AD/Hiller 12/3 Tail Rotor Blade Assembly Provision of Vent Hole Cancelled (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive AD/HILLER 12/3.

Hiller UH-12 Series Helicopters

AD/HILLER 12/3 Tail Rotor Blade
Assembly - Provision of Vent Hole 9/2009

Requirement:

CANCELLED.

This AD is cancelled on 27 August 2009.

Background:

This AD, raised in 1961 against Hiller Aircraft Corporation Service Information Letter (SIL) No. 133, required a modification to tail rotor blades by drilling a vent hole in the root fitting to alleviate pressure pulsations within the blade and the attendant flexing of the blade skin.  Compliance was required before 15 February 1961.

As all affected aircraft would have been modified long ago, this AD is no longer required.

David Villiers
Delegate of the Civil Aviation Safety Authority

15 July 2009