SDR ASAA2016012615035

Service difficulty report · Warning Flag · Boeing 737990ER

Difficulty date: January 26, 2016
Submitted: January 28, 2016
Operation: Air carrier
Aircraft: N408AS
Make and model: Boeing 737990ER
Aircraft serial: 41732
Aircraft time: 12,556 hours, 4,021 cycles
System (JASC): 3460 · Flight Management Computing Hardware System
Part: Warning Flag
Condition: False Activation
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

VTK FLAG APPEARED ON LEFT DU. NO MAP FLAG ON EITHER SIDE. LNAV AND VNAV DROPPED OFF LINE AND BOTH FMC UNITS DISPLAYED THE MENU PAGE. PROBLEM SELF CORRECTED BACK TO NORMAL OPERATION WITHOUT MOVING THE OVERHEAD FMC SWITCH. ACFT GROUNDED. UNABLE TO DUPLICATE/VERIFY DISCREPANCY. PERFORMED FIM 34-61, TASK 801 SENSOR TEST GOOD. INFLIGHT FAULTS SHOWED ONLY LAST FLIGHT LT FMC FAULTED WITH INTERMITTENT RATE FAULT. NO CURRENT FAULTS. OPS NORMAL REF AMM 34-61-00, OPS TEST FMCS SENSOR TEST.