Included in this page are typical guidelines for locating engine malfunctions on most turbine engines. Since it would be impractical to list all the malfunctions that could occur, only the most common malfunctions are covered. A thorough knowledge of the engine systems, applied with logical reasoning, solves most problems that may occur.
Figure enumerates some malfunctions that may be encountered. Possible causes and suggested actions are given in the adjacent columns. The malfunctions presented herein are solely for the purpose of illustration and should not be construed to have general application. For exact information about a specific engine model, consult the applicable manufacturer’s instructions.
Indicated Malfunction
|
Probable Causes
|
Suggested Action
|
Engine has low rpm,
exhaust gas temperature, and fuel flow when set to expected engine pressure
ratio.
|
• Engine pressure
ratio indication has high reading error.
|
• Check inlet
pressure line from probe to transmitter for leaks.
|
• Check engine
pressure ratio transmitter and indicator for accuracy.
|
||
Engine has high rpm,
exhaust gas temperature, and fuel flow when set to expect engine pressure
ration.
|
• Engine pressure
ratio indication has low reading error due to:
|
|
- Misaligned or
cracked turbine discharge probe.
|
• Check probe
condition.
|
|
- Leak in turbine
discharge pressure line from probe to transmitter.
|
• Pressure-test
turbine discharge pressure line for leaks.
|
|
- Inaccurate engine
pressure ratio transmitter or indicator.
- Carbon particles
collected in turbine
discharge pressure line or
restrictor orifices.
|
• Check engine
pressure ratio transmitter and indicator for accuracy.
|
|
Engine has high exhaust
gas temperature, low rpm, and high fuel flow at all engine pressure ratio
settings.
|
• Possible turbine
damage and/or loss of turbine efficiency.
|
• Confirm indication
of turbine damage by:
- Checking engine
coast-down for abnormal noise and reduced time.
- Visually inspect
turbine area with strong light.
|
NOTE: Engines with damage
in turbine section may have tendency to hang up during starting.
|
• If only exhaust gas
temperature is high, other parameters normal, the problem may be thermocouple
leads or instrument.
|
• Re-calibrate
exhaust gas temperature instrumentation.
|
Engine vibrates throughout
rpm range, but indicated amplitude reduces as rpm is reduced.
|
• Turbine damage.
|
• Check turbine as
outlined in preceding item.
|
Engine vibrates at high
rpm and fuel flow when compared to constant engine pressure ratio.
|
• Damage in
compressor section.
|
• Check compressor
section for damage.
|
Engine vibrates throughout
rpm range, but is more pronounced in cruise or idle rpm range.
|
• Engine-mounted
accessory such as constant-speed drive, generator, hydraulic pump, etc.
|
• Check each
component in turn.
|
No change in power setting
parameters, but oil temperature high.
|
• Engine main
bearings.
|
• Check scavenge oil
filters and magnetic plugs.
|
Engine has higher than
normal exhaust gas temperature during takeoff, climb, and cruise. Rpm and
fuel flow higher than normal.
|
• Engine bleed-air
valve malfunction.
|
• Check operation of
bleed valve.
|
• Turbine discharge
pressure probe or line to transmitter leaking.
|
• Check condition of
probe and pressure line to transmitter.
|
|
Engine has high exhaust
gas temperature at target engine pressure ratio for takeoff.
|
• Engine out of trim.
|
• Check engine with
jetcal. Re-trim as desired.
|
Engine rumbles during
starting and at low power cruise conditions.
|
• Pressurizing and
drain valve malfunction.
|
• Replace
pressurizing and drain valves.
|
• Cracked air duct.
|
• Repair or replace
duct.
|
|
• Fuel control
malfunction.
|
• Replace fuel
control.
|
|
Engine rpm hangs up during
starting.
|
• Subzero ambient
temperatures.
|
• If hang-up is due
to low ambient temperature, engine usually can be started by turning on
fuel booster pump or by positioning start lever
to run earlier in the
starting cycle.
|
• Compressor section
damage.
|
• Check compressor
for damage.
|
|
• Turbine section
damage.
|
• Inspect turbine for
damage.
|
|
High oil temperature.
|
• Scavenge pump
failure.
|
• Check lubricating
system and scavenge pumps.
|
• Fuel heater
malfunction.
|
• Replace fuel
heater.
|
|
High oil consumption.
|
• Scavenge pump
failure.
|
• Check scavenge
pumps.
|
• High sump pressure.
|
• Check sump pressure
as outlined in manufacturer’s maintenance manual
|
|
• Gearbox seal
leakage.
|
• Check gearbox seal
by pressurizing overboard vent.
|
|
Overboard oil loss.
|
• Can be caused by
high airflow through the tank, foaming oil, or unusual amounts of
oil returned to the tank through the vent system.
|
• Check oil for
foaming.
• Vacuum-check
sumps.
• Check scavenge
pumps.
|
Troubleshooting Turbojet Engines
RELATED POSTS
Combustion Section Inspection
Turboprop Operation and Troubleshooting
Turbine Engine Calibration and Testing
Troubleshooting EGT System and Aircraft Tachometer System