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-7b ENG LOW PERFORMANCE


mamun
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Guessing flag check was seeing if a 5th or 10th puck was stuck open?

You could also man on the stand it...a bleed port gasket could be blown out, could cause performance problems. Anything bleed air related could be leaking, sometimes tough to find (hence the man on the stand run)

Maybe stating the obvious, but is the torque gage calibrated correctly? Another thing, in LSGI, do the anti ice check, should see at least a 24 degree rise. Anything less and an anti ice component could have failed (ant-ice=fail safe) many an anti ice solenoid have failed and been the culprit to a low power -7

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We have a low power checklist for just such an occasion. I'm not going to explain each step as I assume you'd know how to perform each check. If you don't, let us know.

1. Perform a thorough Intake and Exhaust inspection.

2. Inspect 5th and 10th stage compressor blades for curling and buildup, and valves for freedom of movement, valve lines for leaks

3. Check propeller and engine rigging

4. Visually inspect thermocouples, then test with high current or resistance tester

5. Check TD control system with a "Y" box

6. Perform visual and continuity check on thermocouple harness, "T" block, and Y-lead

7. Check or change speed valve filter

8. Inspect torquemeter pickup, verify correct number of shims.

9. Apply bleed air and inspect for leaks around anti-ice valves and ducts

10. Perform Man-on-the-stand run for air leaks and flag check.

Operate engine

11. Perform torquemeter calibration

12. Perform LSGI anti-ice check

13. Perform 850 TIT anti-ice check

14. Check engine performance (generator off, engine hydro off, bleed air off, air temp with hand held thermometer, compare with other motors.)

15. Check Compressor Discharge Pressure.

16. If low power persists, perform comp wash and recheck (already done)

If the LSGI anti-ice check passes, I usually get some power back by resealing the left and right inlet anti-ice valves anyway. The internal seals just don't last.

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