N52TH

HISTORY OF FLIGHTOn February 11, 2018, about 1059 Pacific standard time, an experimental, amateur-built Cirrus VK-30, N52TH, impacted terrain near Agua Dulce, California. The private pilot and three passengers were fatally injured, and the airplane was substantially damaged. The airplane was registered to the pilot who was operating it as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions existed near the accident site about the time of the accident, and no flight plan was filed for the flight, which originated from Henderson Executive Airport (HND), Las Vegas, Nevada, about 1000.

The pilot's wife reported that she had dropped her husband and three passengers off at HND; they had planned to fly to Van Nuys Airport (VNY), Van Nuys, California. She added that this was a trip that her husband had flown multiple times.

A witness hiking in a park about 2 miles north of the accident site reported that he saw the airplane about 2,000 to 3,000 ft above the ground. He added that, as the airplane approached the mountains, it looked like the wind had "pushed the right wing up." He then heard the engine sound increase, like the pilot "throttled forward" as the airplane entered a vertical descent.

According to the Las Vegas terminal radar approach control facility, about 0954, the pilot requested and was granted visual flight rules flight following services. The last communication with the accident airplane was at 1027 when the pilot was issued an updated altimeter setting, which he acknowledged. PERSONNEL INFORMATIONThe pilot, who was also the airplane builder, age 65, held a private pilot certificate with a rating for airplane single-engine land. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on August 11, 2017; on the application for that certificate, he reported 1,240 total hours of flight experience and 15 hours in the previous six months. The pilot's flight logbook was not located. AIRCRAFT INFORMATIONThe airplane (serial number 143), a low-wing, composite monoplane powered by a Continental IO-550-G engine (serial number 679050) rated at 280 horsepower, was built by the pilot/owner. An FAA special airworthiness certificate in the experimental category was issued on July 21, 1999.

The engine was mounted mid-fuselage facing rearward, and the propeller was located at the aft end of the fuselage (commonly referred to as a "pusher" configuration). A torque tube (driveshaft) and forward and aft elastomeric couplings (dampers) were used to transfer power from the propeller flange located on the front of the engine crankshaft to the rear-mounted, constant-speed propeller.

According to maintenance records, the most recent condition inspection was completed on January 1, 2018, at a recorded Hobbs time of 1,032.6 hours. (The Hobbs hour meter indicated 1,037.7 hours at the accident site.) The most recent condition inspection for the engine was started on December 16, 2017, at a recorded Hobbs time of 1,031.6 hours. The entry did not specify if the inspection was completed. The last time that an engine condition inspection was specified as completed in the logbooks was December 9, 2006.

The engine drive system was most recently balanced on April 28, 2009, at a Hobbs time of 701.1 hours, following the replacement of a coupling. Whether the forward or aft coupling was replaced was not specified. A review of the available records did not yield a description of how the system was balanced.

On January 9, 2010, at a Hobbs time of 736.5 hours, during an annual condition inspection, the entry indicated that the coupling was reworked for "concentricity to shaft." No further details of the work were provided.

On December 31, 2017, at a Hobbs time of 1,032.6 hours, during an annual condition inspection, the entry indicated that the flywheel and coupling bolts were retorqued. No further details of the work or torque values were provided. METEOROLOGICAL INFORMATIONAccording to information from Leidos Flight Service, the pilot received a weather briefing about 1 hour before departing on the flight.

The 1055 recorded weather observation at Whiteman Airport (WHP), Los Angeles, California, located about 13 miles south-southeast of the accident site, included calm wind, 10 statute miles visibility, clear sky, temperature 20°C, dew point -4°C, and an altimeter setting of 29.94 inches of mercury.

A weather study conducted by a National Transportation Safety Board meteorological specialist identified no significant weather around the accident site about the accident time. The complete weather study is in the public docket for this investigation. AIRPORT INFORMATIONThe airplane (serial number 143), a low-wing, composite monoplane powered by a Continental IO-550-G engine (serial number 679050) rated at 280 horsepower, was built by the pilot/owner. An FAA special airworthiness certificate in the experimental category was issued on July 21, 1999.

