What happened
On September 24, 2009, a Frazier Tangent experimental airplane, registration N72TZ, collided with terrain during high-speed taxi tests at Nampa Municipal Airport in Nampa, Idaho. The aircraft, which was of the pilot's own design, was being operated under Part 91 regulations.
During the testing phase, the pilot was performing high-speed taxi runs. According to a colleague, the pilot routinely raised the nose of the aircraft during these tests. During the specific run that led to the accident, the aircraft became airborne and reached an altitude of approximately 122 feet above ground level. The airplane then entered a right-hand turn, stalled, and impacted the ground in a flat attitude. The pilot sustained 1 fatal injury.
The investigation
Data recovered from the aircraft's electronic flight information system (EFIS) provided a detailed account of the final seconds of the taxi run. The records showed that in the 16 seconds preceding the accident, the aircraft's pitch rose rapidly from 8 degrees to nearly 45 degrees. Simultaneously, the airspeed decreased from 55 knots to 22 knots. The data indicated the aircraft reached a peak altitude of 2,506 feet MSL before descending.
Investigators examined the wreckage, which was found upright in a dirt infield next to the runway. The landing gear had collapsed into the fuselage, and the propellers had sustained damage with blades sheared off at the hub. An FAA inspector confirmed that control continuity existed between the ailerons, rudder, and canard.
Technical analysis revealed that the aircraft featured a pusher configuration with two 28-hp engines mounted facing aft. To address previous issues with pitch responsiveness, the pilot had recently moved the center of gravity aft and enlarged the canard control surfaces. A colleague noted that in this specific configuration, a reduction in power can create a pitch-up tendency while the wheels are on the runway.
Findings
- The aircraft was in the early stages of ground handling and taxiing testing.
- The aircraft's pitch increased sharply during the final moments of the taxi run.
- Toxicology results showed the presence of diphenhydramine, a sedating antihistamine, though investigators could not conclusively determine if this contributed to the accident.