1AD/GBK 117/11 Amdt 1 - Tension-Torsion Straps

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Eurocopter BK 117 Series Helicopters

AD/GBK 117/11

Amdt 1

Tension-Torsion Straps 11/99

Applicability: All Eurocopter MBB-BK 117 helicopters.

Requirement: Action in accordance with Eurocopter Alert Service Bulletin ASB-MBB-BK 117-10- 120 Revision 1, dated August 31 1999.

Note 1: The calendar time in service commences with date of issue of the initial certificate of airworthiness issued for the aircraft, or date of first installation for any replacement tension-torsion straps fitted, and is continuous from that date.

Note 2: LBA AD 1999-284/2 dated 1 September 1999 refers.

Compliance: At the times or number of flights stated in Eurocopter Alert Service Bulletin ASB- MBB-BK 117-10-120 Revision 1, dated 31 August 1999. For the purpose of section

1.D.3 a date of 18 August 1999 must be used as the reference date. Return to service of tension-torsion straps in accordance with section 1.D.4 applies only to parts which exceed 10 years calendar time in service on 18 August 1999.

This Amendment becomes effective on 4 November 1999.

Background: Failure of a tension-torsion strap installed in a US registered BK-117 helicopter caused a fatal crash of the aircraft. The actions of the Eurocopter Service Bulletin have been taken as a precautionary measure. The service limit placed on the tension- torsion strap is presently 10 years (since installation) or 25000 flights, whichever occurs first. Limited return to service of tension torsion straps following inspection is permitted for parts installed for less than 15 years, provided an inspection of the part is made.

Amendment 1 is issued in response to minor amendments of the Eurocopter Service Bulletin. As the amendments are for clarification, the initial compliance date is unchanged from the initial issue of this Directive.

The original issue of this Airworthiness Directive became effective on 18 August 1999.