AD/G164/15 Amdt 2 Rudder Main Spar (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) AD/G164/15 Amdt 1 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.

Schweizer (Grumman) G-164 (Ag-Cat) Series Aeroplanes

AD/G164/15 Amdt 2 Rudder Main Spar 1/2009

Applicability:

Aircraft Models G-164, G-164A, G-164B, G-164B with 73-inch wing gap,
G-164B-15T, G-164B-34T, G-164B-20T, G-164C, G-164D, and G-164D with
73-inch wing gap; all serial numbers.

1.    Drill an access hole and accomplish a visual inspection of the lower end internal cavity of the rudder main spar tube for corrosion, using a boroscope; also accomplish a visual inspection of the exterior of the rudder main spar tube for corrosion.

Refer to Steps 1 through 3 of Grumman American Aviation Corporation Ag-Cat Service Bulletin No. 61, dated 6 June 1977, when accomplishing Requirement 1.

2.    If corrosion is found during any Requirement 1 inspection, repair or replace damaged part(s); as specified in Steps 5 and 6 of Grumman American Aviation Corporation Ag-Cat Service Bulletin No. 61, dated 6 June 1977, and appropriate maintenance manual.

3.    After each inspection, repair, or replacement required by this Directive, corrosion protect the spar tube internal cavity by filling with warm, raw linseed oil, Paralketone, or CRC3 (LPS Heavy Duty Rust Inhibitor Type 3), or suitable equivalent protector for alloy steel, and allow to drain.  Seal access hole with Scotch caulking compound, a suitable silicon based sealant, or equivalent; as specified in Step 4 of Grumman American Aviation Corporation Ag-Cat Service Bulletin No. 61, dated 6 June 1977.

4.    Verify rigging check of the rudder in accordance with the appropriate maintenance manual.

As of 30 days after 19 December 2008, a rudder may only be installed if it has been inspected in accordance with Requirement 1, is free of corrosion, and has had the corrosion protection applied and sealed as specified by Requirement 3.

Note:  FAA AD 2008-22-21 Amdt 39-15718 refers.

Compliance:

1.a. For aircraft previously affected by this Directive:  Initially inspect within 60 months after the last inspection required by the previous issue of this Directive, or within 30 days after 15 January 2009, whichever occurs later.  Repetitively inspect thereafter at intervals not to exceed 60 calendar months.

1.b. For aircraft not previously affected by this Directive:  Initially inspect within 30 days after 15 January 2009.  Repetitively inspect thereafter at intervals not to exceed 60 calendar months.

2.    Before further flight after any inspection in which corrosion is found.

3.    Before further flight after any Requirement 1 inspection, and after any repair or replacement required in Requirement 2.

4.    Before further flight after any Requirement 1 inspection, and after any repair or replacement required in Requirement 2.

This Amendment becomes effective on 15 January 2009.

Background:

The manufacturer received reports of significant corrosion on the main tubular spar of the rudder assembly.

Amendment 1 introduced a calendar time compliance in lieu of operating time, a separate compliance for aircraft that are operating in a severe corrosive environment, and an additional internal inspection of the spar for corrosion in response to a local report of a rudder main spar failure that was precipitated by internal corrosion.

Amendment 2 is issued to align this Directive with the requirements of a new FAA AD, which changes compliance times and expands the applicability to include all
G-164 series aircraft.  The AD was prompted by the failure of the rudder main tubular spar on a later production aircraft not previously affected.

David Villiers
Delegate of the Civil Aviation Safety Authority

24 November 2008