On September 7, 2006, at 1345 eastern daylight time, a Beech F33A, N3708B, was substantially damaged when it impacted trees and terrain during a forced landing near South Windsor, Connecticut. The certificated private pilot incurred minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, which departed Boire Field (ASH), Nashua, New Hampshire, destined for Hartford-Brainard Airport (HFD), Hartford, Connecticut. The personal flight was conducted under 14 CFR Part 91. According to the pilot, while in cruise flight at 3,000 feet he set the engine rpm to 2,500, and reduced the mixture "lean of peak," which corresponded to a fuel flow of 17 gallons per hour. Shortly after he contacted the air traffic control tower at Hartford Airport, he began a descent to 1,500 feet by reconfiguring the engine controls to 18 inches of manifold pressure, and 2,300 rpm; however, he did not adjust the mixture control. Upon reaching 1,500 feet, the pilot increased the manifold pressure, but then realized that there was a problem because the airplane continued to descend. He then noted that the engine rpm had dropped to 2,000, so he advanced the propeller knob forward. He also set the throttle to the full forward position; however, there was no change in engine performance. The airplane continued to descend and the pilot realized that he would have to land the airplane in the trees immediately in front of him, with no other suitable landing sites available. The pilot configured the airplane for a 100 knot descent. He had planned to turn off the fuel selector valve and the master switch, but the airplane then struck the trees. Several witnesses were interviewed or provided written statements that depicted a similar series of events. The witnesses reported hearing and seeing the accident airplane as it descended. They described the engine sound as intermittent "sputtering," "popping," or "having trouble." The pilot held a private pilot certificate with ratings for airplane single engine land, and instrument airplane. His most recent Federal Aviation Administration (FAA) third class medical certificate was issued on October 1, 2004. The pilot reported 2,134 total hours of flight experience, 1,419 hours of which were in the accident airplane make and model. The accident airplane was manufactured in 1980. According to the pilot, the airplane had accumulated 2,229 total hours of operation at the time of the accident. According to aircraft maintenance records, the airplane was equipped with a Teledyne Continental Motors IO-520-BB engine, which had been modified by Ultimate Engines to an IO-550-B/UE. On October 28, 2004, at 1,620 total aircraft hours, the engine was fitted with a Tornado Alley Turbo-normalizing system. On February 1, 2006, at 1,983 total aircraft hours, the engine was disassembled, cleaned, inspected, and repaired. On March 10, 2006, at 2,017 total aircraft hours, the fuel injector nozzles for cylinders 1, 2, 5, and 6 were replaced. Since that date, there were seven additional entries in the engine maintenance logbook including a replacement of the alternator, five oil changes, and an entry on the date of the accident to adjust the oil pressure "up slightly." The weather conditions reported at HFD, about 2 nautical miles east of the accident site, at 1353, included winds from 110 degrees at 3 knots, 10 statute miles visibility, few clouds at 4,200 feet, temperature 75 degrees Fahrenheit, dewpoint 55 degrees Fahrenheit, and an altimeter setting of 30.06 inches of mercury. The engine was removed from the airframe and shipped to Teledyne Continental Motors to be test run under the supervision of an FAA inspector. Several components were fitted to the engine in order to allow it to run on the test stand, including a manual wastegate controller. The intake balance tube and intercooler assembly were also weld repaired. The engine subsequently started normally on the first attempt, without hesitation or stumbling. The engine rpm was then advanced in steps for warm up. The throttle was advanced to 1,200 rpm for 5 minutes, and the engine exhibited varying interruptions of power and stumbling. When the throttle was advanced to the full open position, the engine reached a maximum rpm of 1,450. Subsequent troubleshooting revealed that all six fuel injector lines were loosely attached to the fuel manifold valve. The fuel lines were tightened, and the engine was started again. The engine ran at 1,600 rpm and 2,100 rpm for 5 minutes, before the throttle was advanced to the full open position. The engine sustained 2,644 rpm, and performed without any hesitation, stumbling, or interruption for the duration of the test run. Additionally, the engine was operated at idle and advanced to full throttle with no abnormalities noted.