What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
PIC stated: "after a short flight around the Montauk area, I entered the right hand traffic pattern to rwy 24 at Montauk Airport. The approach and landing were normal. As the aircraft was in the rollout it began moving toward the left side of the runway. Full right rudder and right brake would not compensate for the approximate 20-25 degree angle divergence toward the left edge of the runway. As the aircraft came to a complete stop the left wing dropped significantly as the left main gear spread outward (tire moved outboard toward the left wingtip). The propeller contacted the runway pavement. I secured the aircraft and the 2 (two) passengers and I exited the aircraft. After looking at the left spring steel gear leg, it was obvious that it failed and collapsed.
As the FAA filed it
PIC STATED: "AFTER A SHORT FLIGHT AROUND THE MONTAUK AREA, I ENTERED THE RIGHT HAND TRAFFIC PATTERN TO RWY 24 AT MONTAUK AIRPORT. THE APPROACH AND LANDING WERE NORMAL. AS THE AIRCRAFT WAS IN THE ROLLOUT IT BEGAN MOVING TOWARD THE LEFT SIDE OF THE RUNWAY. FULL RIGHT RUDDER AND RIGHT BRAKE WOULD NOT COMPENSATE FOR THE APPROXIMATE 20-25 DEGREE ANGLE DIVERGENCE TOWARD THE LEFT EDGE OF THE RUNWAY. AS THE AIRCRAFT CAME TO A COMPLETE STOP THE LEFT WING DROPPED SIGNIFICANTLY AS THE LEFT MAIN GEAR SPREAD OUTWARD (TIRE MOVED OUTBOARD TOWARD THE LEFT WINGTIP). THE PROPELLER CONTACTED THE RUNWAY PAVEMENT. I SECURED THE AIRCRAFT AND THE 2 (TWO) PASSENGERS AND I EXITED THE AIRCRAFT. AFTER LOOKING AT THE LEFT SPRING STEEL GEAR LEG, IT WAS OBVIOUS THAT IT FAILED AND COLLAPSED.