NTSB Identification: LAX90DUA01.
The docket is stored on NTSB microfiche number 42854.
Accident occurred Thursday, June 28, 1990 in TORRANCE, CA
Probable Cause Approval Date: 12/08/1992
Aircraft: HOMEBUILT JP-350-1, registration: N350JP
Injuries: 1 Minor.

THE PILOT OF THE HOMEBUILT SERVICED THE PROPELLER HUB WITH 120 PSI PRIOR TO DEPARTURE. AFTER TAKEOFF HE LOST CONTROL OF THE PROPELLER AND THE ENGINE LOST THRUST. EXAMINATION OF THE PROPELLER ASSEMBLY REVEALED NO EVIDENCE OF A PRE-IMPACT MALFUNCTION. THE PROPELLER BLADES HAD BEEN SHORTENED AND THE PROPELLER OVERSPEED OCCURRED BECASUE THE BLADES WERE NOT COUNTERWEIGHTED. HARTZELL STATED THE 120 PSI CHARGE IN THE HUB WAS INSUFFICIENT TO COUNTERACT THE AERODYNAMIC TWISTING MOMENTS AND PREVENT THE OVERSPEED.

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

THE AIRCRAFT COLLISION WITH THE GROUND AFTER THE PILOT EXPERIENCED A LOSS OF ENGINE THRUST DUE TO PROPELLER OVERSPEED CONDITION. CONTRIBUTING TO THE ACCIDENT WAS THE PILOT'S IMPROPER SERVICING OF THE PROPELLER HUB THAT ALLOWED THE OVERSPEED TO OCCUR.

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