft resale value depreciation, but the difference in aircraft condition after say 10 years is massive. After 6 years, mine still looks and smells like it was brand new.

I also keep a 0.5kg bag of silica gel permanently in the aircraft, and this is changed for a fresh one whenever I fly - on average once a week. The expired bag is baked at +120C overnight to recycle it; I bought about 10 of these and bake them all together when I have a number of them to do. They came from GeeJay Chemicals and the material is self-indicating orange to green silica gel, supplied in stitched cloth bags. Rough measurements with a relative humidity meter suggest that one of these bags placed anywhere inside the cockpit reduces the RH by around 10 percentage points which represents a large decrease in the condensation potential.

Many owners get the inside voids of the aircraft sprayed with a corrosion inhibiter; the two main brands are ACF-50 and Corrosion-X. This is cheap but needs to be done every few years. I had mine done with ACF-50; a "customer-assisted" (I did the various inspection covers) job cost under £300.

Oil analysis is highly recommended. The cost is around £10-£20 per sample (taken at each oil change) and it should give an early warning of things not being right inside the engine. I purchased a large number of pre-paid test kits which are sent off to Aviation Laboratories in the USA.

Engine Management

This is important on the larger air-cooled engines. It is however easy to follow some simple procedures; the following is TB20 only:

Climb is done simply with all three levers fully forward until top of climb. The exception here is when climbing to more than about 7000ft when a transition to a +500fpm cruise climb is better as it avoids a too-rich mixture for the altitude, and helps cooling. More clever pilots can climb using the constant-EGT method: pick any cylinder and look at the EGT shortly after takeoff, and then progressively lean so as to maintain that EGT as you climb (this also produces a near-constant CHT throughout the climb). One should avoid exceeding +400F CHT at any time (Lycoming's redline is at an eye-watering +500F); this is almost impossible to achieve if climbing at Vy, never mind Vx, so one normally trims forward to climb at about 120kt for a greater cooling airflow and that works nicely. The rate of climb is barely lower at 120kt than at 95kt and the engine is much cooler. The only reason for climbing at steeper angles is for obstacle clearance and I know of no airport in Europe where one needs to do that beyond the initial climb-out (although there are some elsewhere). If there is a general problem maintaining CHTs below 400F then it is likely that the baffles around the engine are knackered and are allowing air to leak past, without going through the cylinder fins; these baffles are made of a flexible fabric-like material widely used in aviation. A great article on how to comprehensively repair the baffles is here. The other potential reason for a high CHT in climb is that the fuel servo full throttle flow rate can sometimes end up being set near the low end of its allowed range; the upper limit is 24.8 GPH and it is worth having it adjusted to this figure if CHTs are a problem and the baffles are OK.

At top of climb, transition to cruise by trimming forward, waiting for the target speed to be reached and then setting the engine to the desired operating point. There is much debate on this, and the IO-540-C4D5D engine is rated at 100% power indefinitely so you could just burn along at some 160-165kt IAS... with the fuel flow rate to match (23GPH at low level). Such data as there is suggests that 60-65% is going to make the engine last much longer and a setting of 23"/2300rpm/11.2GPH (this flow rate is when leaned very slightly lean of peak; LOP) delivers about 138kt IAS. I fly at this setting all the time, except that I find the engine is smoother at 2400 than 2300 - this is most likely engine specific. The efficiency of normal petrol engines is best about 25F LOP and the curve around that point is very flat anyway, so the best-MPG point is achieved anywhere at or just past peak EGT - there is no need to get overly precise about it. It's hard to get it wrong anyway since the power (and thus speed) drops off pretty fast if you lean too far into the LOP region.. LOP is the way to operate this type of engine - it gives cool clean operation and great fuel economy.

Optimal economy cruise: Some experiments on this trip suggest that at FL100 and about 5% under MTOW one can achieve 140kt TAS (2200rpm, 9.0GPH) which gives an endurance of 9.5 hours and 1300nm zero-fuel range. FL200 was also easily reached on that flight, and the TAS up there is also 140kt (2575rpm, 100F ROP). On this trip, the range was stretched even further.

