Airworthiness Directive · Amendment 39-16701 · Fuselage
The Boeing Company Model 737-300, -400, and -500 Series Airplanes
Superseded. A later AD replaced this one: AD 2015-16-08. 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 737-53A1319, dated April 4, 2011.
We are adopting a new airworthiness directive (AD) for the products listed above. This emergency AD was sent previously to all known U.S. owners and operators of these airplanes. This AD requires repetitive external eddy current inspections of the lap joints at stringers S-4R and S-4L, along the entire length from body station (BS) 360 to BS 908. If a crack indication is found, the AD requires either confirming the crack by doing internal eddy current inspections, or repairing the crack. As an alternative to the external eddy current inspections, the AD provides for internal eddy current and detailed inspections for cracks in the lower skin at the lower row of fasteners at stringers S-4L and S-4R. This AD was prompted by a report indicating that a Model 737-300 series airplane experienced a rapid decompression when the lap joint at stringer S-4L between BS 664 and BS 727 cracked and opened up due to cracking in the lower skin at the lower row of fasteners. We are issuing this AD to detect and correct such cracking, which could result in an uncontrolled decompression of the airplane.
Comply with this AD within the compliance times specified, unless already done.
At the applicable time specified in paragraph (g)(1), (g)(2), or (g)(3) of this AD: Except as provided by paragraphs (h) and (i) of this AD, do external eddy current inspections of the lap joint at stringers S-4R and S-4L, along the entire length from body station (BS) 360 to BS 908, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011. If any crack indication is detected, before further flight, either confirm the crack indication by doing eddy current inspections from the interior of the fuselage in the lower skin at the lower row of fasteners at stringer S-4L and S-4R, in accordance with Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011, or repair in accordance with paragraph (j) of this AD.
(1) For airplanes that have accumulated fewer than 30,000 total flight cycles as of the effective date of this AD: Inspect before the accumulation of 30,000 total flight cycles, or within 20 days after the effective date of this AD, whichever occurs later.
(2) For airplanes that have accumulated 30,000 or more total flight cycles and fewer than 35,000 total flight cycles as of the effective date of this AD: Inspect within 20 days after the effective date of this AD.
(3) For airplanes that have accumulated 35,000 total flight cycles or more as of the effective date of this AD: Inspect within 5 days after the effective date of this AD.
(h) For areas repaired with external doublers, paragraphs (h)(1) and (h)(2) of this AD apply.
(1) If the repair meets the criteria specified in paragraphs 3.B.1.c.(1) and 3.B.1.c.(2) of Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011, no inspection of the lower skin at the lap joint lower fastener row is required under the doubler.
(2) If the repair does not meet the criteria specified in paragraphs 3.B.1.c.(1) and 3.B.1.c.(2) of Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011, inspect the lower skin lap joint lower row internally in the area covered by the doubler, in accordance with Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011.
(i) The inspections required by paragraph (g) of this AD may alternatively be done by internal eddy current and detailed inspections for cracks in the lower skin at the lower row of fasteners at stringer S-4L and S-4R, along the entire length from BS 360 to BS 908, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-53A1319, dated April 4, 2011.
(j) If any crack is found during any inspection required by this AD: Before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (l) of this AD.
(k) Repeat the inspections specified in either paragraph (g) or (i) of this AD thereafter at intervals not to exceed 500 flight cycles. Either inspection method may be used at any repetitive inspection cycle.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
