Airworthiness Directive · Amendment 39-17109 · Wings
The Boeing Company Airplanes
This AD applies to all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, certificated in any category.
We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. This AD requires inspecting parts or doing a records review to determine if certain trailing edge flap carriages are installed, doing repetitive inspections for corrosion, and flaking or missing thermal coating on suspect carriage spindles, and related investigative and corrective actions, if necessary; this AD also provides optional terminating action for the repetitive inspections. This AD was prompted by reports of corrosion found on carriage that are located on the outboard flaps. We are issuing this AD to detect and correct corrosion of the carriage spindle, which could result in a fracture; fracture of both the inboard and outboard carriage spindles, at the forward ends through the large diameters, on a single flap assembly, could adversely affect the continued safe flight and landing of the airplane.
Within 90 days after the effective date of this AD, do an inspection of the part or a records review to determine whether a suspect carriage with a high velocity oxygenated fuel (HVOF) thermal coating is installed at wing butt line (WBL) 254 or WBL 355, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1319, dated April 16, 2012, as revised by Boeing Alert Service Bulletin 737-57A1319, Revision 1, dated June 6, 2012. If no suspect carriage is installed, no further action is required by this paragraph.
(1) For airplanes on which any suspect carriage is installed, or if the part number of the carriage cannot be determined: Within 90 days after the effective date of this AD, or within 180 days after installation of a suspect carriage, whichever occurs later, do a detailed or borescope inspection of the forward end of the carriage spindle for corrosion and flaking and missing thermal coating, and do all applicable related investigative and corrective actions, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1319, dated April 16, 2012, as revised by Boeing Alert Service Bulletin 737-57A1319, Revision 1, dated June 6, 2012. Do all applicable related investigative and corrective actions before further flight. Repeat the detailed or borescope inspection thereafter at intervals not to exceed 180 days.
(2) For the purposes of this AD, a “serviceable part” can be either a suspect part (i.e., a carriage with HVOF thermal coating) or a non-suspect part (i.e., a carriage that does not have HVOF thermal coating).
Replacement of a suspect carriage with a new or serviceable carriage without HVOF thermal coating, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-57A1319, dated April 16, 2012, as revised by Boeing Alert Service Bulletin 737-57A1319, Revision 1, dated June 6, 2012, terminates the requirements of paragraph (h) of this AD for that carriage spindle only.
As of the effective date of this AD, a serviceable HVOF-coated carriage may not be installed on an airplane unless the actions required by paragraph (h)(1) of this AD are done on that carriage prior to installation.
