"Doug" wrote in message
oups.com...
Mike,
Yes, Gas Turbine Engines. But what design, what manufacturer?
Different airplanes and different engines behave differently.

But think about it. Heat gets generated at lower altitude. There is a
thermal lag. That heat gets dissipated at higher altitude. If you are
climbing VERY fast, the incoming air is less dense, you can set up a
cycle where heat is accumulating faster than it can be transferred due
to the denser air creating more combustion. Sort of like having an
extra boost of turbo charging. With the slower airspeed in a climb, and
if the engine is operating close to the edge of it's heat dissipation
maximum, it COULD cause overheating. Anyway, you see my point, I hope.
(Even if it is wrong in this case).

But I will yield, as I have no supporting data. The supporting data
would be a climb limitation in the manufacturers flight manual. I don't
have it, but I am sure it exists. These internet arguments are never
won anyway. I'm not really interested in winning. Probably should have
worded my initial statement a little less concretely. I honestly
thought this was the cause. Apparently not, or at least not sure yet,
or not public yet. Whatever.

It's just my theory. Sorry about the two pilots dying. That is a tough
one for the families I am sure. Whatever the reason is, I am sure we
all want it found out so that other pilots and passengers can benefit
from the knowledge.

Airline travel is very safe, statistically, by the way. But you already
know that.

Sorry if I ruffled any feathers..


Frankly the overtemping due to climb theory is ridiculous and it doesn't
matter what gas turbine engines you are talking about. The fuel controllers
constantly sample inlet air temp and pressure along with the pressure at the
compressor discharge and trim the fuel flow to prevent the hot section
temperature from changing without power lever movement. More sophisticated
fuel controllers will allow the temp to rise with decreasing mass flow to
the temperature limit (or one of several limits) while keeping some other
parameter constant (like N1, fan rpm) then trim the fuel flow back to avoid
over temping the hot section. In any case it is fuel flow (ie mixture) that
determines temperature and the fuel controller is not going to be fooled by
climbing fast.

You are thinking about the problem like you would a piston engine.
Limiting turbine engine temperatures are analogous to EGT on a piston
engine, they are *not* analagous to CHT on a piston engine. It is a
function of fuel flow which is constantly monitored and adjusted by the fuel
controller...ie a *mixture* issue not a cooling issue.

Mike
MU-2