Cumberland

The airplane was loaded to within a few hundred pounds of its maximum gross takeoff weight, and departed from an airport located in a valley, surrounded by rising terrain. Although visual conditions prevailed at the accident airport, fog was present in the adjacent valleys. During the initial climb after takeoff, the right engine lost partial power due to a failure of the number one cylinder exhaust valve. The pilot secured the right engine; however, he was unable to maintain a climb with only the left engine producing power. The airplane was manufactured in 1964. Review of weight and performance data published at the time of manufacture, revealed that the airplane should have been able to climb about 400 feet-per-minute with a single engine producing power. No current weight and balance data was recovered, and due to impact and fire damage, the preimpact power output of the left engine could not be determined. Both engines were last overhauled slightly more than 12 years prior to the accident, and flown about 310 hours during that time. For the make and model engine, the manufacturer recommended overhaul at 1,200 hours of operation, or during the twelfth year.

Approximately 16 minutes prior to the accident the pilot was cleared for the localizer DME approach. The aircraft collided with the mountainous terrain on a heading of about 220° at approx 8.5 dme on a bearing of 051° from the airport. As indicated on the loc/dme runway 23 approach plate, the minimum altitude between the outer marker, 6.6 dme, and 10 dme was 3,000 feet. Elevation at the accident site was 2,000 feet; airport elevation was 776 feet. Post crash fire consumed most of the wreckage but the cabin heater was not in the fire area. The pilot's reported carboxy hemoglobin (co) was 20%. Autopsy revealed multiple extreme impact injuries. Products of combustion were found on fresh air side of cabin heater/heat exchanger. Source of combustion products were not determined. All three occupants were killed.