AD 90-10-05

90-10-05 CALIFORNIA DEPARTMENT OF FORESTRY; GARLICK HELICOPTERS; HAWKINS AND POWERS AVIATION, INC.; HERCULES; INTERNATIONAL HELICOPTERS, INC.; OFFSHORE CONSTRUCTION; OREGON HELICOPTERS; PILOT PERSONNEL INTERNATIONAL, INC.; SMITH HELICOPTERS; SOUTHERN AERO CORPORATION; SOUTHWEST FLORIDA AVIATION; AND WEST COAST FABRICATIONS (these helicopters were manufactured by Bell Helicopter Textron, Inc under military contract): Amendment 39-6596. Docket No 89-ASW-52.

Applicability: Model UH-1A, UH-1B, UH-1E, UH-1F, UH-1H, UH-1L, and TH-1L helicopters, certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent failure of the tail rotor duplex bearing which could result in loss of tail rotor control and subsequent loss of the helicopter, accomplish the following:

(a) Within the next 100 hours' time in service after the effective date of this AD, determine if the tail rotor gearbox duplex bearing sets, P/N 204-040-424-001, havingthe following serial numbers are installed in the tail rotor gearbox output quill, P/N 204-040-012-009:

Serial Numbers

1 thru 182

MB183 thru MB382 MB442 MB486 MB513 MB518 MB519 MB524 MB530 MB531 MB544 MB545 MB548 MB549 MB551 MB553 MB554 MB561 MB659 MB743 MB744 MB760 thru MB769

MB927 thru MB936

If a part with any of the listed serial numbers is installed, replace with a serviceable part before further flight.

(b) In accordance with FAR Sections 21.197 and 21.199, the helicopter may be flown to a base where the requirements of this AD may be accomplished.

(c) An alternate method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be used when approved by the Manager, Rotorcraft Certification Office, ASW-170, Rotorcraft Directorate, FAA, Southwest Region, Fort Worth, Texas.

This amendment (39-6596, AD 90-10-05) becomes effective on June 5, 1990.