United States of America

It was determined that the explosion of the airplane was the consequence of the presence of a 11 inches crack located above the left side door that broke away in flight, causing an explosive decompression of the cabin. In such conditions, the crew was unable to maintain control of the airplane.

Double engine failure on final approach due to icing conditions. The following contributing factors were reported:
- Improper operation of powerplant on part of the pilot-in-command,
- Improper operation or failed to use the anti-icing/deicing equipment,
- Ice-carburetor,
- Conditions conducive to carburetor/induction system icing,
- Complete failure of both engines,
- Icing conditions,
- Both propellers found in feathered position after impact.

The accident was the consequence of improper IFR operation on part of the flying crew. The following factors were considered as contributing:
- Airframe ice,
- Snow,
- Icing conditions with sleet and freezing rain,
- Turbulences associated with thunderstorm activity,
- The crew decided to descend below the minimum descent altitude,
- Both landing lights were ON in heavy snow falls.

Loss of control after the right wing partially failed during climb. The following factors were considered as contributing:
- Wing attachment fitting, bolts,
- Fatigue fracture,
- FAA replacement time requirement inadequate on part of the company personnel,
- Lower right main wing/fuselage root JT attach fitting.

Failure of the left engine in flight for undetermined reason. Loss of control during a go-around manoeuvre after the crew failed to obtain flying speed as the flaps were fully deployed. The following findings were reported:
- Powerplant failure for undetermined reason,
- The pilot-in-command failed to obtain/maintain flying speed,
- The pilot-in-command misused or failed to use flaps,
- Improper emergency procedures,
- Suspected mechanical discrepancy,
- Left engine propeller feathered in flight.

Controlled collision with ground caused by the combination of the following factors:
- The pilot-in-command failed to follow the approved procedures and directives,
- Failure to provide adequate directives in manual equipment on par of the operational supervisory personnel,
- High obstructions,
- Accumulation of ice on windshield,
- The pilot-in-command failed to use or incorrectly used miscellaneous equipment such as windshield anti-icing and de-icing systems,
- Icing conditions including sleet and freezing rain,
- The pilot did not follow the company informal go-around procedures,
- There were no go-around procedures in the company operations manual,
- Mountain obscured by ice on windshield.

Wheels-up landing caused by a crew error. The following factors were considered as contributing:
- The pilot-in-command failed to extend the landing gear on approach,
- The crew failed to use the approach checklist,
- Failure of the landing gear warning and indicating components,
- Inadequate maintenance and inspection on part of the maintenance personnel,
- The gear warning horn was improperly set.

Double engine failure caused by a fuel starvation. The following factors were considered as contributing:
- Mismanagement of fuel on part of the pilot,
- Miscalculation of fuel consumption on part of the pilot,
- Fuel starvation,
- Double engine failure,
- Fuel in tip tanks only as the others were empty,
- Undetermined amount of fuel lost due to broken O ring seal,
- Fuel level control valve.

Improper operation of brakes and/or flight controls during takeoff. Collision with trees. Inadequate supervision of flight on part of the pilot-in-command. Fire after impact.

Uncontrolled descent and collision with ground during initial approach caused by icing conditions. The following factors were reported:
- Low ceiling,
- Fog,
- Icing conditions including sleet and freezing rain,
- Airframe ice,
- Ice propeller,
- Weather slightly worse than forecast,
- Approach control advised icing conditions in clouds,
- Pilot reported heavy icing,
- Full deicing equipment activated.