What happened
On 11 November 2012, a Rockwell Commander 112, registration OO-XXX (implied Belgian registration), was performing a series of touch-and-go landings at EBTN airfield. During the downwind leg of a second attempt, the pilot configured the aircraft for landing. Shortly thereafter, the engine began to sputter and lost all power.
Despite the pilot's attempts to restore power by switching fuel tanks and manipulating the throttle, the engine continued only to windmill. Facing a rapid loss of altitude and the obstacle of an electrical power line, the pilot executed an emergency belly landing in a cultivated field. The aircraft sustained significant damage to the fuselage, propeller, and left wing, but the pilot escaped the wreckage uninjured.
The investigation
The AAIU(Be) investigation focused on the fuel system after finding no obvious mechanical anomalies during the initial inspection. Investigators discovered that the fuel gascolator contained a white liquid, identified as water, along with black particles and a gelatinous substance.
Several technical issues were identified regarding the aircraft's fuel management. The fuel tank drain nuts were found to be installed upside down, which restricted the efficiency of the draining process. Additionally, the fuel tank caps were not watertight due to degraded O-rings. The investigation also noted that the aircraft had recently been washed with a garden hose, and the fuel system had not been drained following this cleaning. Furthermore, the gascolator drain valve was difficult to access, as it lacked a remote control system, and the pilot had not been following the full pre-flight draining procedure prescribed in the flight manual.
Findings
- The primary cause of the engine failure was water contamination within the fuel system.
- The contamination was facilitated by several contributing factors:
- The fuel tank drain nuts were installed in an orientation that obstructed proper drainage.
- The fuel tank caps failed to provide a watertight seal.
- The fuel system was not drained after the aircraft had been cleaned with water.
- The pilot did not perform the full pre-flight inspection, specifically omitting the draining of the fuel selector valve.
- The gascolator drain was difficult to operate manually without a remote system.
Safety action
The AAIU(Be) issued two recommendations to the FAA regarding the aircraft's Type Certificate Holder:
- A requirement to provide clearer instructions for the correct installation of the PN: 1000B-2A valve drains.
- An update to the Maintenance Manual's Inspection Intervals Chart to explicitly include the 25-hour gascolator draining operation.