History of Flight
On June 12, 2013, about 0659 Pacific daylight time, an experimental amateur-built Graves SH-2F airplane, registration N15GG, was destroyed when it struck terrain near Montague, California. The airplane was operated by the pilot-owner under 14 CFR Part 91. The private pilot/owner occupied the left seat, and a commercial pilot occupied the right seat; both sustained fatal injuries. Visual meteorological conditions existed, and no flight plan was filed. The flight originated from Montague Airport - Yreka Rohrer Field (1O5) at about 0641.
The airport manager informed the NTSB investigator that the owner had stated the previous afternoon that he was selling the airplane and planned a flight with another pilot to give them a "feel for the airplane" for demonstration to potential buyers.
Local law enforcement reported that witnesses near the accident site heard maneuvering sounds followed by impact. Shortly after, the wreckage was located in an open field. One witness reported that the airplane appeared to attempt a barrel roll before impact. Other witnesses stated the engine was at high power prior to impact; one witness noted a rough running tone rather than a smooth hum.
Personnel Information
The 77-year-old private pilot/owner held a private pilot certificate with single-engine land rating and a third-class medical certificate issued March 22, 2011, with corrective lenses limitation. He reported 2,536 total flight hours. His logbook was not obtained.
The 55-year-old commercial pilot held commercial and flight instructor certificates with single-engine, multiengine, instrument, and glider ratings, and a second-class medical certificate issued May 29, 2013, with corrective lenses limitation. He reported 5,355 total flight hours. His logbook was not obtained.
Aircraft Information
The two-seat, low-wing, retractable-gear experimental amateur-built airplane (serial number 3051) was completed in 1992. It was powered by a Lycoming IO-360-A1B6 engine (200 horsepower) and equipped with an MT adjustable pitch propeller. Maintenance records were not obtained.
Meteorological Information
Recorded data from Siskiyou County Airport (6 miles northwest) at 0653 indicated wind 050° at 5 knots, visibility 10 statute miles, clear sky, temperature 8°C, dew point 2°C, and altimeter 30.11 inHg.
Wreckage and Impact Information
The airplane impacted an open field and came to rest inverted. All major structural components were within about 40 feet of the main wreckage. The wreckage was recovered for examination.
Medical and Pathological Information
Autopsies of both pilots by the Siskiyou County Coroner determined cause of death as "multiple traumatic injuries." Toxicology tests on the left-seat pilot detected ethanol in muscle, fluoxetine and norfluoxetine in liver and kidney, olanzapine in muscle and liver, and warfarin in muscle and liver. Tests on the right-seat pilot detected metoprolol in liver and cavity blood.
Tests and Research
Examination revealed the engine separated from the fuselage; the forward fuselage separated aft of the flaps; the left wing separated. Flight control continuity was established to both cockpits; separations were consistent with overload or due to emergency response. The flap interconnect bolt and nut were missing. The fuel selector was in main tank position; throttle, propeller, and mixture levers were full forward; magneto switch set to both.
The engine was intact but crankshaft would not rotate. Internal continuity was established. Both magnetos produced spark. No preexisting anomalies were found except the disconnected flap torque tube.
A Garmin GPSMap 496 was recovered. Data from the accident flight (Flight 118) showed the airplane departing Runway 33, climbing to about 4,000 feet msl, then cruising at groundspeeds of 140-150 knots. About 4 minutes after takeoff, groundspeed decreased to 125 knots. The airplane then maneuvered, reaching altitudes between 3,700 and 6,000 feet msl and groundspeeds up to 167 knots. Over the final 8 seconds, the airplane descended from 4,948 to 3,638 feet msl with groundspeeds fluctuating from 53 to 73 knots. The last data point was at 06:59:03 at 3,638 feet msl and 73 knots; the accident site was directly below.