NTSB Identification: CHI98FA017.
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Accident occurred Monday, October 06, 1997 in POPLAR GROVE, IL
Probable Cause Approval Date: 02/28/2000
Aircraft: Beech G35, registration: N129B
Injuries: 2 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot reported that he was cruising at 4,000 feet msl in clear sky conditions with smooth air, then he initiated a descent. He said that while descending through about 3,200 feet msl at 185 mph with a 5 degree nose down attitude and 15 degree left turn, the control yoke started oscillating fore and aft about 1/2 inch. The oscillations increased to about 1 inch fore and aft, and the airplane experienced 3 or 4 'solid jolts.' After about 5 seconds, the pilot reduced power, and the vibrations stopped. He continued to his destination and landed uneventfully. According to the Pilot Operating, the airplane's never exceed airspeed (Vne) was 202 mph. The maximum cruise airspeed (Vno), was 175 mph. Inspection of the airplane revealed that the aft fuselage received extensive damage between fuselage station (FS) 256.9 and the 233.5 bulkhead. The longerons were bent downward with a permanent 2.5 to 3 inch bend. The left and right side fuselage panels below the stabilizers exhibited 45 degree buckling from the bottom of the FS 256.9 bulkhead to forward of the stabilizer cuffs. The bottom fuselage panel forward of the 256.9 bulkhead had popped rivets and torn skin. There were three creases in the right stabilizer. No pre-existing cracks were found on the longerons. The ruddervators were properly balanced.

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

flutter for an undetermined reason, which resulted in structural damage to the aft fuselage.

Full narrative available

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