AD/JBK 117/26 - Tail Rotor Transmission Attachment Nuts (Cth)

AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Kawasaki BK 117 Series Helicopters AD/JBK 117/26 Tail Rotor Transmission Attachment Nuts 2/2008 TX

Applicability: Kawasaki BK117 series helicopters. Requirement: 1. Inspect for cracks on the four (04) attachment nuts of the tail rotor transmission in accordance with Kawasaki Service Bulletin No.KSB-117-291 dated 11 December 2007 or later Japan Civil Aviation Bureau (JCAB) approved revisions.

If cracks are found, replace all attachment nuts with new nuts.

2. If nuts are replaced with new nuts in accordance with Requirement 1 of this AD, inspect new nuts (after installation) for cracks.

If any cracks are found, replace all attachment nuts with another set of new nuts.

Note: JCAB Airworthiness Directive No. TCD-7195-2007 dated 11 December 2007 refers. Compliance: Before further flight, after the effective date of this AD. This Airworthiness Directive becomes effective on 18 December 2007. Background: During an inspection after installation of the tail rotor transmission, cracks have been detected on the four attachment nuts. Loss of nut self-locking torque due to cracking may lead to the failure of tail rotor transmission.