PT6 compressor stalls
- Thread starter JayAre
- Start date
That's what I said.
This all developed after a different c/t disk was changed. Wouldn't the bleed valve adjust for different air ratio?
deadstick
Well-Known Member
I imagine it was removed to do the c/t work. If there is now a leak between the bleed valve and the compressor case, it could do it.
PWC published a "PT6A Pilot Familiarization." It has been quite handy.
Found it:
http://www.rwrpilottraining.com/uploads/3/0/3/7/3037605/pt6_pilot_familiarization.pdf
PWC published a "PT6A Pilot Familiarization." It has been quite handy.
Found it:
http://www.rwrpilottraining.com/uploads/3/0/3/7/3037605/pt6_pilot_familiarization.pdf
deadstick
Well-Known Member
This deal with the bleed valve sticking is during a power reduction. At lower N1s, the compressor sucks in more air than the engine can use, right? So this valve is open to dump the excess. At higher N1's the supply/demand of air is more efficient, so P3 air closes it because the pressure of the P2.5 air is less than the P3.
If you make a power reduction that would require the valve to open and it doesn't (ie P2.5 air is escaping around the valve and not providing resistence to P3), then the compressor kinda gets clogged and backed up with air which upsets the smooth flow of air into the combustion chamber. Fuel keeps flowing plus no air gives you too much fuel when the air arrives and ya get some vibrations (not good ones) , surges, and crazy temps.
If you make a power reduction that would require the valve to open and it doesn't (ie P2.5 air is escaping around the valve and not providing resistence to P3), then the compressor kinda gets clogged and backed up with air which upsets the smooth flow of air into the combustion chamber. Fuel keeps flowing plus no air gives you too much fuel when the air arrives and ya get some vibrations (not good ones) , surges, and crazy temps.
Cessnaflyer
Wooooooooooooooooooooooooooooooo
This is what our KA B200 was doing before the FCU got stuck at full throttle.
Power settings IIRC were 85% during the run up. Never did it during the start sequence, but would do it during flight in a power reduction around 1500Tq. I never could get it to duplicate with MX or they couldn't do it also. Until today with another pilot it went ape #$%^ . For some reason I remember in training is to "lightly malletize the bleed valve with end of screw driver".
Boris Badenov
Fortis Leader
So basically, they stall because they suck too much.
eightballfreight
Mission accomplished
Ops check good
deadstick
Well-Known Member
braunpilot
What day is it?
Anything that doesn't grown or sound manly turn Boris off...unless the pays just right.
msw
Well-Known Member
When you shut down a PT6A-41 or -42 (like on a KA200) will - should - the Compressor Bleed Valves stay open? (They should be open at the low power settings prior to engine shutdown, right?) Or, at shutdown, do they automatically spring closed, then re-open again at the next engine start-up?
msw
Well-Known Member
Yup, got that. I'm wondering, where do they "rest", with NO N1, no P3, no P2.5 ........ i.e. with the engine shut down? (Assuming no malfunctions)