AlexTB20 wrote:
I did some pictures with the plane in flight, that show at an altitude of 3,500ft with 75% (2450 rpm and 23.7 mp) an indicated air speed of 137-140 knots.
According to the handbook for somewhat younger models from s/n 948, what you had was more than 75%, which would be
4500ft: 2400 @ 23.3 or 2500 @ 22.5 → 157kt
2500ft: 2400 @ 23.8 or 2500 @ 23 → 154 kt
So even discounting for some inaccurate reading of MAP or altitude etc, that is pretty slow.
I would not take that leap of faith….
Afterthought: you did set the temp correction to the correct values ? You did check the ground speed (up/down) on the GNS (could be the pitot after all) ? You did check the fuel flow and not starve the engine with the red lever ?
AlexTB20 wrote:
I haven’t yet paid for it, I will do that on Monday if you guys don’t change my mind till then, I still have 2 days to fly it. Do you know any method to check it in flight to see if it is somehow skewed/rigged?
Alex, don’t buy this plane unless it is legally contingent on all airworthiness items being corrected at current owner’s expense and money in escrow. You are asking for a disaster if not. .
JasonC wrote:
Alex, don’t buy this plane unless it is legally contingent on all airworthiness items being corrected at current owner’s expense and money in escrow. You are asking for a disaster if not. .
Alternative: You make a contract, but execution only after a pre-buy carried out by a shop that has not maintained it but is knowledgable on TB20* and everything found over xxx k (your call), which is directly or indirectly related to airworthyness or performance (incl. range/efficiency) gives you the right to rescind the agreement.
In the local shop at our airfield, there have been heavy and unpleasant surprises at the first 50/100hr service or annual…
And these guys dont even claim to be particular experts..
I am with Jason here.
*(recomm. on request)
AlexTB20 wrote:
In regards to the left-right yoke play, do you have any on your plane?
None that I have noticed so far.
Probably not perfectly zero, but for practical experience de-facto nothing.
ch.ess wrote:
I am with Jason here.
And so am I…I agree with everything that Jason says….
Alex, with all due respect to you…you would want your brains examined if you went ahead on this aircraft with all of the defects that you have described..putting it right could cost more than they are asking for the plane.
For a start I would not even get in it with 2cm free play on the yoke!!!
Did they ever overcome the spar corrosion problems on these aircraft, or was it just the early ones affected ?
If you are determined to go ahead you should get a very detailed independent pre-buy and then maybe take it from there?
AlexTB20 wrote:
@ch.ess I will fly it tomorrow and post all data here, I will most probably make a website with all the pictures…
No Alex, posting pictures isn’t what you need. You need a proper aircraft engineer to inspect this aircraft. This is the last time I will say it but you seem intent on buying this aircraft and please don’t.
Mine does 138-140kt IAS at low level, say 3000ft, at 23" / 2400rpm / 11.5 USG/hr, and a couple of others, including old ones, did exactly the same. But this assumes accurate instrumentation, including an accurate flow totaliser to get the accurate fuel flow.
TKS opinions vary. The STC says no performance change. Some reports said 3kt-7kt speed loss but none of them were credible as none of them were based on careful measurements, or the TKS installation was done under the same owner.
I can check the play on my 2002 plane next time I fly.
You can upload photos here – see Posting Tips
The reason this plane is problematic is because there are indicators of a generally poor attitude and that is always a good indicator of other issues. For example a TB20 is not a plane for VFR €100 burger runs, so a problem with ILS glideslope is indicative of a “don’t care” attitude in all areas – because an ILS is the ultimate lifesaver so anybody smart will make sure it works.
One approach is to get the seller to pay for an Annual and to include fixing the known issues. I know of several cases where this was done. If the seller refuses, that is saying a lot.
Peter wrote:
One approach is to get the seller to pay for an Annual and to include fixing the known issues. I know of several cases where this was done. If the seller refuses, that is saying a lot.
