History of Flight
On July 2, 2008, about 1307 Pacific daylight time, an amateur-built Mauck RV-6A experimental airplane (N27WR) was substantially damaged when it impacted trees while maneuvering near Sierraville, California. The aircraft was registered to Tahoe Athletic Adventures Inc of Tahoe City, California, and operated by the pilot under 14 CFR Part 91. The pilot, the sole occupant, was killed. The flight originated from Truckee-Tahoe Airport (TRK) about 1254 as a personal local flight. Visual meteorological conditions prevailed, and no flight plan was filed.
A concerned family member reported the airplane missing later that day. The FAA issued an Alert Notification, and the wreckage was located by air units on July 5, about 1050, in a heavily wooded area 1.5 miles northwest of Sierraville Deerwater Airport (O79).
Two witnesses along the estimated flight path reported observing a low-flying airplane. One witness, about 18 miles southeast of the site, paused a phone conversation until the airplane passed northward. Another, about 13 miles southeast, saw it fly east then turn south until out of sight, noting a "swooshing" sound. No witnesses observed the accident sequence.
Surveillance video at TRK showed the airplane taxiing toward the runway at 1253.
Personnel Information
The pilot held a private pilot certificate with airplane single-engine land and glider aero tow ratings. A second-class medical certificate was issued on September 25, 2007, with the limitation "night flying prohibited." Logbook records showed 167.8 hours total flight time, 68.8 hours in the accident make/model, 24.7 hours in the previous 90 days, and 7.2 hours in the previous 30 days. A biennial flight review was completed on September 20, 2007.
Aircraft Information
The two-seat, low-wing, fixed-gear airplane, serial number 21073, was manufactured in 1991. It was powered by a Lycoming O-360-A1A engine (S/N L-13080-36A) rated at 180 horsepower, equipped with a Sensenich two-bladed fixed-pitch propeller. Maintenance records showed a conditional inspection on July 2, 2008, at a tachometer reading of 203.2 hours, during which the engine-driven fuel pump was replaced. The tachometer at the accident site read 203.8 hours, 0.6 hours after the inspection.
A fuel slip indicated the pilot purchased 20 gallons of fuel on July 2 at 1240.
Meteorological Information
Automated observations at TRK (24 miles southeast) at 1245 reported wind from 210° at 10 knots, visibility 10 statute miles, clear sky, temperature 28°C, dew point -2°C, altimeter 30.15 inHg. At Blue Canyon Airport (32 miles southwest) at 1252, wind from 240° at 5 knots, visibility 2 statute miles, haze, clear sky, temperature 23°C, dew point 7°C, altimeter 30.16 inHg. A US Forest Service lookout 12 miles east-southeast reported visibility of 1/4 to 1/2 miles with heavy smoke around midday. A local law enforcement officer stated visibility was marginal due to smoke on the day of the accident.
Wreckage and Impact Information
FAA examination revealed the airplane came to rest inverted in tall trees about 1.5 miles northwest of O79. The left wing was mostly separated from the fuselage, and the engine was separated from the firewall. All primary flight controls were located at the site. The wreckage energy path measured about 200 feet from initial contact to where the engine came to rest.
Medical and Pathological Information
An autopsy on July 8, 2008, determined the cause of death as blunt force trauma. Toxicological tests by CAMI detected ethanol in liver (74 mg/dL), muscle (117 mg/dL), blood (20 mg/dL), spleen (26 mg/dL), kidney (33 mg/dL), and N-butanol in muscle (20 mg/dL) and N-propanol in muscle (3 mg/dL), blood (1 mg/dL), kidney (1 mg/dL). Diphenhydramine was detected in the liver (amount unspecified). Specimens exhibited evidence of putrefaction, and the pathologist noted that the postmortem blood ethanol concentration (64 mg/dL) may be a decomposition artifact.
Tests and Research
On July 22, 2008, at Plain Parts, Pleasant Grove, California, the recovered airframe and engine were examined under NTSB supervision. The fuselage forward of the rear cabin was severely fragmented; the main wing spar separated from the fuselage. Flight control continuity was established from the cockpit to all primary controls; aileron and elevator torque tubes and rudder cables were separated at multiple points, consistent with overload. The attitude indicator's gyro was intact with rotational scoring on the housing.
The engine was partially attached to the mounts; the mount separated from the firewall but some wires remained attached. The forward crankcase was heavily damaged, with a missing bottom left portion and cracks on the top forward portion. The propeller flange separated from the crankshaft; the carburetor, alternator, starter, and oil cooler separated. Top spark plugs and accessories were removed. The crankshaft would not rotate by hand; cylinders #3 and #4 were removed and exhibited normal operation signatures. Mechanical continuity was established throughout the engine and valve train.
The propeller remained attached to its mounting flange but separated from the crankshaft. One blade had a leading edge gouge 3-4 inches long and spanwise scratches on the forward side. The other blade was missing about 4 inches of the tip and had chordwise scratches on the forward side. No mechanical anomalies were noted with the recovered engine, airframe, or flight control system.