HANFORD, CA, USA
N6057U
BEECH A-36
RADAR DATA SHOWS THE AIRPLANE IN NORMAL CRUISING FLIGHT UNTIL ABOUT 2 MINUTES BEFORE THE ACCIDENT, WHEN IT ENTERED INTO A GRADUAL DESCENT. THE DESCENT CONTINUED TO INCREASE TO A HIGH VERTICAL SPEED. THE LAST FOUR RADAR TARGETS SHOWED THAT THE AIRPLANE DESCENT EXCEEDED 3,400 FEET/MINUTE; THE LAST TWO RADAR TARGETS SHOWED THAT THE AIRPLANE DESCENT EXCEEDED 7,500 FEET/MINUTE. EXAMINATION OF THE WRECKAGE SHOWED THAT THE HORIZONTAL STABILIZERS INITIALLY SEPARATED, FOLLOWED BY BOTH WINGS.
History of Flight On July 12, 1995, at 1745 hours Pacific daylight time, a Beech A-36, N6057U, sustained an in-flight breakup and crashed about 4 miles northeast of Hanford, California. The pilot was conducting a visual flight rules (VFR) personal flight to Columbia, California, and had filed a VFR flight plan. The airplane, registered to and operated by the pilot, was destroyed. The certificated commercial pilot and his passenger sustained fatal injuries. Visual meteorological conditions prevailed. The flight originated at Long Beach Airport, Long Beach, California, at 1630 hours. The pilot's son told National Transportation Safety Board investigators in a telephone interview on July 13, 1995, that the pilot and his wife were going to Columbia for a mini-vacation. The pilot intended to return on July 16, 1995. An Federal Aviation Administration (FAA), Western-Pacific Region Quality Assurance Division, AWP-5, specialist reported that after departing Long Beach Airport and opening his VFR flight plan, the pilot did not communicate with any air traffic facilities. The pilot was not required to contact any air traffic control facilities during the flight. Several ground witness, including a certificated airline transport pilot, were interviewed by Safety Board investigators. The ground witnesses reported that the engine "revved-up" to maximum power followed by an explosive sound. When they looked up, the airplane was breaking up and fell to the ground. Scattered airplane debris was drifting to the southeast. Lemoore Naval Air Station (NAS), Lemoore, California, air traffic personnel provided Safety Board investigators with radar data of the traffic near the accident area at the time of the accident. The radar data showed an airplane emitting a 1200 (VFR) transponder code traveling in a northwesterly direction toward Columbia. Between 1739:00 and 1743:38 hours, the airplane was flying at 10,600 feet msl (all altitudes herein, unless otherwise noted, are mean sea level altitudes) at 150 knots. Between 1743:38 and 1744:29 hours, the airplane descended to 9,900 feet; the rate of descent, on a linear scale, was about 823.53 feet per minute (fpm). Between 1744:29 and 1744:34 hours, the airplane descended to 9,700 feet; the rate of descent, on a linear scale, was about 2,400 fpm. Between 1743:34 and 1744:38 hours, the airplane descended to 9,200 feet; the rate of descent, on a linear scale, was about 7,500 fpm. At 1744:48 hours, the radar target entered the coast mode and was never reacquired. The accident coordinates of the main wreckage are: 32 degrees, 22.88 minutes north, and 119 degrees, 33.00 minutes west. Crew Information The pilot held a commercial pilot certificate with airplane single and multiengine land and instrument airplane ratings. He also held a third-class medical certificate which was issued by the FAA, Medical Certification Branch, Oklahoma City, Oklahoma. The certificate contained a "Not valid after 5-31-96 and a Must have available glasses for near vision" limitation endorsement. According to the pilot's medical records, he suffered a myocardial infarction (heart attack) on September 6, 1991. On May 2, 1992, the pilot applied for a third-class medical certificate. On May, 7, 1992, the Medical Certification Branch, Medical Advisory Panel, granted the pilot a medical exemption and he received the third-class medical certificate on May 2, 1995. On April 22, 1971, the FAA Medical Certification Branch granted the pilot a Statement of Demonstrated Ability waiver to hold a second-class medical certificate because of "No useful vision in left eye." Safety Board investigators did not recover the pilot's flight hours logbook and were unable to determine if the pilot satisfied the general recency of experience requirements of 14 CFR Part 91. The flight hours listed on page 4 of this report were obtained from the pilot's last FAA medical application form dated May 2, 1994. A certified flight instructor reported in a written statement that on July 19, 1994, she gave the pilot ground instruction in preparation of the biennial flight review (BFR). On July 20, 1994, she and the pilot flew the accident airplane. During the flight, the pilot wanted to use the autopilot, as he was having control problems when he was manually flying the airplane. The next flight occurred on July 22, 1994. On this flight he was unable to satisfactorily manually fly the airplane. The pilot's handling of the airplane was unsatisfactory and the instructor would not sign-off the BFR. Later that day, the pilot departed Long Beach Airport and flew to Palomar Airport, Carlsbad, California. When he returned to Long Beach Airport, the pilot showed the instructor his logbook that showed