AD 78-16-01

78-16-01 BELL HELICOPTER TEXTRON (BHT): Amendment 39-3271. Applies to Models 206A and 206B helicopters, serial numbers 148 and 414 through 913, certificated in all categories.

Compliance is required within the next 500 hours times in service after the effective date of this airworthiness directive unless already accomplished.

To minimize the possibility of loss of directional control due to failure of the tail rotor drive shaft, remove and replace the tail rotor drive shaft bearing hangers with improved bearing hangers as specified below:

a.

REMOVE INSTALL (Shim Type) (Spring Type) One (1) hanger P/N 206-040-345-5 One (1) hanger P/N 206-040-345-9 or P/N 206-040-355-1 One (1) hanger P/N 206-040-346-5 One (1) hanger P/N 206-040-346-17 Five (5) hangers P/N 206-040-338-1 Five (5) hangers P/N 206-040-338-9

b. Shim type hangers modified to the spring type using instructions provided in Technical Bulletin No. 206-77-7 will be acceptable for compliance with this AD.

c. All spring clamp type bearing hangers, P/N's 206-040-338-9, 206-040-355-1, 206-040-345-9, and 206-040-346-17 must be installed with the spring on the left side of the tail boom.

d. To prevent bearing hangers from chafing the drive shaft cover, the cover must be modified in accordance with Bell Helicopter Company Technical Bulletin No. 206-76-2 dated January 7, 1976, (misdated 206-76-2), or later FAA approved revision or FAA approved equivalent.

e. Removal and replacement, as prescribed by paragraph a., must be in accordance with the applicable maintenance and overhaul instructions.

Bell Helicopter Company Service Bulletin No. 206-77-9 pertains to and provides instructions for accomplishing the intent of this AD. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part thereof pursuant to U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Service Manager, Bell Helicopter Textron, Post Office Box 482, Fort Worth, Texas 76101. These documents may also be examined at Office of the Regional Counsel, Southwest Region, Federal Aviation Administration, 4400 Blue Mound Road, Fort Worth, Texas 76106, and at Federal Aviation Administration Headquarters, 800 Independence Avenue, S.W., Washington, D.C. 20591.

Equivalent means of compliance with the modifications prescribed by this Airworthiness Directive may be approved by the Chief, Engineering and Manufacturing Branch, Flight Standards Division, Southwest Region, Federal Aviation Administration, Post Office Box 1689, Fort Worth, Texas 76101.

This amendment becomes effective September 14, 1978.