SDR ASAA2017112022648

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: November 20, 2017
Submitted: November 21, 2017
Operation: Air carrier
Aircraft: N434AS
Make and model: Boeing 737990ER
Aircraft serial: 61620
Aircraft time: 6,810 hours, 2,198 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Location: Left
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 IN 15 MINUTES DURING CRUISE FLIGHT. SELF-RESOLVED BOTH TIMES, COULD NOT MODIFY ROUTE AFTER. SELECTED FMC BOTH ON RT IAW QRH FMC FAIL CHECKLIST, RESOLVED THIS PROBLEM. NOTE THAT AFTER RESOLVING, THE LEFT FMC DID HAVE A POSITION ON POS SHIFT 3/3 BUT WAS STILL CAUSING A CONFLICT. ACFT GROUNDED. PERFORMED FIM 34-61, TASK 836 AND LT FMC OPS NORMAL. GROUND FUNCTIONAL CHECKED GOOD.