SDR ASAA2017111022525

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: November 10, 2017
Submitted: November 13, 2017
Operation: Air carrier
Aircraft: N492AS
Make and model: Boeing 737990ER
Aircraft serial: 44110
Aircraft time: 7,741 hours, 2,638 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

LT FMC FAILED MULTIPLE TIMES DURING CRUISE FLIGHT. EACH FAILURE CONSISTED OF BOTH FMC CDU'S BLANK ALONG WITH VTK ON LT NAV DISPLAY. FOLLOWED QRH THRU STEP NR 6 AND FMC RESTORED WITHIN 30 SECONDS HOWEVER, INTERVALS OF FAILURES OCCURRED SHORTER SO WE OPERATED FMC TRANSFER SWITCH BOTH ON R. GROUNDED - YES. COULD NOT DUPLICATE. REF FIM 34-61 TASK 836, TEST PASSED. NO HISTORY 90 DAYS. THIS CLEARS MEL 34-36J.