Service difficulty report · Limit Switch · Boeing 757224

Difficulty date
July 25, 2024
Submitted
July 29, 2024
Operation
Air carrier
Aircraft
N17126
Make and model
Boeing 757224
Aircraft serial
27566
Aircraft time
93,459 hours, 22,849 cycles
Part
Limit Switch
Part number
900042816
Part serial
0028
Condition
Faulty
Location
Stab Trim
Part time
55,654 hours, 17,836 cycles
Stage of operation
CL
How discovered
O
Nature of condition
O
Precautionary procedure
A

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

What was found

STAB TRIM CAUTIO ON CLMB OUT. AUTOPILOT CAUTION EICAS FOLLOWED 3 TIMESDEBRIEFED CREW AND WAS INFORMED THAT STAB TRIM CAUTION CAME ON PRIOR TO A/P ENGAGEMENT ON CLIMB. PERFORMED MCDP BITE IAW AMM 22-02 TASK 801; FOUND SEVERAL PREVIOUS FLIGHT LEGS A/P CAUTION MESSAGES, 110290, 130290 AND 110311. LT STCM SHOWS FSPM/SPM FAULT. PERFORMED SPM BITE IN REF WITH FIM 27-48 FAULT TREE 804 & FOUND MODULE LIGHT ON. NEEDS LT SPM M10408 NIS IN EWR SWAPPED LT AND CENTER SPM'S - NO HELP, RETURNED TO ORIGINAL POSITIONS. FOUND STAB TRIM NOT TRIMMING NOSE DOWN WITH CENTER HYDS AND HALF-SPEED NOSE DOWN WITH CENTER & RT HYDS, BUT OK BOTH DIRECTIONS WITH ALTERNATE SWITCHES. T/S SYS PER SSM 27-40-01 POWER AT ARM DOWN SOLENOID AT LT STCM (D1829 PIN 6) WILL NOT ILLUMINATE LOAD LIGHT WITH NOSE DOWN COMMAND. THE LOAD LIGHT WILL ILLUMINATE AT LT LSPTM (M10899 D1837 PIN 18). BYPASSING M10899 BY JUMPING D1837 PIN 18 TO 24 WILL ILLUMINATE LOAD LIGHT AT ARM DOWN SOLENOID D1829 PIN 6. ALTHOUGH LT LSPTM M10899 WAS REPLACED ON 7/21/2024, IT IS CONFIRMED AT FAULT. CAN USE 19-2748-9-9002 OR 53-2748-9-9001 IN LT POS -NIS. LOG DESIGNATED AS CAT ITEM. REF L/P 8728586. R & R 19-2748-9-9002,