Applicability: Applies to Bell Helicopter Textron Canada (BHTC) Model 206L series helicopters as indicated. Tailboom assemblies modified in accordance with Technical Bulletin (TB) 206L-96-191, or BHT-206-SRM-1, section 6-3-4, with upper tailboom skin P/N 206-033-004-155 installed, are not affected by this directive.

Effective date: December 31, 1998

Compliance : Required as indicated in TC AD CF-98-27

THE FOLOWING AIRWORTHINESS DIRECTIVE (AD/ MAY BE APPLICABLE TO AN AIRCRAFT, WHICH OUR RECORDS INDICATE IS REGISTERED IN YOUR NAME. ADs ARE ISSUED PURSUANT TO CANAD/AN AVIATION REGULATION ICAR) 593. PURSUANT TO CAR 605.8b 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 MAV INVALIDATE THE FLIGHT AUTHORIZATION OF THE A/RCRAR. 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 series helicopters as indicated. Tailboom assemblies modified in accordance with Technical Bulletin (TB) 206L-96-191, or BHT-206-SRM-1, section 6-3-4, with upper tailboom skin P/N 206-033-004-155 installed, are not affected by this directive.

Compliance is required as indicated, unless already accomplished.

Cracking has been reported on tailbooms of earlier designs. If left. undetected, these cracks could lead to failure of the tailboom and loss of control of the helicopter. Bell has issued Alert Service Bulletins (ASB) 206L-87-47 Revision C, dated 23 October 1989, and 206L-97-107 Revision A, dated 4 February 1998, detailing inspections required to detect cracks and providing applicable modifications.

To ensure the structural integrity of all affected tailbooms, accomplish the following measures as applicable:

Part 1.
Applies to Model 206L series helicopters, S/N 45001 through 51283, having unmodified tailboom assemblies P/N 206-033-004-003, -011, -045 and -103.

Within the next 200 hours air time after the effective date of this directive, but not later than 31 May 1999, 159.35 by m modify the tailboom between boom station BS 151.15 and 159.35 by installing doubler P/N 206-704-167-111 with clip P/N 206-033-407-119, and re-identify the tailboom by adding the suffix "FM" to the original part number as outlined in Part I of ASB 206L-87-47 Revision C.

Part 2.
Applies to the following Model 206L series helicopters:

having tailboom assemblies of the following part numbers:

206-033-004-003FM, -003FM1
206-033-004-OllFM, -011FM1, -011FM2, -011FM3
206-033-004-103FM, -103FM1
206-033-004-045FM

(a)For tailbooms with a sheet metal tail rotor gearbox support, within the next 100 hours air time after the effective date of this directive and at every 1000 (+ 10 % ) hours air time thereafter, perform an Eddy Current inspection as outlined in Part I of ASB 206L-97-107 Revision A.

(b)For tailbooms with a cast tail rotor gearbox support P/N 206-033-426-001 and that do not have upper skin P/N 206-033-004-155 installed, within the next 200 hours air time after the effective date of this directive, but not later than 31 May 1999, install nutplate assemblies as per Part II of ASB 206L-97-107 Revision A.

Part 3.
For all Model 206L helicopters affected by Parts 1 and 2 above, replacement of the tailboom with any tailboom listed below constitutes terminating action for the requirements of Parts 1 and 2 of this directive:

206-033-004-003FM2
206-033-004-OllFM4
206-033-004-103FM2
206-033-004-045FM1, -045FM2
206-033-004-143, -143FM1
206-033-004-175, -175FM1
206-033-004-177

Note: The reference to MIL-STD-6866, for fluorescent dye penetrant inspection as listed in ASB 206L-97-107 Revision A, Part II, paragraph 4, page 9, has since been replaced by American Society for Testing and Materials Standard ASTM E1417-95a, "Practice for Liquid Penetrant Examination".

This directive become effective 18 October 1998.

For Minister of Transport
J.E. Hurley
Acting Chief, Continuing Airworthiness