On May 23, 1995, at 1440 central daylight time, a Piper PA-23- 250, N6092Y, sustained substantial damage as a result of an engine fire after the landing phase of flight. The commercial pilot reported no injury to himself or to the passenger. The 14 CFR Part 91 flight departed Seymour, Indiana, en route to Michigan City, Indiana. Visual meteorological conditions prevailed and an instrument flight plan was filed. The pilot reported that after shut down on the ramp at Michigan City, he noticed signs of an engine fire in the right engine cowling. A fire truck was summoned and the fire extinguished. A witness reported that he saw the airplane taxiing and turning around at the south end of runway 20. As it turned and started back taxiing down the runway, he saw fire coming from the right engine. He saw the airplane taxi to the terminal and two people jump out after the aircraft had stopped. He reported that people used portable fire extinguishers until the firefighters arrived and put out the fire. The Federal Aviation Administration examined the airplane on June 30, 1995, and determined that the aircraft had received substantial damage as a result of severe fire damage to the right engine, engine compartment, nacelle, and adjacent airframe structures. On August 11, 1995, an Airworthiness Inspector from the Federal Aviation Administration inspected the aircraft. He reported that the intense heat from the engine fire burned the right landing gear doors, bottom engine cowling, and the top engine cowling to about ten (10) inches behind the firewall. He found six (6)quarts of oil showing on the dip stick on the right engine and no signs of oil leakage. He turned the propeller by hand and the engine appeared to turn freely. The magnetos were destroyed by the engine fire. He reported that it appeared that the fire started above the turbo charger unit. Fire occurred in the area between the engine and back of the engine firewall. Due to the high heat at the firewall, extensive damage was done to the firewall and the engine accessories. The hydraulic and fuel hoses above the turbo charger were destroyed. He reported that the cause of the fire could not be determined at this point.