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N637PS accident description

Missouri map... Missouri list
Crash location Unknown
Nearest city Osceola, MO
38.050308°N, 93.698265°W
Tail number N637PS
Accident date 05 Nov 2008
Aircraft type Johnson Leonard G Cozy MK-IV
Additional details: None

NTSB Factual Report


On November 5, 2008, at 0945 central standard time, a Johnson Cozy MK-IV experimental airplane, N637PS, piloted by a private pilot, was destroyed when it struck a power pole during a forced landing at Osceola Municipal Airport (3MO), Osceola, Missouri following a loss of engine power during a cross country flight. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 CFR Part 91 without a flight plan. The pilot was seriously injured. The cross-country flight originated at St. Charles Airport (3SQ), St. Charles, Missouri, and was en-route to Tradewind Airport (TDW), Amarillo, Texas.

The pilot had just completed a multi-day, cross country flight from California to Kitty Hawk, North Carolina using a biofuel called N-butanol. The purpose of the flight was to demonstrate the viability of flight using an alternative fuel to aviation gasoline (AVGAS). He had completed the demonstration portion of the trip and was on a return leg to California, having filled up two times with AVGAS. While cruising at 6,500 feet mean sea level (MSL) the airplane engine overheated, then quit producing power. The pilot said the engine started running rough as engine exhaust temperatures (EGT) reached 490 degrees. There was a slow power loss as the EGT reached 570 degrees. The pilot performed a forced landing on an unimproved, grassy area at 3MO. The airplane struck a power pole, crossed a paved road, and struck a second power pole.

The pilot stated that when he was performing his before landing checklist, when he elected to deploy the landing brake, the electric landing brake switch was already in the deploy position and the landing brake enunciator light was illuminated. He thought he had probably inadvertently deployed it, prior to the overheat condition, manipulating some airplane controls while in turbulence and wearing bulky, cold weather gloves.


The pilot, age 55, held a private pilot certificate with a rating for airplane single-engine land. His last Federal Aviation Administration (FAA) third-class medical was issued July 1, 2008, with the limitation "Must Wear Contact Lenses."

The pilot indicated on the National Transportation Safety Board Form 6120.1, Accident/Incident Report he had 378.6 total flight hours and had accumulated 30 hours in the preceding three months.


The 2000-model Leonard Johnson Cozy MK-IV, serial number 287, was a mid wing airplane, with fixed main landing gear, retractable nose gear, and was configured for one occupant. The airplane was powered by a direct drive, carbureted, air-cooled, six cylinder reciprocating engine in a "pusher" configuration. The engine was a Lycoming O-360-A2G, rated at 180 horsepower, and was driving a two-bladed propeller.

When the airplane was built, the owner installed an electric landing brake system. This system utilized an electric switch for activation and an electric motor for actuation. It also utilized an orange enunciator light on the center portion of the cockpit instrument panel to provide a visual alert that the landing brake was deployed. The original design called for a mechanical system which utilized a lever for deployment and retraction, which also provided a visual indication of deployment.

According to the pilot, the airplane had experienced an overheat condition on the number three engine cylinder on October 30, 2008. That condition was attributed to a cracked helicoil in the spark plug hole. The affected cylinder was replaced and the engine operated normally until the day of the accident.

The last airplane inspection was a Conditional inspection on April 3, 2008. The airplane had accumulated 119.4 total hours at the time of the accident. The engine had accumulated 36.1 hours since its last overhaul and 13.4 hours since its last inspection.


The pilot landed the airplane on a grassy, unimproved area on the airfield. The airplane traveled several hundred feet and impacted a power pole. The airplane then crossed a paved road, impacted a second power pole and came to rest inverted. Both wings and a portion of the nose separated from the airplane. Both wings were fractured into multiple pieces.


One designer of the Cozy MK-IV airplane was interviewed regarding the operation and limitations of the airplane's Landing Brake (LB) system. The following information was obtained from statements he made during that interview.

"Some airplane builders installed an electrical controller for the LB, activated by an electric switch, as a modification of the original design. The use of an electrical LB system was not recommended or part of the original design. The use of an electrical controller could prevent the LB from blowing back if deployed above 85 KIAS. The location of the LB activation switch could prevent timely retraction in the event of a go around situation."

The following information was extracted from the Cozy MK-IV builder and operators' manual:

"LANDING AIRBRAKE – A drag device used to allow a steeper approach and to provide more deceleration in the flare. This belly-mounted "speed brake" is deployed by a lever on the center console. It is extended on downwind after gear extension and left down until after landing. Maximum speed with the airbrake down is 85 knots (100 mph). Above this speed, the brake automatically closes."

"The awkward position of the brake handle in the deployed position aids in reminding the pilot that the brake is down if he forgets it on his takeoff checklist. Climbs should be avoided with the brake down, as cooling and climb rate are reduced. The brake induces a mild buffet when down. During landing and taxi the landing brake provides some prop protection from rocks being kicked up by the nose wheel."

NTSB Probable Cause

A total loss of engine power due to an obstruction of airflow as a result of the pilot's inadvertent actuation of the landing brake.

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