Service difficulty report · Hmu · Boeing 737890

Difficulty date
February 7, 2022
Submitted
February 15, 2022
Operation
Air carrier
Aircraft
N558AS
Make and model
Boeing 737890
Aircraft serial
35177
Aircraft time
56,333 hours, 16,452 cycles
Part
Hmu
Part number
1853M56P12
Part serial
BECW1131
Condition
Faulty
Location
#1 Engine
Part time
76,893 hours, 27,716 cycles
Stage of operation
TX
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

DURING ENGINE START THE #1 ENGINE ACCELERATED ABOVE NORMAL IDLE SPEED. WE SHUT IT DOWN AS N2 APPROACHED 72%. GROUNDED - YES. VERIFIED #1 ENG IDLE APPROX. 62%, FUEL FLOW .83, EGT 303. AFTER IDLE N2 SPEED ESTABLISHED. N2 AND FUEL FLOW GRADUALLY INCREASED UNCOMMANDED UNTIL FUEL WAS CUTOFF FOR SAFETY. NO ENG FAULTS OR FAULT HISTORY PRESENT IN CDU. ACCOMPLISHED ACTUATORS TEST PER B737-800 AMM 71-00-00 AND TEST PASSED. THROTTLE TRA ANGLE UNCHANGED AT 36.4 TO DURING ACCEL EVENT. REMOVED AND REPLACED HMU-FUEL PUMP PACKAGE PER T/C N8473000, N8473001,N8473002,N8473003. ALL OPS & LEAK CKS GOOD.