SDR ASAA2019102193058

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: October 19, 2019
Submitted: October 22, 2019
Operation: Air carrier
Aircraft: N492AS
Make and model: Boeing 737990ER
Aircraft serial: 44110
Aircraft time: 15,645 hours, 5,116 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Fmc
Condition: Malfunctioned
Stage of operation: DE
How discovered: O
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

WHILE DESCENDING ON THE IRONMAN 2 RNAV ARRIVAL, APPROACHING CLIFY INTERSECTION, THE AIRCRAFT ENTERED A RIGHT HAND TURN INSTEAD OF A LEFT TURN. LNAV & VNAV WERE ENGAGED. AUTOFLIGHT SYSTEM HAD AUTO SWITCHED TO LEVEL CHANGE & APPROACH MODE WITHOUT FLIGHT CREW INPUT. GROUNDED - YES. PERFORMED DFCS BITE TEST PER B737-900 FIM 34-61 TASK 825, FOUND NO FAULTS. FMC BITE TEST WITH NO FAULTS. NO ISSUES AT THIS TIME. A/C GOOD FOR SERVICE.