Applicability: Applies to Bell Helicopter Textron Canada (BHTC) Model 206L-4 helicopters equipped with High Altitude Tail Rotor Kit P/N 206-704-722-101 (BHT-206-SI-2054) installed; and to all spare yoke assemblies P/N 406-012-102-107 having previous time in service.

Effective date: July 27, 1998

Compliance: Required as indicated in TCA CF-98-11

Transport Canada Civil Aviation, No.: CF-98-11, Date: 16 June 1998

THE FOLLOWING AIRWORTHINESS DIRECTIVE (AD) MAY BE APPLICABLE TO AN AIRCRAFT, WHICH OUR RECORDS INDICATE IS REGISTERED IN YOUR NAME. ADs ARE ISSUED PURSUANT TO CANADIAN AVIATION REGULATION (CAR) 593. PURSUANT TO CAR 605.84 AND THE FURTHER DETAILS OF CAR STANDARD 625, APPENDIX H, THE CONTINUING AIRWORTHINESS OF AN AIRCRAFT IS CONTINGENT UPON COMPLIANCE WITH ALL APPLICABLE ADs. FAILURE TO COMPLY WITH THE REOUIREMENTS OF AN AD MAY INVALIDATE THE FLIGHT AUTHORIZATION OF THE. AIRCRAFT. ALTERNATIVE MEANS OF COMPLIANCE SHALL BE APPLIED FOR IN ACCORDANCE WITH CAR 605.84 AND THE ABOVE-REFERENCED STANDARD.

Applies to Bell Helicopter Textron Canada (BHTC) Model 206L-4 helicopters equipped with High Altitude Tail Rotor Kit P/N 206-704-722-101 (BHT-206-SI-2054) installed; and to all spare yoke assemblies P/N 406-012-102-107 having previous time in service.

Compliance is required as follows, unless already accomplished:

(i) Within 100 hours air time, but not later than 1 October 1998, for installed yokes; and

(ii) Prior to installation, for spare yokes having previous time in service.It was determined that the tail rotor yoke is susceptible to static and dynamic overloads. The use of a previously overloaded yoke creates a safety hazard since the airworthiness of the overloaded yoke has been seriously compromised. There are a number of possible events that can lead to overloading the yoke. Installation of a new witness stop will allow for timely detection of the overload condition. BHTC Alert Service Bulletin 206L-96-104 Rev. A, dated 25 October 1996, refers.

To ensure the continuing airworthiness of the tail rotor yoke, accomplish the following:

l. Perform a dimensional inspection of the tail rotor yoke and install a new stop P/N 206-0ll-752-101 as outlined in Part II of BHTC Alert Service Bulletin 206L-96-104 Rev. A, or later revision approved by the Director, Aircraft Certification, Transport Canada.

2. Incorporate the Rotorcraft Flight Manual Supplement, “High Altitude Tail Rotor System”, Revision 1, dated 8 August 1996, in the basic Flight Manual.

This directive becomes effective 17 July 1998.

For Minister of Transport

B. Goyaniuk

Acting Chief, Continuing Airworthiness

For further information contact a Transport Canada Centre, or Mr. Bogdan Gajewski, Continuing Airworthiness, Ottawa, telephone (613) 952-4450, facsimile (613) 996-9178 or e-mail gajewsb@tc.gc.ca.