78-08-06 BRITISH AIRCRAFT CORPORATION: Amendment 39-3186. Applies to Model BAC 1-11 200 and 400 Series airplanes certificated in all categories, which have a rear passenger door installed in the aft pressure bulkhead.
Compliance is required as indicated.
To detect cracking and prevent possible failure of the door structure under pressure loads, accomplish the following:
(a) Prior to accumulating 30,000 landings or within 800 flight hours time in service after the effective date of this AD, whichever occurs later, unless accomplished within the last 800 flight hours, and thereafter at intervals not to exceed 800 flight hours from the last crackfree inspection, inspect the passenger door in the aft pressure bulkhead for cracks in accordance with paragraph 2.2 of the section entitled "Accomplishment Instructions" of British Aircraft Corporation Alert Service Bulletin 52-A-PM5448, issue 2, dated July 4, 1977, or an FAA-approved equivalent.
(b) If horizontal cracks arefound during the inspection required by paragraph (a) of this AD which do not exceed the combined limitations of (b)(1) and (b)(2) noted below, the doors may remain in service provided the cracks are stop drilled and inspected for crack propagation at intervals not to exceed 50 flight hours from initial crack detection.
(1) Cracks in the skin panel must not exceed 3 inches in length and must be limited to one crack per bay or one crack adjacent to and on either side of a horizontal member of the primary backup structure of the door.
(2) Cracks in the horizontal members of the primary backup structure which are parallel to and between the heel line and lightening holes must not exceed 2 inches in length, must be limited to one crack per horizontal member and adjacent horizontal members must be crackfree.
(c) If horizontal cracks are found during the inspection required by paragraph (a) of this AD which do not exceed the combined limitations noted in (c)(1) and (c)(2)below, the doors may remain in service provided the cracks are stop drilled and inspected for crack propagation at intervals not to exceed 50 flight hours from initial crack detection and the cabin pressure differential is limited to a maximum of 5.5 pounds per square inch for flight operations with cracks unrepaired.
(1) Cracks in the skin panel must not exceed 6 inches in length and must be limited to one crack per bay or one crack adjacent to and on either side of a horizontal member of the primary backup structure of the door.
(2) Cracks in the horizontal members of the primary backup structure are of the type and do not exceed the limitations of paragraph (b)(2) of this AD.
(d) Within 300 flight hours from the initial detection of a skin crack in excess of 3 inches in length, repair cracks in doors which are allowed to remain in service subject to the conditions in paragraphs (b) and (c) of this AD in accordance with sections 51-20-0 and 52-02-5 of the Structural Repair Manual for the Model, and thereafter continue to inspect the door in accordance with paragraph (a) of this AD at intervals not to exceed 800 flight hours time in service.
(e) If cracks are found during any of the inspections required by this AD that exceed the limitations specified in subparagraphs (b)(2) or (c)(1) of this AD, or are of a type which extend across the door frame, vertically across horizontal members, from a lightening hole to the heel line of the horizontal member, or between lightening holes, before further pressurized flight, repair the cracks in accordance with sections 51-20-0 and 52- 02-5 of the Structural Repair Manual for the Model and thereafter continue to inspect the door in accordance with paragraph (a) of this AD at intervals not to exceed 800 flight hours from the time of the repair.
(f) Upon incorporation of British Aircraft Corporation Modification 52-PM5448, compliance with this AD is no longer required.
(g) For the purpose of complying with this AD where number of landings has not been recorded, subject to acceptance by the assigned FAA maintenance inspector, the number of landings may be determined by dividing the total airplane flight hours by the operator fleet average time from takeoff to landing for the airplane type.
(h) Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Aircraft Certification Staff, AEU-100, Europe, Africa, and Middle East 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.
NOTE: For additional clarification of types of cracking to be expected and crack limitations, refer to British Aircraft Corporation Alert Service Bulletin 52-A-PM5448, issue 2 (pages 1 and 2) dated July 4, 1977, and issue 1 (pages 3-5) dated March 16, 1977.
This amendment becomes effective May 15, 1978.