History of Flight
On October 28, 2014, about 1433 central daylight time, an experimental, amateur-built RV-4, N70PM, was destroyed during an off-airport forced landing near John Henry Key Airport (7TA8) in Boerne, Texas. The pilot, the sole occupant, was fatally injured. The airplane was registered to and operated by the pilot. Day visual meteorological conditions prevailed, and no flight plan was filed for the local personal flight conducted under 14 CFR Part 91. The airplane had departed from Boerne Stage Field Airport (5C1) at an unknown time.
Several witnesses reported that the airplane was maneuvering between 500 and 800 ft above ground level when the engine sounds suddenly stopped. The airplane then entered a steep bank, began flying toward 7TA8, descended, and disappeared from view. The airplane impacted trees and terrain and came to rest upright about 100 ft from the edge of runway 22 at 7TA8. There was an immediate postimpact fire that consumed much of the airplane. The pilot initially survived the accident but succumbed to his injuries the following day.
Personnel Information
The pilot, age 70, held a Federal Aviation Administration (FAA) private pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent third-class FAA medical certificate was issued on September 25, 2014, with the restriction that he must have glasses available for near vision. Complete copies of his personal flight records were not available; however, a review of his most recent logbook indicated 1,687 hours of total flight experience. His flight experience in the accident airplane make and model was about 50 hours, with 10.6 of those hours accumulated within the previous three months. The most recent flight review was completed on January 16, 2013.
Aircraft Information
The airplane was issued an FAA special airworthiness certificate on March 2, 2013. It was a low-wing, fixed conventional landing gear, single-engine airplane powered by a 155-horsepower Lycoming O-320-D2J carbureted engine, which drove a Performance Propellers, Inc. model 70/70, 2-bladed, fixed-pitch, wood propeller. The airplane was of conventional aluminum construction with a cantilever low-wing, conventional tail surfaces, and a 2-seat tandem cockpit accessed through a hinged canopy. A maintenance logbook entry showed an empty weight of 939 pounds and a maximum gross weight of 1,500 pounds. The most recent condition inspection was completed on May 12, 2014, at an aircraft total time of 23.7 hours. At the time of the accident, the airplane had accumulated a total time of 50.1 hours, and the engine had 1,825.1 hours.
Meteorological Information
At 1435, the automated weather observation system at 5C1, about 8 miles south of the accident site, reported wind from 200 degrees at 3 knots, visibility 10 miles, scattered clouds at 2,800 ft, temperature 27°C, dew point 17°C, and an altimeter setting of 30.03 inches of mercury. Review of a carburetor icing probability chart showed the potential for icing at cruise power and a potential for serious icing at glide power.
Airport Information
7TA8 was a non-towered airport with a field elevation of 1,400 ft msl. The only runway, 4/22, was a turf runway 2,300 ft long by 100 ft wide. The airport was surrounded by rugged hilly terrain, with much of the area thickly wooded.
Wreckage and Impact Information
The airplane impacted densely-wooded, hilly terrain on a south-southwesterly heading at an estimated elevation of about 1,400 ft msl, approximately 200 ft northwest of runway 22 at 7TA8. The first impact was to upper branches of cedar trees at about 8 ft above ground level. Both impact-separated propeller blades were found nearby. Ground scars, wreckage debris, and numerous broken branches littered the area along a wreckage distribution path of about 145°. All flight control surfaces and major components were accounted for. The main wreckage came to rest upright about 89 ft from the initial tree impact. The tip of the left wing was oriented about 190°, and the partially-separated upright fuselage was oriented about 300°. The engine and engine mount remained connected to the forward firewall, which was adjacent to the forward fuselage, almost completely separated from the fuselage by fire damage. The hub of the wood propeller remained attached to the propeller flange but was partially consumed by fire. The empennage and tail surfaces were completely separated and came to rest partially inverted about 10 ft northwest of the engine. The vertical stabilizer had leading edge impact damage at the root. The right wing was mostly consumed by fire, while the left wing drained about 2 gallons of clean 100LL aviation fuel. The left flap was observed in the full-down position; the right flap position could not be determined due to impact and fire damage. Flight control linkages and engine controls exhibited severe impact and thermal damage, precluding a confirmation of preimpact control continuity, though separations appeared consistent with impact damage.
Medical and Pathological Information
An autopsy performed by the Bexar County Medical Examiner's Office concluded that the pilot died as a result of conflagration injuries sustained in the airplane crash. Forensic toxicology detected lorazepam, midazolam, morphine, norketamine, and propofol, which were traced to the pilot's post-accident hospital care. Additionally, cetirizine, an over-the-counter antihistamine, was detected in liver and blood, but the amount was too low to quantify.
Tests and Research
The wreckage was moved to another location for further engine examination. The engine and accessories sustained impact, fire, and heat damage. The exhaust and induction systems displayed significant heat and impact damage. The carburetor had separated on impact and displayed thermal damage. All fluid-carrying lines in the engine compartment were fire-damaged, and the oil system was impact- and fire-damaged. Severe thermal damage prevented a useful examination of the magnetos, fuel pump, carburetor, or any other components. On initial attempts, the engine would not rotate. After engine accessories were removed and the engine was partially disassembled, the crankshaft and valve train rotated freely with no interference.