99-02-02: Flexplates

99-02-02 ROBINSON HELICOPTER COMPANY: Amendment 39-10991. Docket No. 98-SW-79-AD. Supersedes AD 95-06-07, Amendment 39-9177, Docket No. 94-SW-22-AD and Priority Letter AD 98-14-08, Docket No. 98-SW-30-AD. Applicability: Model R22 helicopters, with forward flexplate (flexplate), part number (P/N) A947-1, A through D, or P/N A193-1, installed, 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 (b) 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 case does the presence of any modification, alteration, or repair remove any helicopter from the applicability of this AD. Compliance: Required within 25 hours time-in-service (TIS) or 15 calendar days, whichever occurs first, unless accomplished previously. To prevent failure of the flexplate, which could result in failure of the main rotor drive system and subsequent loss of control of the helicopter, accomplish the following: (a) Remove the flexplate and replace it with an airworthy flexplate, P/N A947-1 E or F, in accordance with following: (1) With the clutch disengaged, support the forward end of the clutch shaft, P/N A166-1, and remove the forward flexplate, P/N A947-1 or A193-1, and the intermediate flexplate, P/N A947-2 or P/N A193-2. Record any shim locations for reinstallation.(2) Install a zero TIS forward flexplate, P/N A947-1 E or F, and any shims that were noted. Use washers, P/N AN960-516 or AN960-516L, under the nut so that 2-4 threads are exposed. Torque the fasteners. (3) Inspect the sheave alignment. (4) Inspect the clutch shaft, P/N A166-1, angle. (5) Reinstall the intermediate flexplate and shim. NOTE 2: Robinson R22 Maintenance Manual, Sections 1.320, 7.230, 7.240, and 7.330 pertain to paragraphs (a)(2), (a)(3), (a)(4), and (a)(5) of this AD, respectively. NOTE 3: Robinson Helicopter Company R22 Service Bulletin SB-75, dated November 22, 1994, pertains to the subject of this AD. (b) 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, Los Angeles Aircraft Certification Office, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles Aircraft Certification Office. NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Los Angeles Aircraft Certification Office. (c) 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 helicopter to a location where the requirements of this AD can be accomplished. (d) This amendment becomes effective on February 1, 1999.