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Restoration of a 1983 Socata TB20 Trinidad

As many of you may already know from other threads, last year I made a big mistake and bought a pre GT, 1983 Socata TB 20 that was in a deplorable state. It had some serious mechanical issues (yoke play/slack on both ailerons and elevator controls, loss of about 10kt of speed most probably due to rigging, etc.) Just to quote @Peter here, this plane hasn’t seen grease in years, let alone had any applied to it :) I have attached some pictures with the plane as it was, to this post.

Despite being warned by some experienced members of this forum, blinded by the fact it had a TKS system (pretty expensive to install later) and some good avionics, I went ahead and bought it anyway for about EUR 90,000, thinking anything can be solved later (naïve as I was, I thought it shouldn’t cost me more that EUR 10,000).

Now I have to admit it was a mistake, but as I love this plane I want to bring it in a very good condition and hopefully learn some things along the way. I have received some repair shops references, made a plan, and I am almost ready to send it to the maintenance shop. As I am new to this, please have a look at it and let me know what needs to be corrected or added to it. If it will be more time or cost effective to do it in a different order, split it, add or remove anything, please let me know:

1. The aircraft should be suspended on jacks and some parts should be removed from the aircraft (engine cowlings, ailerons, rudder, horizontal stabilizer, windshields, doors, all the lights, antennas). If I want to be thorough and I can find a really good mechanic there, landing gear should be also removed and inspected.

Mechanical defects such as yoke slack/play should also be diagnosed and repaired (or defective parts ordered) at this stage.

2. Old paint from the body and all the previously dismantled parts should be chemically removed. Sanding can be used on rusty steel parts, such as landing gear, but not on the aluminum skin. Special care should be taken with the TKS anti ice system, which has thousands of tiny, laser drilled wholes that can be filled by mistake with glue, dust or paint. An inspection of the body and parts for any external or internal corrosion and cracks should be done and any needed skin parts should be ordered or repaired.

At this stage any loose rivets, rusty screws, nuts, rods, etc. should also be replaced. New rubber seals for doors, windows, etc. should be ordered. New wing roots too.

3. Anti corrosion treatment, base and primer should be applied on body, parts and landing gear.

4. New paint should be applied on the body and all parts.

5. All mechanical parts should be installed back to the body, a rebalance of all the moving parts should be performed, making sure the retractable gear doors are flush when closed and everything should be greased according to the Socata lubrication guide.

6. Placards and liveries (TRINIDAD text and tail number) should be put to the aircraft. If Aerocoat is not too expensive, it can be applied. Lights, antennas, windshields should be installed back to the body, any needed new plastic, silicone or rubber seals should be used.

Engine, exhaust and interior can be left untouched for the time being.

All sorts of TB series specific issues, such as internally corroded parts, spent fuel tank seals, etc. can be found along the process. Based on the findings and the parts cost, I may fix and replace some or all of those. If some parts are expensive or hard to find and don’t put me at immediate risk, I can schedule a later fix for those.

The most important things for me right now (in order of their importance) should be:

A. Make sure there is no more yoke slack when controlling the ailerons and the horizontal stabilizer, the landing gear works every time with no blockages due to rust, dirt, or lack of lubrication.

B. All the metallic parts are treated for corrosion and have a new paint, all moving parts are lubricated accordingly.

C. There are no exterior old parts made of plastic, silicone or rubber left on the aircraft.

Please feel free to correct me and make any needed changes to this plan.

Thank you all for your support!










Last Edited by AlexTB20 at 17 Apr 23:35
LRIA, Romania

Hello Alex,

Good to see that you are ready to move forward now. I am still not sure it was such a grave mistake buying this plane as it has also got a lot speaking for it: quite good avionics and the TKS System just for starters. I like the panel with the electronic engine instruments, the Sandel and the GNS´s. Also from the outside, the plane looks quite nice.

I don´t think from what I see that the overall paint is so bad it needs to be done totally any time soon. The engine also looks quite clean from the pictures. I also can´t see any corrosion in the picture of the tail compartment and it does have the usual french anti corrosion treatment which also the Reims Cessnas are famous for. From where I am sitting, this does not look bad to me at all.

