AD 77-10-06

77-10-06 BELL HELICOPTER TEXTRON: Amendment 39-2897. Applies to Models 206A and 206B helicopters certificated in all categories as indicated below:

Compliance required within the next 100 hours time in service after the effective date of this Airworthiness Directive (AD), unless already accomplished.

To minimize the possibility of loss of directional control due to failure of the tail rotor drive shaft, remove and replace tail rotor drive shaft bearings, bearing hangers, retaining rings, and shaft segments as specified in items 1 through 7 below:

1. Helicopter Serial Numbers 1 through 413: Tail Rotor Drive Shaft Installation Part Number 206-040-301-1:

a.

Remove Install One (1) hanger, P/N 206-040-336-1 One (1) hanger, P/N 206-040-346-9 One (1) hanger, P/N 206-040-335-1 One (1) hanger, P/N 206-040-345-9 Five (5) hangers, P/N 206-040-331-1 Five (5) hangers, P/N 206-040-338-5 Seven (7) bearings, P/N 206-040-339-1 Seven (7) bearings, P/N206-040-339-9 Twelve (12) retainers, P/N RR216C -------------------------- One (1) shaft, P/N 206-040-320-7 One (1) shaft, P/N 206-040-320-11

b. To prevent bearing hangers from chafing the drive shaft cover, the cover must be modified in accordance with Bell Helicopter Company Technical Bulletin Number 206- 76-2 dated January 7, 1976, (misdated 206-76-2) or later FAA-approved revision or FAA- approved equivalent.

2. Helicopter Serial Numbers 414 through 913: Tail Rotor Drive Shaft Installation Part Number 206-040-301-7:

Remove Install Seven (7) bearings, P/N 206-040-339-3 or -5 Seven (7) bearings, P/N 206-040-339-9

3. Helicopter Serial Numbers 414 through 637: Tail Rotor Drive Shaft Installation Part Number 206-040-301-7:

Remove Install One (1) shaft, P/N 206-040-320-7 One (1) shaft, P/N 206-040-320-11

NOTE: Shaft P/N 206-040-320-7 may be reworked to configuration of Shaft P/N 206-040-320-11. See Part V of Bell Helicopter Company Service Bulletin Number 206-76-12.

4. Helicopter Serial Numbers 914 through 1251: Tail Rotor Drive Shaft Installation Part Number 206-040-301-13:

Remove Install Seven (7) bearings, P/N 206-040-339-3 or -5 Seven (7) bearings, P/N 206-040-339-9

5. Helicopter Serial Numbers 1252 through 1993: Tail Rotor Drive Shaft Installation Part Number 206-040-301-19:

Remove Install Seven (7) bearings, P/N 206-040-339-3 or -5 Seven (7) bearings, P/N 206-040-339-9

6. Removal and replacement as prescribed by paragraphs 1 through 5 must be in accordance with the applicable maintenance and overhaul manual instructions.

7. All spring clamp type bearing hangers, Part Number 206-040-338-5, must be installed with the spring on the left side of the tail boom.

Bell Helicopter Company Service Bulletin 206-76-12 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 hereof pursuant to 5 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, P.O. Box 482, Fort Worth, Texas, 76101. These documents may also be examined at Office of the Regional Counsel, Southwest Region, FAA, 4400 Blue Mound Road, Fort Worth, Texas, 76101, and at FAA Headquarters, 800 Independence Avenue S.W., Washington, D.C., 20591.

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

Upon request of the operator, an FAA maintenance inspector, subject to prior approval of the Chief, Engineering and Manufacturing Branch, Flight Standards Division, Southwest Region, Federal Aviation Administration, may adjust the compliance time prescribed by this AD, if the request contains substantiating data to justify the increase for that operator.

This amendment becomes effective May 13, 1977.