AL 2005-09
12 December 2005
A privately registered Luscombe Model 8E aircraft was on a visual flight rule (VFR) flight and when rudder difficulties were encountered, the pilot carried out a precautionary, uneventful landing at the nearest airport. The pilot subsequently reported that the aircraft's vertical stabilizer and rudder had nearly separated from the aircraft. There were no injuries or other damage to the aircraft.
The initial event was the failure of the vertical stabilizer rear spar bracket, which led to a failure of the forward bracket. There were only two rivets that prevented the vertical fin from departing the aircraft. It is most likely that if the vertical fin had departed the aircraft in flight, this would have resulted in a loss of control of the airplane. A Transportation Safety Board analysis on the failed vertical stabilizer determined that the failure was the result of the separation of the rear spar attachment. This separation occurred due to the formation of fatigue-cracking under normal service loading and the length of the cracks attained critical dimensions over time.
Federal Aviation Administration (FAA) Airworthiness Directive (AD) 94-16-02, which supersedes AD 79-25-05, requires replacing the vertical stabilizer forward attachment fitting, Luscombe part number (P/N) 28415, 28444, or 28453, with either Luscombe P/N 28455, manufactured by the Don Luscombe Aviation History Foundation (DLAHF), P/N U28444, a welded steel fitting manufactured by the Univair Aircraft Corporation, or an FAA-approved equivalent part. This action replaces the existing aluminum fitting with a steel vertical stabilizer forward attach fitting on Luscombe Model 8 series airplanes that have round-tipped vertical stabilizer installations. The actions specified by this AD are intended to prevent failure of the vertical stabilizer as a result of a cracked fitting, which could result in loss of control of the airplane.
Although it has not been determined what initiated the bracket to crack, there are considerations to take into account. The Luscombe Model 8E airplane has the capability to do aerobatics and many have been utilized for this purpose. Most of the airplanes were manufactured in the 1940s and have been subjected to the elements for many years. Transport Canada, Continuing Airworthiness Web Information System (CAWIS) indicates there are 138 Luscombe Model 8 series airplanes and three Luscombe Model 11 series airplanes on the Canadian registry.
Transport Canada recommends that all owners of the Luscombe airplanes ensure that the area specified above, which is the forward and rear attachment fittings, be periodically inspected for condition, security and corrosion.
Any further defects or occurrences should be reported to Transport Canada, Continuing Airworthiness, Ottawa, via the Service Difficulty Reporting program.
For further information contact a Transport Canada Centre, or call Mr. Marcel Gauthier, Continuing Airworthiness, Ottawa, telephone 613 952-4364, facsimile 613 996-9178 or e-mail gauthmr@tc.gc.ca.
For Director, National Aircraft Certification
B. Goyaniuk
Chief, Continuing Airworthiness
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