Airworthiness Directive · Amendment 39-14294 · Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes
Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes
Superseded. A later AD replaced this one: AD 2019-16-12. Comply with the one in force.
This AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.
The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD requires repetitive inspections of the stiffeners at left buttock line (LBL) and right buttock line (RBL) 6.15 for cracks; and replacement of both stiffeners with new, improved stiffeners if any stiffener is found cracked. This AD also allows replacement of both stiffeners at LBL and RBL 6.15 with new, improved stiffeners, which terminates the repetitive inspections. This AD is prompted by reports of cracks in the stiffeners at LBL and RBL 6.15 on the rear spar of the wing center section. We are issuing this AD to detect and correct cracks in the stiffeners at LBL and RBL 6.15, which could result in damage to the keel beam structure and consequently reduce the capability of the airplane to sustain flight loads.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
The term “service bulletin,” as used in this AD, means the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1269, Revision 1, dated September 16, 2004.
Before accumulating 15,000 total flight cycles, or within 180 days after the effective date of this AD, whichever occurs later: Do a detailed inspection of the stiffeners at LBL and RBL 6.15 for cracks, in accordance with Part I of the service bulletin. Thereafter at intervals not to exceed 4,500 flight cycles, repeat the detailed inspection until the stiffeners at LBL and RBL 6.15 have been replaced with new, improved stiffeners, in accordance with paragraph (h) or (i) of this AD.
Note 1: For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
If any crack is found during any inspection required by this AD, before further flight, replace both stiffeners with new, improved stiffeners by doing all of the applicable actions in Part IV through Part IX, as applicable, of the service bulletin; except where the service bulletin specifies to contact Boeing for appropriate action: Before further flight, repair using a method approved in accordance with the procedures specified in paragraph (l) of this AD. Accomplishing the replacement terminates the repetitive inspections required by paragraph (g) of this AD.
(i) Replacement of both stiffeners at LBL and RBL 6.15 with new, improved stiffeners in accordance with paragraph (h) of this AD terminates the repetitive inspections required by this AD.
The actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 737-57A1269, dated December 4, 2003, are acceptable for compliance with the corresponding actions required by this AD.
Inspections done before the effective date of this AD in accordance with Boeing All Operator Telex M-7200-01-00426, dated February 19, 2001, are acceptable for compliance with the requirements of paragraph (g) of this AD.
