What happened
On 4 February 2015, a Maule MX-7-180C, registration N1052U, was performing a private flight from Perth to Strathaven Airfield. While executing the final approach for Runway 27, the pilot transitioned from the right base leg and began a descent from 800 ft. The pilot had configured the aircraft with three stages of flap and adjusted the propeller RPM to 2,500.
During the descent, the pilot noted that the aircraft was sinking and observed that the airspeed had dropped to 55 mph, which was below the intended target of 60–70 mph. In an attempt to correct the speed, the pilot applied full power; however, the engine coughed and ceased operation. Following the engine failure, the pilot attempted to maneuver the aircraft toward a field for a forced landing. During this maneuver, the aircraft entered a stall and struck trees before coming to rest in a field. The pilot sustained no injuries, though the aircraft suffered significant damage to the engine, propeller, cowling, fuselage, wings, struts, windscreen, and empennage.
The investigation
The investigation focused on the cause of the engine stoppage. The pilot suggested that the failure might have been caused by water in the fuel or carburettor ice. While the pilot typically applies carburettor heat when entering the circuit, he could not definitively confirm if this had been performed during this specific flight.
Data regarding the environmental conditions indicated a moderate risk of carburettor icing at cruise power and a serious risk of icing at descent power, according to the Civil Aviation Authority's icing charts. At the time of the report, the carburettor float chamber had not been inspected for water contamination.