AD 75-20-05

75-20-05 BOEING: Amendment 39-2371 as amended by Amendment 39-2426 is further amended by Amendment 39-2446. Applies to all Boeing Model 747 series airplanes certificated in all categories. Compliance required as indicated unless already accomplished. To prevent fore flap separations, accomplish the following: A. Within the next 100 flights after the effective date of this AD, unless accomplished within the last 200 flights, and at intervals thereafter not to exceed 350 flights: 1. Inspect all fore flap track, airload rollers for freedom of movement, and inspect upper and lower surfaces of the tracks and rollers for evidence of sliding. Inspect and lubricate rollers in accordance with procedures described in Boeing Service Bulletin 747-57-2107 dated November 3, 1972, or later FAA approved revisions, or the Boeing 747 Maintenance Manual. Replace any seized rollers before further flight unless, upon inspection: (a) The fittings attaching the fore flap to the sequencecarriage are found free of cracks. (b) The exposed surfaces of the fore flap tracks are found free of galling. (c) The flap is found free of any evidence of binding or racking. If (a) - (c) are accomplished the airplane may continue in service for a maximum of 10 flights before the seized rollers are replaced, provided the fore flap tracks are lubricated prior to each flight. 2. Inspect the attach (sequence) fittings of the inboard trailing edge fore flap (P/N 65B39025-1 and -2 opposite, or 65B39025-3 or 65B02015-1 and -2 opposite inboard fitting) for cracks in accordance with Boeing Service Bulletins 747-57-2119, Revision 2, dated June 20, 1975, and 747-57- 2088, Revision 2, dated June 30, 1975, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. Replace any cracked fittings before further flight if any crack exceeds the limits listed in Boeing Service Bulletin Nos. 747-57-2088 or 747-57-2119. 3. Inspect the outboard fore flap inboard carriage frame for cracks in accordance with Boeing Service Bulletin 747-57-2126, Revision 2, or later FAA approved revisions, or in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. Parts found cracked which are within the limits of Figure 1, Part III of Boeing Service Bulletin 747-57-2126, may be repaired in accordance therewith and reinspected at intervals not to exceed 40 landings. If cracks exceed the limits given in Boeing Service Bulletin 747-57-2126, replace the fitting before further flight. B. Unless already accomplished, with the next 350 flights after the effective date of this AD: Remove the existing steel bolts attaching the fore flap carriage stop to the flap tracks on the outboard flaps and install new bolts with sealant in accordance with Boeing Service Bulletin 747-57- 2128, Revision 1, dated April 25, 1975, or later FAA approved revisions. C. 1. Replace the three forward inboard fore flap airload rollers with new or overhauled rollers on or before December 31, 1976. The replacement rollers are to be lubricated with MIL-G-23827 grease, or an equivalent grease approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, which does not contain molybdenum disulfide (MoS2) as an additive. Airplanes delivered with the redesigned rollers which have been lubricated at an interval not greater than that allowed by this AD, need not have these bearings replaced. 2. Replace all inboard trailing edge fore flap attach fittings on or before December 31, 1976, in accordance with Boeing Service Bulletin No. 747-57-2119, Revision 2, and Boeing Service Bulletin No. 747-57-2088, Revision 2, or later FAA approved revisions, or replace fittings in a manner approved by the Chief, Engineering and Manufacturing Branch, FAA Northwest Region. D. Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, FAA Northwest Region, may adjust the repetitive inspection intervals specified in this AD to permit compliance at an established inspection period of the operator, if the request contains substantiating data to justify the adjustment period. Fleet average flight time may be used to calculate the number of flights. E. Unless already accomplished, on or before the next airload roller scheduled inspection, cut inspection holes in the mid flaps in accordance with Boeing Service Bulletin No. 747-57-2138. F. Replacement of the remaining inboard fore flap airload rollers and all outboard fore flap airload rollers with new or overhauled rollers lubricated with MIL-G-23827 or equivalent constitutes terminating action for the inspections required by paragraph A1. Replacement of both the inboard and outboard fore flap attach fittings constitutes terminating action for the inspections required by paragraphs A2 and A3. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive, who have not already received these documents from the manufacturer, may obtain copies upon request to Boeing Commercial Airplane Company, P. O. Box 3707, Seattle, Washington 98124. The documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington.

Amendment 39-2371 became effective October 24, 1975. Amendment 39-2426 becomes effective December 12, 1975. This amendment 39-2446 becomes effective December 12, 1975.