What happened
On the night of June 17, 1999, a Eurocopter BO 105 was deployed from Magdeburg for an urgent police search mission involving a missing child. The mission required the crew to operate using night vision goggles (NVG). Approximately 25 minutes after takeoff, while the helicopter was in a hover at roughly 200 feet above the Elbe River, the first engine failed. Within seconds, as the crew attempted to execute the single-engine landing procedure, the second engine also failed at an altitude of approximately 150 feet.
The pilot initiated an autorotation in an attempt to reach the eastern bank of the river, but was unable to reach land. The helicopter performed an emergency landing in the shallow waters of the Elbe. The aircraft became partially submerged, resulting in damage to the tail rotor blades and water ingress into the cabin. The two crew members were rescued by the water police approximately 10 minutes after the landing. There were no injuries to the crew.
The investigation
The BFU investigation established that both main fuel pumps had been left in the off position. The investigation focused on the operational aspects of the failure and identified that the crew had used adhesive tape to temporarily secure a filter cover on the cockpit caution panel because the original mounting eyelet had broken. During the flight, vibrations caused this taped filter to slip, obsculating the top row of warning lights on the caution panel.
Findings
- The primary cause of the dual engine failure was the failure to activate the main fuel pumps.
- The crew was unable to notice the low fuel warning because the makeshift filter cover obscured the relevant warning lights on the caution panel.
- The crew's ability to monitor the instruments was further compromised by the use of night vision goggles, which required the cockpit instrument lighting to be turned off, making the caution panel visible only when a warning light was actively illuminated.
- Contributing factors included high-pressure mission requirements, stress, and a cockpit workload distribution that limited the crew's ability to cross-check each other's actions.
- The aircraft design contributed to the severity of the event, as the BO 105 lacks a master caution light or an audible low-fuel warning, and the fuel pump activation procedure requires separate, staggered steps which increased the risk of human error.
Safety action
- The BFU issued a safety recommendation to the Luftfahrt-Bundesamt (LBA) to amend the flight manual and checklist for the BO 105 so that all fuel pumps are activated together prior to engine start.