Airworthiness Directive · Amendment 39-15301 · Boeing Model 747-400 Series Airplanes
Boeing Model 747-400 Series Airplanes
This AD applies to Boeing Model 747-400 series airplanes, certificated in any category; as identified in Boeing Service Bulletin 747-21A2439, Revision 2, dated May 24, 2007.
The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-400 series airplanes. This AD requires repetitive inspections to detect discrepancies of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and applicable corrective actions. This AD also requires an inspection to identify the part number, shop code, and build date of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and applicable corrective actions, which end the repetitive inspections. This AD results from a report of an uncommanded up and down pitch movement of an airplane in flight and resistance in the elevator controls on the ground during taxi. We are issuing this AD to prevent cracking and buckling of the forward or rear heat exchanger shell of the air distribution system of the crew rest area, which could result in jamming of the rudder and/or elevator control cables and consequent reduced controllability 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.
At the applicable times specified in the Table 1 of paragraph 1.E. of Boeing Service Bulletin 747-21A2439, Revision 2, dated May 24, 2007, except as provided by paragraph (g) of this AD, do the actions specified in paragraphs (f)(1) and (f)(2) of this AD by accomplishing all the actions specified in the Accomplishment Instructions of the service bulletin.
(1) Do repetitive general visual inspections to detect discrepancies (i.e., cracks, creases, deformation, deflection, and interference with the rudder and/or elevator cables) of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and do the applicable corrective actions, until the actions required by paragraph (f)(2) of this AD are done. The applicable corrective actions must be done before further flight.
(2) Do an inspection to identify the part number, shop code, and build date of the forward and rear heat exchanger shells of the air distribution system of the crew rest area, and before further flight, do the applicable corrective actions. Accomplishing these actions ends the repetitive inspections required by paragraph (f)(1) of this AD.
(g) Where Boeing Service Bulletin 747-21A2439, Revision 2, dated May 24, 2007, specifies a compliance time “after the release date of the service bulletin” or “after the date of Revision 02 of the service bulletin,” this AD requires compliance within the specified compliance time after the effective date of this AD.
Actions done before the effective date of this AD in accordance with Boeing Alert Service Bulletin 747-21A2439, dated November 3, 2005; or Boeing Service Bulletin 74721A2439, Revision 1, dated July 24, 2006; are acceptable for compliance with the corresponding actions specified in this AD.
(i) If a forward heat exchanger shell, part number 65B41601-52, is found installed during the replacement required by paragraph (c) of AD 2001-18-04, amendment 39-12430, or was installed during the inspection required by paragraph (d)(2) of that AD (AD 2001-18-04 refers to Boeing Alert Service Bulletin 747-21A2412, dated January 20, 2000; or Revision 2, dated November 30, 2000; as the appropriate sources of service information for accomplishing the required actions): Actions required by paragraphs (f)(1) and (f)(2) of this AD are not required for that forward heat exchanger shell only.
As of the effective date of this AD, no person may install a heat exchanger shell having a part number identified in the “Existing Part Number” column of the table specified in paragraph 2.C. of Boeing Service Bulletin 747-21A2439, Revision 2, dated May 24, 2007, on any airplane.
