NTSB Factual Report

HISTORY OF FLIGHT

On November 6, 2010, at 1000 eastern daylight time, an experimental Airborne Classic weight-shift aircraft, N582YA, was substantially damaged during an impact with terrain following a loss of engine power while maneuvering near Crow Island Airport, Stow, Massachusetts. The certificated sport pilot and one passenger were seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal local flight conducted under Title 14 Code of Federal Regulations (CFR) Part 91.

According to witness, after performing a preflight inspection of the weight shift control, two seat "trike", the pilot taxied to the west end of the airfield. The pilot then completed an engine magneto check, took off, and flew around the traffic pattern and landed.

After he landed the witness asked the pilot "how it was," and he replied that it was a bit rough between the trees over the water on final approach at the east end of the island. He also stated that the air "higher up" was fairly smooth.

The pilot then, "went over things about the trike", and helped his nephew put on a helmet and headset. His nephew then climbed aboard the trike and got in the back seat. The witness stated that the wind at the time was "5 to 10 out of the Northwest."

Shortly thereafter the witness observed the trike takeoff to the east, and when it passed over the "white hangar" at the airport, the witness "heard a funny metallic sound" come from the trike. A few seconds later the engine quit. The witness believed that it was not just a partial loss of power, "but a full stop," as the propeller blades were not rotating.

The trike at this point was about 30 feet above the trees just before the end of the island. The witness stated that they were lower than he would have expected, and not far enough to the right (south), over the swamp as was usually done to provide an extra margin of safety to turn in to the airport in the event of an engine out.

He next observed the trike gliding for 5 to 10 seconds before it turned "sharply" to the left, "in what appeared to be an attempt to do a 180 degree turn to land back on the runway." The witness also added that at the time, "They were in a tough spot" as "ahead was trees and water, left was trees and water, and right was trees and water."

He then saw the trike turn "sharply" to the left, and "dive" at what appeared to be a 45 degree angle towards the displaced threshold of the runway. He estimated that the speed was between 60 and 80 miles per hour. The trike impacted the ground about 25 feet from the water's edge, and then bounced for about 30 feet before coming to rest.

PERSONNEL INFORMATION

According to FAA and pilot records, the pilot was issued a sport pilot certificate on September 28, 2010. At the time of the accident he had accrued approximately 131 hours of flight experience.

AIRCRAFT INFORMATION

The accident aircraft was a weight shift control light sport aircraft commonly referred to as a "Trike", in which the pilot controls the attitude of the wing by changing the aircraft's center of gravity. It consisted of an aluminum and fabric Rogallo type wing coupled to a two seat, three wheeled undercarriage. It was equipped with a 65 horsepower, Rotax 582, 2-stroke engine which was installed in a pusher propeller installation at the rear of the undercarriage.

According to the FAA, the aircraft was issued an airworthiness certificate on May 10, 2007.

AIRPORT INFORMATION

According to the State of Massachusetts Department of Transportation's Aeronautics Division, Crow Island Airport was classified by the state as a private restricted use landing area. It had one runway oriented in a 09/27 configuration. Runway 9 was turf covered, and in fair condition. The total length of the runway was approximately 2,170 feet, and its width was approximately 50 feet.

WRECKAGE AND IMPACT INFORMATION

Examination of the wreckage by a Federal Aviation Administration (FAA) inspector revealed that the cockpit had separated from the frame during the impact sequence and the aircraft was substantially damaged. No evidence of any preimpact flight control or structural failure of the aircraft was discovered.

Examination of the 2-stroke engine also did not reveal any evidence of preimpact failure or malfunction of the rotary valve intake, the ignition system, the carburetors, or the fuel pump.

Internal examination revealed however, the presence of vertical grooves and transfer of material from the pistons on the walls of the cylinders which was indicative of a "four-corner" or "cold seizure" and discoloration on the piston domes, which was indicative of the engine being operated with too lean of a mixture.

METEOROLOGICAL INFORMATION

The recorded weather at Laurence G. Hanscom Field Airport (BED), Bedford, Massachusetts, approximately 10 nautical miles east of the accident site, at 0956, included: wind 320 degrees at 6 knots, visibility 10 miles, sky clear, temperature 7 degrees C, dew point 2 degrees C, and an altimeter setting of 30.10 inches of mercury.

TESTS AND RESEARCH

Maintenance Records Review

Review of the maintenance records disclosed that no entries existed in the maintenance records regarding numerous items, such as carburetor readjustments and checks, that were required to be accomplished at specified intervals as part of the maintenance schedule listed in the Rotax Aircraft Engines Maintenance Manual.

According to maintenance records, on August 25, 2009, after the aircraft's original engine had accumulated 182.5 hours of operation, the spark plugs were changed. This was the last entry that listed the total time of operation for either the aircraft or the engine.

Less than a month later, on September 12, 2009 the engine had a "Cold Seizure". As a result, on October 22, 2009 the cylinders were honed and on February 12, 2010, new pistons were installed, along with new gaskets, and the aircraft was returned to service.

On May 15, 2010, an annual inspection was completed and the aircraft was "found to be in a condition for safe operation" but on September 25, 2010 the engine once again had a problem when the front cylinder lost compression due to a broken piston ring.

On October 9, 2010, the aircraft's "Blue Head" model 99 engine was removed and an older "Gray Head" model 90 engine, which had already accumulated approximately 125 hours of operation, was installed. The gearbox and carburetors however, were reused from the previous engine. This engine than accrued another 4 hours of operation prior to the accident.

Piston Seizures

According to the engine manufacturer, there are several types of piston seizures and reasons why a seizure could occur, but all seizures are caused by heat or friction.

A "four-corner" or "cold seizure" is caused when the piston expands faster than the cylinder and the clearance between the piston and cylinder is reduced.

According to the engine manufacturer, possible causes of a piston seizure include:

• Too low an octane fuel used or fuel with too much alcohol used

• Jetting too lean or failure of the fuel system i.e. clogged fuel line or filter, fuel tank not venting, air leak into crankcase

• Spark plug heat range too hot

• Restricted exhaust system: back pressure too high, modified exhaust system.

• Overheated loosely-installed spark plugs

• Lack of oil or wrong oil quality, e.g. gear oil, automotive oil

• Unnecessary additives being used in the fuel, i.e. octane boosters, high performance additives, upper cylinder lubricants, etc.

• Improper pitch of the propeller blades causing improper loading on the engine

ADDITIONAL INFORMATION

Despite multiple attempts to contact the pilot, telephone calls and correspondence went unanswered and no NTSB Pilot/Operator Aircraft Accident/Incident Report was received.

NTSB Probable Cause

The operator's inadequate engine maintenance, which resulted in a total loss of engine power. Contributing to the accident was the pilot's decision to conduct a downwind takeoff.