FRANKLIN, PA, USA
N5164K
RYAN NAVION A
WITNESSES REPORTED HEARING THE ENG SPUTTERING AND BACKFIRING DURING WHAT THEY REPORTED WAS A LONG, SLOW TAKEOFF GROUND RUN. THEY STATED THE ENG RPM SEEMED TO DECREASE AS THE ACFT PASSED THE TERMINAL BUILDING IN A SLOW SPEED, HIGH PITCH ATTIUDE. THE ACFT THEN DESCENDED BEHIND TREES. AUTO GAS WAS FOUND IN THE ACFT FUEL SYSTEM AND NO SUPPLEMENTAL TYPECERTIFICATE (STC) FOR AUTO GAS WAS FOUND FOR THE ACFT. POST ACCIDENT INSPECTION REVEALED THE #2 EXHAUST VALVE WAS VISIBLY WARPED. THE #3 EXHAUST VALVE GUIDE WAS BROKEN AND MOVED WITH THE STEM AS IT WAS REMOVED FROM THE CYLINDER. THE #4 EXHAUST VALVE WAS ALSO TIGHT IN THE GUIDE. COMPRESSION WAS CHECKED AND THE #2 CYLINDER COMPRESSION WAS ZERO.
DUE TO IMPROPER GRADE OF FUEL IN THE AIRPLANE AND BENT AND BINDING EXHAUST VALVES, THE AIRPLANE ENGINE HAD A PARTIAL LOSS OF POWER DURING THE TAKEOFF GROUND RUN. THE PILOT DID NOT ABORT THE TAKEOFF AND THE AIRPLANE STALLED AND COLLIDED WITH TREES WHEN THE PILOT FAILED TO MAINTAIN FLYING AIRSPEED.
Source: NTSB Aviation Accident Database
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