The engine was mounted mid-fuselage facing rearward, and the propeller was located at the aft end of the fuselage (commonly referred to as a "pusher" configuration). A torque tube (driveshaft) and forward and aft elastomeric couplings (dampers) were used to transfer power from the propeller flange located on the front of the engine crankshaft to the rear-mounted, constant-speed propeller.

According to maintenance records, the most recent condition inspection was completed on January 1, 2018, at a recorded Hobbs time of 1,032.6 hours. (The Hobbs hour meter indicated 1,037.7 hours at the accident site.) The most recent condition inspection for the engine was started on December 16, 2017, at a recorded Hobbs time of 1,031.6 hours. The entry did not specify if the inspection was completed. The last time that an engine condition inspection was specified as completed in the logbooks was December 9, 2006.

The engine drive system was most recently balanced on April 28, 2009, at a Hobbs time of 701.1 hours, following the replacement of a coupling. Whether the forward or aft coupling was replaced was not specified. A review of the available records did not yield a description of how the system was balanced.

On January 9, 2010, at a Hobbs time of 736.5 hours, during an annual condition inspection, the entry indicated that the coupling was reworked for "concentricity to shaft." No further details of the work were provided.

On December 31, 2017, at a Hobbs time of 1,032.6 hours, during an annual condition inspection, the entry indicated that the flywheel and coupling bolts were retorqued. No further details of the work or torque values were provided. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted terrain between rolling hills and power transmission lines about 2.5 miles southeast of Agua Dulce, California.

Damage to the lowest of the three power lines was noted. The transmission lines were located about 106 ft above the main wreckage. The power company that owned the power transmission lines reported that there were no interruptions in service and no faults recorded about the time of the accident.

All major structural components of the airplane were located at the accident site. The main wreckage comprised the fuselage area from the aft seat rearward, both wings, and most of the empennage.

The majority of the wreckage was contained within an area about 100 ft in diameter, with the exception of the left horizontal stabilizer fairing, which was located about 2,500 ft west of the main wreckage.

The cabin area was fracture-separated from the front seats forward to the nose cone and was located near the main wreckage.

The right wing remained partially attached at the wing root. The wing area outboard of the aileron fracture-separated but remained with the main wreckage. The fuel cap was found in place. The aileron remained attached to the wing. The flap remained attached to the wing and appeared to be in the retracted position.

The left wing remained attached to the fuselage. Wire strike marks were noted on the top of the wing skin. The fuel cap was found in place. The aileron remained attached to the wing and exhibited some impact damage. The flap remained attached to the wing and appeared to be in the retracted position.

The empennage remained mostly attached to the fuselage and exhibited extensive damage. The right horizontal stabilizer remained partially attached but exhibited extensive damage. The right elevator remained attached to the horizontal stabilizer and the inboard 2 ft displayed extensive damage. The left horizontal stabilizer was separated from the empennage and was located about 80 ft from the main wreckage. The left elevator remained attached to the horizontal stabilizer. Red paint transfer marks were noted on the trailing edge of the left elevator about 25 inches inboard of the elevator tip. The vertical stabilizer remained attached to the empennage and displayed little damage. The rudder remained attached to the vertical stabilizer and was mostly intact.

The engine remained attached to the fuselage and was mostly intact. The propeller remained attached to the aft driveshaft flange. Two of the three wooden propeller blades were broken. The propeller spinner remained attached and displayed little damage; no rotational damage was noted.

All four engine mounts were broken. The engine-driven fuel pump was removed and inspected. Fuel was present in the fuel hoses attached to the engine-driven fuel pump and fuel was released when the pump was removed from the engine; the undamaged drive coupling was manually rotated with no binding noted.

A sample of the fuel captured from the fuel hose tested negative for water contamination.

The top sparkplugs were removed and inspected. When compared to a Champion "Check-A-Plug" chart, the wear appeared to be "normal" with normal coloration, with the exception of the sparkplugs from cylinder Nos. 3 and 5, which were oil contaminated.

All piston crowns...