What happened
On November 10, 2003, a Hughes 269C helicopter, registration PH-HKH, was performing a ferry flight near Hank, Netherlands. The flight was part of a larger mission involving an inspection of pipeline routes for the Defense Pipeline Organization. During the return leg of the flight, flying at approximately 600 feet, an observer on board requested that the cabin heating be turned off to reduce the temperature.
In an attempt to demonstrate that the heating was not active, the pilot attempted to manipulate the control knob. Shortly after this action, the engine began to falter, forcing the pilot to immediately initiate an autorotation procedure. During the descent, the pilot likely arrested the vertical descent rate too early, resulting in a hard landing. The impact caused unrecoverable damage to the aircraft. Both occupants managed to exit the wreckage, with one person sustaining light injuries.
The investigation
Investigators examined the cockpit configuration and the pilot's actions following the engine failure. Upon inspecting the aircraft after the crash, the pilot discovered that the fuel shut-off valve had been completely pulled out. This led to the realization that instead of activating the heating, the pilot had accidentally closed the fuel supply to the engine.
The investigation focused on the physical layout of the center console. It was noted that the heating control knob and the fuel shut-off knob were nearly identical in design and tactile feel. Both knobs featured a similar locking ring, and the lack of distinct tactile feedback made it difficult to distinguish between them by touch alone.
Findings
- The primary cause of the engine failure was the accidental closure of the fuel supply by the pilot.
- The pilot's attempt to demonstrate the heating status involved manipulating a control without visually confirming the specific knob being used.
- A significant contributing factor was the highly similar design of the heating and fuel shut-off controls, which lacked distinct tactile differences.
- While the labels on the controls were legible, the identical physical characteristics of the knobs allowed for a manual error during a routine interaction.