Here is some data collected on a test flight. The IAS was kept constant as this is a direct measure of thrust. The RPM was kept constant as this keeps propeller efficiency constant. The MP was varied to achieve the same IAS in all three cases.

Conditions: 5600ft, QNH=1031mb, +4C, 2400 RPM

The above shows that 25F LOP does not yield additional efficiency over Peak EGT. However, LOP operation is cooler than Peak EGT.

Thermal management (shock cooling avoidance) is done easily enough by always (unless safety issues override) reducing the MP gradually, 1" at a time. John Deakin on Avweb has written a lot on engine management and this is worth reading but the reality is considerably simpler. The best evidence for/against shock cooling is here and this suggests that the danger exists only above a certain - fairly high - CHT; logical since aluminium weakens substantially above the 350-400F area. If a rapid power reduction is unavoidable (e.g. a glide approach during a checkride) this should be fine provided the engine is cooled well beforehand. Engine management issues tend to imply that one should avoid flying circuits with a TB20 and I would agree with that. If your instructor insists you go and bang around a load of circuits, try to do it in somebody else's plane! That's what most people do.

High altitude cruise, e.g. FL150-200, is different because there is not enough air out there to deliver even 60% power, so one is grateful for anything one can get. A higher RPM of course sucks more air into the engine, so 2500 or even 2575 (the maximum) is used. At the highest altitudes, or when you simply want all the power you can get to get somewhere and aren't worried about the fuel flow, 100F rich of peak (ROP) gives the best power - this is easy to set by leaning any one cylinder to peak EGT, noting the EGT, and then enriching by 100F.

During descent, there is very little to do. If you were at peak EGT or LOP during cruise, the mixture does not need touching during the descent. The engine will end up being leaner and leaner as you go down, but this doesn't matter as one doesn't need the power anyway. Just remember to reset the mixture for the proper low level cruise setting (say ~ 11GPH for ~ 140kt) when levelling off. Technically, one should enrich the mixture during the descent to maintain the engine operating point but why bother unless the power is actually needed? The engine isn't going to stop. However, if descending from a high altitude, say 18,000ft, some enrichment (for extra power) will eventually be needed if the rate of descent.is shallow.

The normal way to fly the circuit to land is to set it up for downwind nicely trimmed for 90kt (which happens at about 16-18" MP, in level flight), drop the gear and 1st stage of flap and increase the MP by 2" to compensate for the extra drag, turn base at 90kt, turn final at 90kt, and select the landing flap somewhere during final which all by itself reduces the speed to 80kt - exactly as required. Significant forward yoke movement is required when the landing flap is selected to prevent "balooning" and to maintain the "glideslope". On very short final, reduce power for about 70kt, gradually reducing it further as required at touch-down.

Instrument approaches terminating with a circle to land need to be flown carefully if there is terrain nearby, and in such cases one may well need to be configured fully for landing (gear down and landing flap) early on, so as to fly the tight base turn at the lowest possible speed of not much over 80kt.

Desirable Upgrades?

Pilots who walk around airshows looking for somewhere to spend the £30k which is burning a hole in their pocket would be frustrated with the TB20GT because more or less everything is already there, and any avionics upgrade that actually does something useful would cost a huge fortune; well into 5 digits. Avionics shops (who ritually hate doing quotes anyway) will be equally frustrated with such an owner... However, here are some "retail therapy" suggestions...

To some degree it depends on one's view of the future regulatory climate.

In the USA, a 2002 TB20GT should be safe equipment-wise for many years; a 406MHz ELT may have to be fitted in 2009.

In Europe, regardless of the aircraft registration, it could be very different. Currently a Mode S transponder is virtually mandatory for any serious touring but is easy to fit. 406MHz ELT requirements are being defined now. ADS-B may come many years later. GPS approaches are another thing - if you always fly to airports with ILS then GPS approaches are irrelevant. Conventional GPS approaches are no problem but if the "vertical guidance" GPS approaches ever come along then a significant avionics upgrade will be needed.

