Oshkosh, WI, USA
N888SM
Beech F35
The airplane was destroyed when it impacted terrain while on short final. The pilot advised the air traffic control tower that he was going to land short. A witness reported that he saw the airplane flying low with its wings wobbling. The witness also stated that the airplane's nose and left wing dropped and he lost sight of the airplane. An analysis of the airplane's radio transmissions revealed the sound of a warning horn that was consistent with the stall warning horn from a Beech Bonanza. An engine run revealed no anomalies.
HISTORY OF FLIGHT On April 17, 2001, at 0816 central daylight time, a Beech F35, N888SM, operated by Basler Turbo Conversions, was destroyed on impact with terrain during final approach to runway 36 (8,002 feet by 150 feet, grooved concrete) at the Wittman Regional Airport (OSH), Oshkosh, Wisconsin. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 maintenance test flight was not operating on a flight plan. The commercial pilot was fatally injured. The local flight originated at 0744. The pilot was to take the airplane from the company's maintenance hanger located on the south side of the airport to a company hanger located on the north side of the airport for storage. He called the Director of Maintenance to ask if he could perform a maintenance test flight so as to verify if everything was working; the Director of Maintenance concurred. According to the Director of Maintenance a test flight would incorporate a checkout of airplane systems, but there are no specific maneuvers that would be performed. He added that stalls would normally not be performed during a test flight. At 1307:47, N888SM transmitted, "oshkosh tower bonanza eight eight eight sierra mike is ten miles to the southwest inbound for landing." At 1307:53, Oshkosh air traffic control tower (LC/GC) transmits, "bonanza eight eight eight sierra mike oshkosh tower rodger report three mile left base for runway three six." At 1307:59, N888SM transmitted, "call a three mile left base for runway three six eight sierra mike." At 1312:04, N888SM transmitted, "oshkosh tower bonanza eight sierra mike is on a three mile left base for runway three six." At 1312:08, LC/GC transmitted, "bonanza eight sierra mike rodger cleared to land runway three six." At 1312:1, N888SM transmitted, "cleared to land eight sierra mike." At 1315:34, N888SM transmitted, "tower eight sierra mike is going to be landing short in a." At 1315:39, N888SM transmitted, "oh my god." There were no further transmissions by N888SM. A witness reported, "...I saw the plane just clearing the trees. I said to the truck driver that guys to low he is going to make it to the runway. I didn't hear the motor because of my forklift running. It didn't look like he turned at all it looked from the side like he ran out of airspeed and tried to land in the field." A second witness reported, "...I looked up and saw an airplane very low going north towards the airport. The wing were wobbling side to side and it started turning left and the nose dropped down [and] left wing was down. The plane almost made a u-turn with nose very low and then I lost sight of it." A third witness reported, "...heard another transmission 'Oh God' and a stall warning horn in the background...". PERSONNEL INFORMATION The pilot, age 31, was employed by Basler Turbo Conversions as the Assistant Director of Maintenance on January 15, 1998. He held an airline transport pilot certificate with a multi-engine land rating and a DC-3TP type rating. He also held commercial pilot privileges for single-engine land airplanes. He held a certified flight instructor certificate with airplane single-engine and instrument airplane ratings. He also held a mechanic certificate with airframe and power plant ratings. He was issued a first class medical certificate on June 27, 2000, with a restriction, "must wear corrective lenses." According to the pilot's logbook, as of April 6, 2001, he accumulated a total flight time of 1,828 hours, of which 1,029.8 hours were in single engine land airplanes. He last flew the accident airplane on November 27, 2000, for 2.7 hours on a flight from OSH-08C-OSH. AIRCRAFT INFORMATION The 1955 Beech F-35, serial number D-4051, was powered by a Continental E-225-8 engine, serial number 30356-D-4-8, rated at 225 horsepower at 2,650 rpm for takeoff and 185 horsepower at 2,300 rpm for maximum continuous operation. Logbook entries indicate that an annual inspection was performed on April 10, 2001, at a Hobbs time of 2,147.3 and a aircraft total time of 6,990.4. The accident airplane's fuel system was modified on June 17, 1980 with