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) AD/AT 600/4 Amdt 2 and issues the following 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.
Airtractor 600 Series Aeroplanes
AD/AT 600/4 Amdt 3
Engine Mount
8/2009
 
Applicability:
Model AT-602 aircraft, serial numbers 0001 through 1141.

Requirement:
1.    For engine mounts without gussets installed, inspect the engine mount in accordance with Snow Engineering Co. SL No. 253 Revision C, dated
17 April 2008:
a.     For aircraft with less than 5,000 hours time in service; at the initial and repetitive times specified in the Compliance section.
b.    For aircraft with 5,000 hours time in service or more; at the initial and repetitive times specified in the Compliance section.
2.    For engine mounts with gussets installed, inspect the engine mount in accordance with Snow Engineering Co. SL No. 253 Revision C, dated
17 April 2008:
a.     For aircraft with less than 5,000 hours time in service; at the initial and repetitive times specified in the Compliance section.
b.    For aircraft with 5,000 hours time in service or more; at the initial and repetitive times specified in the Compliance section.
Note:  FAA AD 2009-11-05 Amdt 39-15915 refers.

Compliance:
1.a. Initially, upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 August 2007, whichever occurs later.  Repetitively thereafter at intervals not to exceed 300 hours time in service.
1.b. Initially, upon accumulating 5,000 hours time in service or within the next 10 hours time in service after 30 July 2009, or within the next 100 hours time in service from the last inspection performed, whichever occurs later.  Repetitively thereafter at intervals no to exceed 100 hours time in service.
2.a. Initially, upon accumulating 1,300 hours time in service or within the next 100 hours time in service after 30 July 2009, whichever occurs later.  Repetitively thereafter at intervals not to exceed 300 hours time in service.

 
 
2.b. Initially, upon accumulating 5,000 hours time in service or within the next 10 hours time in service after 30 July 2009, or within the next 100 hours time in service from the last inspection performed, whichever occurs later.  Repetitively thereafter at intervals no to exceed 100 hours time in service.

 
This Amendment becomes effective on 30 July 2009.

Background:
The FAA received reports of cracked engine mounts.  Such cracking, unless detected and corrected, could result in failure of the engine mount and possible separation of the engine from the aircraft.
Amendment 1 was prompted by reports received by the FAA of two Model AT-802A aircraft with cracked engine mounts below the initial compliance time.  The FAA determined that the initial inspection is required when the aircraft reaches a total of 1,300 hours time in service.
Amendment 2 retained the inspection actions of FAA AD 2007-13-17 and required incorporation of engine mount gussets as a mandatory terminating action for the repetitive inspection requirement.
Amendment 3 is issued in response to a new FAA AD, which was prompted by a report of a Model AT-602 aircraft with a crack completely through the gusset that was installed as required in FAA AD 2008-10-12.  Consequently, this Directive requires repetitive inspections of engine mounts of all previously affected aircraft with or without gussets installed.

David Villiers
Delegate of the Civil Aviation Safety Authority
18 June 2009