Menu Sign In Contact FAQ
Banner
Welcome to our forums

Socata TB21 GT versus Cessna TR182

I don’t think that has any scientific backing.

You’re probably right, but it does no harm either. Now that my new engine is run in, the temps are very good – never above 400 in any phase of flight.

LFMD, France

I believe a lower RPM reduces the detonation margin. Not that you should be anywhere near detonation anyway but…

400F is too high, especially at high power, for any of these engines, to be done repeatedly.

Administrator
Shoreham EGKA, United Kingdom

UdoR wrote:

The turbo is a very handy tool on its own for ice avoidance.
Just to add: It helps against carburetor icing, too

Peter wrote:

That’s what people usually do. They say “that is why I bought a turbo”

Really? I pamper the turbo and thus the engine as much as reasonable, I don’t even take off with the allowed 115% when the runway is comfortably long and/or there are nice fields behind it… I really don’t want the exhaust pipes nor the turbo charger to glow red hot, especially as they’re wrapped in glass fiber.

EDBW, Germany

These engines are fuel injected. No carb.

Yes you can get fuel servo icing but the conditions are more complicated in a TIO-540. I think you have a different engine! This is a TB21 thread.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

400F is too high, especially at high power, for any of these engines, to be done repeatedly.

Turbo engines have a different alloy (composition) and are, according to what I could research, fine until 35°F more than NA engines. So 400F on a turbo engine translates to 365 on o NA engine in terms of the hardness of the material, or if you defined 400°F as a hard limit for a NA engine, it’s 435°F on a turbo’ed Lycoming. (not that I go anywhere near that high, just to put it into perspective). It also depends on whether it’s Lycoming or Continental.

Lower RPM is only potentially slightly worse (according to GAMI data) if you leave the throttle full forward. As soon as the plane is tidied up after takeoff I reduce to 25/25 (about 75% power) and that’s better than full power.

Germany

Turbo engines have a different alloy (composition)

No doubt true for “proper” turbos but turbo-normalised engines are just regular engines with a turbo bolted on (at least, the TR182 certainly is). It’s never boosted above 30" (or shouldn’t be anyway) so doesn’t need to be any different from an NA engine.

On temperatures, our engines are red-lined at 500. Then about 20 years ago the consensus moved to be that you should avoid anything above 400, with various metallurgical arguments in support. No idea what it is now. I knew a guy who had an SR20 and he was practically ready to pull the chute if any temps went above 380.

My TR182 made it to TBO, nearly half flown by me, sticking to 400 as the max temp.

LFMD, France

Indeed; I can’t find any reference for a different material for the TIO-540 used in the TB21.

The 500F recommendation goes back to the 13th century – nobody takes that seriously today. 400F is the consensus today, but like so many things it is not a hard relationship. There is a gradual loss of tensile strength above say 300F. You can probably find the graphs in John Deakin’s classic book (I bought it many years ago). So e.g. if you have to do a sudden shutdown (e.g. a PFL on a checkride) then maybe 330F is the target value below which you can’t crack anything.

But there are many variables e.g. a stock TB21 didn’t have an EDM700 – because the EDM was not certified as primary for a TB21* (only for the TB20). So TB21s tend to have just one CHT probe. And if you fit an EDM you have to retain the original EGT/CHT gauge. Another one is that baffle seal quality makes a huge difference; see the thread I linked.

Would I swap my TB20GT for a TB21GT if offered the option totally free of charge? There is a question

Administrator
Shoreham EGKA, United Kingdom

TR182 1982 with MT prop digital AP and aspen is the second option… payload 535kg – no problem for my family… but older design… landing gear – worse construction… carburated turbo normalized engine – but no problem reported and reach tbo very often… speed almost the same… consumption too… range with 355kg inside awesome – 5h no prob… price the same… engine 1500h to TBO prop NEW – experiences ? :) thx a lot…

Last Edited by FeRrYs at 27 Nov 16:31
Czech Republic

I loved my TR182 and was devastated when I lost it in a landing accident. Yes it’s an older plane, but I had fewer problems with it in the 20 years and 1000 hours I owned it than I have with the TB20 in less than two years – really.

The gear is certainly weird but very reliable. The only serious failure mode is if you lose the hydraulic fluid. I had to hand-pump mine down a couple of times (once for electrical failure, once for a faulty switch), no issue at all.

The carbureted engine is a complete non-issue. Carb icing is unknown because the carb is tucked into the back of the engine – horrible for mx but great for (non) icing. I was getting about 150 KTAS in mine before the wing reassembly, which knocked off a few knots.

If I hadn’t lost it I planned to do a dual-GI275 upgrade. It had a 530W/430 which was fine, the GTN750 is better but I didn’t know that then.

Last Edited by johnh at 27 Nov 16:50
LFMD, France

At least for this particular choice, the alternative seems very straightforward to me:
Want more comfort & modernity? Get the TB.
Want more payload & short field capability ? Go for the TR182.

I believe any running cost, reliability or other considerations between the two will be trumped by this obvious mission difference (except maybe avionics which can indeed lead to vast differences in required investment)

France
Sign in to add your message

Back to Top