As for your plan:

It will depend if you go ahead with a full repaint. As I said, I do not see an immediate necessity, I think the plane looks quite nice from the outside. A repaint is a huge project and viciously expensive. Unless you want to do that now, I see no reason to go for that expense at this time. In any case, painting is usually done somewhere else than the normal maintenance.

AlexTB20 wrote:

Mechanical defects such as yoke slack/play should also be diagnosed and repaired (or defective parts ordered) at this stage.

Yes.

AlexTB20 wrote:

parts should be removed from the aircraft (engine cowlings, ailerons, rudder, horizontal stabilizer, windshields, doors, all the lights, antennas).

Why? Ok, the cowlings are easy but why remove all the control surfaces let alone the windshield? If you get a full paint job then yes, otherwise most of the worn parts such as actuators, control rods or the screws which are corroded can be replaced without a full removal. What is wrong with the doors? Do they close properly? If so, new rubber seals by all means, but you don´t need to remove the doors for that.

AlexTB20 wrote:

The most important things for me right now (in order of their importance) should be:

A. Make sure there is no more yoke slack when controlling the ailerons and the horizontal stabilizer, the landing gear works every time with no blockages due to rust, dirt, or lack of lubrication.

B. All the metallic parts are treated for corrosion and have a new paint, all moving parts are lubricated accordingly.

C. There are no exterior old parts made of plastic, silicone or rubber left on the aircraft.

A: Agreed.

B: All metallic parts which show wear or open corrosion need to be treated. Parts which do not and which have intact paint and corrosion treatment (such as the tail compartment looks like to me) are ok for a long while.

C: Are you referring to the belly cover seen on one of the pictures? This one should definitly be painted properly.

I would make the landing gear overhaul and the analysis of the slack in the controls my absolute priority. Sort these two things out and you are good to fly for a while unless there are other things which can not be seen on the pictures.

LSZH, Switzerland

I tend to agree with MD above.

It is just that you have to do a lot of dismantling for a properly done repaint, and while that is being done, it makes sense to do the mechanicals – especially as these need to be removed, cleaned, stripped, inspected/repaired/replaced as necessary, and painted in a colour which hopefully matches the plane. And not all “new” parts from Socata are painted; many are just primed while others are badly painted.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

It is just that you have to do a lot of dismantling for a properly done repaint, and while that is being done, it makes sense to do the mechanicals – especially as these need to be removed, cleaned, stripped, inspected/repaired/replaced as necessary, and painted in a colour which hopefully matches the plane.

While this is true, quite a few locations that require serious dismantling are hidden both aerodynamically and visually, and are to be painted for corrosion protection only, which does not necessarily have to be done as part of full aircraft respray.

LKBU (near Prague), Czech Republic

I intend to send the plane to Cavendish Aviation in UK, if their prices are not too high. I can see they already overhauled a TB and they have a guy there, Steve, that seems to be specialized on paint jobs.

I thought it would be better to insist for a full repaint, as most of the parts need to be dismantled and it’s easier to inspect any hidden damage this way. If this will prove to be too expensive and it will ground the plane for too long, I can do it in steps, at different maintenance shops.

I’ve seen the thread mention by you above, and the fact that I may end up with refurbished and improperly painted parts from Socata really worries me. I thought I could find brand new parts.

In fact, I have exactly the same issue, LH landing gear door has a play of about 2 cm, the other is almost fixed with no visible slack/play. I wouldn’t want to pay EUR 1,000 for one rod and two bearings, only to end up with some used parts from another plane…

LRIA, Romania

This may be of interest. There is a lot of recycling going on these days, but you always get a nice EASA-1 form

You should fix those gear doors ASAP because if they (or the linkages) get buggered, you have a bill for a few k right away. I am intimately familiar with that mechanism and 2cm indicates a lot of wear somewhere and, especially if you are to work on the most strict interpretations of interpretations of interpretations of “regs” (e.g. no repair of any component is permitted unless there is a Component Maintenance Manual published; the standard line from the owner of the Socata owners’ group) and have to buy all new stuff. The gear door which is stuck is hopefully not worn much but needs to be sorted because only the great power of the hydraulics is moving it.

With a carefully rebuilt and shimmed linkage you should have 5-10mm of play, at the bottom of the gear door.