the installation of Brittan Industries Model M668 wing tip fuel tanks and a fuel selector assembly, part number 55001, under Beech Kit 35-668-3 and supplemental type certificate (STC) SA4-1629. An electric Dukes Astronautics auxiliary fuel pump was also installed under STC SA1375WE . The stall warning indicator on Beechcraft Bonanza F35 airplanes consists of a warning horn and flashes a red light on the instrument panel as an incipient stall develops. The stall warning indicator is triggered by a sensing vane on the leading edge of the left wing. The warning signal is intermittent at first and will then become steady as the airplane approaches a complete stall. A landing gear warning system, which consists of a intermittently sounding horn, is provided for Beech F35 airplanes. The warning is actuated when the throttle is retarded below 12 inches of inches of manifold pressure with the landing gear retracted. METEOROLOGICAL INFORMATION The OSH automated surface observing system recorded, at 0753; winds from 360 degrees at 16 knots gusting to 22 knots; 10 statute mile visibility; temperature -1 degrees Celsius, dew point -7 degrees Celsius; altimeter setting of 30.30 inches of mercury. WRECKAGE AND IMPACT INFORMATION The airplane was lying inverted approximately 5,396 feet south of the approach end of runway 36 in a muddy agricultural field with north south rows. The airplane was oriented on a tail to nose magnetic heading of 320 degrees with the trailing edge flaps retracted and the main landing gear extended. The engine, right wing, and empennage were attached to the airframe. An outboard section of left wing, approximately 1/2 span in length, was lying next to the main wreckage. Flight control continuity was confirmed from the empennage control surfaces and wings to the flight controls. The left wing outboard aileron bell crank exhibited an overstress separation. No obstruction or binding of the flight controls was noted. The extension of the elevator jack screw was 1.1 inches which equates five degrees tab up. The range of trim tab travel for Beech F35 airplanes is 10 degrees tab up to 31 degrees tab down. Both tip tanks were broken open and empty. The right auxiliary tank had a fuel level which was about one inch below the tank filler neck; the right main tank had less than 1/4 cup of fuel. The left main tank contained approximately two gallons of fuel. The left auxiliary tank was broken open and empty. Inspection of the cockpit revealed that the gear selector handle was down, the magnetos were selected to the both position, and the battery and alternator switches were in the on position. The flap selector switch was destroyed. The altimeter setting was 30.24 inches of mercury. The Hobbs meter and tachometer indicated 2,148.7 and 1,966.84, respectively. The fuel selector was between the "right main" and "auxiliary". The valve was removed and was able to be rotated by hand and no detents were noted. The tip tank selectors were in the "off" position. There was approximately two tablespoons of fuel in the gascolator and its strainer was unobstructed. There was fuel in the primer line. The main fuel line from the firewall to the engine driven pump contained approximately three drops of fuel. The fuel line from the outlet of the engine driven pump to the pressure carburetor also contained fuel. The carburetor was separated through an attachment point to the engine. Approximately one spoonful of fuel was noted in the carburetor's return line. The propeller exhibited twisting on one blade. The second blade was straight. The tachometer was indicating the same time as it did on May 30, 1997. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed by the Winnebago County Coroner on April 17, 2001. According to the coroner, a bottle of partially used Afrin was found in the pilot's jacket. According to the FAA Forensic Toxicology Fatal Accident Report of the pilot, phenylpropanolamine, ephedrine and pseudophedrine were detected in urine and 6.135 (ug/ml, ug/g) acetaminophen was detected in blood. Pseudoephedrine is a common decongestant with a trade name Sudafed that is found in many over-the-counter cold and allergy preparations. Ephedrine is sold as an asthma medication (trade name Primatene) available over the counter in tablet form. Ephedrine and pseudoephedrine are often found together in the herbal supplement "Ma Huang" (also known as "ephedra"). Ma Huang is used as an "energy booster", stimulant, weight loss product, or decongestant in many nutritional supplements. Phenylpropanolamine is an over-the-counter decongestant, also marketed as a weight loss product. It is also a