May Air Express

While in cruise flight at 9,000 feet MSL, the left engine began to 'run rough and lose power.' The pilot said he interpreted the problem as carburetor icing and applied carburetor heat. With the engine still running rough, the left propeller was feathered and the left engine shut down. Restart attempts were not successful. Unable to maintain altitude, the pilot requested to land at a nearby airport. After descending through IMC weather, the pilot realized that he would not make it to the airport, and executed a forced landing to rough/uneven terrain. Examination of the engines revealed that the alternate air doors were missing on the right and left engine. The hinges for the doors were attached to both carburetors and showed no evidence of distortion or impact damage. The doors were not found at the wreckage site. A missing alternate air door would allow ambient air to enter the carburetor, rendering the carburetor heating system ineffective. According to carburetor icing probability charts, the reported temperature and dew point values would be favorable to the formation of induction system icing.

The pilot reported that the airplane lifted off at 70 knots. After accelerating in ground effect the airplane became 'unstable in the roll axis' so he added power. He reported that the left wing tip contacted the runway approximately 3/4 the way down the runway. The pilot then added additional power at which point the left wing contacted the grass off the left side of the departure end of the runway. The pilot then reduced the power to idle and landed the airplane in the grass collapsing the landing gear. The pilot reported that the engines sounded normal throughout the accident sequence. Investigation revealed another Beech 18 had taken off on the same runway, but in the opposite direction of N916TM less than one minute prior to the accident.