79-04-01 R3 BOEING: Amendment 39-3410 as amended by Amendment 39-3577 is further amended by Amendment 39-3889 and Amendment 39-4000. Applies to all Boeing Model 727 series airplanes certificated in all categories. Compliance required as indicated below. To prevent main landing gear-up landings as a result of structural failure in the lock system, accomplish the following: \n\n\tA.\tUnless already accomplished, within the next 1,500 landings after March 12, 1979, or prior to the accumulation of the threshold listed in the table below, whichever occurs later, replace the components listed in the table in accordance with Boeing Service Bulletins Nos. 727-32-211, Revision 4, or 727-32-237, Revision 2, or 727-32-286, Revision 1, or later FAA approved revisions, or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. As an alternate to replacement, the applicable components may be inspected for cracks in accordance with inspection methodsspecified in Boeing Service Bulletin No. 727-32-211, Revision 4, or 727-32-286, Revision 1, or later FAA approved revisions, or other methods approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region at the intervals specified in the table. Cracked parts must be replaced prior to further flight.\n \tB.\tUnless already accomplished, within the next 3,000 landings after March 12, 1979, replace (1) the left and right hand main gear manual extension gearbox horizontal supports, P/N 65-24575-1, with P/N 65-69156-1 and (2) the left and right hand main gear manual extension support yokes, P/N 65-26300- 1/-2 or 65-26300-7/-8, 65-81412-1/-2, with P/N 65-26300-21/-22 or 65-26300-23/-24 in accordance with the applicable procedures of Boeing Service Bulletin Numbers 727-32-164, Revision 2, and 727-32-204, Revision 1, or later FAA approved revisions, or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. Replacement of the gearbox housing is not required if the bushing/fastener configuration described in Boeing Service Bulletin No. 727-32-164, Revision 2, or later FAA approved revisions, or equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, is installed in each horizontal support attach hole for the gearbox housing. As an alternate to replacement of items (1) and (2) above, within the next 3,000 landings after March 12, 1979, and thereafter at intervals of 3,000 landings, eddy current inspect the horizontal supports and penetrant or eddy current inspect the support yokes in accordance with Boeing Service Bulletin No. 727-32-164, Revision 2, and Boeing Service Bulletin No. 727-32-204, Revision 1, or later FAA approved revisions, or in an equivalent manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. Cracked parts must be replaced prior to further flight. \n\tC.\t1.\tWithin the next 600 landings after October 9, 1979, unless accomplished within the last 900 landings preceding October 9, 1979, in accordance with the original issue of this AD, and thereafter at intervals not to exceed 1,500 landings, accomplish the rotational force tests on the main landing gear uplock hook assemblies (2 per airplane) in accordance with the procedures specified in Paragraph III of Boeing Service Bulletin No. 727-32-212, Revision 2, or later FAA approved revisions, for assembly P/Ns 65-24485-3, -4, and -6, and Boeing Service Bulletin No. 727-32-245, Revision 4, for assembly P/Ns 65-24485-7, or later FAA approved revisions, or alternate procedures approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. Rework and/or replace uplock hook assembly components as required to obtain the acceptable hook rotational forces specified in the service bulletins. \n\tC.\t2.\tOn or before July 1, 1982, accomplish the main landing gear uplock assembly modification specified in Boeing Service BulletinNo. 727-32-245, Revision 4, dated August 31, 1979, or later FAA approved revisions, or an alternate approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. This modification constitutes terminating action for the requirements of Paragraph C.1 above. \n\tD.