2000-01-11: Tension-Torsion (TT) Strap

2000-01-11 EUROCOPTER DEUTSCHLAND GMBH: Amendment 39-11509. Docket No. 99-SW-60-AD. Supersedes Emergency Priority Letter AD 99-17-07, Docket No. 99-SW-49-AD. Applicability: Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, certificated in any category. NOTE 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters 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 (f) 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 main rotor blade (blade) separation due to failure of a tension-torsion (TT) strap, accomplish the following: (a) Before further flight, (1) Create a component log card or equivalent record for each TT strap. (2) Review the history of the helicopter and each TT strap. Determine the age since initial installation on any helicopter (age) and the number of flights on each TT strap. Enter both the age and the number of flights for each TT strap on the component log card or equivalent record. Where the number of flights is unknown, multiply the number of hours time-in-service (TIS) by 5 to determine the number of flights. (3) If the number of flights and age cannot be determined, remove the TT strap from service. (4) Remove any TT strap from service that has either accumulated 25,000 or more flights or is equal to or greater than 180 months ofage. (b) When a TT strap age is equal to or greater than 120 months and less than 180 months and the number of flights on the TT straps are less than 25,000, inspect the TT strap in accordance with paragraph 2.B.2 of the "Accomplishment Instructions," Eurocopter Deutschland GMBH Alert Service Bulletin MBB-BK 117 No. ASB-MBB-BK 117-10-120 (ASB), Revision 1, dated August 31, 1999, according to the following: (1) If the age is greater than or equal to 120 months but less than 132 months and has less than 22,000 flights, inspect the TT strap within the next 6 weeks. If the number of flights equals or exceeds 22,000, inspect the TT strap before further flight. (2) If the age is greater than or equal to 132 months but less than 144 months and has less than 19,000 flights, inspect the TT strap within the next 5 weeks. If the number of flights equals or exceeds 19,000, inspect the TT strap before further flight. (3) If the age is greater than or equal to 144 months butless than 156 months and has less than 16,000 flights, inspect the TT strap within the next 4 weeks. If the number of flights equals or exceeds 16,000, inspect the TT strap before further flight. (4) If the age is greater than or equal to 156 months but less than 168 months and has less than 13,000 flights, inspect the TT strap within the next 3 weeks. If the number of flights equals or exceeds 13,000, inspect the TT strap before further flight. (5) If the age is greater than or equal to 168 months but less than 180 months and has less than 10,000 flights, inspect the TT strap within the next 2 weeks. If the number of flights equals or exceeds 10,000, inspect the TT strap before further flight. Remove any TT strap from service before exceeding the allowable number of flights or 180 months, whichever occurs first. (c) If a defect is found as a result of the inspection, remove the TT strap from service prior to further flight. (d) If no defect is found as aresult of the inspection in paragraph (b), a maximum of 500 flights is permitted on a one-time basis before the TT strap must be replaced, provided the limits of paragraphs (a)(4) and (b) are not exceeded. (e) TT straps, part number (P/N) 2604067 or J17322-1, are not eligible for installation. Prior to installation, P/N 2604067 or J17322-1 must be re-identified according to paragraph 2.B.1 of the "Accomplishment Instructions" of the ASB, Revision 1, dated August 31, 1999. (f) 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, Regulations Group, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Regulations Group. NOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Regulations Group. (g) Special flight permits may be issued for up to five flights in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the helicopter to a location where the requirements of this AD can be accomplished. (h) The inspections and re-identification of TT straps shall be done in accordance with the "Accomplishment Instructions," paragraph 2.B.1 and 2.B.2, of Eurocopter Deutschland GMBH Alert Service Bulletin MBB BK 117 No. ASB-MBB-BK 117-10-120, Revision 1, dated August 31, 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 American Eurocopter Corporation, 2701 Forum Drive, Grand Prairie, Texas 75053-4005, telephone (972) 641-3460, fax (972) 641-3527. Copies may be inspected at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC. NOTE 3: The subject of this AD is addressed in Luftfahrt-Bundesamt (LBA), Federal Republic of Germany, AD 1999-284, dated August 6, 1999. (i) This amendment becomes effective on January 28, 2000. FOR FURTHER INFORMATION CONTACT: Charles Harrison, Aerospace Engineer, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff, 2601 Meacham Blvd., Fort Worth, Texas 76137, telephone (817) 222-5128, fax (817) 222-5961.