Airworthiness Directive · Amendment 39-15796 · Boeing Model 737-300, -400, and -500 Series Airplanes
Boeing Model 737-300, -400, and -500 Series Airplanes
Superseded. A later AD replaced this one: AD 2009-02-06 R1. Comply with the one in force.
This AD applies to Boeing Model 737-300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 737-53A1279, dated December 18, 2007.
We are adopting a new airworthiness directive (AD) for certain Boeing Model 737-300, -400, and -500 series airplanes. This AD requires repetitive high frequency eddy current inspections for cracking of the 1.04-inch nominal diameter wire penetration hole in the frame and frame reinforcement, between stringers S-20 and S-21, on both the left and right sides of the airplane, and related investigative and corrective actions if necessary. This AD results from reports of cracking in the frame, or in the frame and frame reinforcement, common to the 1.04-inch nominal diameter wire penetration hole intended for wire routing. We are issuing this AD to detect and correct cracking in the fuselage frames and frame reinforcements, which could reduce the structural capability of the frames to sustain limit loads, and result in cracking in the fuselage skin and subsequent rapid depressurization of the airplane.
Comply with this AD within the compliance times specified, unless already done.
The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1279, dated December 18, 2007.
(1) The “condition” column of paragraph 1.E. of Boeing Alert Service Bulletin 737-53A1279, dated December 18, 2007, refers to total flight cycles “at the date given on this service bulletin.” This AD applies to the airplanes with the specified total flight cycles as of the effective date of this AD.
(2) Where the service bulletin specifies to contact Boeing for instructions for removing damage and repairing cracking: Before further flight, remove the damage or repair the cracking using a method approved in accordance with the procedures specified in paragraph (i) of this AD.
(3) Although the service bulletin referenced in this AD specifies to submit information to the manufacturer, this AD does not include that requirement.
At the applicable time specified in paragraph 1.E., “Compliance,” of the service bulletin, except as specified by paragraph (f)(1) of this AD: Do a high frequency eddy current (HFEC) surface inspection or an HFEC hole/edge inspection for cracking of the 1.04-inch nominal diameter wire penetration hole in the frame and frame reinforcement, between stringer S-20 and S-21; and do all applicable related investigative and corrective actions; by accomplishing all the actions specified in the Accomplishment Instructions of the service bulletin, except as specified by paragraphs (f)(2) and (f)(3) of this AD. Do all applicable related investigative and corrective actions before further flight. Thereafter, repeat the inspections at the applicable intervals specified in paragraph 1.E. of the service bulletin.
Doing the repair in Part 3 or the preventative modification in Part 5 of the service bulletin terminates the repetitive inspection requirements of this AD.
