AD/JBK 117/31 Tail Rotor Balance Weights (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 117/31 Tail Rotor Balance Weights 3/2009

Applicability:

All Model BK117 Series helicopters.

Requirement:

Inspect the tail rotor balance weights and control levers in accordance with the instructions of Kawasaki Service Bulletin (SB) No. KSB-117-297 original issue, or later JCAB approved revision.

If, during any inspection required by this Directive, damage is detected which exceeds the acceptable limits specified in SB No. KSB-117-297 original issue, or later JCAB approved revision, before further flight, replace the affected components with serviceable parts.

Note:  JCAB AD TCD-7416-2009 refers.

Compliance:

Within 2 months or 100 flight hours after 12 March 2009, whichever occurs first; and thereafter at intervals not to exceed 660 flight hours or 30 months, whichever occurs first.

This Airworthiness Directive becomes effective on 12 March 2009.

Background:

During a periodic inspection, corrosion was detected on the tail rotor balance weights in the area of the thread.  At advanced stage, this corrosion could possibly destroy the threads.  Unless prevented, undetected corrosion on the tail rotor balance weights in the area of the attachment threads could lead to failure of the threads, possible separation of tail rotor parts, and subsequent severe tail rotor vibration.

David Punshon
Delegate of the Civil Aviation Safety Authority

22 January 2009