a BFR logbook sign-off by another instructor. Aircraft Information The pilot's son gave the Safety Board a copy of the airplane's maintenance logbooks. Examination of the logbooks showed that the last annual 100-hour inspection was completed on the airplane and engine on July 21, 1994. The airframe accrued 2,008.4 hours (tachometer hourmeter 174.4 hours); the engine accrued 2,008.4 total flight hours; 174.4 hours since major overhaul. All of the required airworthiness directives were complied with at the time of the inspection. The altimeter, transponder, and static systems tests required by 14 CFR 91.411 & 91.413 were accomplished by Future Avionics, Long Beach, California, on July 20, 1994. There were no deferred maintenance discrepancies noted during the logbook examination. Communications There were no known communications between N6057U and any FAA air traffic facility after the flight departed the Long Beach Airport Class D airspace (formerly the airport traffic control area). In addition to the Lemoore NAS radar data noted under History of Flight, the FAA, Oakland Air Route Traffic Control Center, provided National Track Analysis Program (NTAP) radar data between 1735 and 1750 hours. The radar data shows an airplane displaying a 1200 code flying at level flight and then entering a steep descent. The airplane target entered the coast mode (the airplane's speed was too fast to acquire another target) and then disappear. The last radar target's coordinates were near the main wreckage coordinates. Wreckage and Impact Information The main fuselage came to rest in a corn field, inverted, about 4 miles northeast of Hanford, California, about 0.3 miles north of the last radar target; the fuselage was facing in a southwesterly direction. Scattered airplane debris was found along a southeasterly ground path that extended 0.53 statute miles from the main fuselage. All of the airplane major components were found. Both wings and the horizontal stabilizers separated from the airplane. Safety Board investigators examined the airframe and engine on July 14, 1995, at Valley Aircraft Parts, Inc., Tulare Airport, Tulare, California. Airframe Examination: Both wing spars (front and rear) are normally attached to a front and rear carry-through assembly made up of two channels (upper and lower) which are attached with extruded aluminum material. The carry-through assembly is reinforced with additional web extrusions. Right Wing: The front wing carry-through separated about 8 inches inboard of its wing-to-fuselage attach fittings; the rear spar separated about 28 inches outboard of its wing-to-fuselage attach fittings. The front carry-through lower channel fractured surface exhibited compression crippling. The upper channel fracture displayed downward (counterclockwise viewing the fractured surface toward the wing tip) rotational overload characteristics on the front side of the fractures, and tensile overload characteristics on the aft side of the fractures. The aft section of the rear web exhibited a 45-degree buckling signature. The buckling began at the rear left lower side (as viewed from the trailing edge toward the leading edge) to the upper right side of the web. The lower spar channel displayed extensive "S" bending. The rear spar separated about 28 inches outboard of its wing-to-fuselage attach fittings at the landing gear retract trunnion. The fracture surface displayed extensive downward bending and the spar was bent forward about 9-degrees. The rear carry-through assembly displayed extensive compression buckling at the midsection and the upper channel displayed ground impact damage. The middle seat tracks and their respective front attach brackets were found bent downward. The lower spar displayed compression crippling. The back side of the spar web displayed an impact mark on the landing gear trunnion. The upper skin displayed two vertical tear marks above the wheel well. The leading edge was found folded downward about 98 inches outboard of the root section. The upper skin was found folded upward about 45 degrees; the lower skin section tore away in several pieces. The aileron separated from its attach points and broke into two pieces; the aileron fractured about 17 inches from the outboard end. The inboard end of the aileron was found twisted rearward and downward. The flap separated from its attach points and broke into 3 pieces; the fractured areas were about 27 and 70 inches from the inboard side. The right main gear strut separated. The gear attach fittings displayed torsional and compression signatures. Left Wing: The front wing carry-through separated about 42 inches inboard of its wing-to-fuselage attach fittings. The lower section of the upper channel fracture was found twisted aft and the lower section was twisted downward in compression. The lower channel was found bent downward and exhibited extensive compression fractures. The rear spar separated about 28 inches outboard of its wing-to-fuselage attach fittings at the landing gear retract trunnion. The upper channel displayed extensive "S" bending from the wing-to-fuselage attach fittings extending outboard. The aileron and flap assemblies separated from their respective attach points and broke into several