Beech G35 N4606D accident near New Smyrna Beach, Florida

Probable cause

The pilot's inadvertent encounter with turbulence that was not forcast.

NTSB analysis

The airplane was in cruise flight above its published maneuvering speed, but below its published never-exceed speed, when it experienced "5-6 sharp vibrations" that measured -1 to + 3.9 g's and caused the airplane to pitch up and down violently and roll to the left. At that time, the pilot-rated passenger reported hearing "popping and tearing" from the area of the baggage door. The pilot disengaged the autopilot and slowed the airplane. The vibrations stopped. He then performed a slow descent and completed a safe landing at his destination airport. Examination of the airplane, a monoplane with a "V" tail, revealed downward bending of the rear fuselage with diagonal buckling of the skin on each side, and tearing of the skin on the bottom. The two elevators were found properly attached, and properly balanced. A weather study revealed cumulus clouds developing in the area on the satellite imagery, and therefore the potential for convectively induced turbulence from towering cumulus clouds. The soundings also noted an inversion near the airplane's cruise altitude, with rapidly drying air above. The vertical wind shear was 5 knots per 1,000 feet at that layer, which corresponded to moderate or greater turbulence. There were no weather advisories current along the route of flight during the period of the accident.

Text from the NTSB. Open the NTSB docket for NYC08LA164 for the full record.