AD/INST/13 Venting of SEP 2 Servomotor Clutches Modification 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/INST/13.

Instruments and Automatic Pilots

AD/INST/13 Venting of SEP 2 Servomotor
Clutches - Modification 3/2009

Requirement:

CANCELLED.

This AD is cancelled on 12 March 2009.

Background:

This unique Australian AD raised in 1975 against Smiths Industries Ltd Service Bulletin (SB) SB 22-872 required a modification to the servomotor by introducing two vent holes in the armature assembly of the clutch assembly to assist the clutch to disengage when power supplies were removed.

Compliance was at next repair or reconditioning of the servomotor.

At the time the AD was raised, the SB compliance was mandatory on repair or overhaul (manufactures TBO recommendation was 12,000 hrs or 5 years).  A subsequent amendment to the SB changed this compliance to recommended on repair or overhaul.  No overhaul period was indicated.

Given the foregoing, and the extended time this AD has been promulgated it is considered that the affected servomotors would have been modified by now, therefore this AD is considered to be no longer required.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 January 2009