Administrator
Shoreham EGKA, United Kingdom

AlexTB20 wrote:

I wouldn’t want to pay EUR 1,000 for one rod and two bearings, only to end up with some used parts from another plane…

You might want to have your parts checked. Possibly they can be refurbished. I had control rods on my airplane which looked worse than yours and we took them out, had them cleaned and stripped and below they turned out perfectly ok, it was all surface problems. I would almost be sure that the ones you have on the ailerons might turn out that way, the controls salvagable and only the screws bolts e.t.c. need replacing.

AlexTB20 wrote:

In fact, I have exactly the same issue, LH landing gear door has a play of about 2 cm, the other is almost fixed with no visible slack/play.

This needs to be addressed ASAP. Not sure if it needs a new part or mere adjustment or refurbishment of the existing one but it should be checked by a TB savvy mechanic. 2 cm is too much, like this it might not close flush and hence hang in the slipstream and produce drag and wear. This might be part of the 10 kt speed loss you see.

I think it is clear that in mid term your landing gear needs to come off and be cleaned and painted. I am just not sure about the rest of the plane. The paint of the fusellage does not look bad at all. A full repaint would take 2-3 months certainly. If you want to go there, I’d wait with that for winter and use the summer season to fly.

My take is: Get the gear doors checked pronto and at the same time have someone assess the condition of the whole gear. If the gear is sufficiently lubricated and good to go until the next annual or at least until end of season, then get the door done and the rest lubed and then enjoy the plane for the summer, then do the gear strip/repaint in winter when you don’t need the plane anyway.

LSZH, Switzerland

AlexTB20 wrote:

As many of you may already know from other threads, last year I made a big mistake and bought a pre GT, 1983 Socata TB 20 that was in a deplorable state.

After having followed both threads from the beginning, I am going to join the choir of encouragements. It sounds like you are auto-flagellating yourself excessively. It is hard to get good help these days, especially when you are starting out as a plane owner. Lots of ropes to learn.

It sounds like you went out of your way to assess the state of the plane before you closed the deal. Maybe the fact that the people/shops you used were partial because they had previously worked on the airplane, maybe they had some sort of relationship with the previous owner. The aviation scene is small and it is quite common to find that people have conflicts of interest, or overly careful about the statements they make for some reason.

Owning an airplane, if it was not the case before you quickly learn that you need to use your own judgement rather than blindly trusting whatever you are told. Being technically savvy is an absolute must. Those who just leave the keys to the service center are had over a barrel. Plenty of stories. Just watch some of the Savvy Aviation (Mike Busch) videos.

In December of 2016 I purchased a 2005 Columbia 400. I knew there were a number of airworthiness issues (chapter 4) that had to be taken care of:

  • Rudder hinge AD requiring repetitive breakdown inspections every 25 hours (not complied with) or replacement of the hinges.
  • Carbon monoxide detector not replaced or overhauled (every 7 years)
  • 10 year seatbelt replacement not complied with
  • DOT inspection of O2 bottles (5 years)

I had also planned to upgrade at least one of the GNS430s to WAAS (done)

After purchase the following things popped up:

  • Before takeoff on my ferry flight to new home base one cylinder stopped firing
  • Problems starting in cold weather
  • Starter adapter failed
  • PFD backlighting failed
  • COM1 reception sensitivity poor
  • Random ignition problems (maybe related to issues with cold weather starts)
  • Oil cooler cross-fitting replacement required by AD
  • De-icing failed – poor design
  • Inflatable door seals and pressure switch leaked
  • TIT probe failed
  • EGT probe failed
  • Erratic CHT probe

And the icing on the cake – the issues I would really have liked to be without:

  • Cabin heat failed – maintenance induced – someone forgot to reconnect a bleed air hose
  • O2 systems leaked severely – maintenance induced – someone forgot to tighten some fittings
  • Significant oil leaks – maintenance induced (during replacement of the oil cooler cross-fitting and starter – missing O-ring on the starter)
  • Brand new starter failed – maintenance induced – after starter adapter replacement the starter was installed too close to a carbon baffling which it chafed and shorted the starter solenoid.

This has fortunately not prevented me from flying around 100 hours during the first year of ownership. The two remaining issues I have are the ignition issue, and the de-ice issue.

