Background
The airplane had been parked outside on the ramp overnight, exposed to rain, snow, and temperatures below 32 degrees Fahrenheit. Other pilots reported that their aircraft, also parked outside, were covered with a layer of ice topped by 1/4 to 1/2 inch of snow or frost. Ramp personnel deiced the accident airplane with a heated glycol-water mixture. The PenAir ramp supervisor who performed the deicing believed the upper wing surface was clear of ice but did not physically touch the wing to verify. It could not be determined whether the pilot visually or physically inspected the wing and tail surfaces after deicing. However, the high-wing configuration would have hampered the pilot's ability to see residual clear ice.
Accident Sequence
The airplane, with the pilot and nine passengers aboard, crashed shortly after takeoff from runway 01. A witness reported a normal flight until the aircraft suddenly pitched up, rolled 90 degrees left, and yawed left. It then descended nose-down until out of view. Engine monitoring data showed a maximum altitude of about 651 feet above mean sea level. The airplane crashed in a level attitude.
Investigation Findings
Investigators found no evidence of pre-impact failures in the structure, flight controls, or instruments. Examination of the engine and propeller revealed no pre-impact anomalies, and the engine was running at impact. Company records indicated the commercial pilot completed initial CE-208 training two months before the accident, with 74 hours in type.
Probable Cause
The official probable cause was determined to be an in-flight loss of control resulting from upper surface ice contamination that the pilot-in-command failed to detect during preflight inspection. Contributing was the lack of a requirement for CE-208 pilots to closely examine the upper wing surface for ice under ground icing conditions.