AD/DHC-1/6 Engine Mount Pick-Up Bolt Inspection 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/DHC-1/6.

De Havilland DHC-1 (Chipmunk) Series Aeroplanes

AD/DHC-1/6 Engine Mount Pick-Up Bolt - Inspection 11/2008

Requirement:

CANCELLED.

This AD is cancelled on 23 October 2008.

Background:

This unique AD was raised in 1954 against De Havilland (Canada) Technical News Sheet (TNS), Series "C” No. 39, issue 2, or Air Navigation Order (ANO) 105.1.14.15.6.1.  The AD required repeat inspections of the engine mount pick-up bolts following a report of one upper engine mount to firewall pick-up bolt being found broken partly due to the nut bottoming at the plain portion of the bolt shank during torquing.  TNS No. 39 issue 5 was introduced in 1956 cancelling all previous issues and recommending that a careful check be made of all four pick-up bolts for looseness at the next Daily Inspection and should any bolt be suspect modification 1/701 be embodied.  The modification introduced parallel shank bolts in lieu of stepped shank bolts.  Compliance was required at intervals not exceeding 50 hours TIS.

As there is no record of any failures of these bolts during compliance with this AD in the mandatory reporting system, and current maintenance schedules adequately contain the requirement, this AD is no longer required.

David Villiers
Delegate of the Civil Aviation Safety Authority

10 September 2008