\tUnless already accomplished, within the next 3,000 landings after March 12, 1979, accomplish the inspection/cleanup and replacement, as necessary, of the main landing gear manual extension support yoke attach bolts (2 per side) in accordance with Figures 1 and 2, as applicable, of Boeing Service Bulletin No. 727-32-251, or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. \n\tE.\tWithin the next 1,500 landings after March 12, 1979, or prior to the accumulation of 6,000 landings whichever occurs later, and thereafter at intervals not to exceed 1,500 landings, magnetic particle or eddy current inspect the main landing gear uplock lower shaft assemblies, P/Ns 65-24489-3 and 65- 43772-1/-2 in accordance with Boeing Service Bulletin No. 727-32-257, Revision 1, or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. \n\t\tCracked parts must be replaced with serviceable parts prior to further flight. Terminating action consists of replacement of the uplock lower shaft assembly with an improved shaft in accordance with Figure 2 of Boeing Service Bulletin No. 727-32-257, Revision 1, or in a manner approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. \n\tF.\tAccomplish one of the following: \n\t\t1.\tOn or before July 1, 1982, install the main landing gear safety bar mechanism, LH and RH sides, in accordance with Boeing Service Bulletin No. 727-32-275, dated March 28, 1980, or later FAA approved revisions, or an equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. If Boeing Service Bulletin Numbers 727-32-237, Revision2, dated March 9, 1979; 727-32-251 dated March 11, 1977; and 727-32-257, Revision 1, dated July 21, 1978; or later FAA approved revisions, or equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, have been accomplished, the improved safety bar mechanism or FAA approved equivalent need not be installed until December 31, 1983. \n\t\t2.\tOn or before July 1, 1982, replace the main landing gear lock system components with improved components in accordance with Boeing Service Bulletin No. 727-32-237, Revision 2, dated March 9, 1979, or later FAA approved revisions, or equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, and thereafter overhaul and maintain the main landing gear lock system in accordance with a supplemental overhaul/maintenance program acceptable to the assigned FAA maintenance inspector and approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. (Recurring action taken under the overhaul/maintenance program shall be recorded to show the status of compliance with this AD.) \n\tAccomplishment of Paragraph F.1. constitutes terminating action to Paragraphs A, D, and E above. If Paragraph F.2. is accomplished, the requirements of F.2. supersede Paragraphs A, D, and E. \n\tG.\tOn or before July 1, 1982, (1) replace the main landing gear manual extension system gearbox horizontal supports, LH and RH sides, Boeing P/N 65-24575-1, with Boeing P/N 65-69156-1 in accordance with Boeing Service Bulletin No. 727-32-164, Revision 2, dated June 22, 1979, or later FAA approved revisions, or an equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, (2) replace the main landing gear manual extension system support yokes, LH and RH sides, Boeing P/Ns 65-26300-1/-2, 65-26300-7/-8, 65-81412-1/-2, 65-26300-11/-12, and 65-26300- 17/-18 with Boeing P/Ns 65-26300-21/-22 or 65-26300-23/-24 in accordance with Boeing Service Bulletin No. 727-32-204, Revision 3, dated December 7, 1979, or later FAA approved revisions, or an equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, and (3) replace the main landing gear manual extension system gearbox housing, Boeing P/N 65-27485-1/-2, LH and RH sides, with Boeing P/N 65-27485-11/-12 in accordance with Boeing Service Bulletin No. 727-32-279, dated June 22, 1979, or later FAA approved revisions, or an equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region. The replacement accomplished per this paragraph constitutes terminating action to Paragraph B of this AD. \n\tH.