PRNAV is the biggest dark object on the horizon which could cost dearly in terms of pointless equipment upgrades; JAA TGL-10 is one reference but is ambiguous in places - see notes on EHSI below.

Quite what all the 3rd world airlines flying into Europe are going to do about PRNAV is an interesting question; I guess ATC will have to forever continue supporting non-PRNAV-capable aircraft and Eurocontrol will have to swallow this one. Currently there is no PRNAV-mandatory enroute airspace, except reportedly the Amsterdam TMA at night, and every PRNAV SID/STAR I have seen has an "advise ATC if not PRNAV capable" option.

Honeywell have dropped all development on the KLN94 and while this supports most IFR procedures, and is a super simple unit which does everything needed in practical IFR flying, it does not come with a LoA (letter of authorisation) for PRNAV. This came from Honeywell USA on 9th July 2008: The KLN 94 is not going to be upgraded for PRNAV or AC 90-100A. It is non-compliant for RNAV Type SID/STAR's. The general explanatory letter from Honeywell is here. The importance of this depends on whether any European country makes PRNAV absolutely mandatory for significant chunks of airspace. There is no problem flying PRNAV procedures with the KLN94 but without the manufacturer authorisation it cannot be done legally. Similarly, the KLN94 does not support most RNAV Transitions (see the LOWW example) which is not a problem right now but might be in years to come.

It is possible to replace the Honeywell centre avionics stack (two KX radios, KLN94, KMD550) with two GNS530 sized units and there would be a bit of room to spare.

Eurocontrol just love to play with new ways to control the world and there seems to be a widening gulf between what navigation capability is mandated and what is actually required for IFR flight. You might need PRNAV, RNAV SID/STAR capability, GPSS, it would be "sexy" to have a GPS/autopilot system which can automatically enter and fly a holding pattern, but the reality is that ATC just give you "own nav to", "direct to", "turn left/right heading XXX", "report localiser established", "contact tower" kind of stuff and that is more or less it. Privately, senior IFR ATCOs tend to be highly sceptical about the new stuff because the "real world of IFR" runs on radar, the ATCO is paid to maintain separation and gets into big trouble if he fails, and they cannot see this ever changing. I think they may be right - at least for many years. The only show-stopper would be 8.33kHz channel spacing - if this gets mandated below FL200 then you have to get it.

When considering avionics upgrades to a GT, look at the TB20GT Type Certificate. This is both FAA and DGAC (and thus EASA) approved and anything on it can be installed straight in, with no certification required. For example, the Garmin 430/530 are on the TB20/21GT TC and I believe there are processes available to install the W versions. On the other hand, a pre-GT TB predates this TC and EASA registered owners have had some fun installing the Garmin units where they wanted two of them. I know of one case where EASA required a Major Mod approval for a dual-530 installation, on the silly grounds that a failure of one of them could affect the other one, via the data crossfill interconnection.

There is a point of view that Garmin will gradually take over the whole world, either by pushing everybody out of the piston market or by taking them over and then closing down competing product lines. This would mean that a G1000 (or whatever they call it this year) glass cockpit may be regarded as the only futureproof avionics fit, with everything else being a dead-end. However the G1000 is not a present retrofit option and if it was it would be a huge job. This may be an excessively gloomy scenario but inter-avionics compatibility is an increasing issue; for example the very pretty Aspen EFD1000 is not likely to ever be certified to act as a primary AI for some older autopilots. Also, if Aspen become really successful they will become a prime takeover target for Garmin who will kill off any superfluous parts of the product range.

