L-1011 APU: Fault Flags (49-7)

There are four fault circuits that will cause the APU to shut down to protect against malfunctions that could damage the APU. The fault circuits are:

• OVERSPEED N2 - Free turbine speed in excess of 110%
• LOW PRESS OIL - Oil pressure drop below 50 PSI for 10 seconds with ≥ 55% RPM
• HIGH OIL TEMP - Protects against high oil temperature
• OVERTEMP TGT - Protects against over temperature TGT during starting and in normal operation. 

Any fault or combination of faults will shut down the APU automatically.