LAX02FA134

According to witnesses, the airplane was seen approaching the motor sports park from the southwest at approximately 1,200 feet agl and at a "faster than usual" rate of speed. The airplane was in a "sharp, 90-degree bank," as it began to circle the park in a level turn. After circling around to the east, the airplane returned to a wings-level attitude and began to climb. Shortly thereafter, the tail of the airplane began to "shake violently" and separate from the airplane. One witness said he heard a loud noise as "the tail came off, and all of it started falling apart." He said the tail section separated first, then the airplane pitched over, and the left wing broke off. Witnesses saw the airplane enter a downward spiral. As the airplane descended, the engine separated and the passenger was ejected. The airplane then entered an inverted flat spin and impacted the ground 1,000 feet north of park. An examination of the airplane's left wing, and stabilizers revealed structural failures consistent with overload. According to the manufacturer's Flight Strength Diagram or Vn diagram for the G35, abrupt control column deflection at a speed of 113 knots (Va, or maneuvering speed) could produce a 4.4 G structural load (Limit Load factor), while abrupt control column deflection at or above 152 knots (Vno/Vc, or maximum structural cruise speed) could produce a 6.6 G structural load (Ultimate Load limit). Examination of the recorded radar data disclosed that the airplane was traveling at 142 knots at the time of the breakup. Engineering analysis concluded that in a level turn, the bank angle required to achieve Limit Load is 76.8 degrees, and the bank angle required to achieve the Ultimate Load is 81.2 degrees. FAA toxicology testing of the pilot revealed the presence of Diphenhydramine in urine, and Norverapamil, and Verapamil in urine and liver.

History of flight

On April 11, 2002, at 1006 Pacific daylight time, a Beech G35, N4487D, owned and operated by the pilot, was destroyed following an in-flight breakup and subsequent impact with terrain approximately 7 miles west of Willows, California. The private pilot and his passenger were fatally injured. Visual meteorological conditions prevailed. No flight plan had been filed for the personal flight being conducted under 14 CFR Part 91. The flight originated at Red Bluff, California, at approximately 0950.

The accident occurred near the Thunderhill Motorsports Park. At the time of the accident, the park was open and drivers were road-testing their cars on the track. Several safety officials, who were monitoring the track, witnessed the accident. Two witnesses said that the airplane approached the racetrack from the southwest.

Witness #1, who was located in the Turn 5 tower, said the airplane approached the track from the west near turn ten (see attached track diagram) at approximately 1,200 feet above the ground. He watched it for a few seconds before his attention was diverted. When he saw the airplane again, it was south of the track, flying over the water tank. He said that it was traveling "faster than usual," and the airplane was in "sharp, 90-degree bank," as it began to circle the park in a level turn. The airplane continued to circle the track, going towards the east then towards the north. After circling around the east side of the track, the airplane returned to a wings-level attitude and began to climb. As soon as it began to climb, the tail started to shake and pieces of it came off. He said when the tail pieces fell off, the airplane went into a flat, inverted, counter clockwise spin, and it hit the ground.

Witness #2, who was located in the Start-Finish tower, first noticed the airplane as it was turning near the water tank. It was approximately 1,200 feet above the ground. The airplane was flying normal, but was "kind of banking, [in] an easy, constant turn." The airplane wasn't going "real fast," or "real slow." As the airplane continued to circle around the east side of the track, it "started to climb a little bit more as he was making a bank." The witness stated that as the airplane was turning to the north, he said the empennage began to shake "violently" and then separate from the airplane. He said he heard a loud noise and "the tail just came off, and all of it started falling apart." He said the tail section separated first, then the airplane pitched over and the left wing broke off. When the airplane began to spiral down, the engine separated and the passenger was seen to fall out. The airplane then entered an inverted flat spin and impacted the ground 1,000 feet north of the race track.

Personnel information

The pilot held a private pilot certificate with an airplane single-engine land rating, dated July 30, 1973; a mechanic's certificate with airframe and powerplant ratings, dated June 7, 1991, and a third-class airman medical certificate, dated December 5, 2001, with the limitation, "Not valid for any class after December 31, 2002."