Mode S: I installed this in 2005; the Garmin GTX330 costs around £2500 plus VAT. It cannot go in the same location as the old KT76C because it is longer; it goes where the KR87 ADF was and the ADF is moved to the previous transponder location. One could go for the Honeywell KT73 instead of the GTX330, which is a plug-in swap for the KT76C. KT73 owners report that its display is much more sunlight readable than the GTX330's LCD display (and indeed my first GTX330 had to go back because the display was unreadable despite having tried every display adjustment in the configuration pages) and the 4 rotary knobs make it easier to set the squawk when in turbulence. The GTX330 offers the option to auto-switch between AIR and GND modes using GPS ground speed which is nice but introduces some issues.

The GTX330 also offers the option of an OAT probe which would provide a useful backup for the factory probe. However, the accuracy of this add-on is widely reported to be poor - anything up to several degC out - and there is no "official" way to adjust it.

EDM700: This is a multi-cylinder engine monitor made by JPI which is virtually necessary for this type of aircraft. It came as factory standard with most TB20GTs. It is also necessary in order to collect the data required to purchase the GAMI injectors. Other similar products are EI and Insight. Some of these come with a fuel flow feature, eliminating the separate fuel flow instrument (below).

Fuel Totaliser: This is another virtual necessity for anybody who does serious flying. The Shadin system was factory installed on most of the later TB20GTs. However, as mentioned before, the flow transducer needs to be installed in the right place and on the TB20s this was never done at the factory. This is the Microflo-L from Shadin:

406MHz ELT: This is coming in for both Euro- and N-reg aircraft. FAA rules have long mandated an ELT but the 406MHz requirement is new. Socata used to fit an Artex ELT-200 (and the GT is pre-wired for this) which is 121.5+243MHz and this will need to be changed. The most logical replacement is the Artex ME-406 (121.5+406MHz) which fits onto the same mounting points, and according to Artex uses the existing ELT-200 wiring and instrument panel switch cluster. The larger tri-band (121.5+243+406) ELTs which were popular a few years ago are not worth installing because 243MHz monitoring will soon cease, and they need an adaptor bracket to be made which some avionics installers like to turn into a major certification project...

GAMIs: This is a highly recommended upgrade which costs about $1000. GAMI sells a set of fuel injectors which are actually secondhand Lycoming injectors but selected to balance up the air/fuel flow to the six cylinders. This improves fuel consumption and reduces vibration.

TCAS: The Ryan/Avidyne 600 system is the most popular and costs around £10k-£20k depending on who does it and whether N-reg or G-reg. I didn't go or this because it is essentially worthless until Mode C/S transponders are made mandatory, which is never likely to happen outside UK controlled airspace, and inside CAS this issue largely disappears. This is a large installation job which involves moving around existing antennae; basically the whole interior needs to come out so it needs to be done by an avionics shop who you really trust.

GPWS: The comprehensive solution to this is the Honeywell IHAS system (which can also include a TCAS module) which costs around the same as the above. I eventually obtained a similar functionality by fitting a £1500 Garmin 496 into the yoke and connecting its audio warning output to an unused output of the aircraft intercom.

EHSI: This is an electronic replacement for the Bendix/King HSI, and the two main options are Honeywell and Sandel. These products also provide an RMI functionality with remotely mounted ADF and VOR receivers. The cost varies for the usual reasons but is the bigger part of £10k. The original remote (mechanical) B/King gyro module is retained. A reasonable excuse for an EHSI would be to replace an ailing HSI. In some cases it is a cost effective way to obtain GPSS (also called "roll steering") functionality; this provides hands-off automatic waypoint sequencing, with the aircraft turning at each waypoint, and the course pointer slewing around to the next track, all by itself. This extract from JAA TGL10 document suggests this functionality is mandatory for PRNAV airspace, but offers "an acceptable alternative" avoiding it, though currently (9/2008) the interpretation of this concession varies between avionics shops and some say the full autoslew function is required. I did not install an EHSI because the existing HSI does all that is needed, and I could get GPSS by connecting a few wires between the KLN94 and the KFC225 (although that would not deliver an auto-slewing course pointer because the mechanical HSI does not have that capability).

