On March 31, 2002, about 1005 central standard time, a Piper Malibu PA-46-310P, N9103Q, sustained substantial damage during a forced landing to the Mississippi River near South St. Paul, Minnesota, after it experienced a complete loss of engine power after an engine fire in cruise flight. The 14 CFR Part 91 personal flight departed Fleming Field (SGS), South St. Paul, Minnesota, at 1000 en route to Storm Lake, Iowa. The pilot and two passengers were not injured. Visual meteorological conditions prevailed. An instrument flight rules (IFR) flight plan had been filed. The pilot reported that he preflighted the airplane in a heated hangar. After the preflight he fueled the airplane with AVGAS so that the airplane had a total of about 110 gallons. He checked the fuel tanks for water contamination and none was noted. The run-up was normal and no discrepancies were noted. He departed runway 34 and turned downwind. He leveled off about 1,850 feet msl in order to stay below Class B airspace until he could receive the IFR clearance. The pilot reported that he pulled back the throttle to 30 inches of manifold pressure and then pulled the cabin heat lever out about halfway. He activated the standby vacuum pump and noted that it was operating properly. He reported that about 1-2 seconds after activating the vacuum pump, the alternator annunciator light came on. He reported that the two passengers smelled something burning about 2 seconds after the alternator annunciator light came on. He reported that about 2 seconds later the engine lost power abruptly, without any roughness or surging. He checked the manifold pressure and it read 30 inches, but the engine RPM was dropping. He started a turn back to SGS and declared an emergency. He reported that he soon realized that the airplane had insufficient power to reach SGS, and he decided to make a forced landing to the Mississippi River near the Wipline Seaplane Base. He reported he cleared a line of trees and then lowered the nose in order to maintain about 90 knots airspeed. He flared the airplane and attempted to land near the stall speed. He reported he landed tail first approximately 70 knots. The airplane remained upright. The pilot and two passenger exited the airplane and started swimming for shore about 80 feet away. A fisherman in a boat rescued them from the water and took them safely to shore. The airplane was retrieved from the river. The right wing had separated from the fuselage on impact with the water. The empennage and left wing received substantial damage. The engine cowling came off during the water impact. Federal Aviation Administration inspectors examined the airplane and engine. The inspection of the engine revealed that the engine turned normally when the propeller was rotated. No damage was noted to the cylinders or accessories. The right side heat exchanger manifold downstream from the turbocharger had a crack about 1/2 around the circumference of the pipe. Fire and heat damage was noted on a wire bundle located adjacent to the exhaust crack. Another area of heat and fire damage was noted near the top of the engine. Bare wires on the P-leads were found in the area of the heat damage. When the magnetos were checked, it was observed that the P-leads were grounded and no electrical current was getting to the magnetos. Further examination of engine revealed that a B-nut fuel line connector on the fuel line that came from the engine driven fuel pump through the engine baffling was loose. The loose fuel connector was adjacent to the burned area where the P-leads were burned through. The heat exchanger was sent to the National Transportation Safety Board's (NTSB) Materials Laboratory for further examination. The examination revealed that a crack existed in the body of the heat exchanger adjacent to the flange. The crack had propagated around approximately 70 percent of the circumference of the heat exchanger. A "soapy water" test was conducted. The report stated, "The two ends of the exhaust pipe were closed from the outside air, the crack on the heat exchanger was coated with very soapy water, and compressed air was blown in the exhaust pipe. No bubbles formed on the crack near the flange, indicating that the crack did not propagate to the inside of the exhaust pipe." The NTSB report also stated, "Visual and binocular microscopic observations both showed that the crack did in fact propagate through the exterior layer of the heat exchanger in many places; however, the wall of the exhaust pipe was not cracked on any section around the circumference of the flanged end." A review of the airplane's maintenance records revealed that the last annual inspection was conducted on March 7, 2002. The airplane had flown about 37 hours since the last annual inspection. The engine had a total time of 1,974 hours since the last major overhaul, and about 700 hours since the last top overhaul. The airframe had a total time of about 2,842 hours. The engine logbook indicated that on March 29, 2002, the oil and oil filter had been changed. The standby vacuum pump was also replaced. The fuel line that was found with the loose B-nut was located directly above the standby vacuum pump.