Service difficulty report · Apu · Boeing 737890

Difficulty date
March 31, 2013
Submitted
April 5, 2013
Operation
Air carrier
Aircraft
N592AS
Make and model
Boeing 737890
Aircraft serial
35190
Aircraft time
19,848 hours, 6,258 cycles
Part
Apu
Condition
Faulted
Stage of operation
CR
How discovered
O
Nature of condition
J
Precautionary procedure
O

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

APU COLD SOAKED, START ATTEMPT FAILED DUE TO APU FAULT. FAULT LIGHT REMAINED ILLUMINATED, START WAS ATTEMPTED AT 38,000 FT. INTERROGATED CDU MAINT MESSAGE 49-31016 INDICATED- OVERTEMP SHUTDOWN. REVIEW OF APU REPORT 34 DATA SHOWS APU START SWITCH WAS NOT SELECTED TO OFF AFTER APU CSS ATTEMPT WITH FAULT LIGHT. IF THE APU SWITCH IS NOT SELECTED OFF AFTER FAULT LIGHT ILLUMINATION, THE FAULT LIGHT WILL REMAIN ILLUMINATED. THE APU FAULT LIGHT WILL EXTINGUISH IN 5 MINUTES WHEN THE APU SPEED IS LESS THAN 7 PERCENT, THE APU SWITCH IS OFF, THE APU CDU BITE IS OFF AND THE APU FUEL SHUTOFF VALVE IS CLOSED. CSS RULED INCOMPLETE. UNABLE TO DUPLICATE DEFECT. PERFORMED APU STARTING AND OPERATION IAW MM 49-11-00-860-801 AND APU OPS TEST IAW MM 49-11-00-710-801 3 TIMES - ALL TESTS PASS.