76-04-06 BRITISH AIRCRAFT CORPORATION: Amendment 39-2523. Applies to BAC 1- 11 200 and 400 Series airplanes certificated in all categories.
Compliance is required as indicated.
To detect cracks in the horizontal stabilizer structure and prevent possible horizontal stabilizer failure, accomplish the following:
(a) For airplanes equipped with horizontal stabilizers that do not incorporate the modification contained in Part (d) of British Aircraft Corporation Service Bulletin 55-PM3485, comply with paragraph (c) of this AD as follows:
(1) If the horizontal stabilizer has accumulated less than 28,000 total landings on the effective date of this AD -
(i) Prior to the accumulation of 30,000 total landings, inspect in accordance with paragraph (c) of this AD;
(ii) Prior to the accumulation of 35,000 total landings, reinspect in accordance with paragraph (c) of this AD; and
(iii) Thereafter, continue to inspect in accordance with paragraph (c) of this AD at intervals not to exceed 2500 landings since the last inspection.
(2) If the horizontal stabilizer has accumulated 28,000 or more total landings but less than 30,000 total landings on the effective date of this AD -
(i) Prior to the accumulation of an additional 1000 landings or 30,501 total landings, whichever occurs earlier, unless already accomplished within the preceding 1000 landings, inspect in accordance with paragraph (c) of this AD;
(ii) Prior to the accumulation of 35,000 total landings, reinspect in accordance with paragraph (c) of this AD; and
(iii) Thereafter, continue to inspect in accordance with paragraph (c) of this AD at intervals not to exceed 2500 landings since the last inspection.
(3) If the horizontal stabilizer has accumulated 30,000 or more total landings but less than 32,000 total landings on the effective date of this AD -
(i) Prior to the accumulation of an additional 500 landings or 32,101 total landings whichever occurs earlier, unless already accomplished within the preceding 2500 landings, inspect in accordance with paragraph (c) of this AD;
(ii) Prior to the accumulation of 35,000 total landings reinspect in accordance with paragraph (c) of this AD; and
(iii) Thereafter, continue to inspect in accordance with paragraph (c) of this AD at intervals not to exceed 2500 landings since the last inspection.
(4) If the horizontal stabilizer has accumulated 32,000 or more total landings but less than 35,000 total landings on the effective date of this AD -
(i) Prior to the accumulation of an additional 100 landings, unless already accomplished within the preceding 5000 landings, inspect in accordance with paragraph (c) of this AD;
(ii) Prior to the accumulation of 35,000 total landings or 2500 landings from the last inspection, whichever occurs later, reinspect in accordance with paragraph (c) of this AD; and
(iii) Thereafter,continue to inspect in accordance with paragraph (c) of this AD at intervals not to exceed 2500 landings since the last inspection.
(5) If the horizontal stabilizer has accumulated 35,000 or more total landings on the effective date of this AD -
(i) Prior to the accumulation of an additional 50 landings unless already accomplished within the preceding 2500 landings, inspect in accordance with paragraph (c) of this AD; and
(ii) Thereafter, continue to inspect in accordance with paragraph (c) of this AD at intervals not to exceed 2500 landings since the last inspection.
(b) For airplanes equipped with horizontal stabilizers that incorporate the modification contained in Part (d) of British Aircraft Corporation Service Bulletin 55-PM3485 comply with paragraph (c) of this AD as follows:
(1) If the horizontal stabilizer has accumulated less than 39,000 total landings on the effective date of this AD -
(i) Prior to the accumulation of 40,000 total landings, inspect in accordance with paragraph (c) of this AD.
(ii) Thereafter, continue to inspect in accordance with paragraph (c) at intervals not to exceed 6000 landings since the last inspection.
(2) If the horizontal stabilizer has accumulated 39,000 or more total landings on the effective date of this AD -
(i) Prior to the accumulation of 1000 additional landings, unless already accomplished within the last 6000 landings, inspect in accordance with paragraph (c) of this AD.
(ii) Thereafter, continue to inspect in accordance with paragraph (c) at intervals not to exceed 6000 landings since the last inspection.
(c) Inspect the horizontal stabilizer structure for cracks in accordance with paragraphs 2.3.1, 2.3.2, and 2.3.3 of British Aircraft Corporation Alert Service Bulletin 55-A-PM 5208, Issue No. 1, dated November 14, 1974, or an FAA-approved equivalent.
(d) If any cracks are found during an inspection required by paragraph (a) or (b) of this AD, before further flight, conduct the detailed inspection of the horizontal stabilizer structure in accordance with the applicable provisions of paragraphs 2.5 through 2.5.2 of British Aircraft Corporation Alert Service Bulletin 55-A-PM 5208, Issue No. 1, dated November 14, 1974, or an FAA-approved equivalent.
(e) If, during an inspection required by paragraphs (a), (b), (d), or (e) of this AD, cracks are found only in the outboard channel brackets, accomplish the following:
(1) Measure the cracks in accordance with the criteria specified in paragraphs 2.6.1. and 2.6.2. of British Aircraft Corporation Alert Service Bulletin 55-A-PM 5208, Issue No. 1, dated November 14, 1974.
(2) If cracks measure, in length -
(i) Less than 0.3 inches, reinspect the crack for crack propagation at intervals not to exceed 500 landings since the last inspection;
(ii) 0.3 inches or more but less than 0.4 inches, reinspect the crack for crack propagation at intervals not to exceed 200 landings since the last inspection; and
(iii) 0.4 inches or more but less than 0.5 inches, reinspect the crack for crack propagation at intervals not to exceed 100 landings since the last inspection.
(3) Continue performing the inspections required by paragraphs (a), (b), and (d) of this AD.
(f) If a crack if found in an outboard channel bracket that measures 0.5 inches or more in length or a crack of any length is found in any other component of the horizontal stabilizer during any of the inspections required by this AD, before further flight, except as provided in paragraph (g) of this AD, replace the component with a new part of the same part number or an FAA-approved equivalent.
(g) Upon the request of an operator, the Chief, Aircraft Certification Staff, Europe, Africa and Middle East Region may adjust crack length limitations, approve alternate repetitive inspection intervals, or approve rework procedures to provide for continued operations by an operator, without the replacement of parts, as required under paragraph (f) of this AD, if data substantiating such action is submitted by the operator.
(h) 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 total hours' time in service by the operator's fleet average time from takeoff to landing for the airplane type.
This amendment becomes effective March 4, 1976.