NTSB Identification: NYC98LA154.
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Accident occurred Sunday, July 26, 1998 in SHERMANS DALE, PA
Probable Cause Approval Date: 01/28/2000
Aircraft: JOHNSON REVOLUTION MINI-500, registration: N805JJ
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

After 45 minutes of flight, and on final approach, the engine lost power. The helicopter landed hard, the main rotor struck the tail boom, and the helicopter rolled over on its left side. Examination of the helicopter revealed fuel and oil were available, and the throttle linkage was intact. The pilot/owner had recently installed a Power Enhancement Package to the Rotax 582 UL DCDI engine, and adjusted the needle jets to produce suitable EGTs. Based on subsequent research, the pilot stated that engine problems could have occurred going from half, to full throttle rapidly because the main jet was too restrictive to allow enough fuel to pass through quickly. The NTSB database revealed 23 Mini-500 accidents in 1997 and 1998. Within that list, 11 involved a loss of engine power. The Rotax 582 operator's manual stated: ' Danger! This engine, by its design, is subject to sudden stoppage! Engine stoppage can result in crash landings. Such crash landings can lead to serious bodily injury or death. Never fly the aircraft equipped with this engine at locations, airspeeds, altitudes, or other circumstances from which a successful no-power landing cannot be made, after sudden engine stoppage.'

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The builder/pilot's carburetor modification that did not allow for rapid fuel demand, which resulted in a loss of engine power of final approach.

Full narrative available

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