Will Require Inspection Of Horizontal Spar Attachment Pins

The FAA published an AD on Monday for certain model 737 airplanes requiring the inspection of attach pins of the horizontal stabilizer rear spar, and replacing certain attach pins with new, improved attach pins. The AD is expected to affect about 1,050 airplanes in the fleet. The cost per individual airplane is estimated to be around $9,627, for a total compliance cost to U.S. airlines of $10,108,350.

The AD covers 737-600, -700, -700C, -800, -900, and -900ER series airplanes. It is the result of reports of an incorrect procedure used to apply the wear and corrosion protective surface coating to attach pins of the horizontal stabilizer rear spar.

For airplanes having line numbers 1 through 3534 inclusive: Before the accumulation of 56,000 total flight cycles, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later, inspect to determine the part number of the attach pins of the horizontal stabilizer rear spar. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number of the attach pin can be conclusively determined from that review. If, during the inspection required by paragraph (g) of this AD, any horizontal stabilizer rear spar attach pin has P/N 180A1612-3 or 180A1612-4, prior to the accumulation of 56,000 total flight cycles on the pin, or within 3,000 flight cycles after the effective date of this AD, whichever occurs later, replace with a new attach pin having P/N 180A1612-7 or 180A1612-8, respectively, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-55-1093, dated April 9, 2012.

The FAA said is is issuing this AD to prevent premature failure of the attach pins, which could cause reduced structural integrity of the horizontal stabilizer to fuselage attachment, resulting in loss of control of the airplane. The effective date for the AD is May 20, 2013.

(737-900ER image provided by Boeing)

FMI: Federal Register