History of Flight
The accident occurred at about 1500 Pacific daylight time on July 22, 2017. The airplane, an Applegate Panzl S331E, registration N331ST, impacted terrain while conducting aerobatic maneuvers near Apple Valley, California. The private pilot was fatally injured and the airplane sustained substantial damage. The pilot was operating under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed. The local personal flight originated from Apple Valley Airport at about 1445.
The pilot was practicing her aerobatics routine and was performing the sixth figure of a nine-figure routine. A witness familiar with the routine stated that the airplane entered a 45° descent, executed a right snap roll, then entered a left roll. The airplane continued descending, rolling at a slower rate until impact. The witness reported that the pilot had adequate altitude to complete the maneuver.
An in-cockpit video captured the flight. During the engine run-up, the pilot confirmed flight control continuity, and aileron surfaces moved accordingly. The pilot departed and began the aerobatic routine about 3 minutes into the flight. About 4 minutes into the routine, the airplane entered a 45° inverted downline and performed 1.5 snap rolls to the right. The pilot momentarily stopped the roll at 4,100 ft and started a roll to the left. The right aileron was observed trailing edge down; the left aileron was not visible. The pilot moved her body to the right, consistent with a right control stick input, but the airplane continued rolling left at an increasing rate. The right aileron then showed an upward deflection; left aileron deflection could not be determined. The airplane continued left roll until impact. No distress calls were transmitted.
Personnel Information
The pilot held a third-class FAA medical certificate issued November 15, 2016. On the application, she reported 982 total flight hours, with 39 hours in the previous six months. She had been flying aerobatics since 2006. She purchased the airplane in 2015 and accrued about 189 flight hours in it, 45 of which were in the previous 12 months.
Aircraft Information
The airplane's most recent annual inspection was completed on December 8, 2016. The maintenance log indicated disassembly and reassembly, installation of a new control stick, and inspection of ailerons, aileron hinges, and attach points, all recorded as satisfactory.
Wreckage and Impact Information
The airplane impacted sandy desert terrain in an approximate 45° nose-down, upright attitude. The engine was mostly embedded in a 2-ft-deep crater; wood propeller blades were fractured near the hub and fragments found at the crater bottom. The engine cowling, cabin, and both wing skins were heavily fragmented and separated from the underlying structure. Impact marks consistent with wing leading edges were visible. The cabin was heavily damaged; aft fuselage skin was still attached but crushed. The empennage was mostly intact and undamaged.
Control continuity was established throughout the airframe with two breaks: one in the left aileron control assembly and one in the elevator control assembly. The NTSB Materials laboratory examined fracture surfaces. The left aileron control rod end showed flat areas emanating from the inner diameter of the outer ring, transitioning to angular planes near the outer diameter. One fracture surface had smearing that obscured fine features; the other exhibited feathery features consistent with fatigue cracking. The elevator control fracture showed features consistent with shear overstress.
The engine sustained crush damage to oil sump, exhaust, and induction systems. Magnetos were heavily damaged and could not be tested; ignition harness was destroyed. Top spark plugs varied in coloring but were consistent with normal operation. Fuel nozzles were clear of debris. Borescope examination revealed no mechanical damage, detonation, or foreign object ingestion. Engine rotation established continuity, thumb compression on all cylinders, and appropriate valve movement. No anomalies precluding normal operation were found.
Medical and Pathological Information
An autopsy by the San Bernardino County Coroner listed the cause of death as multiple blunt force injuries. The FAA Bioaeronautical Sciences Research Laboratory performed forensic toxicology with negative results for carbon monoxide and drugs. 85 mg/dL ethanol detected in blood was likely from postmortem production.