AD/LA-4/25 Amdt 1 Horizontal and Vertical Stabiliser Attachment Fitting (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/LA-4/25 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.

Consolidated Aeronautics, Colonial and LA-4 Series Aeroplanes

AD/LA-4/25 Amdt 1 Horizontal and Vertical Stabiliser Attachment Fitting 9/2005 TX

Applicability:

Models Colonial C-2, Lake LA-4, Lake LA-4A, Lake LA-4P, and Lake LA-4-200 aircraft, all serial numbers.

Requirement:

1.    For aircraft with less than 825 hours time in service on any horizontal stabiliser attachment fitting part number 2-2200-21, remove the affected attachment fitting(s) from the aircraft and inspect in accordance with the Inspection and Repair section and the Appendix of Revo Inc. Service Bulletin (SB) B-78, dated 3 April 1998.  If any cracks, fretting, or corrosion are found, replace affected attachment fittings before further flight.

2.    For aircraft with 825 hours or more time in service on any horizontal stabiliser attachment fitting part number 2-2200-21, replace the affected attachment fitting(s).  If necessary, trim the horizontal stabiliser rear beam doubler flange to provide positive clearance to the fitting(s) in accordance with the Inspection and Repair section and the Appendix of SB B-78.

3.    For all aircraft, inspect the horizontal stabiliser attachment fittings, part number 2-2200-21, in accordance with SB B-78 as follows:

a.     Move the elevator as required to see the fittings, ensuring that the aft face of the fittings are visible.

b.    Clean the fittings.  Pay special attention to the radius edges of the fitting just outboard of the fitting ear.

c.     Visually inspect the fittings for cracks using a flashlight (a small magnifying glass or boroscope is recommended).  Pay special attention again to the radius edges just outboard of the fitting ear.  Also, inspect as far forward on the edge as possible because some cracks progress along the forward face of the fitting that is mostly hidden by the horizontal stabiliser rear beam.

d.    Reference the sketch on page 1 of SB B-78 to see where the crack is likely to originate.

Replace cracked fittings before further flight.

With any replacement of the horizontal stabiliser attachment fittings, measure the gap between the horizontal skin and the horizontal stabiliser attachment fitting part number 2-2200-21, in accordance with SB B-78.  If gap is less than 1/16-inch, trim the skin to provide at least 1/16-inch, before further flight.

Do not install used serviceable fittings, unless the hours time in service is known and the fitting has been inspected in accordance with the Inspection and Repair section and the Appendix of SB B-78.

Report the results of the Requirement 1 inspection to CASA AD Cell, even if no damage is found.  Report the results of any Requirement 3 repeat inspection where cracks are found.  Report the results within 10 days after the inspection.

Note:  FAA AD 2005-12-02 Amdt 39-14118 refers.

Compliance:

1.    Within 25 hours time in service after 8 July 2005.

2.    Within 25 hours time in service after 8 July 2005, and replace thereafter upon the accumulation of 850 hours time in service.

3.    After the initial inspection or replacement; at intervals not to exceed 50 hours time in service or annual inspection, whichever occurs first.

This Amendment becomes effective on 8 July 2005.

Background:

The FAA received a report of loss of control of a Lake LA-4 aircraft during flight.  During climb-out following take-off, the pilot heard a loud bang, and the aircraft pitched over into a vertical dive, with loss of elevator control.  During the pilot’s efforts to regain control, another loud bang was heard and sufficient control was regained to manage a safe landing.  Investigation revealed interference between the horizontal stabiliser skin and the attachment fitting, which caused fretting and consequent fatigue cracking and fracture of the attachment fitting.

Amendment 1 is issued in response to a new FAA AD, which was prompted by several reports of fatigue cracks in the horizontal stabiliser attachment fitting part number 2-2200-21 on Model LA-4-200 aircraft that were in compliance with FAA AD 98-10-12.  This includes a fatal aircraft accident attributed to a fatigue crack in the horizontal stabiliser attachment fitting.

David Villiers
Delegate of the Civil Aviation Safety Authority

7 July 2005