AD/ENST 28/26 Amdt 2 - Tail Rotor Drive Shaft Couplings (Cth)

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES

Enstrom F-28 Series Helicopters

AD/ENST 28/26 Amdt 2

Tail Rotor Drive Shaft Couplings 10/90

Applicability: All F-28A, 280, F28C, F-28C-2, 280C , F-28F and 280F models equipped with part number 28-13609 couplings.

Requirement: Part 1: Disassemble and inspect couplings in accordance with Service Directive Bulletin No. 0065 Rev B.

Part 2: Partially disassemble and lubricate couplings in accordance with Service Bulletin No. 0065 Rev B.

Part 3: Carry out a Rockwell "C" material hardness check in accordance with Service Bulletin No. 0065 Rev. B.

Note: Use Aeroshell Grease 16 or 22, or an approved equivalent FAA AD 83-18-64 Amendment 39-4721 refers to Revision A of Service Directive Bulletin.

Compliance: Part 1: Within 25 hours time in service after 1st October 1983 or no later than the 31 October 1983, whichever occurs first and thereafter every 600 hours time in service or annually whichever occurs first. Part 2: At each maintenance release inspection. Part 3: Unless already accomplished, prior to the issue of the next maintenance release after 31 January 1985.

Any coupling which fails the material hardness test must be retired from service. Couplings must be retired from service at a total time in service of 1200 hours. Those couplings with more than 1200 hours time in service, retire within 50 hours time in service after 31 January 1985.

Background: This directive is amended to include a one time material hardness inspection, and the retirement life of the couplings in accordance with the manufacturers recommended revised Service Bulletin 0065. This amendment requires all couplings failing the hardness test to be retired from service".