Service difficulty report · Acm · Boeing 7879

Difficulty date
February 7, 2025
Submitted
February 10, 2025
Operation
Air carrier
Aircraft
N24974
Make and model
Boeing 7879
Aircraft serial
40942
Aircraft time
32,970 hours, 3,124 cycles
Part
Acm
Part number
7110121H01
Part serial
7103640
Condition
Faulted
Location
Left
Part time
8,723 hours, 811 cycles
Stage of operation
CR
How discovered
O
Nature of condition
B
Precautionary procedure
O

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

What was found

REF LOG PAGE 3794923 L1 CAC SHUTDOWN HAD BURN SMELL LIKE A MATC H NOTED TSHOOTING FOUND L PACK ACM FAILED REF LP 3794918 FOR ACTION PACK ACM L LEFT PACK AIR CYCLE MACHINE (ACM) FAILED. FIM TASK REF : 31-90-F8-01A-421B-A CMC MSG# 2165211 FLIGHT STATUS: L INTERMITTENCE CODE: H PH: CRUISE NARRATIVE: LEFT PACK CONTROL UNIT CHANNEL 1 THE L1 CAC HAS 4 HITS IN THE PAST 12 LEGS WHERE AS THIS IS THE FIRST HIT FOR THE LEFT ACM. SUGGEST PERFORMING TORQUE CHECKS OF THE CAC AND ACM REF AMM 21-51-19-04A AND 21-52-02-00A IF POSSIBLE TO DETERMINE FAULTY UNIT. PERFORMED TSHOOTING IAW FIM 21-50-F1 FOUND BOTH L1 & L2 CACS OPERATING BUT L ACM 0RPM. ACM L INOPERATIVE AND DEACTIVATION PERFORMED WITH ACM PIN PER AMM A-21-00-00-58A-721B-A. REMOVED SPEED SENSOR IN TOOLING BOX PLACED ON BOARD AT MRD FOLDER IN F/DECK MEL COMPLIED OK TO PLACE THE LEFT ACM ON MEL. DEACTIVATION OF THE ACM RENDERS IT UNSERVICEABLE, AND IT MUST BE REPLACED UPON CLEARING THIS ITEM. REMOVED LEFT ACM REF DMC-B787-A-21-52-02-01A-520A-A ADD EMP:U407356,U331961 MACHINE, AIR CY OFF 79-2152-9-0005 3640 ON 0000 MACHINE, AIR CY OFF 79-2152-9-0005 3640 ON 79-2152-9-0005 9204 R&R LEFT ACM, COMPLETED OPS CHECK AND LEAK CHECK, BOTH PASSED. NO FAULTS REF AMM DMC-B787-A-21-52-02-01A-720A-A ROTABLE PARTS CHANGE WAS INDICATED - TT # 1301456 SN OFF 3640

More about the Boeing 787-9