According to the pilot's flight logbook, he had accumulated a total of 1,617.0 flight hours. Categories of flight time were not given. His last flight review was dated January 11, 2002. As of the last logbook entry, dated April 6, 2002, he had accumulated 16.0, 8.5, and 2.9 hrs in the previous 90, 60, and 30 days, respectively. The pilot was a retired aeronautical engineer.

Aircraft information

N4487D, a model G35 (S/N D-4612) was manufactured by the Beech Aircraft Corporation in April 1956. It was equipped with a Continental E225-8 engine, (s/n 36328-D-70-8-R), rated at 225 horsepower, equipped with a Hartzell (m/n HC-A2MV204A1 two-blade, all metal, constant speed propeller.

According to the maintenance records, the pilot did all the routine maintenance and 100-hour inspections on the airplane. On November 1, 2000, both ruddervators were removed for repair. The left ruddervator was reskined, and both ruddervators were repainted and balanced checked. The most recent 100-hour/annual inspection was completed on June 12, 2000, at an airframe total time of 6,058.0 hours.

According to aircraft records, on January 1,1988, Beech Kit 35-4016-3 was installed on the empennage in accordance with Beechcraft Mandatory Service Bulletin No. 2188. The kit included stabilizer reinforcement components and instructions on inspecting the empennage and aft fuselage. On June 6, 2000, the airplane was complied with AD 94-20-04 inspection, which listed ruddervader balance requirements and the inspection of the aft fuselage.

At the time of the accident, airframe total time was 6,119.4 hours, and engine total time was 1,658.6 hours.

Meteorological information

Weather recorded at 0948 at Chico Municipal Airport, located approximately 26 nautical miles northeast of the accident site, was: wind, calm; visibility, 40 statute miles; sky condition, broken at 9,500 feet and 25,000 feet; temperature, 18 degrees C; altimeter setting, 30.15.

Wreckage and impact information

The wreckage was confined to an area of approximately 1,000 square feet. The left wing, engine cowling, left ruddervator, and left main landing gear door were located in the southeastern quadrant. The right ruddervator was located in the southwestern quadrant. The engine and attached propeller, and the right and left ruddervator balance weights were located in the northwestern quadrant of the debris field. The terrain was a soft, irrigated, and cultivated field with low vegetation.

The inverted fuselage and attached right wing impacted the ground on a magnetic heading of 360 degrees. The left wing was located approximately 490 feet at 162 degrees from the fuselage. The engine and attached propeller were located approximately 410 feet at 286 degrees from the fuselage. The engine was embedded in the ground approximately 3 feet deep. The distance between the engine and the left wing was approximately 800 feet.

The associated ground scar and crush lines on the fuselage were consistent with the airplane being in a flat, inverted, counter clockwise spin, as stated by witness #1. The upper portion of the cabin was crushed downward to the right and aft. The engine and propeller, engine cowling, and nose cowling were missing. The nose landing gear doors were closed. The attached right wing was buckled downward at a position approximately 7 feet inboard of the wing tip. The right main landing gear doors were closed. The right wing's aileron and flap were still attached. The aft portion of the fuselage was crushed downward. The left and right ruddervators and tail cone were missing. Inboard sections of the forward and aft spars, for the left and right ruddervators, remained attached to the fuselage. There was an 8-inch tear in the fuselage skin, beginning at and extending from a fuselage pass through hole in front of the forward spar attachment point for the left stabilizer at fuselage station (F.S.) 256. The left ruddervator trim cables, each attached to half of the elevator tab horn, were extending through the tear. There was an 1-inch tear in the fuselage skin, beginning at and extending from a fuselage pass through hole in front of the forward spar attachment point for the right stabilizer at F.S. 256. A portion of the fractured right ruddervator trim cable extended through the tear.

The upper left portion of the wing's forward spar carry-through structure was fractured and bent downward. The lower left portion of the wing's forward spar carry-through structure was fractured, buckled, and compressed inward. The forward attachment fitting for the left wing was missing. A 2-foot-wide section of fuselage skin, surrounding the lower portion of the left wing root area, was separated from the fuselage. This section of skin was curled and crush