Airworthiness Directive · Amendment 39-16566 · Nacelles/pylons
The Boeing Company Model 737-300, -400, and -500 Series Airplanes
This AD applies to all The Boeing Company Model 737-300, -400, and -500 series airplanes, certificated in any category.
We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires repetitive inspections for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, and corrective actions if necessary. This new AD requires replacing the midspar fuse pins with new, improved fuse pins, which would terminate the repetitive inspections. This AD was prompted by a report of corrosion damage of the chrome runout on the head side found on all four midspar fuse pins of the nacelle strut. Additionally, a large portion of the chrome plate was missing from the corroded area of the shank. We are issuing this AD to prevent damage of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut, which could result in reduced structural integrity of the fuse pins, and consequent loss of the strut and separation of the engine from 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 time specified in paragraph 1.E., “Compliance” of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007; except, where that service bulletin specifies a compliance time after the date on that service bulletin, this AD requires compliance within the specified compliance time after November 13, 2008 (the effective date of AD 2008-21-03): Do a detailed inspection for discrepancies of the fuse pins of the inboard and outboard midspar fittings of the nacelle strut by doing all the actions, including all applicable corrective actions, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007; or Boeing Alert Service Bulletin 737-54A1044, Revision 2, dated January 20, 2010. Do all applicable corrective actions before further flight. Repeat the inspection at the time specified in paragraph 1.E. of Boeing Special Attention Service Bulletin 737-54-1044, dated December 10, 2007. Accomplishing the actions of paragraph (h) of this AD terminates the requirements of this paragraph.
Within 120 months after the effective date of this AD, replace all midspar fuse pins having part number (P/N) 311A1092-2 with a midspar fuse pin having P/N 311A1092-3, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-54A1044, Revision 2, dated January 20, 2010. Accomplishing the requirements of this paragraph terminates the requirements of paragraph (g) of this AD for that fuse pin.
(i) Actions done before the effective date of this AD in accordance with Boeing Special Attention Service Bulletin 737-54-1044, Revision 1, dated November 26, 2008, are acceptable for compliance with the corresponding requirements of this AD.
