AD 97-20-16 Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters

Models named: MBB-BK117 A-1, A-3, A-4, B-1, B-2, C-1. Read the applicability below — it usually turns on serial or part numbers too.

Model MBB-BK117 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 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 use the authority provided in paragraph (f) to request approval from the FAA. This approval may address either no action, if the current configuration eliminates the unsafe condition, or different actions necessary to address the unsafe condition described in this AD. Such a request should include an assessment of the effect of the changed configuration on the unsafe condition addressed by this AD. In no [[Page 52657]] case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD.

Required as indicated, unless accomplished previously. To prevent failure of the tail boom vertical fin (vertical fin) and subsequent loss of control of the helicopter, accomplish the following: (a) Before further flight, remove the tail rotor drive shaft between the intermediate and tail rotor gearboxes and the yaw servo (if installed). Thoroughly clean the vertical fin spar and adjacent areas and visually inspect the following for cracks or loose rivets: (1) Both surfaces of the vertical fin spar, part number (P/N) 105-304061.03, P/N 1120-30406.03, or P/N 117-30423-03, paying particular attention to the area extending from the top edge of the third lightening hole from the top of the vertical fin spar to halfway between the fourth and fifth lightening hole (see Figure 1). (2) The skin and left-hand and right-hand frame sheets. (b) If a crack or loose rivet is found in the area described in paragraph (a) of this AD (see Figure 1), before further flight, repair in accordance with the Appendix, ``Repair of BK117 Vertical Fin'', to Eurocopter Alert Service Bulletin MBB-BK117 No. ASB-MBB- BK117-30-106, Revision 3, dated May 5, 1997. Thereafter, perform the inspection described in paragraph (a) of this AD at intervals not to exceed 300 hours TIS. (c) If a crack or lose rivet is found in the area other than that described in paragraph (a) of this AD, including any crack that is found to extend into the skin, P/N 105-304011.18 or P/N 1120- 30402.08, before further flight, contact the Rotorcraft Standards Staff. Reporting requirements have been approved by the Office of Management and Budget and assigned OMB control number 2120-0056. (d) If no crack or loose rivet is found as a result of the inspection required by paragraph (a) of this AD, thereafter, until the repair is made in accordance with the Appendix, ``Repair of BK117 Vertical Fin'', to Eurocopter Alert Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30- 106, Revision 3, dated May 5, 1997, conduct the visual inspection required by paragraph (a) of this AD at intervals not to exceed 100 hours TIS. (e) Within 600 hours TIS after the effective date of this AD, accomplish the repair to the vertical fin in accordance with the Appendix, ``Repair of BK117 Vertical Fin'', to Eurocopter Alert Service Bulletin MBB-BK117 No. ASB-MBB-BK117-30-106, Revision 3, dated May 5, 1997. Thereafter, perform the visual inspection required by paragraph (a) of this AD at intervals not to exceed 300 hours TIS. (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, FAA, Rotorcraft Directorate, Rotorcraft Standards Staff. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Standards Staff. BILLING CODE 4910-13-U [[Page 52658]] [GRAPHIC] [TIFF OMITTED] TR09OC97.025 BILLING CODE 4910-13-C [[Page 52659]] Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft Standards Staff. (g) Special flight permits will not be issued. (h) The inspections and repair shall be done in accordance with Eurocopter Deutschland GmbH (ECD) Alert Service Bulletin ASB-MBB- BK117-30-106, Revision 3, dated May 5, 1997, including Appendix. 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 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 (Germany) AD 97-144/2, dated June 5, 1997. (i) This amendment becomes effective on October 24, 1997. Issued in Fort Worth, Texas, on September 26, 1997. Eric Bries, Acting Manager, Rotorcraft Directorate, Aircraft Certification Service. [FR Doc. 97-26792 Filed 10-8-97; 8:45 am] BILLING CODE 4910-13-U