SDR ASAA2021040234496

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: April 2, 2021
Submitted: April 5, 2021
Operation: Air carrier
Aircraft: N402AS
Make and model: Boeing 737990ER
Aircraft serial: 41189
Aircraft time: 31,144 hours, 10,066 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Location: Right
Stage of operation: NR
How discovered: V
Nature of condition: O
Precautionary procedure: K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

MOMENTARY LOSS OF LNAV, VNAV, FMC PROMPT ON MENU PG OF BOTH MCDU'S FOR APPROX 10 SECS, COULD NOT ENGAGE LNAV OR VNAV UNTIL PROMPT RETURNED AT WHICH LNAV VNAV ENGAGED NORMALLY. NO VTK FLAG ON EITHER MAP DISPLAY. A/P HAD SWITCHED TO CWS PITCH & ROLL. I DON'T RECALL IF MAP DISPLAY MOMENTARY BLANKED OR NOT. GROUNDED - YES. L FMC LOGGED R FAIL LAST FLT. R FMC LOGGED L FAIL LAST FLT. FMC'S OP OK. NO HISTORY.