What happened
On 20 September 2000, a Eurocopter EC-120, registration G-BZIU, was conducting a private flight from Cork toward Hook Head, with plans to continue to Galway. During the cruise phase, the pilot discovered that the right-side yaw pedal could no longer move past the center position. Suspecting that an object was obstructing the mechanism, the pilot contacted the Air Corps Helicopter Detachment at Waterford Airport for guidance.
To ensure a safe landing despite the restricted control, the pilot diverted to Casement Aerodrome, which offered a larger runway and better wind conditions. After performing several practice approaches to assess the aircraft's handling and to burn off excess fuel, the pilot executed a run-on landing on a concrete runway prepared with a foam blanket by the Air Corps Crash Rescue Service. While the pilot maintained the correct heading during the initial touchdown, the aircraft began an uncontrolled left turn of approximately 110 degrees as the speed decreased. The helicopter eventually came to a stop on the runway without any damage or injuries to the one crew member and one passenger on board.
The investigation
An AAIU inspector observed the final landing and subsequently inspected the aircraft. The investigation revealed that a mobile phone had become wedged between the yaw control horn and the aircraft's perspex bubble window on the starboard side. This obstruction limited the rightward movement of the pedal to just 10 mm from the center.
The investigation identified that the cockpit floor of the EC-120 was flat and carpeted, with a gap of approximately 50 mm between the floor edge and the bubble window. Because the aircraft maintains a slightly nose-down attitude during cruise, and due to standard in-flight vibrations, loose items can easily migrate forward. The investigation also found a pencil loose on the cabin floor, suggesting that the pre-flight check for unsecured items had been insufficient.
Findings
- The primary cause of the control restriction was a mobile phone sliding from the rear seat, moving across the carpeted floor, and falling into the underfloor area where it jammed the control horn.
- The design of the cockpit floor lacked a raised edge or lateral protection to prevent items from slipping into the gap between the floor and the windscreen.
- The pre-flight inspection failed to secure loose objects that could pose a hazard to flight controls.
Safety action
Following the investigation, safety recommendations were issued to the manufacturer, Eurocopter. In response, the manufacturer issued a notice to operators regarding the importance of inspecting the underfloor area before flight and committed to implementing modifications, such as adding covers between the floor and the canopy, to prevent objects from entering the control area.