SEA95FA012

Witnesses stated that they heard the airplane over the water, then they heard a sound like an explosion. The airplane was found submerged in the lake. After retrieval, it was noted that the entire length of the leading edge of the right wing was crushed rearward. The fuselage from the nose to just aft of the cabin was crushed up and rearward. The left wing and engine were not retrieved. No evidence was found to indicate a mechanical failure or malfunction. A pilot who flew over the lake a short time after the accident reported rough and turbulent conditions with severe downdrafts. He also reported that the water was rough and choppy with white caps.

History of flight

On October 27, 1994, approximately 1330 mountain daylight time, an amphibian United Consultants UC-1, N9501U, sank in Fremont Lake, Pinedale, Wyoming. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local instructional flight. The airplane was substantially damaged and the flight instructor and private pilot were fatally injured. The flight had departed from the Pinedale Airport at 1317.

Personnel at the airport reported that the private pilot was receiving instruction to obtain the multi-engine sea rating. On the day of the accident, witnesses heard an airplane on the lake and reported hearing a "backfire" and "revving" from the engine(s) before an "explosion" was heard. None of these witnesses saw the airplane at the time of the accident.

Approximately ten minutes after the notification came in of a possible accident, a pilot at the airport took off over the lake and reported rough and turbulent conditions with severe down drafts. The water was rough and choppy with white caps.

The co-owner of the airplane reported that he flew the airplane earlier in the day and indicated that there were no problems with the airplane at that time. Before the morning flight, the pilot fueled the airplane with 35 gallons of fuel. After the morning flight, the airplane was fueled with 17 gallons of fuel. It is estimated that the fuel tanks were approximately half-full for the afternoon flight.

Personnel information

The flight instructor's first flight, check ride and issuance of the multi-engine sea rating was accomplished on June 21, 1994, after four and a half hours flight time. The flight instructor then departed to Pinedale on the same day. At the time of the accident, the flight instructor had accumulated a total flight time in all aircraft of 20,837 with 47.5 hours in the UC-1.

The private pilot's flight logbook indicates a total flight time of 5,095 hours, with seven hours of dual flight instruction in the UC-1. A total time of 139.8 hours were accumulated in a single-engine sea airplane. It was reported by friends that the private pilot owned the single engine version of the UC-1, known as the Republic RC-3 Seabee.

Aircraft information

The aircraft logbooks indicate that an annual inspection was completed on June 21, 1994. After the airplane was delivered to Pinedale, another mechanic logged in the left engine log book that the engine was removed due to metal contamination. The engine was overhauled and signed off on August 24, 1994. The last logbook entry for both engines was on October 14, 1994, when the propellers for both engines were removed, cleaned and inspected before re-installation. The mechanic reported that the airplane was in an airworthy condition, however, work was in progress to refurbish items not critical to flight.

Wreckage and impact information

The wreckage was located in approximately 120 feet of water and 150 yards from the east shore of the lake. Underwater video was taken of the site before it was disturbed. The wreckage was laying upside down and severely deformed. A view of the tail wheel indicated that the tailwheel was in the retracted position. The main landing gear was partially separated from the fuselage. The wreckage was retrieved, however, during the process, the left wing and left engine were lost and not recovered. Also not recovered were the cockpit instrument panel, vertical stabilizer, and the outboard section of the left horizontal stabilizer.

After the wreckage was recovered and secured in a hangar, the wreckage was examined. The right wing was broken in three sections. The flap remained attached to one section at the outboard hinge and was bent. The aileron was attached at one hinge on another section of the wing and also displayed leading edge crushing. The engine had separated from the nacelle. The entire length of the leading edge of the wing was crushed rearward and sections of the wing skin were torn. The sponson remained attached at the wing. The front of the sponson imploded.

The fuselage was bent upward and aft from the nose to aft of the cabin. The underside skin was crushed and formed into the structural members. The top of the cabin area was torn away. Control continuity was established from the cockpit area to the aft attachments in the empennage. The right horizontal stabilizer remained attached with the elevator in place. The rudder had separated from the vertical stabilizer at the hinges. The left sponson had separated from the wing at the wing attachment and was found floating in the water near shore. Except for where the sponson separated at the attach points, the sponson was not damaged.

The main landing gear had completely separated from the fuselage during the recovery process. Viewed in the hangar, the hydraulic gear mechanism rod was partially extended and the rod was bent slightly. It could not be determined in what position the gear was at the time of the accident. The tailwheel was viewed in the extended position in the hangar. It was noted that during the underwater recovery, a rope was tied around the tailwheel and the main landing gear.

The right engine was examined. The propeller remained attached to the crankshaft. Both blades were bent rearward with slight "S" bending noted. Both blades exhibited tearing of the metal material at the tips. The crankshaft was found to rotate easily.

Rocker arm, accessory gear and valve train continuity was established. Compression was developed in each cylinder. All spark plugs displayed normal operating signatures. Both magnetos produced a spark with hand rotation.

The fuel inlet screen was free from contaminants. The diaphragm in the fuel manifold valve was found partially torn along the stem. The injector lines were free of contaminants. The oil pressure screen and oil suction screen were removed and free of contaminants.

Medical and pathological information

The Sublette County coroner reported that the cause of death to both pilots was a result of brain extrusion and crushing head injury.

Toxicological samples were sent to the Federal Aviation Administration Civil Aeromedical Institute, Oklahoma City, Oklahoma, for examination. The results of the tests were negative for both pilots.

Additional information

The wreckage was released to the owner's representative on November 30, 1994. At the time of the release, the wreckage was stored in a hangar at the Pinedale Airport. The owner's representative stated that another attempt to retrieve the remainder of the wreckage at the bottom of the lake may take place during the summer of 1995.

Underwater video was taken by divers from Divers Rescue International, Fort Collins, Colorado. Copies of the originals were provided for review during the investigation.