SDR ASAA2018033124090

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: March 31, 2018
Submitted: April 2, 2018
Operation: Air carrier
Aircraft: N478AS
Make and model: Boeing 737990ER
Aircraft serial: 44105
Aircraft time: 10,865 hours, 3,669 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Stage of operation: TX
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

DURING PREFLIGHT, EXPIERIENCED DUAL FMC FAILURE. FMC PROMPT ON CDU APPEARED, THEN DISAPPEARED. UNABLE TO ALIGN IRS. ACFT GROUNDED. UNABLE TO DUPLICATE DEFECT, RETURNED FMC SWITCH TO NORMAL POSITION AND BOTH SYSTEMS OPERATED NORMALLY. FMC BITE IAW FIM 34-61 TASK 801. SHOWED NO FAULTS LOGGED ON EITHER FMC. PERFORMED FMCS OPERATIONAL TEST FOR LEFT AND RIGHT IAW AMM 34-61-00-710-801, ALL TESTS PASSED.