Service difficulty report · Indication Sys · Boeing 737990ER

Difficulty date
March 16, 2013
Submitted
March 19, 2013
Operation
Air carrier
Aircraft
N409AS
Make and model
Boeing 737990ER
Aircraft serial
41733
Aircraft time
273 hours, 85 cycles
Part
Indication Sys
Condition
Malfunctioned
Location
Apu Oil Sys
Stage of operation
TX
How discovered
O
Nature of condition
N
Precautionary procedure
O

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

What was found

APU MAINT LIGHT ILLUMINATED AFTER APU START. FOUND FAULT CODE 49-91227 (LOW OIL QTY) LOGGED FOUR TIMES SINCE MARCH 10TH IN MX HISTORY LOG. PERFORMED FIM TASK 49-90, TASK 804 INITIAL EVALUATION. INTERMITTENT FAULT SINCE THIS FAULT CODE NOT SHOWING ON THE CURRENT STATUS PAGE. VERIFIED OIL QUANTITY TO BE FULL AT FMC AND AT APU SIGHT GLASS. INSPECTED WIRE HARNESS FROM P16 TO P10434. CHECKED RESISTANCE AND MEGGED WIRE HARNESS, NO FAULTS FOUND. WD 49-94-21 SUGGEST REPLACING OIL QTY LEVEL SENSOR. FIM TASK 49-90, TASK 804. REPLACED OIL LEVEL SENSOR REF MM 49-94-11. OIL LEVEL SENSOR INSTALLATION TEST CHECKED GOOD IAW MM 49-94-11-400-801, LEAK CHECKED GOOD. CDU BITE CHECK LOGGED NO FAULTS IN CURRENT STATUS, APU OPS CHKS GOOD REF MM 49-11-00-860-801.