Hello all
Long story short, currently undergoing my CB-IR practical formation (started navigation), I am negotiating with my instructor to do some navigation flights on a TB20 to optimize the non-availability of both my aéroclub IFR aircraft for a few weeks (and by the way, getting two birds with one stone : hours counting towards the CB-IR, AND getting my RU endorsement).
I began to check aircraft pilot information manual, and noticed that, even if the maximum certified ceiling is 20.000 fts, all the performance figures stop at 12500 fts.
Question is real simple : why ?
thank you.
Gallic Shrug 
It doesn’t matter. You only have to comply with any POH limitations, such as the 20000 feet limit. Just because there is no performance table for something, doesn’t mean you can’t do it.
That said, you are not likely going to go above 12500 feet during your IR training, will you?
I don’t think the 20k is a limitation on the TB20.
Hi Jeff
Based on your forum name and a few other hints in previous messages I’m guessing the said TB20 is based in the south west, in a town well known for its castle and grand prix ;-)
If that’s the case I totally recommend you have a try with it: totally different class from the club DR400s. And also fully deiced.
Enjoy!
boscomantico wrote:
It doesn’t matter. You only have to comply with any POH limitations, such as the 20000 feet limit.
It matters if you want to know what is lost/gained in terms of speed/time/fuel. I guess when nothing is mentioned, you will lose on everything. Above 8-10k feet there is not much power left in a NA engine.
LeSving wrote:
Above 8-10k feet there is not much power left in a NA engine.
Not percentage-wise, but if there was a surplus of power from the start (as in most high performance aircraft, even if NA) it can still make sense to go higher.
Airborne_Again wrote:
Not percentage-wise, but if there was a surplus of power from the start (as in most high performance aircraft, even if NA) it can still make sense to go higher.
I guess, but with no performance data, I would think there is not enough power left to gain any performance by doing so.
Above 8-10k feet there is not much power left in a NA engine.
That is utter bullsh*it.
You get a more or less linear dropoff in the rate of climb, from surface to the operating ceiling. The operating ceiling itself depends on the power to weight ratio, mainly, and on the wing aerofoil.
A TB20 has a ROC of 1000fpm at MSL and this drops linearly to zero at 20000ft (ISA). In colder air one can go higher – I have done FL210. I posted a pic of the altimeter here but can’t find it right now.
As to why Socata didn’t publish the data, it is probably because they have no obligation to, and their customer base doesn’t ask that question often.