Actually typically you pay for the annual while he agrees to pay for rectification works.
@JasonC, today the aircraft was inspected at their local maintenance facility. I told them that I want a pre-sale inspection, however they said there is no standard pre-sale inspection, and to tell them what would I want to be inspected.
I searched online for a pre-sale inspection list and, as I couldn’t find one, I just used the Socata TB20 Maintenance Manual and told them to perform the first 27 listed inspections, which basically mean inspection of all external airframe parts, removal of engine cawlings and most of the inspection doors, to check for corrosion, leaks and cracks.
There were no signs of corrosion or leaks at the engine, battery, tail cone or wing spars. The landing gear was not maintained very well, as most of the components show signs of oxidation, and there is rust on various steel bolts and screws that must be probably replaced, if not for any functional issue, at least for cosmetic reasons.
The horizontal stabilizer and aileron play which seem too big for me, are NORMAL for the maintenance guy!
If I move the ailerons up and down with my hands, there is a play of a out 4mm before the yoke inside the cockpit moves. The same with the horizontal stabilizer. Maybe I can leave with that, and hope it can change with some new rods and ball bearings.
But if I go inside the cockpit and rotate the yoke left to right, there is a ‘backlash’, a play of the yoke that be rotated from left to right for about 1.5-2cm measured at the yoke’s extremities, before the ailerons move. I could get a grip with my left hand on the central place behind the dashboard (where the wirings are) through an inspection window from outside and rotate the yoke with mi right hand. It seems the play is located between the yoke and that central assembly that transmits the yoke movement further to the ailerons. So at least doesn’t seem to be from any awkward positioned push rods inside the airframe.
The maintenance guy says that the yoke play is common, it doesn’t affect plane’s airworthiness and can easily be repaired with some spare parts worth of a few hundred euros. I asked how much exactly and he started laughing and said it will be at least 2 weeks before he can get the part numbers and prices.
The whole inspection took about 3 hours and except that, there are only minor defects, such as the strobe light not working, adf antenna inoperable, autopilot not going down the ILS glide slope, AND passenger door touching the frame in its way down, even if it closes well after the. There is also a play of about 2cm for the left landing gear wheel door, but @Peter said in one of his articles that is normal to have a play movement, when on the ground. The right wheel’s door is fine.
After that I took the aircraft with an instructor to make the difference training, which strangely took just 46 minutes (I expected a few hours) , after he signed my logbook stating I can fly the airplane.
In flight the aircraft seems to stay level, with no tendency to go left or right or drop a wing in stalls. However, there is this annoying loss of speed of about 10 knots. Maybe that’s because the mixture was too rich (is that a possibility?) , or I haven’t flown it at exactly the parameters stated in the POH. That’s why I said I will take pictures in flight tomorrow, so you can see the exact altitude, manifold pressure, rpm, outside temperature, mixture, indicated air speed and GPS ground speed. Maybe you can see any mistake I make.
The owner says the new MT 3 blade propeller causes the speed loss (and max ceiling to be lower) and if I revert to an original one it should be fine. He is not willing to invest in any repairs or improvements, and says this plane has already cost him too much. So, more or less take it or leave it. He even advised me to buy a new GT model if I am willing to invest more in making it ‘as new’.
Or, maybe the landing gear door not being fully closed can induce such a drag and therefore the speed loss? The plane has also the TKS system and that may add to the speed loss.
Tomorrow I will fly the plane again and let you know.
I am very eager to buy a TB20, hence my nickname (with no previous experience on any Socata) and I wouldn’t want to make an impulse buy. The plane feels like a sports car compared to the 172s I used to fly lately, and I am prepared to spend more in repairing it. However, if that can be as you said as much as the plane’s asking price, that would be unthinkable.
I initially expected to spend a few thousands for used bolts and ball bearings to correct the yoke movements, a few thousands for the interior and maybe 10,000 for a paint job and some new plexiglass. But I may be… naive?
Thank you all for your time and advice.
