Airworthiness Directive · Amendment 39-15714 · Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR Series Airplanes
Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR Series Airplanes
This AD applies to all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes, certificated in any category.
The FAA is superseding an existing airworthiness directive (AD) that applies to certain Boeing Model 747 series airplanes. That AD currently requires repetitive inspections for cracking and corrosion of all exposed surfaces of the carriage spindles (including the inner bore and aft links) of the trailing edge flaps, and additional inspection and corrective action if necessary. That AD also currently requires repetitive overhaul of the carriage spindle and aft link, which terminates the repetitive inspections. This new AD adds a repetitive inspection to detect broken parts, and revises the overhaul threshold and repetitive intervals. This AD results from analysis that showed additional inspections should be done to prevent the loss of a flap, and that the flight-hour-based interval should be revised to a flight- cycle-based interval, because the greatest loads on the spindles happen during takeoff and landing. We are issuing this AD to detect and correct failed carriage spindles or aft links of the inboard or outboard trailing edge flaps. Such failure could cause the flap to depart the airplane, reducing the flightcrew's ability to maintain the safe flight and landing 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.
For all airplanes except those airplanes on which the repetitive overhauls required by paragraph B. of AD 90-17-19 are being accomplished as of the effective date of this AD: Prior to the accumulation of 30,000 flight hours or 8 years on each new or previously overhauled flap carriage spindle, whichever occurs first, remove the aft link and thrust collars from the trailing edge flaps' carriage spindles and perform a detailed inspection of all exposed surfaces of the carriage spindles, including inner bore, and aft links to detect cracking and corrosion, in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989.
Note 1: For the purposes of this AD, a detailed inspection is: “An intensive examination of a specific item, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at an intensity deemed appropriate. Inspection aids such as mirror, magnifying lenses, etc., may be necessary. Surface cleaning and elaborate procedures may be required.”
(1) If no cracking or corrosion is found, repeat the inspections required by paragraph (f) of this AD at intervals not to exceed 12 months until the carriage spindles are overhauled in accordance with paragraph (g) of this AD.
(2) If a cracked carriage spindle or aft link is found, prior to further flight, replace the part(s) in accordance with the service bulletin.
(3) If corrosion is found on any part of the carriage spindle/aft link assembly, but not on the other assembly on the same flap, perform a repetitive general visual inspection in accordance with the service bulletin at intervals not to exceed 2 months. Overhaul or replace corroded parts in accordance with the service bulletin within 36 months after detection of the corrosion.
(4) If corrosion is found on any part of both carriage spindle/aft link assemblies on the same flap, prior to further flight, overhaul or replace the part(s) in accordance with the service bulletin or repair in accordance with the procedures specified in paragraph (m) of this AD.
Note 2: For the purposes of this AD, a general visual inspection is: “A visual examination of an interior or exterior area, installation, or assembly to detect obvious damage, failure, or irregularity. This level of inspection is made from within touching distance unless otherwise specified. A mirror may be necessary to ensure visual access to all surfaces in the inspection area. This level of inspection is made under normally available lighting conditions such as daylight, hangar lighting, flashlight, or droplight and may require removal or opening of access panels or doors. Stands, ladders, or platforms may be required to gain proximity to the area being checked.”
For all airplanes: Prior to the accumulation of 8 years or 30,000 flight hours on any new or previously overhauled flap carriage spindle, whichever occurs later, remove the carriage spindle and aft link, and overhaul in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989. Repeat the overhaul thereafter at intervals not to exceed 8 years or 30,000 flight hours, whichever occurs earlier. Accomplishment of initial overhaul required by this paragraph terminates the requirements of paragraph (f) of this AD.
The actions specified in paragraphs (i) and (j) of this AD must be accomplished in their entirety, at the specified compliance times, to terminate the requirements of paragraphs (f) and (g) of this AD. There is no terminating action for the requirements of paragraphs (i) and (j) of this AD.
(i) For all airplanes: Within 12 months or 400 flight cycles after the effective date of this AD, whichever occurs later, do a general visual inspection of all eight carriage spindles and aft links to detect a broken carriage spindle or broken aft link, and do all applicable corrective actions before further flight. Repeat the inspection thereafter at intervals not to exceed 400 flight cycles. Do all actions in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. For airplanes identified in Note (d) of Table 1 in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, the initial compliance time and repetitive interval for a flap may be extended to 1,000 flight cycles when new carriages are installed at both the inboard and outboard carriage locations on the flap.
For all airplanes: At the later of the times specified in paragraph (j)(1) or (j)(2) of this AD, remove the carriage spindle and aft link, and overhaul in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008. Repeat the overhaul thereafter at the applicable repeat interval specified in paragraph 1.E., “Compliance,” of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008.
(1) The applicable threshold specified in paragraph 1.E. “Compliance,” of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008.
(2) Within 48 months after the effective date of this AD.
For Groups 1 and 3 airplanes identified in Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008: Replacing the existing 4340M aft link with a new corrosion resistant steel (CRES) aft link in accordance with the Accomplishment Instructions of Boeing Service Bulletin 747-27-2371, dated December 20, 2000, or with an aft link specified in paragraph 3.B.5. of the Accomplishment Instructions of Boeing Service Bulletin 747-27-2280, Revision 6, dated February 14, 2008, terminates the repetitive inspection requirements of paragraph (f) of this AD, and the repetitive overhaul requirements of paragraphs (g) and (j) of this AD for that aft link only. The repetitive inspections for broken parts required by paragraph (i) of this AD cannot be terminated.
Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 747-27-2280, Revision 4, dated April 26, 2001, are acceptable for compliance with the corresponding requirements of paragraphs (f) and (g) of this AD. Actions done before the effective date of this AD in accordance with Boeing Service Bulletin 747-27-2280, Revision 5, dated April 5, 2007, are acceptable for compliance with the corresponding requirements of paragraphs (i) and (j) of this AD.
