WILLIAMS, CA, USA
N4216X
Ayres S-2R
THE PLT REPORTED HE HEARD SOMETHING BREAK. THE SOUND WAS FOLLOWED BY A VIBRATION. THE PLT THEN TURNED TO LAND ON A ROAD. HE WAS UNABLE TO MAINTAIN ALT AND AIRSPEED. THE ROCKWELL S2R LANDED IN A CULTIVATED FIELD AND NOSED OVER AFTER A COLLISION WITH A DIRT BANK. POST ACCIDENT EXAM OF THE PROP HUB ASSEMBLY REVEALED THAT THE COUNTERWEIGHT BEARING SHAFT WAS FRACTURED ON ONE OF THE PROP BLADES. THIS WOULD ALLOW ONE PROP BLADE TO ROTATE AT A DIFFERENT PITCH ANGLE. THE ROCKWELL S2R HAD A TWO BLADED HAMILTON STANDARD 12D40-305 PROP INSTALLED. IT HAD BEEN MODIFIED IN ACCORDANCE WITH STC #SP1408NW WHICH REPLACES THE HAMILTON STANDARD COUNTERWEIGHT BEARINGS WITH MIDWEST AVIATION ROLLERS.
Source: NTSB Aviation Accident Database
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