ENNIS, TX, USA
N4662D
Beech G35
According to the pilot, the airplane was traveling approximately 180 mph, at 2300 rpm and 20-23 inches of manifold pressure (mp), in a wings level descent. While descending through 2,500 feet, the pilot felt a minor vibration in the yoke and rudder pedals, which persisted between three and five seconds. The pilot reduced power (approximately two or three inches of mp), the airplane decelerated to 160 mph and the vibration ceased. The airplane's never exceed airspeed (Vne) is 202 mph, and the maximum cruise speed (Vno) is 176 mph. Examination of the airplane revealed that the aft fuselage sustained damage between the FS 233.5 and FS 256.9 bulkheads. The lower longerons were buckled. The belly skin located at FS 256.9 bulkhead was separated from the fuselage. The damage was consistent with symmetric downward overload. The ruddervators were checked and determined to be properly balanced.
HISTORY OF FLIGHT On January 18, 1999, at 1445 central standard time, a Beech G35 airplane, N4662D, was substantially damaged while descending from cruise flight. The instrument rated private pilot, who was the registered owner and sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 personal flight and a flight plan was not filed. The flight originated from the New Braunfels Municipal Airport, New Braunfels, Texas, at 1400, and was destined for the Ennis Municipal Airport, Ennis, Texas. According to the pilot, the airplane was traveling approximately 180 miles per hour (mph), at 2300 rpm, 20-23 inches of manifold pressure (mp), in a wings level descent. While descending through 2,500 feet, the pilot felt a minor vibration in the yoke and rudder pedals, which persisted between three and five seconds. The pilot reduced power (approximately two or three inches of mp), the airplane decelerated to 160 mph and the vibration ceased. The flight continued to the Ennis Municipal Airport, and landed without further incident. The pilot parked the airplane on the ramp and left the airport, not realizing that the airplane had been damaged. When the pilot returned to the airport, airport personnel advised the pilot of damage to the empennage of the airplane. The pilot stated that he experienced "no difficulty controlling the airplane" during the flight. PERSONNEL INFORMATION The pilot held a private pilot certificate (single-engine land) and an instrument rating. He had accumulated a total of 320 flight hours, of which 78 hours were in the make and model of the accident airplane. Additionally, the pilot was issued a third class medical certificate in January of 1997. AIRCRAFT INFORMATION The pilot purchased the 1956 "V-Tail" Bonanza, serial number D-4862, in December of 1998. The aircraft was equipped with a 225-horsepower Continental E225-8 reciprocating engine. The engine was powered by a two-bladed Hartzell, HC-A2X20 propeller. According to the aircraft logbook, the most recent pitot-static check was performed on June 20, 1996. The airplane underwent its most recent annual inspection on December 1, 1998. At the time of the annual the airframe had accumulated a total of 3,562.54 hours and the engine had accumulated a total of 488.4 hours since major overhaul. When the accident occurred, the airplane had accumulated a total of 3,635.0 hours. The airplane was examined for items installed that were not original to the airplane as manufactured. The installed items included: 1. V-type air inlet scoop on aft side of fuselage. 2. One piece windshield. 3. Hartzell hydraulic propeller. 4. Bracket air filter. According to the pilot's operating handbook, the airplane's maximum structural cruising airspeed (Vno) is 176 mph and the airplane's never exceed airspeed (Vne) is 202 mph. A review of the airframe logbook indicated that the ruddervators were re-skinned on June 15, 1991. Further examination of the aircraft's logbooks revealed that the airplane had no recorded history of major damage during its lifetime. METEOROLOGICAL INFORMATION At 1453, the nearest weather observation facility, at the Terrell Municipal Airport (located 30 miles northeast of the Ennis Municipal Airport), reported winds from 160 degrees at 12 knots, overcast skies at 7,000 feet and visibility 10 miles. The pilot reported that the weather conditions at the time of the accident were clear skies, light winds and no turbulence. DAMAGE TO AIRCRAFT On March 10, 1999, the airplane was examined by an NTSB investigator, the FAA inspector, a representative from Raytheon Aircraft Company, and a representative from the American Bonanza Society, at the Ennis Municipal Airport. The examination revealed that the airplane sustained damage to the aft fuselage. Both sides of the aft fuselage exhibited diagonal skin wrinkling (from the upper forward to the lower aft) between the fuselage station (FS) 256.9 (front stabilizer spar attachment) and FS 233.5 bulkheads. The lower longerons were buckled. The belly skin was torn away from the FS 256.9 bulkhead. The ruddervators, stabilizers and trim tabs did not exhibit any damage. Both stabilizers were securely attached to the FS 256.9 and FS 272 bulkheads. Both ruddervators were attached to the stabilizers, and no hinge wear was observed. Both trim tabs were undamaged with their hinges properly threaded. The empennage control system did not exhibit any improper installations. The right rear engine mount exhibited one sheared rivet. Additionally, three rivets were observed sheared at the front right engine mount. TESTS AND RESEARCH The ruddervators were checked for balance utilizing the force method. The right and left ruddervators exhibited static balance moments (M) of 18.10 and 17.75 inch-pounds respectively (the required range of M is 16.80 to 19.80 inch-pounds). The left ruddervator (including counterweights and trim tabs) weighed 8.54 lbs., and the right ruddervator (including counterweights and trim tabs) weighed 8.33 lbs. The right and left ruddervator counterweight assemblies (including the attaching shells) were removed. Both assemblies exhibited "-40" part numbers. They weighed 3.17 and 3.33 pounds, respectively. The left assembly contained 6 washers and the right assembly contained 2 washers. The counterweights exhibited secure attachment. A propeller dynamic balance was performed. At an engine tachometer reading of 2,300 RPM, the frequency was between 0.05 and 0.1 inches per second (IPS). ADDITIONAL INFORMATION The airplane was released to the registered owner.
Flutter of the empennage for an undetermined reason, which resulted in damage to the aft fuselage.
Source: NTSB Aviation Accident Database
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