After I finally managed to crank up the engine for my first flight to new base, during taxiing I leaned aggressively as I always do. The engine started to run rough and I noticed one of the cylinders had stopped firing on both mags and nothing I tried restored combustion. The flight was scrapped. We removed the injector for the cylinder and found nothing. We removed the plugs, inspected them, dried them and put everything back together. The engine started and ran on all cylinders, and I managed to perform the ferry flight a few days later. Last summer, I felt that there was something that was not quite right when flying up to Scandinavia. On the flight to Copenhagen, at FL180, LOP I felt there was some power loss, or fluctuations in power. When I went ROP the issue went away. It made me a little nervous, so before my next trip to the Balkans I had the engine looked over and borescoped. I also spent quite a bit of time looking at engine data trying to figure out what was going on. But I did not find anything. Then in February, during the coldest day of the year I was unable to start. We pulled the bottom plugs, cleaned, gapped, checked we had sparks on all cylinders and both mags. Put everything back together and the engine started and ran normally. This was the first time I actually saw the plugs and I realised they were Champion with the slotted screw in the well. After checking which plugs were incriminated in the resistance “scandal”, confirming that my plugs were indeed the ones, and experiencing another mag check issue (I do my mag checks very lean), I decided that everything pointed to faulty plugs and ordered Tempest. None of the mechanics that were involved ever suggested to check plug resistance, or even knew about the issue. They did the bomb test and were happy the plugs were OK. Maybe I am jumping the gun a little bit, but given the reports on the resistance in these plugs, even when new, the fact that I always have the problem on a different plug, usually only on one plug, the fact that I run LOP, that I do the mag check very lean… everything in my mind points to faulty plugs. Also the fact that the problem does not occur ROP is an indication.

Wrt to the de-icing system, I have had several issues. First the alternator belt went to shreds. Then the rectifier bridge on the alternator failed. Then a wire on the stator came loose. The alternator is no longer supported by Kelly. And right now something happened again that I will discover on Saturday. Another issue is that the 8500 W alternator is driven by a pulley off the starter adapter that previously drove the A/C (lower power requirement) and everyone seems to agree that this is cruising for a bruising. So Kelly sells an upgrade which consists of swapping one of the bus alternators (60A/24V) with the deice alternator, which I have bought and will get installed sometime this year.

One of the things that I have been very frustrated over is getting access to mechanics. I have now found 2 EASA mechanics on the field which are more than willing to lend a hand, but I also decided that I needed to get my hands dirty rather than always depending on people who may not be available when I need them.

Learning where to get parts and supplies, where to get stuff repaired, what freight alternatives exist etc is also a steep learning curve.

So you see, @AlexTB20, whatever you buy you need to get over some hurdles – even if you buy new. However, the more complex the aircraft, and the more systems, the more hurdles. So hang in there. Focus on the important stuff – reliability and airworthiness issues – not cosmetics.

LFPT, LFPN

I have to wonder.
Who would know if I (assuming it was me that bought this ’plane) dismantled the landing gear myself, stripped, cleaned repainted and reassembled using new bearings/bushes where necessary?

Forever learning
EGTB

Noooooobody

On some landing gears (e.g. King Air) there is a documented procedure for pushing the bushes out (on a hydraulic press) or reaming them out oversize. I have seen it done. But I don’t think anything on the TB gear bushes is officially serviceable. But you have to do it in practice, mostly on the door linkages, because the little bits are so expensive and relatively flimsy and they wear out rapidly no matter how much you grease them.

However, if you do it without arranging with your maintenance company to look the other way, they are likely to notice the “brand new” landing gear and they might take some drastic action, starting with kicking you out, all the way to filing a report to the CAA. All this has actually happened. Someone here even wrote about it. Accordingly, in such scenarios, owners arrange for the maint co. to look the other way. In practice you can’t do it without the plane on jacks, in a hangar (can’t use jacks outdoors, in case of wind, a heli operating nearby, etc) so where would you do such a job? If you have such a super facility then you should be using a freelance engineer anyway (with a CAMO probably – hard to avoid).

BTW, regarding the gear door play, some play is ok and you adjust the linkages (on jacks) so the doors are “just tight” when the gear is all way up. Any mechanic must know this exact process.

Administrator
Shoreham EGKA, United Kingdom
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