What happened
On 23 January 2007, a De Havilland DHC8-300, registration PH-DMU, operated by Denim Air for Air Nostrum, was performing a scheduled passenger flight from Pamplona to Barcelona. During the final approach to runway 25R at Barcelona airport, the crew attempted to extend the landing gear but found that only the main landing gear had deployed. The nose landing gear remained retracted, and the crew noted mechanical vibrations near the nose gear area.
After an initial aborted landing, the crew entered a holding pattern at 3,500 ft. They attempted both the normal and the emergency gear extension procedures, but the nose gear failed to lock in the down position. The captain declared an emergency and, after approximately 20 minutes of attempting to resolve the issue, decided to proceed with the landing. To mitigate the risk, the captain instructed passengers to move to the rear of the cabin to shift the center of gravity.
The aircraft landed on runway 2lar 25L. The crew maintained the nose of the aircraft off the ground for as long as possible, only allowing it to touch the asphalt during the final stages of the landing roll. The aircraft traveled approximately 214 meters with the nose dragging on the runway before coming to a stop. The aircraft was evacuated via the runway, and there were no injuries among the 19 passengers or 4 crewmembers.
The investigation
The CIAIAC investigation focused on the sequence of events following the aircraft's previous arrival at Pamplona airport. The investigation established that the aircraft had landed in Pamplona under conditions involving slush on the runway. During the subsequent takeoff from Pamplona, slush that had entered the nose gear wheel well froze into ice blocks.
Upon inspection of the aircraft after it was removed from the runway via crane, investigators found that the alternate extension mechanism functioned correctly once the aircraft was in a position to allow the gear to drop. During this process, several 10-cm pieces of ice fell from the nose gear wheel well. Furthermore, a layer of ice over 5 cm thick was found on the nose gear leg and the wheel well doors. Post-accident operational tests confirmed that the gear functioned normally once all ice had melted.
Findings
- The primary cause of the accident was the inability to extend the nose landing gear because it was jammed by ice.
- This ice formed from slush that had entered the wheel well during the aircraft's previous landing at Pamplona airport.
- The slush was not detected during the pre-flight inspection prior to the flight to Barcelona.
- The crew's attempts to melt the ice by flying at a lower altitude or in a warmer environment were not pursued during the holding pattern.
- The aircraft sustained minor damage, specifically to the nose gear wheel well doors, which detached after grinding against the runway.