SDR ASAA2020083173111

Service difficulty report · Fmc · Boeing 737890

Difficulty date: August 27, 2020
Submitted: August 31, 2020
Operation: Air carrier
Aircraft: N570AS
Make and model: Boeing 737890
Aircraft serial: 35185
Aircraft time: 50,502 hours, 15,066 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Location: Right
Stage of operation: CR
How discovered: 9
Nature of condition: O
Precautionary procedure: O

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

What was found

IN OCEANIC AIRSPACE A MOMENTARY ANP SPIKE CAUSED THE ANP FIELD TO TURN AMBER, RNP WENT TO 10. LNAV AND VNAV REVERTED TO CWS ROLL AND ALTITUDE HOLD. GROUNDED - YES. REF B737-800 FIM 22-11 TASK 811, 22-11 TASK 801, 34-61 TASK 801. FMC-L FLIGHT 1 SHOWS: FMC-R PRES LAT. DFCS BITE SHOWS NO CURRENT FAULTS ON BOTH, CH A +B. CH-B SHOWS MSG: 22-11822, 22-11071 ON LEG 01. NO CURRENT FAULTS OR IN HISTORY FOR ADIRU 1 + 2. DFCS TESTS GOOD. ALL REQUIRED TESTS PASSED.