70-05-03 BRITISH AIRCRAFT CORPORATION: Amdt. 39-947. Applies to model BAC 1- 11, 400 series airplanes.
Compliance required as indicated.
To prevent fatigue failure of the main landing gear, inner door jack attachment, saddle bracket structure, located on the keel in the main landing gear bay at station 575, accomplish the following:
(a) For airplanes which have not incorporated British Aircraft Corporation Modification PM2510 or PM3082 on the effective date of this AD, comply with the following:
(1) Visually inspect all components of the main landing gear, inner door jack attachment, saddle bracket structure assembly which projects outboard on either side of keel structure for cracks or signs of damage in accordance with BAC 1-11 Alert Service Bulletin 53-A- PM 2510, Issue 5, dated May 16, 1969, or later ARB-approved issue, or an FAA-approved equivalent at the following intervals:
(i) For airplanes with less than 2,000 landings on the effective date of thisAD, inspect prior to the accumulation of 2,350 landings, and thereafter at intervals not to exceed 350 landings from the last inspection until the accumulation of 3,500 landings and thereafter at intervals not to exceed 50 landings from the last inspection.
(ii) For airplanes with from 2,000 to 3,500 landings on the effective date of this AD, unless already accomplished within the last 350 landings, inspect within the next 350 landings after the effective date of this AD and thereafter at intervals not to exceed 350 landings from the last inspection until the accumulation of 3,500 landings, and thereafter at intervals not to exceed 50 landings from the last inspection.
(iii) For airplanes with 3,500 or more landings on the effective date of this AD, unless already accomplished within the last 50 landings, inspect within the next 50 landings after the effective date of this AD and thereafter at intervals not to exceed 50 landings from the last inspection.
(2) Within thenext 50 landings after the effective date of this AD or before the accumulation of 5,000 landings, whichever occurs later after the effective date of this AD, unless already accomplished, and thereafter at intervals not to exceed 5,000 landings from the last replacement, replace the upper web angles P/N AK27-1639 with serviceable web angles of the same part number. Compliance with this subparagraph may be discontinued after the modifications specified in either subparagraph (3)(ii), (3)(iii) or (3)(iv) have been accomplished.
(3) If cracks or damage are found during the inspections required by paragraph (a) before further flight accomplish one of the following:
(i) Replace cracked or damaged components with serviceable components of the same part number.
(ii) Modify the saddle bracket structure in accordance with British Aircraft Corporation Model BAC 1-11 Service Bulletin No. 53-PM-2510, Revision 4, dated October 30, 1967, or later ARB-approved issues, or an FAA-approved equivalent, and replace all cracked or damaged components not replaced by Modification PM2510 with new components of the same part number.
(iii) Accomplish the modification and replacement required by subparagraph (ii) of this paragraph and in addition modify the saddle bracket in accordance with British Aircraft Corporation Model BAC 1-11 Service Bulletin No. 53-PM 3082, Revision 3, dated December 2, 1968, or later ARB-approved issues, or an FAA-approved equivalent.
(iv) Accomplish the modifications and replacement required by subparagraph (ii) an (iii) of this paragraph and in addition modify the saddle bracket structure in accordance with British Aircraft Corporation Model BAC 1-11 Service Bulletin No. 53-PM 3871, dated March 31, 1969, or later ARB-approved issues, or an FAA-approved equivalent.
(4) The inspections required by subparagraph (1) of this paragraph may be discontinued after the modifications specified in either subparagraph (3)(ii), (3)(iii), or(3)(iv) of this paragraph have been accomplished.
(b) For airplanes which have incorporated BAC Modification PM2510 within the next 100 landings or before the accumulation of 14,000 landings after Modification PM 2510 was accomplished, whichever occurs later after the effective date of this AD, and thereafter at intervals not to exceed 14,000 landings since the last replacement, replace upper web angles P/N AK27- 10133 with new web angles of the same part number.
(c) For airplanes which have incorporated the modifications required by paragraph (a)(3)(iii), within the next 100 landings or before the accumulation of 20,000 landings after Modification PM 3082 was installed, whichever occurs later after the effective date of this AD, and thereafter at intervals not to exceed 20,000 landings since the last replacement, replace the upper web angles P/N AK27-10133 with new web angles of the same part number.
(d) For the purpose of complying with this AD, subject to acceptance by the assigned FAA maintenance inspector, the number of landings may be determined by dividing each airplane's hours' time in service by the operators' fleet average time from takeoff to landing for the airplane type.
This supersedes Amendment 39-471 (32 F.R. 12711), AD 67-25-3.
This amendment becomes effective March 23, 1970.