8.33kHz Radio: This is currently mandatory at/above FL200 so not currently relevant to a TB20 (but would be on a TB21). Eurocontrol are constantly threatening to bring it lower. Luckily, my KX155A radios can be plug-swapped in minutes for the KX165A/8.33 model, which one can pick up from the usual U.S. sources for not a lot. But the older KX155 (non-A) model cannot! Eurocontrol will refuse a flight plan if it is filed for above FL200 but 8.33 is not ticked.

Backup Vacuum: This is a second electrically driven vacuum pump. It's not a bad idea because the autopilot requires the main horizon which is vacuum powered so if the standard vacuum pump fails, you lose the autopilot as well. It's quite heavy... an alternative viewpoint is to replace the existing vacuum pump every few hundred hours.

TKS: The TB20 came with prop-only TKS de-ice. The full TKS system costs around £25k and is certified for flight into known icing on a G-reg but not on an N-reg (the FAA requires things like two alternators, which is not practical on a TB20). This is probably the greatest mission capability enhancer but it also knocks a good 50kg off the payload. A TB21 with full TKS loses around 100kg relative to a TB20 without TKS, and is thus practically a 2-seater only (albeit a hugely mission capable one).

GNS530W: This is the latest reincarnation of the old GNS530 and together with WAAS/EGNOS supports GPS approaches with vertical "synthetic glideslope" guidance. These are years away from reality in Europe, however. The 530W can also drive the autopilot to fly holding patterns; an impressive feature which would be handy if the need to fly them in the first place was not so incredibly rare. It can fly only published holds, not holds at an arbitrary location. For someone looking to replace the centre stack of a TB20GT with something totally up to date for PRNAV etc, and getting 8.33 capability at the same time, a couple of these would do it nicely.

Chelton: A couple of N-reg TB20/21 owners have installed the amazing system from Chelton. The cost is way into 5 digits but t's impressive. Some - Garmin fans in particular - argue this is a dead end since Chelton is unlikely to be long term committed to supporting piston GA but this is not currently borne out by their very good level of support for the product. There are other similar high-budget avionics options. This is a rather poor image from a Chelton equipped TB21

Air Data Computer: This is a box which takes in various data and interfaces to the GPS, to present various items such as wind speed/direction, TAS, TAT etc. The Shadin ADC-200 is probably the most popular "box" but they also do an attractive panel mounted version: the Digidata, which also does fuel flow. If you get this installed on a TB20, make sure the fuel flow transducer is installed in the right place as per the Shadin STC. I don't think an ADC provides any information relevant to flight at the speeds in question which is not obvious from existing sources; the GPS-calculated "fuel at destination" figure is still based on the current ground speed only regardless of what the remainder of the programmed route looks like in terms of heading (i.e. wind effect) changes, despite the fact that the ADC has calculated the wind data and sent it to the GPS. This is the Shadin Digidata:

Air Conditioning: This is more common in the USA than Europe. As with cars, it is a nice thing to have when operating in hot climates. Some names to check are Keith, WestAir and Aurora. It is however a very expensive option, adds a lot of weight, and from users' reports the equipment does not appear to be reliable.

In-Flight Weather: Unlike the USA, Europe does not currently have a comprehensive satellite weather data service. One German company, MT, offers a service based around their own weather data servers and their own custom made tablet computer but this is an expensive product as well as being very hard to fit anywhere inside a TB20 cockpit. Avidyne are now offering the MLX770 system which is also pricey and again installing any of their MFDs would be a big avionics job in a TB20. However, I have developed a workable low cost in-flight weather (METARs/TAFs/radar/sferics) data display system, using a handheld Thuraya SG-2520 satellite phone, a specially developed web proxy which presents the data in a compact form. It works well, and for long flights, this is a feature you will not want to be without once you have used it.

