SDR ASAA2018031223867

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: March 12, 2018
Submitted: March 14, 2018
Operation: Air carrier
Aircraft: N459AS
Make and model: Boeing 737990ER
Aircraft serial: 36352
Aircraft time: 16,114 hours, 5,339 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
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

LEFT FMC FAILED TWICE EN ROUTE. FOLLOWED QRH AND FMC SOURCE SELECT RETURNED TO NORMAL AFTER A PERIOD OF TIME. 2ND FAILURE DURING A VNAV COMPUTATION INCREASE WITH ALTITUDE CHANGE AND WIND UPDATE. FAILED 3RD TIME AND LEFT FMC SOURCE SELECT SWITCH ON "BOTH ON RIGHT". GROUNDED - YES. MOVED FMC SOURCE SELECT SWITCH TO NORMAL. FMC PROMPT IS PRESENT. T/S AND RESET FAIL LATCH CONDITION PER FIM 34-61 TASK 836 REF NOTE OF SERVICE LETTER 737-SL-34-125. NO HISTORY LAST 30 DAYS, CK'S GOOD FOR SERVICE.