TAXIING ON A CONGESTED RAMP; A PA18 PLT APPLIES EXCESSIVE BRAKING FOR THE CONDITIONS CAUSING THE ACFT TO NOSE OVER ENOUGH TO ALLOW THE PROP TO STRIKE THE GND.

Narrative

AFTER LNDG; I PROCEEDED TO TAXI TOWARDS THE FUELING ISLAND. THE ISLAND WAS CONGESTED AND ADDITIONAL ACFT WERE PARKED ON OR NEAR THE TXWY LEADING TO THE FUEL FACILITY. I WAS TAXIING SLOWLY AT ESSENTIALLY IDLE PWR WHEN A TFC CONFLICT AROSE FROM AN ACFT AHEAD AND TO MY R. I APPLIED IMMEDIATELY BRAKING WHICH CAUSED THE ACFT TO NOSE OVER WITH A SUBSEQUENT PROP STRIKE. THE ACFT IS A CUB CRAFTERS TOP CUB AND IS EQUIPPED WITH 26 INCH TUNDRA TIRES; CLEVELAND DOUBLE PUCK BRAKES; TRIPLE PRESSURE BRAKE BOOSTERS; AND A CTR OF GRAVITY ALIGNED NEAR THE LEADING EDGE OF THE CTR OF GRAVITY ENVELOPE. ALL OF THE ABOVE FACTORS GREATLY INCREASED THE POSSIBILITY OF BRAKE LOCKING AND ACFT NOSE-OVER. FUTURE CORRECTIVE ACTIONS: 1) BETTER PLT KNOWLEDGE AND EXPERIENCE CONCERNING THE ABILITY TO DISCERN THE BRAKING INTENSITY REQUIRED TO LOCK UP THE BRAKES AND WHEELS DURING SLOW SPD TAXI; PARTICULARLY IN AN ACFT WITH BRAKE MODIFICATIONS PERMITTING GREATLY INCREASED BRAKE EFFECTIVENESS. 2) MORE RAPID SCANNING TO THE FRONT AND SIDE OF THE ACFT DURING TAXI OPS; ESPECIALLY IN THE VICINITY OF BUSY FUELING ISLAND ACTIVITIES.