On July 24, 1994, about 1748 eastern daylight time, a Cessna 402C, N318AB, registered to Tropical Transport Services, Ltd., operated by Air Sunshine, Inc., experienced collapse of the right main landing gear during the landing roll at the St. Petersburg/Clearwater International Airport, St. Petersburg, Florida. The flight was conducted under 14 CFR Part 91 as a positioning flight and the operator is a certificated commuter air carrier operating under 14 CFR Part 135. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane sustained minor damage and the airline transport-rated pilot, the sole occupant, was not injured. The flight originated from the Sarasota/Bradenton International Airport, about 1735. The pilot stated that he extended the landing gear selector handle when the flight was on a 8-mile final for a straight in approach and three green lights were illuminated indicating that the gear was down and locked. After a normal touchdown during the landing roll, the right main landing gear collapsed. The airplane veered off the right side of the runway and came to rest on grass. A representative of the operator presented to the NTSB a landing gear actuator which was reportedly from the right main landing gear of the incident airplane. The actuator did not have a data plate nor were any markings observed. The representative first stated that the serial number of the actuator was 3767 but it was determined later by the manufacturer's facility that the suspect actuator was not serial number 3767. An actuator, serial number 3368A had been overhauled on July 30, 1992, and according to the director of maintenance for the operator, was installed on the airplane on August 30, 1992. Review of the aircraft maintenance log entry for this date does not indicate replacement of the right main landing gear actuator. Examination and operational testing of the suspect actuator at a facility of the manufacturer revealed no evidence of failure however several discrepancies were noted. The micro switch was removed for further examination which revealed no evidence of failure or malfunction. The actuator was released to the FAA on October 28, 1994.