Service difficulty report · Coupling · Boeing 737824

Difficulty date
September 26, 2023
Submitted
September 29, 2023
Operation
Air carrier
Aircraft
N11206
Make and model
Boeing 737824
Aircraft serial
30578
Aircraft time
72,300 hours, 26,438 cycles
Part
Coupling
Part number
256A37451
Condition
Worn
Location
Flap Xmsn
Stage of operation
AP
How discovered
O
Nature of condition
F, O
Precautionary procedure
B

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

What was found

FLAP ASYMMETRY/LOCKOUT AT APPROX 25 DEGREES CREW DEBRIEF FLAP ASYMMETRY ON APPROACH WITH FLAPS AT 25 DEGREES. EXTENDED FLAPS TO 30 AND FLAPS LOCKED OUT. FLAP INDICATION SHOWS ASYMMETRY AND LOW HYD LEVEL B SYSTEM. PERFORMED FSEU BITE REF FIM 27-51 TASK 801 WITH MAINT MSG TORQUE TUBE BETWEEN FLAP TRANSMISSION 7 AND 8 NOT ROTATING. TUBE FREELY TURNS AT #7 OUTPUT. SUSPECT TUBE SPLINES STRIPPED. 27-52261 AND TE FLAPS SNSR DIS. REMOVED #7 OUTBOARD FLAP TORQUE TUBE REF AMM 27-51-41 AND FOUND #7 OUTBOARD FLAP TRANSMISSION COUPLING SPLINE WORN. MANUALLY EXTENDED FLAPS TO DOWNSTOP ON BALL SCREW. REMOVED SLEEVE 40 AND COUPLING 45 FROM FLAP TRANS MISSION REF CMM 27-55-80. VERIFIED COUPLING IS WORN . NEW COUPLING AND SEAL ON ORDER. REPLACED #7 GEARBOX OTBD SPLINED SLEEVE AND COUPLING AND TORQUED REF CMM 27-55-80. PARTS USED: 29-2751-3-0514,QTY :1 TORQUE OF COUPLING AT TRANSMISSION #7 GEARBOX PER CMM 27-55-80. REPLACED RH TE FLAP TORQUE TUBE OTBD OF #7 GEARBOX AND SAFETIED. REF MM 27-51-41-400-801.TRAILING EDGE FLAP OPERATIONAL TEST REF. 27-51-00-710-801. ACCOMPLISHED TRAILING EDGE FLAP SYSTEM OPERATIONAL TEST REF AMM 27-51-00-710-801