On December 26, 1993, about 1615 eastern standard time, a Beech A-36-TC, N3736F, owned and piloted by Wright B. Lewis, was substantially damaged during a forced landing to the Hawthorne- Feather Airpark, Hillsboro, New Hampshire. The pilot and passenger were not injured. Visual meteorological conditions prevailed. A flight plan had not been filed for the flight operating under 14 CFR 91. In the NTSB Form 6120.1/2, the pilot stated he departed the Morrisville Airport about 1530, and climbed to 10,500 feet. After cruising for 30 minutes his engine began to run rough and his fuel flow increased from 18 gallons per hour (GPH) to 25 GPH without any changes in the mixture control. He initiated a descent to a nearby airport. During the descent he tried changes in the mixture and boost pump settings, and changed his fuel tank selection. The pilot further stated: "...The engine quit completely between 3000' [feet] and 4000'. My airspeed was 120K [knots]. I spotted the runway about 1/2 mile ahead while heading southeast...I realized I would not make the runway at about 1000' and leveled the wings at about 90K - glided between a tree line and landed gear up in a swamp..." A Federal Aviation Administration (FAA) Inspector's report stated that a post accident investigation revealed fuel in both wing tanks, and that the landing gear was retracted. He further stated, "...All flight controls functioned normally...the fuel gauges read approximately half full on the left and full on the right..." An examination of the engine was performed by an Airframe and Powerplant (A&P) Mechanic on January 21, 1994, at the Hawthorne- Feather Airpark (8B1). During the examination no contamination was found in fuel system. A test propeller was installed and the engine was run. In his report the A&P stated, "...Run up and operational check all limits within factory specifications ... Complete inspection after run and found no discrepancies or problems..." ADDITIONAL INFORMATION The National Weather Service reported the temperature at 10,000 feet in the Portland, Maine area to be a minus 34 degrees celsius (minus 30 degrees fahrenheit) at the time of the accident. The Pilot's Operating Handbook does not address fuel additives for cold weather operations. Teledyne Continental Motors published a service bulletin on November 1987. The subject of this bulletin was recommended fuel and oil grades. In the bulletin it states: "Under certain ambient conditions of temperature/ humidity, water can be supported in the fuel in sufficient quantities to create restrictive ice formation along various segments of fuel system. To alleviate the possibility of this occurring, it is permissible to add isopropyl Alcohol to the fuel supply...Also, ethylene glycol monomethyl ether compounds conforming to military specification MIL-1- 27686E, if approved for use in the aircraft fuel system by the aircraft manufacturer..." In a letter from the owner of a Beech 36TC, he stated that the previous owner of his airplane experienced 3 unexplained cold weather engine failures. He further stated that by adding Prist to the fuel "...We haven't seen the problem since." In another FAA Inspector's report, he stated: "...All indications are that Mr. Lewis' engine was a victim of the severe cold weather...It is uncommon to this office, but, as indicated by operators having aircraft with Continental IO-520 engines installed, this is not uncommon. The answer to this problem is to add LO-FLO-PRIST..."