pieces. These pieces were found scattered throughout the ground debris area. The landing gear was found retracted in the wheel well. Right Stabilizer: The right horizontal stabilizer separated from its spar attach fittings. The forward spar fractured about 7 1/2 inches outboard of its attach fitting (measured from the inboard end of the spar attach fitting). The fracture surface displayed downward (clockwise viewing toward the fuselage) torsional and tensile overload characteristics. The rear spar fractured about 4 1/2 inches outboard of its attach fitting. The fracture surface displayed downward (clockwise viewing toward the fuselage) torsional and rearward tensile overload characteristics. The stabilizer leading edge displayed a 3-inch impact mark about 14 1/2 inches from the inboard end. This mark corresponds to a 3-inch mark on the right tail cone bulkhead about 3 inches from the bottom. The elevator separated from the inboard and outboard attach points and broke into three pieces. The broken piece next to the outboard hinge line was found buckled downward. The elevator trim tab separated from its attach point. The trim tab actuator was not recovered. Left Stabilizer: The left horizontal stabilizer separated from its spar attach fittings. The forward spar fractured about 7 inches outboard of its attach fitting (measured from the inboard end of the spar attach fitting). The fracture surface displayed downward (clockwise viewing toward the fuselage) torsional and tensile overload characteristics. The rear spar fractured about 2 inches outboard of its attach fitting. The fracture surface displayed downward (clockwise viewing toward the fuselage) torsional and rearward tensile overload characteristics. The tail cone fairing did not display impact marks adjacent to the 3-inch marks on the tail cone bulkhead. The elevator separated from its respective inboard and outboard attach fittings and broke into three pieces. The outboard tip balance weight separated 22 inches from the tip; the second broken area was found about 34 inches from the tip, and the remaining piece separated at the inboard end with its trim tab still attached. The leading edge of the elevator was found twisted downward and the inboard section exhibited an external source impact signature. The elevator trim tab actuator was found in the neutral position. Vertical Stabilizer: The vertical stabilizer remained attached at its respective upper fuselage attach points. The lower leading edge contained a 15- inch circular tear; the radius of this tear is equivalent to the airplane's wing leading edge. The upper section of the stabilizer was found bent to the left and rear. The bending began about 22 inches from the base attach point at the rear vertical spar. The folded section displayed ground impact signatures. Cockpit-Cabin: The integrity of the cockpit area was severely compromised. The upper fuselage was found crushed 18 inches from its original position. The control wheel lock pin was disengaged from the column. The control wheel arm displayed a 1-inch impact gouge at its midspan. Only half of the control wheel attach flange remained. The left side of the control wheel retainer was pushed forward and did not contain any control wheel flange pieces; the right side of the retainer contained broken remnants of the flange pieces. With the control wheel flange fractures matched, the control wheel was in the left position. The landing gear motor/actuator was found in the retracted position. Engine Examination: Safety Board investigators established continuity of the gear and valve train assembly. Thumb compression was noted during rotation of the crankshaft. Most of the engine accessories (magnetos, fuel pump, vacuum pump, etc) were found separated from their respective accessory drive attach points. The spark plugs displayed lean operating signatures. Medical and Pathological Information The Kings County Sheriff/Coroner's Office conducted toxicological and post mortem examinations on the pilot. The forensic pathologist, A.L. Dollinger, M.D., attributed the cause of death to cardiac arrest/arrhythmia, acute myocardial infarction, and coronary atherosclerosis. He also noted that he did not find any evidence of hemorrhage from aorta or lung lacerations. The FAA, Civil Aeromedical Institute, Oklahoma City, Oklahoma, conducted toxicology on the pilot. The toxicologist reported that he did not find any evidence of alcohol or drugs. Tests and Research A Beech Aircraft engineer told Safety Board investigators that the accident airplane model is "spiral stable." That is, if the airplane enters into a spiral turn and is uninterrupted by the pilot, it will not roll out on its own. This condition results from the airplane design of the vertical fin. If the spiral is not arrested the airplane will enter into a high speed, steep spiraling turn. Additional Information Safety Board investigators released the aircraft/engine wreckage to the insurers' representative on July 14, 1995. The Safety Board did not retain any wreckage component. The wreckage was at Valley Aircraft Parts, Inc., Tulare, when it was released.
UNDETERMINED.
Source: NTSB Aviation Accident Database
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