Piper PA-34-200, VH-CTT, 7 km north of Oberon, New South Wales, on 10 June 1989

Circumstances:

The pilot was conducting an Instrument Flight Rules flight. Because of a deterioration in the weather at the planned destination, the aircraft was returning to Bankstown. Area forecasts indicated extensive cloud cover with the freezing level in some areas below lowest safe altitude. While cruising at 8000 feet, above cloud, the left engine reduced to about idle power, with the fuel flow decreasing to about five gallons per hour. The pilot carried out a trouble check but was unable to rectify the problem. He was unable to maintain altitude and attempted to feather the left propeller but was unable to move the pitch lever to the feather position. Below lowest safe altitude and having difficulty controlling the aircraft in cloud and turbulence, the pilot decided to make a forced landing as soon as he could see the ground. The aircraft was descended through a hole in the cloud to below the cloud base at 300 - 400 feet above ground level. The pilot selected a small, cleared area for landing. On final approach, he was able to feather the left propeller and also shut down the right engine. During the landing roll, and due to the wet slippery grass, he was unable to prevent the aircraft striking a large rock with the left main gear. The left main gear was torn off by the impact. Subsequent inspection of the left engine revealed a loose connection of the pressure fuel line between the flow divider and injector. The connection was backed off approximately three quarters of a turn. During engine test running, the engine performed normally. However, when the line connector was backed off three quarters of a turn, a substantial spraying fuel leak developed, resulting in the RPM dropping to 1000 and fuel flow decreasing to five gallons per hour. The reason for the loose connection was not established. The propeller feathering function was also normal. It is possible that the fuel leak, which projected towards the pitch control cable in the engine compartment, caused a further lowering of the temperature, resulting in moisture freezing around the cable. When the fuel was turned off and the aircraft descended to a warmer air temperature, the ice thawed, freeing the cable and allowing the pilot to feather the propeller.

Significant Factors:

The following factors were considered relevant to the development of the accident:

1. The engine lost power due to a loose fuel line connection.

2. The pilot was unable to feather the propeller and, as a consequence, the aircraft was unable to maintain altitude.

3. The pilot was unable to prevent the aircraft striking rocks during the landing run. This accident was not the subject of an on-scene investigation.