92-23-01 BELL HELICOPTER TEXTRON, INC. (BHTI); CALIFORNIA DEPARTMENT OF FORESTRY; GARLICK HELICOPTERS; HAWKINS AND POWERS AVIATION, INC; INTERNATIONAL HELICOPTERS, INC.; PILOT PERSONNEL INTERNATIONAL, INC.; SOUTHERN AERO CORPORATION; AND SOUTHWEST FLORIDA AVIATION: Amendment 39-8401. Docket No. 90-ASW-42.
Applicability: All BHTI Model 204B, 205A, 205A-1, 205B, and 212 helicopters, certificated in any category, and military Model UH-1B, UH-1F, and UH-1H helicopters, certificated in the restricted category.
Compliance: Required as indicated, unless accomplished previously.
To prevent separation of the main rotor pillow blocks from the hub assembly as a result of bolt cracking, which could result in loss of the main rotor and subsequent loss of control of the helicopter, accomplish the following:
(a) Within the next 300 hours time in service after the effective date of this AD; or at the next main rotor hub retention strap change; or at the next hub assembly overhaul; whichever occurs first, remove the four bolts, part number (P/N) 204-011-171-003, joining the two pillow blocks to the main rotor yoke assembly. Reinstall the pillow blocks using new (zero time) bolts, P/N 204-011-171-003; nuts, P/N EB080 or 42FLW-820; and washers, P/N 140-007-33S28-3 as follows:
(1) Coat the shank of the bolts with corrosion prevention compound, such as MIL-C-16173 Grade 1, and dry torque the bolts and nuts 65 to 79 foot-pounds. Retorque nuts within 15 to 30 hours time in service after the initial installation. If the torque has reduced below the minimum value of 65 foot-pounds, repeat the torque check at intervals of 15 to 30 hours time in service until the torque remains at or above 65-foot pounds or until the torque check has been accomplished four times. If during the fourth check the torque has reduced below 65 foot-pounds, remove and replace the bolts, washers, and nuts and repeat the torque check procedure of this paragraph.
(2) After initialinstallation or retorque, apply sealant, such as BHTI P/N 299-947-107 TYIII CL7, to the four bolt heads, washers, nuts and yoke mating surfaces to prevent moisture from entering the pillow block retention area.
(b) Thereafter, remove the bolts and associated hardware from the pillow block and replace with new bolts, washers, and nuts as described in paragraph (a) of this AD at each hub assembly overhaul, at each change of the main rotor hub retention strap, or whenever the bolts are removed for any reason.
NOTE: Bell Helicopter Textron, Inc., Alert Service Bulletins 204-90-27, Revision A; 205-90-38, Revision A; and 212-90-62, Revision A, all dated October 11, 1990, pertain to this AD. A copy of the service bulletins may be obtained from Bell Helicopter Textron, Inc., P.O. Box 482, Fort Worth, Texas 76101.
(c) Rework or repair of the bolts, P/N 204-011-171-003; nuts, P/N EB080 or 42FLW-820; and washers, P/N 140-007-33S28-3, is not authorized.
(d) An alternative method ofcompliance or adjustment of the compliance times, which provides an acceptable level of safety, may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, Federal Aviation Administration, Fort Worth, Texas 76193-0170. Operators shall submit their request through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Rotorcraft Certification Office.
NOTE: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Manager, Rotorcraft Certification Office.
(e) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished.
(f) This amendment becomes effective April 23, 1993.