Batesville, AR, USA
N4654D
Beech 35
The v-tail-equipped airplane was descending from cruise flight when it encountered turbulence, which was followed by shaking from the tail of the airplane. The pilot reduced engine power and pulled back slightly on the yoke. According to the pilot, the shaking stopped, and the airplane seemed to operate normally for the rest of the flight. After landing, the pilot noticed damage to the fuselage. Postaccident examination revealed buckling and wrinkling to the aft fuselage skins. Control cable tension could not be determined because of the fuselage damage. The balance of the ruddervators was checked and found to be within the manufacturer's specifications. Based on the available evidence, it is likely that the airplane encountered tail surface flutter in turbulent conditions.
On February 8, 2018, about 1415 central standard time, a Beech G35 airplane, N4654D, sustained substantial damage during a flutter event near Batesville Regional Airport (BVX), near Batesville, Arkansas. The pilot was not injured. The airplane was registered to a private individual and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not on a flight plan. The flight originated from the Beaufort County Airport (ARW), Beaufort, South Carolina, at an unconfirmed time. The pilot reported that most of the flight was uneventful, and the airplane had performed "flawlessly". After about 4 hours of cruising flight, while descending through about 3,500 ft. msl, at 145 kts airspeed, the airplane encountered a few seconds of turbulence, followed by shaking coming from the tail of the airplane. The pilot reduced engine power and pulled back slightly on the yoke. The shaking stopped and the airplane seemed to be handling normally. The airplane then landed at BVX and upon exiting the airplane the pilot noticed the damage to the fuselage. The pilot noted that the flight was smooth except for the short period of turbulence encountered near the destination airport. The accident airplane was equipped with a V-tail empennage arrangement. A postaccident examination of the airplane revealed buckling and wrinkling of the aft fuselage skins. All of the control cables running to the tail surfaces were loose and determination of the control cable tension prior to the event was not possible because of the aft fuselage damage. A balance check of the ruddervators revealed the left was tail heavy with a measured moment of 19.04 inch-lbs, and the right was tail heavy with a measured moment of 18.76 inch-lbs. According to the maintenance manual the acceptable maximum tail heavy moment for the accident airplane ruddervators was 19.8 inch-lbs. The Pilot's Operating Handbook for the accident airplane listed a maximum structural cruising speed of 152 kts, and a maneuvering speed of 113 kts. The airplane manufacturer issued a Safety Communique in 1993 which stated that to prevent flutter in any model airplane, control cable tension inspections should be performed and that after re-painting of control surfaces, verification of the control surface balance should be performed. Additionally, the G35 model was included in the effectivity for Federal Aviation Administration (FAA) Airworthiness Directive (AD) 94-20-04 R2 which was issued to prevent structural failure of the V-tail, which could result in loss of control of the airplane. The actions stated in the AD included inspection and incorporation of the stabilizer reinforcements prescribed in Beech Service Bulletin No. 2188, dated May, 1987. The most recent annual inspection of the airplane, dated April 23, 2017, indicated that the AD had been complied with.
An in-flight control system flutter encounter during a turbulence encounter; the reason for the flutter could not be determined.
Source: NTSB Aviation Accident Database
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