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Aero Precision provides OEM part support for military aircraft operators across more than 20 aircraft


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Posts posted by pjvr99

  1. This is starting to look like a pitchlock problem. Try feathering the prop, place

    throttle to flight idle and unfeather/airstart, see what the blade angle is. Alternately

    during next run, if the engine flames out, place condition to STOP, do not FEATHER

    or use emergency handle, and do not move the throttle from the position

    the flameout occurred. Once engine has stopped, take a look at the blade angle

  2. As a side-note, I have a direct-reading gauge hooked up to the bleed valves during all

    runs on the cell. I had an engine surging intermittently, mostly during throttle back,

    but all throttle settings, and sometimes even at stabilized throttle setting. Eventually,

    during man-on-stand, I heard a puffing sound, and put my hand in front of the speed

    valve. Installing the gauge showed a momentary drop of up to 30psi, thereby opening

    the bleed valves.

    Since then I have found that a difference of more than 10 -15psi between CDP and

    speed valve pressure is enough to momentarily pop the 10the stage valves during

    some throttle movements

    Lquest has asked a good question on the rich/lean, and the cross-over correction

  3. I suspect the engine 'popping' noise is a result of flooding of the compressor

    during the initial attempt to release the prop brake. If the forward drain plug

    was not removed from the RGB, the oil would be forced down the T/M shaft

    into the power section. This would account for oil from the bleed valves and

    drain mast, and masses of smoke from the tail pipe.

    As the bleed valve system gets air from the diffuser, we may assume that

    some of the oil in the compressor got into the speed valve, and is sticking

    part-open or made sensitive to throttle-back movement, and bleed valves

    are popping open

  4. PJ, maybe to late, but maybe your engine anti icing system is operative.....

    I wish it was. Still trying to isolate the problem, but seems to be in the cell somehow, not in the engine

  5. Natops, the torque drops off also. When the system is operating as advertized, the

    change in TIT seldom exceeds 10°C, and fuel flow 50pph.

    Tenten, this is the part that kills me - this is the ONLY check that fails. Everything

    else is right on the money. The checks in the cell are the same as for the aircraft.

    TB400, I checked the wiring, continuity and voltage, all the way back to the engine

    control panel. We have an AM37-T21D

  6. During TD system check, moving the TD switch from AUTO to LOCKED, the

    fuel flow and TIT are supposed to remain unchanged. However after three

    to five seconds, the TIT drops about 20°C and fuel flow 50 - 100pph.

    Three TD amps, 4 TD valves, 3 relay boxes, and a J3 lead have resulted

    in no discernable improvement. Coordinator has been checked, and electrical

    system has been checked all the way back to the TD switch. The engine

    is on the test cell.

    Any thoughts on where I can look for a solution?



  7. Removing the light bulb will not make the master go out.

    Remove the light bulb and remove the diode (from the bad prop) that isolates/seperates the master from the other individual lights. This will extinguish the master so if you get a prop low oil condition the master will illuminate and the "other" individual light.

    If you remove the cannon plug you will disable the 86 degree switch....

    Not sure which cannon plug is referred to, but if on the prop, you lose pressure cutout and pulse generator, too

  8. Hey guys

    I'm running a fine line here, so just ignore me if I am breaking ITAR rules

    and regs. I need to know whether there are any differences in the engine

    stands (QEC, engine roll-over, RGB, turbine, etc) between the T56 and

    the AE2100D3. Also looking for any info on Test Cells (i.e. can my AM37-

    T21D take the AE2100?)

    Any info at all will be greatly appreciated



  9. I've heard of this happening a few times, but as I don't get to the line

    very often, I don't have hands-on experience there - just the one time

    described in the cell. Maybe the valve bushings get corroded or worn

    out, and gets pushed out of position with the higher pressure. Maybe

    the solenoid is weak and can't release against the higher pressure.

    GTC aircraft don't (normally) have the modulating engine bleed-air

    valves, either open or closed, while the APU birds have the ON/OVERRIDE

    type valves which regulate 45 and 75psi. Engines at NGI generally put

    out 78 to 85 psi, so to go less than 45psi would mean starting off

    the APU/GTC or placing the engine(s) in LSGI.

    My guess would be that the mechanicals of the valve are worn out - time

    for a replacement. As a further thought on this subject, I would be on the

    look-out for slow-closing/valve staying open after starter release .....

  10. Some say we reduce the manifold air pressure PSI to less than 45 to allow the engine bleed air regulator valve to "open" (thinks the manifold air pressure is less than 50 PSI)

    And some say it is so the starter control valve can open (against less pressure)...

    I make no claim to either. I know our book says if you get NO propeller rotation to reduce the air pressure to less than 45 PSI and try to restart...

    I know the manifold pressure will be less than "50 PSI" but I also know the starter control valve is subjected to "less" air pressure....



    Natops, are you ok? This must be your most disjointed posting

    ever:-) However, it seems the question refers to starting with an

    engine at normal ground idle.

    It is possible that high air pressure upstream of the valve could

    jam the solenoid. Several years ago I had an engine that was very

    slow to start. After a few minutes, we realized the scoop anti-

    icing valve was open. We replaced the scoop valve only to have no

    rotation when the starter was pressed. Several rapid pushes of the

    button got the engine turning, but another attempt failed.

    On a whim my colleague opened the scoop valve, and pushed the

    starter button - rotation! Result was no rotation with 40psi,

    but 35psi was no problem.

    Don't know of any T.O. or checklist references, though.....

  11. Fluctuation (oscillation) should not be a problem, unless it is occurring

    outside of the 69 - 75C range. If the crew is stressing about it, replace

    the thermostat. If this does not clear the problem, take a look at the

    flap actuator position transmitter. Wiring on an old QEC kit could also have

    you tearing your hair out

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