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99-09-20 BELL HELICOPTER TEXTRON CANADA: Amendment 39-11153. Docket No. 98-SW-49-AD.
Applicability: Model 222 helicopters, serial numbers (S/N) 47006 through 47089, Model 222B helicopters, S/N's 47131 through 47156, and Model 222U helicopters, S/N's 47501 through 47574, 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 (b) 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 fretting induced fatigue cracking of the main rotor flapping bearing assembly (flapping bearing assembly) and around the bolt holes of the main rotor pitch horn (pitch horn), loss of the rotor system, and subsequent loss of control of the helicopter, accomplish the following:
(a) Within 10 hours time-in-service (TIS), and thereafter at intervals not to exceed 150 hours TIS:
(1) Perform a visual inspection of the main rotor hub for fretting between the pitch horn and main rotor grip tangs (grip tangs) and between the flapping bearing assembly and the main rotor yoke assembly. If fretting is found on any part, replace it with an airworthy part.
(2) Verify the torque of the main rotor grip retaining bolts and the flapping bearing assembly bolts in the tightening direction, minimum 100 foot-pounds. If 100 foot-pounds torque is reached without movement of the bolts, torque bolts to 125 foot-pounds.
(3) If any bolt moves before 100 foot-pounds torque is reached, remove the pitch horn or the flapping bearing assembly, as applicable, from the main rotor hub assembly for further inspection. Inspect the pitch horn or flapping bearing assembly, as applicable, and all faying surfaces of the pitch horn, flapping bearing assembly, buffers, main rotor yoke assembly, and the grip tangs for fretting. If fretting is found on any part, replace it with an airworthy part.
(4) Apply corrosion preventive compound to the exposed portions of the bolts and nuts.
NOTE 2: Bell Helicopter Textron Alert Service Bulletin Nos. 222-98-81 and 222U-98-52, both dated April 23, 1998, pertain 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, Rotorcraft Certification Office, FAA, Rotorcraft Directorate. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.
NOTE 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Rotorcraft 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.
NOTE 4: The subject of this AD is addressed in Transport Canada (Canada) AD CF-98-16, dated July 15, 1998.
(d) This amendment becomes effective on May 14, 1999.
