SDR ASAA2021050134723

Service difficulty report · Fmc · Boeing 737990ER

Difficulty date: May 1, 2021
Submitted: May 3, 2021
Operation: Air carrier
Aircraft: N419AS
Make and model: Boeing 737990ER
Aircraft serial: 41734
Aircraft time: 30,128 hours, 9,714 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: O

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

What was found

RIGHT FMC CDU DISPLAY COMPLETELY BLANKED TWICE FOR ABOUT 10 SECONDS EACH TIME AND THEN RETURNED TO NORMAL. FMC CDU FAILS FLAGS- "CALL FAIL", "MSG OFFSET" LIGHTS ILLUMINATED WHEN DISPLAY BLANKED. GROUNDED - YES. FOUND CDU DISPLAY WORKING. VERIFIED 115 VAC BETWEEN PINS 30 AND 31 OF D2221. CHECKS GOOD. REINSTALLED CDU. OPS CHECKS GOOD REF B737-900 FIM 34-61 TASK 804. 2 C/B'S PULLED AND RESET.