An aeroplane which departed East Midlands Airport suffered power loss and the pilots lost control of one of the engines.
The cargo plane which departed the airport near Castle Donington was heading to Stansted Airport when they lost a significant number of flight deck instruments and systems.
The plane which was built in 1989 had two crew members on board when it suffered the power loss 8 nautical miles west of Milton Keynes in May.
With alarms and alerts going off in the cockpit they then lost control of the left engine and the autopilot also disconnected.
The crew then decided to fly the plane back to the East Midlands, where it made an "uneventful landing".
In a field investigation by Air Accidents Investigation Branch (AAIB) published this week they stated that they could not say what caused the failure do to a moisture problem.
The moisture problem even caused the planes black box to stop recording.
The AAIB are now recommending that the black box should be insulated more by the plane's manufactures British Aerospace.
The AAIB report stated: "The crew decided to return to East Midlands Airport where they made a normal landing, following which electrical power was restored without crew action.
"Subsequent testing of the aircraft’s electrical system did not identify the cause of either failure."