N15GGGraves Larry L SH-2F · 1992

On June 12, 2013, about 0659 Pacific daylight time, an experimental amateur built Graves SH-2F airplane, N15GG, was destroyed when it impacted terrain near Montague, California. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot/owner, who was seated in the left seat, and commercial pilot, who was seated in the right seat, were fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight. The local flight originated from the Montague Airport - Yreka Rohrer Field (1O5) near Montague about 0641.

The airport manager reported to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) that the owner of the airplane told him the afternoon prior to the accident that he was selling the airplane, and was going flying with another pilot in the morning to let them "get a feel for the airplane" so he could demonstrate it to potential buyers.

Information provided by local law enforcement revealed that witnesses located near the accident site reported hearing the sound of an airplane maneuvering followed by the sound of impact. Shortly after, the witnesses located the wreckage of the airplane in an open field. One witness reported that prior to the impact with the ground; the airplane appeared to have attempted a barrel roll. Additional witnesses located adjacent to the accident site reported to the NTSB IIC that they heard the airplane's engine running at a high power setting prior to the sound of impact. One witness further reported that 4 minutes prior to the accident, he saw the accident airplane fly over his house, and noted that the engine was at a high power setting, however, it had a rough running tone instead of a "smooth humming sound."

Pilot #1 (left seat pilot/airplane owner)

The pilot/owner, age 77, held a private pilot certificate with an airplane single-engine land rating. A third-class airman medical certificate was issued to the pilot on March 22, 2011, with the limitation stated "must wear corrective lenses for near and distant vision." The pilot reported on his most recent medical certificate application that he had accumulated 2,536 total flight hours. The pilot's personal logbook was not obtained during the investigation.

Pilot #2 (right seat pilot)

The pilot, age 55, held a commercial pilot certificate with an airplane single-engine land, airplane multiengine land, instrument airplane, and glider ratings. The pilot also held a flight instructor certificate with airplane single-engine land and glider ratings. A second-class airman medical certificate was issued to the pilot on May 29, 2013, with the limitation that stated "must wear corrective lenses, not valid for any class after." The pilot reported on his most recent medical certificate application he had accumulated 5,355 total flight hours. The pilot's personal logbook was not obtained during the investigation.

The two-seat, low-wing, retractable-gear experimental amateur-built airplane, serial number (S/N) 3051, was completed in 1992. It was powered by a Lycoming IO-360-A1B6 engine, serial number L-13632-51A, rated at 200 horsepower. The airplane was also equipped with an MT adjustable pitch propeller. The airplane maintenance records were not obtained during the investigation.

A review of recorded data from the Siskiyou County Airport automated surface observing system, located about 6 miles northwest of the accident site, revealed at 0653 conditions were wind from 050 degrees at 5 knots, visibility 10 statute miles, clear sky, temperature 8 degrees Celsius, dew point 2 degrees Celsius, and an altimeter setting of 30.11 inches of mercury.

The two-seat, low-wing, retractable-gear experimental amateur-built airplane, serial number (S/N) 3051, was completed in 1992. It was powered by a Lycoming IO-360-A1B6 engine, serial number L-13632-51A, rated at 200 horsepower. The airplane was also equipped with an MT adjustable pitch propeller. The airplane maintenance records were not obtained during the investigation.

Examination of the accident site by local law enforcement revealed that the airplane impacted an open field, and came to rest inverted. All major structural components of the airplane were located within about 40 feet of the main wreckage. The wreckage was recovered to a secure location for further examination.

Pilot #1 (left seat pilot/airplane owner)

The Siskiyou County Coroner conducted an autopsy on the pilot on June 15, 2013. The medical examiner determined that the cause of death was "multiple traumatic injuries."

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had positive results for 28 (mg/dL, mg/hg) Ethanol detected in Muscle, unspecified levels of Fluoxetine detected in Liver, Fluoxetine detected in Kidney, Norfluoxetine detected in Liver, Norfluoxetine detected in Kidney, Olanzapine detected in Muscle, Olanzapine detected in Liver, Warfarin detected in Muscle, Warfarin detected in Liver

Pilot #2 (right seat pilot)

The Siskiyou County Coroner conducted an autopsy on the pilot on June 15, 2013. The medical examiner determined that the cause of death was "multiple traumatic injuries."

The FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI's report, carbon monoxide, cyanide, volatiles, and drugs were tested, and had positive results for unspecified levels of Metoprolol detected in liver and in cavity blood.

Examination of the recovered wreckage revealed that the engine was separated from the fuselage. The forward portion of the fuselage separated aft of the flaps. The left wing was separated from the fuselage. Aileron, rudder, and elevator flight control continuity was established to both the left and right cockpit controls. All separations in the control cables were splayed (consistent with overload) or cut by emergency response personnel and wreckage recovery. The elevator torque tube exhibited overload signatures. The flap interconnect from the flap bar to the torque tube was found separated. No evidence of a bolt being installed was observed, and the bolt and nut were not located. The airplane was equipped with dual controls, and only the left side had brakes.

The fuel selector valve was in the main fuel tank position. The throttle, propeller, and mixture levers were in the full forward position. The magneto switch was in the "both" position

The engine was intact. Both magnetos and the starter were separated. The fuel pump was partially separated. The induction system and oil sump were crushed upward into the crankcase structure. Underneath the number two cylinder induction tubes, the crankcase was compressed inward and cracked. The engine crankshaft would not rotate by hand. Holes were made in the bottom side of the crankcase to facilitate internal examination of the engine. Internal mechanical continuity of the engine was established.

The left and right magnetos were intact and produced spark on all leads when the magneto driveshafts were rotated by hand. The left magneto was equipped with an impulse coupling, which functioned normally when the magneto drive shaft was rotated. The throttle body and fuel control unit screen was clear of debris. The mixture and throttle levers moved from stop to stop by hand.

The fuel distribution valve screen was free of debris, and the diaphragm was intact.

All three propeller blades were separated and splintered from the propeller hub at the blade root.

With the exception of the flap torque tube disconnected from the flap control bar, the examination of the recovered wreckage revealed no further anomalies with the engine or airframe that would have precluded normal operation.

A Garmin GPSMap 496 was found within the recovered wreckage. The GPS was subsequently shipped to the NTSB Vehicle Recorders Laboratory, Washington, DC, for further examination.

The data extracted from the Garmin GPSmap 496 contained a total of 118 tracklogs. The last recorded tracklog, Flight 118, was found consistent with the accident flight. GPS data depicted the tracklog originating at a hangar complex on the west edge of 1O5. The airplane taxied, crossed Runway 15/33, and appeared to hold short of Runway 33. The data showed that the airplane departed Runway 33, and performed a climbing right turn to the southeast, leveling off at an altitude of about 4,000 feet mean sea level (msl), and established a short cruise flight between groundspeeds of 140 and 150 knots. About 4 minutes after takeoff, the data showed the airplane's groundspeed began to steadily decrease to about 125 knots 2 minutes later.

About 1 minute later, the data showed that the airplane departed its brief cruise profile, and began maneuvering in an area approximately 8 nautical miles southeast 1O5. The airplane maintained a groundspeed of about 125 knots as it turned to the north while maintaining an altitude of about 3,700 feet msl. The data showed that the airplane performed a brief left 180-degree turn to the south and then quickly turned to the right to the northwest. About 2 minutes later, the airplane began an ascending left turn towards the south. The data showed that the airplane leveled between 5,700 and 6,000 feet msl as it traveled south-southeast, reaching a peak groundspeed of 167 knots. The data further depicted that about 44 seconds later, the airplane began a left turn toward the north as the groundspeed reduced to about 130 knots. The data showed that the airplane continued on a northerly heading while groundspeed reduced to about 67 knots at an altitude of about 5,154 feet msl. About 4 seconds later, the groundspeed had slowed to about 62 knots at an altitude of 4,948 feet msl, with a slight course deviation to the left. The remaining 5 data points, spanning about 8 seconds, showed the airplane descending from 4,948 feet msl to 3,638 feet msl, with groundspeeds fluctuating from 53 knots to 73 knots.

The last data point was recorded at 06:59:03 at 3,638 feet msl and a groundspeed of 73 knots. No further GPS data was recorded. The accident site was located almost directly below the last recorded data point.