MINERAL WELLS, TX, USA
N3412L
GYROFLUG SC01B160
THE AIRPLANE HAD BEEN MODIFIED TO BE FLOWN EITHER REMOTELY OR BY THE PILOT. TAKEOFF AND INITIAL CLIMB WERE PERFORMED BY REMOTE CONTROL AND CONTROL WAS TRANSFERRED TO THE PILOT TO POSITION FOR A REMOTE CONTROL LANDING. ANGLE OF BANK INCREASED PAST 90 DEGREES IN A NOSE HIGH ATTITUDE AT ABOUT 425 FEET AGL; THE PILOT TRANSMITTED THAT HE WAS 'GOING DOWN' SHORTLY BEFORE IMPACT. ONE OF THE THREE WOODEN PROPELLER BLADES SEPARATED FROM THE HUB AND WAS FOUND 1/4 MILE FROM THE MAIN WRECKAGE. THE BLADE WAS ATTACHED TO THE HUB PRIMARILY BY 5 LAG SCREWS. THREADS IN THE WOOD BUTT OF THE SEPARATED BLADE WERE STRIPPED. THE 5 SCREWS REMAINED IN PLACE. LAG SCREWS IN THE REMAINING 2 BLADES WERE FOUND UNDERTORQUED. SEVERAL DISCREPANCIES WERE NOTED REGARDING SPECIFICATIONS FOR PROPELLER BLADE ROOT AND SIZE, TOLERANCES, AND LAG SCREWS.
TOTAL PROPELLER BLADE RETENTION FAILURE, THE RESULTANT SEPARATION OF ONE PROPELLER BLADE, AND THE IMPROPER INSTALLATION OF THE PROPELLER BY UNKNOWN MAINTENANCE PERSONNEL.
Source: NTSB Aviation Accident Database
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