SDR ASAA2017080621554

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: August 6, 2017
Submitted: August 8, 2017
Operation: Air carrier
Aircraft: N487AS
Make and model: Boeing 737990ER
Aircraft serial: 44108
Aircraft time: 7,121 hours, 2,341 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Stage of operation: DE
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

ON DESCENT BOTH FMC SHOWED FMC DISAGREE - VERTICAL IN SCRATCHPAD. FLASHED ABOUT 10 TIMES. NO OTHER FAULTS OR INDICATIONS. ACFT GROUNDED. INFLIGHT FAULTS OF RIGHT & LEFT FMC SHOW FCC DATA-SYNC ERROR, LAST FLIGHT. PERFORMED FIM 34-61, TASK 837, DUAL SYSTEM ERROR. EVENT IS AN INTERMITTENT FAULT. GROUND VERIFICATION TEST NORMAL.