What was found
BOLT AND ALTERNATE AIR FLAPPER HINGE FAILURE POSSIBLY DUE TO VIBRATION OVER TIME, WHICH CAUSED ONE OR MORE BUSHINGS TO ENTER THROUGH AN INTAKE VALVES. SYMPTOMS WERE SIMILAR TO A FOULED PLUG; THE PILOT REPORTED THAT HIS EGT ON CYLINDER NR 1 HAD INITIALLY DECREASED AND SUBSEQUENTLY DISCONTINUED THE TAKEOFF AS SOON AS POWER WAS APPLIED. ALSO STATED WAS ABLE TO "BURN IT OFF" AS THERE MAY HAVE BEEN SMALL METAL PIECES CLOGGING THE SPARK PLUGS THAT WERE DISPLACED. AFTER CONTINUED ROUGH OPERATION ON THE GROUND AFTER A HIGH POWER RUN-UP, GROUNDED ACFT IAW DISCREPANCY PROCEDURES. AFTER BORESCOPE INSPECTION, DAMAGE FOUND IN CYLINDERS.