Airworthiness Directive · Amendment 39-16545 · Fuselage
The Boeing Company Model 737-600, -700, -700C, -800, and -900 Series Airplanes
This AD applies to The Boeing Company Model 737-600, -700, -700C, -800, and -900 series airplanes, certificated in any category, as identified in Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009.
We are adopting a new airworthiness directive (AD) for certain Model 737-600, -700, -700C, -800, and -900 series airplanes. This AD requires inspections for scribe lines in the fuselage skin at lap joints, the splice strap at certain butt joints, the skin or doubler at certain approved repair doublers, and the skin at decal locations; and related investigative and corrective actions if necessary. This AD results from reports of scribe line damage found adjacent to the skin lap joints, decals, and wing-to-body fairings. We are issuing this AD to detect and correct scribe lines, which can develop into fatigue cracks in the skin. Undetected fatigue cracks can grow and cause sudden decompression of the airplane.
You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.
At the applicable times specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009 (“the service bulletin”), except as provided in paragraph (i) of this AD, do detailed external inspections for scribe lines in the fuselage skin at lap joints, the splice strap at certain butt joints, the skin or doubler at certain approved repair doublers, and the skin at decals; and do all applicable related investigative and corrective actions, by accomplishing all actions specified in the Accomplishment Instructions of the service bulletin, except as provided by paragraphs (j), (k), (l), (m), and (n) of this AD.
Note 1: The inspection exceptions described in subparagraphs 1.a. through 1.f. in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009, apply to this AD.
Actions accomplished before the effective date of this AD according to Boeing Alert Service Bulletin 737-53A1289, dated January 14, 2009, are considered acceptable for compliance with the corresponding actions specified in this AD.
(i) Where Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009, specifies a compliance time after the date on the service bulletin, this AD requires compliance within the specified compliance time after the effective date of this AD.
(j) Where Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009, specifies to contact Boeing for appropriate action, accomplish applicable actions using a method approved in accordance with the procedures specified in paragraph (p) of this AD.
(k) Where Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009, specifies to contact Boeing for instructions to repair scribe lines: Remove the scribe line damage and install a reinforcing repair using an FAA-approved method.
Note 2: Guidance for repairing scribe damage (e.g., nicks, gouges, scratches, and corrosion) may be found in the Allowable Damage section of the appropriate Boeing 737 Structural Repair Manual (SRM).
Note 3: Operators must obtain an approved damage tolerance evaluation for any repair installed to comply with Section 121.1109(c)(2) or 129.109(c)(2) of the Code of Federal Regulations (14 CFR 121.1109(c)(2) or 129.109(c)(2)).
(l) Inspections are not required in areas where an existing repair covers a potential scribe line or where the scribe line is within 10 inches of the repair, provided the repair spans a minimum of three fastener rows beyond each side of the potential scribe line location (perpendicular to the scribe line direction). If a repair doubler does not span the potential scribe line location by 3 or more fastener rows, but there is no evidence of scribe lines within 10 inches of the repair, then inspections under the repair are not required.
(m) Where Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009, specifies a compliance time of “before further flight” for inspecting scribe lines less than 0.001 inch deep for cracks, no further inspections are required by paragraph (g) of this AD, provided that correct sealant removal procedures are used for future work at those locations.
(n) If records show that the airplane has never been stripped and repainted under the dorsal fin fairing since delivery from Boeing, then this AD does not require inspections specified in paragraph (g) of this AD for the butt joint, lap joint, and repairs in the areas under the dorsal fin fairing.
At the applicable time specified in paragraph (o)(1) or (o)(2) of this AD: Submit a report of positive findings of cracks found during the inspections required by paragraph (g) of this AD. You may use Appendix B of Boeing Service Bulletin 737-53A1289, Revision 1, dated November 18, 2009. Send the report to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. The report must contain, at a minimum, the inspection results, a description of any discrepancies found, the airplane serial number, and the number of flight cycles and flight hours on the airplane. Under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.), the Office of Management and Budget (OMB) has approved the information collection requirements contained in this AD and has assigned OMB Control Number 2120-0056.
(1) If the inspection was done on or after the effective date of this AD: Submit the report within 30 days after the inspection.
(2) If the inspection was done before the effective date of this AD: Submit the report within 30 days after the effective date of this AD.
