NTSB Identification: ATL97LA027.
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Accident occurred Wednesday, November 27, 1996 in LAFAYETTE, GA
Probable Cause Approval Date: 08/21/1997
Aircraft: Beech 35, registration: N4523V
Injuries: 3 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

Flutter of the empennage occurred during cruise flight. The pilot immediately reduced engine power, and the flutter subsided. Duration of the flutter was about three seconds. An examination of the empennage disclosed that the bulkhead at fuselage station (FS) 256.9 exhibited cracks at the four corners of the assembly. Also, buckling of the fuselage skin was noted adjacent to the damaged bulkhead. The ruddervators were removed from the airframe and balance checked in accordance with the Bonanza 35 Series Shop Manual. The left and right ruddervators exhibited static underbalance moments (trailing edge heavy) of 23.73 and 22.95 inch-pounds, respectively. According to the service manual, the required static underbalance range is 16.80 to 19.80 inch pounds. Both ruddervators had been reskinned (or replaced) and repainted. An unbroken paint seal around the screws (that attached the counterweights to the ruddervators) indicated that the counterweights had not been removed subsequent to repainting.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

failure of maintenance personnel to balance the ruddervator assemblies after they had been reskinned and painted, which resulted in flutter and subsequent damage to the empennage.

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