88-17-09 R1: Tail Rotor Transmission

88-17-09 R1 MCDONNELL DOUGLAS HELICOPTER COMPANY (MDHC) (HUGHES HELICOPTERS, INC.): Amendment 39-5964 as revised by Amendment 39-6400. Docket No. 88-ASW-24. Applicability: Model 369D, E, F, and FF helicopters, certificated in any category, which have tail rotor transmission/tail boom extension mounting studs, Part Number (P/N) MS51992A803-13 or -14, installed. Compliance: Required as indicated, unless already accomplished. (a) To prevent failure of the tail rotor transmission mounting studs (P/N MS51992A803-13 or -14) on MDHC Model 369 D/E helicopters, accomplish the following: (1) Prior to further flight after the effective date of this AD, conduct an initial inspection of the tail rotor transmission attachment to the tail boom casting for any indications of relative motion between the parts in accordance with MDHC Service Information Notice (SIN) DN-151/EN-39/FN-28, Part I, paragraphs a, b, c, d, and e, dated October 10, 1987. (2) Within the next 25hours' time in service after the effective date of this amended AD, and at intervals not to exceed 25 hours' time in service from the last check, conduct a check for security in accordance with MDHC SIN DN-151/EN-39/FN-28, Part II, paragraph a, dated October 10, 1987. The checks required by this paragraph may be performed by the pilot and must be recorded in accordance with FAR Section 43.9. (3) If there are indications of relative motion between the tail rotor transmission and the tail boom casting found by the inspection and check of paragraphs (a)(1) and (a)(2), prior to further flight, remove the tail rotor transmission and replace all four mounting studs in accordance with MDHC SIN DN-151/EN-39/FN-28, Part III, paragraphs a thru j, dated October 10, 1987. (4) At intervals not to exceed 100 hours' time in service from the last inspection after the effective date of this AD, conduct repetitive inspections of the torque of each mounting nut and reapply torque stripe paint in accordance with MDHC SIN DN-151/EN-39/FN- 28, Part IV, paragraphs a and b, dated October 10, 1987. (b) To prevent failure of the tail boom extension mounting studs (P/N MS51992A803-13 or -14) on MDHC Model 369 F/FF helicopters, accomplish the following: (1) Prior to further flight after the effective date of this AD, conduct an initial inspection of the tail boom extension attachment to the tail boom casting for any indications of relative motion between the parts in accordance with MDHC SIN DN-151/EN- 39/FN-28, Part I, paragraphs a, b, c, d, and e, dated October 10, 1987. (2) Within the next 25 hours' time in service after the effective date of this amended AD, and at intervals not to exceed 25 hours' time in service from the last check, conduct a check of the tail boom extension installation for security in accordance with MDHC SIN DN- 151/EN-39/FN-28, Part II, paragraph a, dated October 10, 1987. The checks required by this paragraph may be performed by the pilot and must be recorded in accordance with FAR Section 43.9. (3) If there are indications of relative motion of fretting products between the tail boom casting and the tail boom extension found by the above inspections or checks, prior to further flight, remove tail boom extension and replace all four studs in accordance with MDHC SIN DN-151/EN-39/FN-28, Part III, paragraphs b thru j, dated October 10, 1987. (4) At intervals not to exceed 100 hours' time in service from the last inspection after the effective date of this AD, conduct repetitive inspections of the torque of each mounting nut and reapply torque stripe paint in accordance with MDHC SIN DN-151/EN-39/FN- 28, Part IV, paragraphs a and b, dated October 10, 1987. (c) An alternate means of compliance which provides an equivalent level of safety may be used when approved by the Manager, Western Aircraft Certification Office, P.O. Box 92007, Worldway Postal Center, Los Angeles, CA 90009-2007. (d) In accordance with Sections 21.197 and 21.199, the helicopters may be flown to a base where compliance may be accomplished. These inspections and check procedures shall be done in accordance with MDHC Mandatory SIN DN-151/EN-39/FN-28, dated October 10, 1987. 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 MDHC Technical Publications, Building 543/D214, McDonnell Douglas Helicopter Company, 5000 E. McDowell Road, Mesa, Arizona 85205-9797, telephone (602) 891-6484. A copy may also be inspected at the Office of the Assistant Chief Counsel, Federal Aviation Administration, 4400 Blue Mound Road, Room 158, Building 3B, Fort Worth, Texas, or at the Office of the Federal Register, 1100 L Street NW, Room 8401, Washington, D.C. This AD revises Amendment 39-5964 (53 FR 30023; August 10, 1988), AD 88-17-09, which became effective on August 24, 1988. This amendment (39-6400, AD 88-17-09 R1) becomes effective on December 26, 1989.