Airworthiness Directive · Amendment 39-16167 · Fuselage
The Boeing Company Model 737-300, -400, and -500 Series Airplanes
Superseded. A later AD replaced this one: AD 2011-24-12. Comply with the one in force.
This AD applies to The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category; as identified in Boeing Alert Service Bulletin 737-53A1301, dated September 3, 2009.
We are adopting a new airworthiness directive (AD) for certain Model 737-300, -400, and -500 series airplanes. This AD requires repetitive external non-destructive inspections to detect cracks in the fuselage skin along the chem-mill step at stringers S-1 and S-2 right, between station (STA) 827 and STA 847, and repair if necessary. This AD results from a report of a hole in the fuselage skin common to stringer S-1 and S-2 left, between STA 827 and STA 847 on an airplane that diverted to an alternate airport due to cabin depressurization and subsequent deployment of the oxygen masks. We are issuing this AD to detect and correct fatigue cracking of the fuselage skin panels at the chem-milled steps, which could result in sudden fracture and failure of the fuselage skin panels, and consequent rapid 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.
Before the accumulation of 35,000 total flight cycles, or within 500 flight cycles after the effective date of this AD, whichever occurs later: Except as provided by paragraph (i) of this AD, do an external non-destructive inspection (NDI) to detect cracks in the fuselage skin along the chem-mill steps at stringers S-1 and S-2 right, between STA 827 and STA 847, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1301, dated September 3, 2009. If no cracking is found, repeat the inspection thereafter at intervals not to exceed 500 flight cycles, except as provided by paragraph (i) of this AD.
If any crack is found during any inspection required by this AD, and Boeing Alert Service Bulletin 737-53A1301, dated September 3, 2009, specifies to contact Boeing for repair instructions: Before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (j) of this AD.
(i) Installing an external repair doubler along the chem-milled steps at stringers S-1 and S-2 right, between STA 827 and STA 847, constitutes terminating action for the repetitive inspections required by paragraph (g) of this AD for the repaired area only, provided all of the conditions specified in paragraphs (i)(1), (i)(2), and (i)(3) of this AD are met. The initial inspection required by paragraph (g) of this AD must be accomplished.
(1) The repair is installed after September 3, 2009;
(2) The repair was approved by the FAA or by a Boeing Company Authorized Representative or the Boeing Commercial Airplanes Organization Designation Authorization (ODA) authorized by the FAA to make such findings; and
(3) The repair extends a minimum of three rows of fasteners on each side of the chem-mill line in the circumferential direction.
