Departure and Weight and Balance
The accident flight involved a single-engine airplane carrying two pilots, two passengers, baggage, and equipment. At takeoff, the aircraft exceeded the maximum allowable gross weight by 955 pounds and was 2 inches beyond the aft center of gravity limit.
Inflight and Icing Conditions
After approximately four hours of flight, the pilot decided to divert to an alternate airport due to icing conditions. The airplane had been flying in light freezing rain, which the Pilot's Operating Handbook (POH) stated should be avoided. Additionally, severe mixed icing was reported 25 miles northwest of the intended airport. The air induction lever was found in the primary position, not the required alternate position for icing conditions. The propeller and stall warning heat switches were off.
Accident Sequence
During the descent, while executing a left turn from base leg to final approach for runway 22, the airplane dropped abruptly, struck the ground, and slid for approximately 250 feet. The wings were separated from the fuselage during the ground slide by two trees.
Postaccident Findings
A postaccident engine run was completed satisfactorily. The aircraft's calculated weight at the time of the accident was about 600 pounds over the maximum landing weight, and it remained 2 inches beyond the aft CG limit. Winds at the airport were from 150 degrees at 10 knots, gusting to 16 knots.
Both pilots sustained fatal injuries; both passengers received serious injuries.
Probable Cause
The pilot's improper decision to depart into known adverse weather conditions, and the subsequent encounter with freezing drizzle, resulting in an inadvertent stall and collision with the terrain during an approach to land. Also causal to the accident was the pilot's failure to adhere to the airplane's weight and balance limitations, resulting in an overweight and out of balance flight condition, and his failure to comply with published procedures for flight into icing conditions.