SDR ASAA2020102633417

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: October 26, 2020
Submitted: October 27, 2020
Operation: Air carrier
Aircraft: N469AS
Make and model: Boeing 737990ER
Aircraft serial: 41702
Aircraft time: 23,896 hours, 7,708 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Location: First Officer'S
Stage of operation: DE
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 DESCENT RT FMC (F/O'S SIDE) VTK FLAG MAP FLAG AND "SINGLE FMC OPERATION" ON SCRATCH PAD OF LEFT CDU. RESET ITSELF THEN "VTK" AGAIN FOR 30 SECONDS, RESET ITSELF AND OPERATED NORMALLY UNTIL LANDING. GROUNDED-YES. PERFORMED CDU BITE. FOUND RT FAULT "WATCHDOG TIMER" PRESENT. FMC RIGHT B. ACCOMPLISHED B737-900 FIM 27-51 TASK 806 "WATCHDOG TIMER FAULT. NO MAINTENANCE MESSAGES SHOW, INTERMITTENT FAULT.