Accident Details
On June 3, 2023, at 1320 central daylight time, an experimental, amateur-built Zenith 601XL, registration N601YP, was substantially damaged in an accident near Albertville, Alabama. The commercial pilot was fatally injured. The airplane was operating under Title 14 Code of Federal Regulations Part 91.
A friend of the pilot, a mechanic familiar with the build project, had assisted troubleshooting systems including oil pressure and airspeed interfaces with the Electronic Flight Instrumentation System and Engine Monitoring System. After the airspeed issue was fixed and oil pressure triggers reset, the pilot began another test flight. The mechanic advised the pilot to stay over the airport.
The pilot departed Albertville Regional Airport-Thomas J Brumlik Field (8A0). Recovered electronic instrument data showed the airplane flew southwest, made heading changes, climbed to 4,000 ft msl, then descended and leveled at 2,050 ft msl. Witnesses near the accident site reported the airplane appeared to fly slow and at low power when it suddenly "went full throttle" and nosed over. One witness noted pitch and roll oscillations before descent.
The airplane impacted trees and terrain, coming to rest inverted on the side of a stream bed about 3.5 miles northwest of 8A0 at an elevation of 1,007 ft. All major components were located at the site. The wreckage path was about 50 ft long oriented on a heading of 057° magnetic. The fuselage, empennage, wings, and flight controls were near the primary impact. The engine separated and was found about 40 ft north in a creek bed. Shattered tree branches had features consistent with propeller cuts. Both wings were displaced aft but partially attached to a torsionally twisted wing spar. Two internal fuel tanks were severed from mounts; fuel tanks were compromised with automotive gasoline odor and vegetative fuel blight.
Examination Findings
Airframe examination revealed the electrically-actuated elevator trim was in full up position (nose down trim) and flaps retracted. The empennage separated on impact. Rudder continuity was established through overload breaks. Aileron and elevator control continuity was traced through breaks with broom-straw fracture features. Several cable cuts were from emergency recovery attempts.
Engine and propeller examination showed the propeller hub attached to the flange. Two blades fractured about 3 inches from the hub, one about 9 inches; all bent opposite rotation. Delaminated blade pieces were scattered. Crankshaft continuity was confirmed; smooth action of rockers, valves, and springs with 720° rotation. Compression and suction on all cylinders; spark plugs normal per Champion Aerospace AV-27 chart.
The cockpit was destroyed by impact. The forward-lift clamshell canopy frame was deformed with only plexiglass remnants. Hydraulic lift assist was extended. No secondary canopy latch was found; no witnesses reported canopy open during descent.
The elevator trim actuator was bench-tested at the manufacturer under NTSB supervision. The actuator moved progressively in both directions with appropriate position indications, turned off at limits, and geartrain sound and speed appeared normal. No chafing or exposed conductors; LED position indicator operational. No irregularities were noted.
Flight Data Recorder
The airplane was equipped with a panel-mounted electronic flight instrumentation and engine monitoring system (EFIS/EMS) storing data in non-volatile memory. The NTSB Recorders Laboratory downloaded data covering the entire flight through descent and impact. Data showed no interruption of engine power. Performance data included pitch, yaw, speeds, altitude, heading, and vertical speed. After departure, the airplane performed turns, descents, and straight-and-level flight.
About 30 minutes into the flight, at 2,050 ft msl on a GPS ground track of about 055°, data showed a left roll as pitch decreased. About 20 seconds before data ended, engine power increased from 4,500 rpm to 5,500 rpm and speeds increased. During the final 12 seconds, the airplane reached a maximum left roll near 35° with downward pitch near -20°. It descended at about -900 ft/min; magnetic heading and ground track remained constant. Engine rpm decreased to about 4,900 rpm in the final 5 seconds.
Toxicology and Medical
The Alabama Department of Forensic Sciences performed the pilot's autopsy. Cause of death was blunt force injuries; manner was accident. Heart examination was limited by injury; coronary arteries could not be examined. Within limitations, no significant natural disease was identified.
Death investigator records documented a medical history including prediabetes and vascular issues; source not specified.
Postmortem toxicology by ADFS did not detect any tested-for substances. FAA Forensic Sciences Laboratory detected metformin and glipizide in liver and muscle tissue. Glucose was not detected in vitreous. No blood was available.