Airworthiness Directive · Amendment 39-16166 · Wings
The Boeing Company Model 737-600, -700, and -800 Series Airplanes
This AD applies to The Boeing Company Model 737-600, -700, and -800 series airplanes, certificated in any category, as identified in Boeing Alert Service Bulletin 737-57A1294, dated April 23, 2007.
We are adopting a new airworthiness directive (AD) for certain Model 737-600, -700, and -800 series airplanes. This AD requires an inspection of the free flange, vertical web, and radius between the free flange and vertical web of the lower stringers of the wing center section for drill starts, and applicable related investigative and corrective actions. This AD results from drill starts being found on the free flange of the lower stringers of the wing center section during a quality assurance inspection at the final assembly plant. We are issuing this AD to prevent cracks from propagating from drill starts in the free flange, vertical web, and radius between the free flange and vertical web of the lower stringers of the wing center section lower stringers, which could cause a loss of structural integrity of the wing center section and may result in a fuel leak.
Comply with this AD within the compliance times specified, unless already done.
Before the accumulation of 18,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, do a detailed inspection of the free flange, vertical web, and radius between the free flange and vertical web of the lower stringers of the wing center section for any drill start, and do all applicable related investigative and corrective actions, by accomplishing all the applicable actions specified in paragraphs 3.B.2 and 3.B.4 of the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1294, dated April 23, 2007; except as provided in paragraph (h) of this AD. The applicable related investigative and corrective actions must be done before further flight.
(h) If any crack is found during any inspection required by paragraph (g) of this AD, and Boeing Alert Service Bulletin 737-57A1294, dated April 23, 2007, specifies to contact Boeing for appropriate action: Before further flight, repair the crack using a method approved in accordance with the procedures specified in paragraph (i) of this AD.
