99-21-02: Engine Mounting Tube Assembly

99-21-02 SHORT BROTHERS PLC: Amendment 39-11345. Docket 99-NM-29-AD. Issued September 27, 1999. Applicability: All Model SD3-30, SD3-60, SD3-SHERPA, and SD3-60 SHERPA series airplanes; certificated in any category. NOTE 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (c) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. Compliance: Required as indicated, unless accomplished previously. To prevent failure of the engine mounting tube assembly, which could result in loss of the engine in flight, accomplish the following: Inspections (a) Within 9 months after the effective date of this AD, perform a detailed visual inspection of the taper pins of the engine mounting tube assembly for corrosion in accordance with Shorts Service Bulletins SD330-71-23, dated November 20, 1998, or Revision 1, dated April 26, 1999 (for Model SD3-30 series airplanes); SD3 SHERPA-71-1, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-SHERPA series airplanes); SD3-60 SHERPA-71-1, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-60 SHERPA series airplanes); or SD360-71-18, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-60 series airplanes); as applicable. If corrosion is found on any taper pin, prior to further flight, replace the pinwith a new or serviceable pin. NOTE 2: For the purposes of this AD, a detailed visual inspection is defined as: "As an intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good light at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required." (b) Within 9 months after the effective date of this AD, perform a borescopic inspection of the internal surface of the engine mounting tubes and fittings for corrosion, in accordance with Shorts Service Bulletins SD330-71-23, dated November 20, 1998, or Revision 1, dated April 26, 1999 (for Model SD3-30 series airplanes); SD3 SHERPA-71-1, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-SHERPA series airplanes); SD3-60 SHERPA-71-1, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-60 SHERPA series airplanes); or SD360-71-18, Revision 1, dated February 3, 1999, or Revision 2, dated April 26, 1999 (for Model SD3-60 series airplanes); as applicable. (1) If no corrosion is found on the internal surface of the engine mounting tubes and fittings, no further action is required by this paragraph. (2) If corrosion is found that is within the limits as defined in the applicable service bulletin, repeat the borescopic inspection thereafter at intervals not to exceed 9 months. Replacement of all corroded parts with new or serviceable parts in accordance with the applicable service bulletin constitutes terminating action for the repetitive borescopic inspections required by this AD. (3) If corrosion is found that is outside the limits as defined in the applicable service bulletin, prior to further flight, replace the corroded parts with new or serviceable parts, in accordance with the applicable service bulletin. Alternative Methods of Compliance (c) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, International Branch, ANM-116, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, International Branch, ANM-116. NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the International Branch, ANM-116. Special Flight Permits (d) Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. Incorporation by Reference (e) The actions shall be done in accordance with the following Shorts service bulletins, as applicable, which contain the specified effective pages: Service Bulletin Referenced and Date Revision Level Page Number Date Shown on Page Shown on Page SD330-71-23, November 20, 1998 1-11 Original November 20, 1998 SD330-71-23, Revision 1, April 26, 1999 1, 2 3-11 1 Original April 26, 1999 November 20, 1998 SD3 SHERPA-71-1, Revision 1, February 3, 1999 1, 6-8 2-5, 9-11 1 Original February 3, 1999 November 20, 1998 SD3 SHERPA-71-1, Revision 2, April 26, 1999 1, 2 3-5, 9-11 6-8 2 Original 1 April 26, 1999 November 20, 1998 February 3, 1999 SD3-60 SHERPA-71-1, Revision 1, February 3, 1999 1, 6-8 2-5, 9-11 1 Original February 3, 1999 November 20, 1998 SD3-60 SHERPA-71-1, Revision 2, April 26, 1999 1, 2 3-5, 9-11 6-8 2 Original 1 April 26, 1999 November 20, 1998 February 3, 1999 SD360-71-18, Revision 1, February 3, 1999 1, 6, 8 2-5, 7, 9-11 1 Original February 3, 1999 November 24, 1998 SD360-71-18, Revision 2, April 26, 1999 1, 2 3-5, 7, 9-11 6, 8 2 Original 1 April 26, 1999 November 24, 1998 February 3, 1999 This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be obtained from Short Brothers, Airworthiness & Engineering Quality, P.O. Box 241, Airport Road, Belfast BT3 9DZ, Northern Ireland. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. NOTE 4: The subject of this AD is addressed in British airworthiness directives 014-11-98, 018-11-98, 011-11-98, and 012-11-98. (f) This amendment becomes effective on November 5, 1999.