High Intensity Lighting: There are several systems on the U.S. market - example. This partly overcomes the TB20's rather poor left-wing-only landing/taxi light cluster. The certification is easy on an N-reg but I am not aware of anybody having done it on a European reg. A more radical modification is the fitting of a second identical light cluster to the right wing - this has been done by a friend of mine on a US-based TB10 and the paperwork was awesome even on the N-reg. Technically it is trivial to do.

Illuminated Wingtips: On the TB20GT this was a factory option. The wingtips are the same as the GT ones but they each contain a small conspicuity lamp which makes the aircraft more visible.

For European pilots operating under the N register, I would recommend that they think twice about doing a mod which would be a nightmare should a transfer to an EASA register for necessary one day. If you are doing something, pass it by an avionics shop which has an EASA Design authority and see what they say. It would be a shame to have to rip out some great safety enhancement because it cannot be signed off. The FAA has a list of Major Mods (FAR 43 Appendix A) and something not listed should be a Minor Mod. However, EASA has a ludicrous system where every mod has to be sent off for a decision, and you never know what will come back.

Portable equipment is something else and numerous items were obtained: a life raft, an emergency bag with a GPS, a radio and an EPIRB, and a portable oxygen system which is practically and legally necessary for flying IFR around Europe in the FL100-FL200 region. Plus a comprehensive toolbox good enough for replacing common items like spark plugs and the vacuum pump. And spare autopilot servos! I also purchased a lightweight reflective cockpit cover from Bruce's Custom Covers in the USA which keeps the cockpit cool when parked in hot climates, and stops inquisitive eyes seeing inside and spotting all your expensive kit. Sun does as much damage to the interior as humidity.

Miscellaneous Parts Reference

This will be added to as I come across more parts, and time permitting.

Here

The next aeroplane?

Obviously this depends on the mission specification but assuming one is after European IFR touring combined with "messing about in UK Class G at 2400ft" versatility, the TB20 is very hard to beat because it does that job so very well and does it at the lowest possible cost.

The TB21 is a turbo-normalised TB20 and has a higher (25,000ft versus 20,000ft) operating ceiling and climbs through airway levels a lot faster. However, you don't actually need a +1000ft/min climb rate unless having to clear a mountain at the end of the runway. The TB20 will climb to say 15,000ft perfectly adequately and 19,000ft is OK in the context of a long flight on which gradually rising cloud tops are encountered. However, every flight I have cancelled due to too-high IMC would have involved very likely icing conditions in the climb, so utilising the full capability of the TB21 would ideally need full TKS de-ice and this together with the turbo makes it a virtual 2-seater. This may suit many users though. 19,000ft gets you above the cloud tops perhaps 90% of the time but 24,000ft would do it perhaps 98% of the time.

The TB21 is clearly a better aircraft if doing a lot of European airways flights. However, while it is mostly identical to, and as trouble-free as the TB20, I have seen some spectacular downtime cases where nobody was able to fix some problem on the turbo, and for this reason I am happy I did not buy one. There is not a lot of turbo system troubleshooting experience around the UK; in fact the facilities for working on any nontrivial engine are rather dire all around.

The above comments would apply equally to any other decent IFR tourer with full de-ice and a 25,000ft ceiling, and there are a fair number of those around, both new and old.

Looking at new models, Cirrus, Mooney or Lancair (now Cessna) all offer extra speed, at considerably higher fuel flow rates (physics is physics), but do not offer any technical mission capability increments. I have flown in the Cessna 400 and while its 310HP engine makes it go substantially faster, it delivers exactly the same speed as the TB20, for the same flow rate (139kt IAS measured at 11.2GPH, LOP) which makes one wonder just how much speed has been sacrificed to pander to the perceived U.S. market preference for the "simplicity" of fixed gear. The Diamond DA42 is a nice aircraft which runs on avtur (great for touring to the far corners of Europe and beyond) and offers a spare engine but with Thielert having gone bust Diamond are not a serious contender at present.

