FTW94FA183

Sheepherders near the accident site reported observing the twin engine airplane performing low level maneuvers in the mountains near their vicinity. They later heard the sound of ground impact. The restricted category airplane was equipped with electronic surveying equipment for low level airborne magnetic mapping for mineral exploration. The wreckage was located on the eastern slope of a box canyon at the 7,000 foot elevation. Components and ground scars were found along a 220 foot long path on the 42 to 65 degree down slope of the canyon wall. The mission profile was to conduct a series of low level flights at altitudes ranging from 200 to 500 feet above the ground. Examination of the airplane, engines, and turbochargers, did not reveal any mechanical anomalies.

History of flight

On May 28, 1994, at 0830 Pacific daylight time, a Cessna 310E, N3472Q, was destroyed upon impact with terrain near Battle Mountain, Nevada. The airline transport rated pilot and his passenger sustained fatal injuries. Visual meteorological conditions prevailed for the local flight.

According to the operator, the restricted category airplane was equipped with electronic surveying equipment for low level airborne magnetic mapping surveys for mineral exploration. Due to the sensitivity of the equipment, most missions were flown in the early morning hours, or in the early evenings, when the winds were calm and the area was void of updrafts or downdrafts.

The flight departed with full fuel from the Lander County Airport near Battle Mountain, Nevada, at 0507. The mission profile was to conduct a series of low level flights at an altitude from 500 feet above the ground (AGL) to a minimum altitude of 200 feet AGL.

Sheepherders near the accident site reported observing the airplane performing low level maneuvers in their vicinity, observed the airplane cross a ridge line as the airplane continued away from their location, and subsequently heard what they described as "two popping sounds similar to shotgun blasts." The airplane was located on the east slope of the Shoshone Mountain Range by the local authorities at 0631 on May 30, 1994.

Personnel information

According to the operator, the pilot was hired on June 20, 1990, and had been flying with them in the same capacity since then. Federal Aviation Administration (FAA) records indicated the pilot had a total flight time of 5,250 hours as of September 2, 1993. The company reported that the passenger, a geologists, was employed as the on board operator of the electronic surveying equipment.

Aircraft information

The 1966 model 310E airplane was modified with the 300 horsepower RAM engine, Continental TSIO-520-BC. The RAM conversions were performed by RAM Aircraft Corporation of Waco, Texas. The right engine had 40 hours total time since overhaul and the left engine had 438.1 hours since replacement of all 6 cylinders.

The airplane was purchased by the operator in 1983. Modifications were made to the structure of the airplane for the installation of a magnetometer aft of the airplane empennage within a seven foot tubular plexiglass fairing.

Wreckage and impact information

Wreckage distribution was found on the eastern slope of a box canyon at the 7,000 foot elevation in the Shoshone Mountain Range at 15 miles on the 148 degree radial of the Battle Mountain VOR. Components, ground scars, and physical evidence of post-impact fire extended for 220 feet along the measured 42 to 65 degree downslope. The main fuselage and empennage came to rest inverted on a measured magnetic heading of 265 degrees in a creek bed at the base of the downslope.

The rudder and elevators were found attached to the empennage. Flight control continuity was established. Compression was evident on the lower skin of the right wing tip fuel tank. The aft portion of the right wing tip fuel tank was adjacent to the right engine found in the creek bed. See the enclosed wreckage distribution diagram for details.

Portions of the right engine case and all engine accessories were separated from the engine. The oil pan and portions of the exhaust manifolds were crushed. The ignition harness was destroyed. The left engine was found in the creek bed. Components and accessories remained attached to the left engine.

Both engine crankshafts exhibited circumferential scoring, 45 degree separation areas, and physical evidence of overload stress separation. Propeller blades exhibited bending, leading edge scoring, gouges, and chordwise striations.

The engines and turbochargers were retained for further examination. No evidence of inflight fire was found.

Medical and pathological information

The autopsy was performed by Vernon O. McCarty, M.D., of the Washoe County Coroner's Office on May 31, 1994, at Reno, Nevada.

Test and research

The engine representative examined the engines at Fallon, Nevada, on June 8, 1994. The enclosed report states that engine signatures are consistent with "high power at the time of impact" and "no evidence of pre-impact malfunction."

A teardown and inspection of the turbochargers was conducted on the same day. The Allied Signal representative (enclosed report) stated there were no anomalies that would "preclude operation prior to impact."

The FAA coordinator was present to observe both off site examinations.

Additional data

The airplane was released to the owner's representative following the investigation.