\tAirplanes may be ferried to a maintenance base for replacement of parts in accordance with FAR 21.197. \n\tI.\tUpon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Seattle Area Aircraft Certification Office, 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 increase for that operator.\n \tJ.\tFor the purpose of this AD, when conclusive records are not available to show the total number of landings accumulated by a particular part (or assembly), the number of landings may be computed by dividing the airplane time-in-service since the part (or assembly) was installed in the airplane by the operator's fleet average time per flight for his Model 727 series airplanes. \n\tFor those operators who are unable to determine the total time-in-service or landings accumulated on a part (or assembly) since new, the total number of landings of the airplane on which it is installed may be used. This applies only to the establishment of the total landings for the initial compliance threshold. \n\tNOTE: The overhaul/maintenance program specified in ATA Report 32-30-1, Revision 4, dated September 9, 1980, is an FAA approved program for the purpose of complying with the requirements of paragraph F.2. of this AD. \n\tThe 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). \n\tAll 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. These documents may also be examined at FAA Northwest Region, 9010 East Marginal Way South, Seattle, Washington 98108. \n\n\tAmendment 39-3410 became effective March 12, 1979. \n\tAmendment 39-3577 became effective October 9, 1979. \n\tAmendment 39-3889 became effective September 25, 1980. \n\tThis amendment 39-4000 becomes effective January 25, 1981. \n\n\n\nComponent\nPart No.\nReplacement or Initial Inspection Threshold\t (Landings)\t\t\nRepeat Inspection Interval Not To Exceed (Landings)\n\n\n\n\nDownlock Torque Shaft\n65-78698-1,-2\n35,000\n3,000\n\n-5,-6\n\n\n\n-7,-8\n\n\n\n\n\n\nDownlock Rod Assy.\n69-20527-2 \n\n\n\n69-33654-1\n12,000\n1\n\n69-33654-2\n\n\n\n69-33654-3\n\n\n\n69-33654-4\n\n\n\n69-33654-5\n35,000\n3,000\n\n\n\n\nDownlock Torque Tube \nAssy. \n65-26921-17\n37,000\n3,000\n\n65-26921-18\n\n\n\n\n\n\nUplock\tUniversal Block\n65-24488-1\n10,000 flt hrs or 4 years, whichever occurs first.\n1,500 \n\n-4\n48,000 landings\n3,000\n\n\n\n\nUplock\tUniversal Bolt\nNAS 1106-44D\n11,000\nTo be replaced \n\n69-47743-1\n\n\n\n\n\n\nUplock\tUpper Shaft Assy.\n65-25851-1\n46,000\n3,000 \n\n65-25851-2\n\n\n\n65-25851-5\n\n\n\n65-25851-6\n\n\n\n\n\n\nUplock Lower Crank\n65-49325-1,-2\n\n1,500 \n\n65-49325-5,-6\n3,000\n\n\n65-49325-7,-8\n\n\n\n\n\n\nDownlock Crank 2\n69-25028-1\n\n\n\n-2\n\n\n\n-3\n25,000\n1,500\n\n-4\n\n\n\n\n\t\t\n\n\t\t\n\n1\tWithin 1500 landings from the last inspection or within 1500 landings from October 9, 1979, whichever occurs first,thereafter not to exceed 500 landings. \n\n2\tInitially inspect or replace prior to accumulation of 25,000 landings or within 750 landings from the effective date of this amendment, whichever occurs later. Replacement with steel downlock crank, Boeing Part Number 69-20528-5 or -6 or an equivalent approved by the Chief, Seattle Area Aircraft Certification Office, FAA Northwest Region, terminates the downlock crank inspection requirement of this table. \n\n\n\nComponent\nPart No.\nReplacement or Initial Inspection Threshold (Landings)\nRepeat Inspection Interval Not To Exceed (Landings) \nUplock\tLower Crank Bolt \nNAS 1105-28\t\t\n7,000\nTo be replaced\n\nBACP18T5-( )\t\t\n7,000 \n\n\nMS20392-5C( )\t\t\n(oversize option) \n12,000\n\n\nMS20392-6C( )\t\t \n(oversize option) \n50,000\n\n\n\n\n\nDownlock Rod Bolt (Inboard)\nNAS 1105-13DW\n20,000\nTo be replaced \n\nBACB30LJ5U13\t\tOptional Bolts:\nBACB30LJ5U15 \nBACB30LJ5-16 \nBACB30GE5-16 \n20,000\nTo be replaced \n\n\n\n\nDownlock Rod Bolt (Outboard)\nNAS 1105-13DW\t\t\t\t\t\t\n20,000\nTo be replaced \n\nBACB30LM5DU12\n20,000\nTo be replaced\n\nOptional Bolts: \nBACB30NE5D12 \nBACB30GE5D12 \nNAS 1305-12D