For more ambitions requirements, it depends on how much one wants to pay, and anything which is a lot better than a TB20/21 is going to cost a whole load extra money, not just to purchase but to operate. The planes also get considerably bigger than the TB20-type 10m wingspan, which drastically increases the cost of hangarage. There is an argument that a pressurised turboprop is OK to park outdoors, because the cockpit is sealed and the exposed parts of the engine are made mostly out of special alloys which are naturally corrosion resistant. Operation from grass is also more of a problem, not necessarily due to a lack of power but because the landing gear is not made for it.

A completely alternative viewpoint is that an old piston twin, e.g. a Seneca or Aztec, has a lot of mission capability because they can be equipped with rubber boots, heated props, and can carry plenty of any ice that is left. The prices of these twins are at rock bottom, presumably due to the high cost of avgas, but one can argue that you can buy an awful lot of avgas for the money saved. The old airframes also need a lot of maintenance but again if the purchase price is very low, who cares.... Some twins are still in production but are very expensive. The whole argument for/against old planes (which on any straight arithmetic offer much better value for money than new ones) depends on one's attitude to downtime, general hassle, attitudes of any passengers carried, etc. With a twin you get a spare engine but the ongoing cost of carrying it along is high, and avgas is not getting any cheaper... Most piston twins are over 2000kg, attract Eurocontrol route charges, and generate a significant incentive to fly VFR rather than IFR/airways and this increases the fuel consumption further.

The Piper Mirage is a 6-seat pressurised plane with FL250 capability. Its payload is not great and with full fuel it is really a 2/3-seater - not an unreasonable compromise. It has a long and disturbing history of failures with its engine which is almost identical to the TB20's 250HP IO-540 but is highly tuned to deliver 350HP. In fact it has used two different engines; one Continental and one Lycoming. It is alleged these are due to incompetent engine management by pilots but I doubt it is the whole story. Very few of the engines make TBO without major work.

There is the new Piper Matrix which is an unpressurised Mirage. This is an interesting option for European airways flight, for pilots who are happy to use oxygen. But it has the same engine as the Mirage...

After that, one starts looking at turboprops:

The Jetprop is a Piper Mirage converted with a Pratt & Whitney PT6 turboprop front end

This does everything the Mirage does but with a more powerful and highly reliable engine, and the extra HP gives it a rapid takeoff and climb performance. Its 1999kg MTOW avoids the substantial enroute charges which are collected by Eurocontrol on behalf of the various countries through whose airspace you are flying. Most countries levy these only on IFR flights but a few charge for VFR also. Typically, one starts the job with a used Mirage and these can be had in various conditions depending on how much one pays. 1999 is a significant year, in which Piper reinforced the airframe. The later models use the KFC225 autopilot which is highly regarded as the best available, and for a mysterious reason they don't seem to suffer as many of the problems which the TB aircraft had with it. The Jetprop is universally bad-mouthed by Piper and Socata - just as one would expect. If I was seriously upgrading from the TB20, I would strongly consider the Jetprop.

The Piper Meridian is also a Mirage with a PT6 engine but is an official Piper product. Unfortunately for European pilots it weighs around 2400kg and thus incurs the European route charges.

The above turboprops have an operating cost very (very) roughly 3 times greater than TB20/21-class pistons. They are 6-seaters but cannot carry much more than 2 if carrying full fuel.

For another 2-3 times cost increment one can fly the TBM700

which can carry substantially more load at a slightly higher speed. Its TBM850 replacement is expensive but used TBM700 prices have come down in recent years. The build quality of the TBM is good (though the TBM850 is widely reported by owners to be suffering from various teething troubles) and Socata are milking the product for all they can. This part of the market is going to get really interesting if/when the amazing all-composite Epic Dynasty enters production

Currently this is being sold in the USA under their Experimental category - a novel approach which should mean that the aircraft gets debugged by "normal" pilots before it is sold as a certified model.

The new light jets which always attract the media hype don't compare well with single engine turboprops when it comes to range and payload. However, all this is seriously big money - a whole different world from the TB20.

Last edited 5th January 2009.

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