Nampa, ID, USA
N72TZ
Frazier Tangent
The pilot was performing high speed taxi tests in an experimental category airplane that he had designed and built. The airplane was configured with a T-tail, a canard wing forward of the cockpit with elevator control surfaces, and had two 28-hp engines mounted facing aft along the trailing edge of the wings in a pusher type design. The main landing gear were located forward of the engine nacelles. To address a lack of pitch response experienced during previous tests, the pilot had increased the size of the canard control surfaces, and moved the center of gravity further aft. During the first taxi run the electronic flight information system (EFIS) recorded a maximum pitch of 9 degrees, and maximum airspeed of 67 knots. During the test run that precipitated the accident, the airplane became airborne at the end of the taxi run and rose to about 122 feet above ground level (agl), entered a right-hand turn, stalled, and impacted terrain in a flat attitude. Audible engine sounds could be heard from the airplane throughout the event and the recorded data supported normal engine operation. The last 16 seconds of data recovered from the EFIS corroborated the witness reports, recording the airplane pitching up suddenly from 8 degrees to 45 degrees, the airspeed decaying from 55 to 22 knots, and then entering a rapid vertical descent. A colleague of the pilot stated that in this pusher configured airplane where the propellers are located aft of the main landing gear, a sudden reduction in thrust could cause a pitch up rotation moment around the main landing gear when on the ground. Toxicology testing was consistent with the recent use by the pilot of a medication containing diphenhydramine, an over-the-counter sedating antihistamine that commonly results in impairment; however, the investigation was unable to conclusively determine whether the use of this medication contributed to the accident.
HISTORY OF FLIGHT On September 24, 2009, about 1030 mountain daylight time, a Frazier Tangent, N72TZ, experimental category airplane, collided with terrain during high speed taxi tests at Nampa Municipal Airport, Nampa, Idaho. The commercial pilot operated the airplane under the provisions of Title 14 Code of Federal Regulations, Part 91. The pilot was killed, and the airplane was substantially damaged. Visual meteorological conditions prevailed, and no flight plan had been filed. According to a colleague of the pilot, the pilot was performing high speed taxi tests and routinely raised the nose of the airplane up during the test runs. During the test run that precipitated the accident, the airplane became airborne and rose to about 75 feet above ground level (agl), started a right-hand turn, stalled, and impacted terrain in a flat attitude. Audible engine sounds could be heard from the airplane throughout the event. PERSONNEL INFORMATION The pilot, age 62, held a commercial pilot certificate with ratings for airplane multiengine land, and instrument airplane, with single-engine land private pilot privileges, issued on February 15, 1999. He held a third-class medical certificate issued in April 28, 2009, with the restriction that he possess glasses for near and intermediate vision. Examination of a copy of the pilot’s most recent logbook recorded a total flight time of 2,170 hours, with 994 hours of multiengine time. No flight time was recorded within the last 90 days. His most recent flight review was conducted on June 21, 2008. AIRCRAFT INFORMATION The single seat, twin engine, experimental category airplane, serial number (S/N) 001, was of the pilot's own design, with a conventional T-tail and a forward canard. It was powered by two Hirth F33V, 28-hp engines. The engines were mounted on the inboard trailing edge of each wing facing aft, in a pusher type configuration. The landing gear main mounts are forward of the engine nacelles. The main mounts were fixed and the nose gear was retractable. Each engine was equipped with a Powerfin E-48 fixed pitch composite propeller. A review of a copy of the airplane's maintenance logbook showed that the pilot/builder performed a 100-hour inspection on July 2, 2009, and a special airworthiness certificate was issued on the same date. The airplane had not accumulated any flight time at the time of the inspection. A colleague of the pilot, who is a commercial pilot and airframe and power plant (A&P) mechanic, worked with the pilot on the airplane design, construction, and testing. He said that they were at the beginning of the ground handling and taxiing testing phase. During previous high speed taxiing tests (35-55 knots), pitch was nonresponsive; the nose would not lift to a positive angle of attack (AOA). They added ballast to move the center of gravity (CG) aft of 30 percent mean aerodynamic chord (MAC), and added a larger canard control surface (elevator), which provided the desired pitch control at 45-50 knots. Additionally, he stated that, "It is not uncommon for a pusher prop type aircraft to have a pitch up tendency with a reduction in power when the wheels are on the runway." FLIGHT RECORDERS The airplane was equipped with a Dynon Avionics Flight DEK-D180 electronic flight information system (EFIS) that recorded the following data in 1-second intervals: fuel level (each tank); exhaust gas temperature (EGT) for each engine; cylinder head temperature (CHT) for each engine; pitch; roll; heading; turn rate; airspeed; altitude; vertical speed; g’s; and outside air temperature (OAT). The data provided to the Safety Board investigator-in-charge (IIC) consisted of the taxi run before the accident and the accident taxi run. The data from the first taxi run revealed that the pitch varied between 0 and 9 degrees throughout the run, and a maximum airspeed of 67 knots was achieved. The data from the taxi run that precipitated the accident revealed that during the last 16 seconds of data, the pitch rose rapidly from 8 to almost 45 degrees then suddenly dropped to negative 18 degrees; the airspeed decayed from 55 to 22 knots as the pitch passed from positive to negative. The altitude data showed that just prior to the pitch excursion the airplane was at 2,384 feet (mean sea level), and the peak altitude recorded during the excursion was 2,506 feet before the altitude data decreased, which implied that the airplane climbed approximately 122 feet above the ground before it descended. The recorded airspeed during the last 3 seconds of data was zero. WRECKAGE AND IMPACT INFORMATION The wreckage was located in the dirt infield next to the runway. The airplane was upright with the nose pointed perpendicularly away from the runway edge. The airplane wreckage was completely intact; the landing gear had collapsed into the fuselage. A ground scar was present that extended about 20 feet behind the wreckage. A Federal Aviation Administration (FAA) inspector examined the airplane on scene, and reported that there was control continuity between ailerons, canard, rudder. The engine controls cables from the throttle quadrant in the cockpit were connected to both engines. Each of the three bladed propellers had two blades sheared off at the hub, and one blade still in its hub. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot November 2, 2009, by the Canyon County Coroner, Caldwell, Idaho, Forensic Pathologist. The autopsy findings state that the cause of death was "Blunt force trauma due to an aircraft accident," and noted medical intervention to include an endotracheal tube, a neck brace, EKG pads, pacemaker pads over the torso and catheters in both tibias. Forensic toxicology was performed on specimens from the pilot by the FAA Forensic Toxicology Research Team, CAMI, Oklahoma City, Oklahoma. The toxicological report stated that there was no carbon monoxide, cyanide, or ethanol detected. Atropine was detected in the liver and blood, and diphenhydramine was detected in the liver and blood. The pilot’s most recent application for third-class airman medical certificate, dated April 28, 2009, did not note any medical conditions or the use of diphenhydramine. The pilot’s spouse noted that the pilot took Tylenol PM several times a week to help him sleep.
The pilot's failure to maintain pitch control of the airplane.
Source: NTSB Aviation Accident Database
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