AD/AT-6/2 Horizontal Stabliser Rear Spar Connector Fittings (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (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.

Rockwell (N American) & Autair (Noorduyn) AT-6, BC-1A, SNJ, T-6G, Harvard, & AT-16 Series Aeroplanes

AD/AT-6/2 Horizontal Stabliser Rear
Spar Connector Fittings 7/2008

Applicability:

All Harvard 2 and Harvard 4 aircraft, equipped with single piece design horizontal stabiliser rear spar connector fittings, part number 7721021 (4 fittings per spar).

This Directive is not applicable to aircraft equipped with two piece design connector fittings part numbers 77210213 and 77210214 (8 fittings per spar).

Requirement:

Remove the fuselage to vertical stabiliser fairing assembly and the rear fairing assemblies at the horizontal stabiliser.

Remove the ¼-inch bolts which attach the upper and lower spar connection fittings part number 7721021, of the rear spar assembly.

Remove the four connection fittings from the spar, remove the paint from the connection fittings, and check for cracks using dye penetrant inspection method.  Replace any cracked fittings with serviceable fittings and repaint the fittings found to be crack free.

Inspect the fit between the connection fittings and the spar with a feeler gauge before installation of the bolts.  If gaps greater than 0.010-inches exist, shims are necessary.

Fabricate aluminium shims 3 ⅛ -inch x ¹⁵/₁₆ -inch and of necessary thickness, and place on either side of spar flanges, maintaining a parallel overall dimension to fit inside the connection fitting with a maximum clearance of 0.010-inches.

Drill holes through the shims to match those of the fitting.  Remove all drilling chips, and reinstall bolts and other removed parts in accordance with the aircraft maintenance manual.

Note:  Transport Canada AD CF-82-23 refers.

Compliance:

Unless previously accomplished, before 31 July 2008.

This Airworthiness Directive becomes effective on 3 July 2008.

Background: The Canadian Airworthiness Authority requires accomplishment of this Directive to detect cracking of the horizontal stabiliser rear spar connector fittings, and to check the fit of the connector fittings and the spar.

David Villiers
Delegate of the Civil Aviation Safety Authority

22 May 2008