metabolite of ephedrine and pseudoephedrine. Acetaminophen is a pain killer/fever reducer often known by the trade name Tylenol. TESTS AND RESEARCH An engine run at Teledyne Continental Motors was performed under the supervision of the National Transportation Safety Board. The engine carburetor was fractured at it's base and could not be repaired. A replacement carburetor was then attached and used for the engine run. The engine was run at idle, 1,200 rpm, 2,100 rpm, and full power (2,670 rpm), with no discrepancies noted which would have precluded engine operation during the accident flight. During post accident interviews, the chief pilot from March 1997 to June 1999 stated he sat down with a former chief pilot to review N888SM's systems and mostly how to operate the fuel system. He then checked himself out, which was the only time he performed stalls. There was not much formalized instruction because it was not a complex airplane. The airplane was a "funny airplane" with the V-tail and the fuel system was "overcomplicated." The fuel selector was equipped with three fuel selectors. He stated that the fuel selector was equipped with detents and there was no pulling or pushing of the selector to move it between detents. He stated that it was a visual thing where you would have to look at the fuel selector to see its position. He stated that you could have pushed the fuel selector with your heel to move it. During flight, they would let a fuel tank run dry because of gauge inaccuracy and then switch tanks for maximum range. The pilot flew for him as a first officer and he did not remember any problems with his flying and also stated the he was a "pretty sharp guy". According to the Airplane Flying Handbook, FAA-H-8083-3, Recognition of Stalls, states, "Pilots must recognize the flight conditions that are conducive to stalls and know how to apply the necessary corrective action. They should learn to recognize an approaching stall by sight, sound, and feel. The following cues may be useful in recognizing the approaching stall: Vision is useful in detecting a stall condition by noting the attitude of the airplane. This sense can only be relied on when the stall is the result of an unusual attitude of the airplane. Since the airplane can also be stalled from a normal attitude, vision in this instance would be of little help in detecting the approaching stall. Hearing is also helpful in sensing a stall condition. In the case of fixed-pitch propeller airplanes in a power-on condition, a change in sound due to loss of revolutions per minute (RPM) is particularly noticeable. The lessening of the noise made by the air flowing along the airplane structure as airspeed decreases is also quite noticeable, and when the stall is almost complete, vibration and incident noises often increase greatly. Kinesthesia, or the sensing of changes in direction or speed of motion, is probably the most important and the best indicator to the trained and experienced pilot. If this sensitivity is properly developed, it will warn of a decrease in speed or the beginning of a settling or mushing of the airplane. The feeling of control pressures is also very important. As speed is reduced, the resistance to pressures on the controls becomes progressively less. The lag between these movements and the response of the airplane becomes greater, until in a complete stall all controls can be moved with almost no resistance, and with little immediate effect on the airplane. Several types of stall warning indicators have been developed to warn pilots of an approaching stall. The use of such indicators is valuable and desirable, but the reason for practicing stalls is to learn to recognize stall without the benefit of warning devices." A sound spectrum study was performed on all the radio transmission from N888SM by the National Transportation Safety Board. The frequency response of the pilot's headset, the aircraft's radios and the tower's recording system were such that no signatures associated with the engine were recorded during N888SM's transmissions. About 8.5 seconds from the beginning of N888SM's last transmission, a signature corresponding to the stall warning horn of a Beech Bonanza was noted. ADDITIONAL INFORMATION Basler Turbo Conversions, FAA, Raytheon Aircraft Company, and Teledyne Continental Motors were parties to the investigation. The wreckage and engine were released to Basler Turbo Conversions.
The pilot's failure to maintain adequate airspeed which resulted in a stall. The low altitude was a contributing factor.
Source: NTSB Aviation Accident Database
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