What happened
On August 8, 2005, at approximately 16:50 local time, a Bell 412 EP helicopter, registration EC-HFD, was performing a scheduled domestic passenger flight from Ceuta to Malaga. The aircraft was carrying two crew members and seven passengers. While cruising at 5,000 feet, the left rear emergency window became detached from the aircraft structure.
The detachment occurred after a minor passenger, while adjusting his seating position in the confined space, inadvertently struck one of the lower corners of the window. The pilot noticed a change in cabin pressure and noise levels and was alerted to the situation by a passenger. Upon confirming that the window detachment had not caused structural damage to the airframe, the crew reduced the aircraft's altitude and airspeed to improve stability and passenger comfort. The helicopter subsequently landed safely at Malaga Airport with no injuries to the crew or passengers.
The investigation
The CIAIAC examined the mechanical design of the emergency window, which is designed to detach when pressure is applied to the lower corners to facilitate ground evacuations. The investigation reviewed the maintenance history of the window, noting it had been replaced in 2002. Investigators also analyzed the manufacturer's design specifications, which state that a force of 50 lbs (28 kg) is required to trigger the detachment mechanism.
The investigation also looked into passenger safety procedures, including the use of safety briefing DVDs, safety cards, and verbal warnings provided by the crew. The commission noted that while passengers in side-facing seats are warned not to lean against the windows, these warnings are often delivered while the sliding doors are open, making the stickers and instructions difficult to see or understand for non-Spanish speakers.
Findings
- The primary cause of the window detachment was an inadvertent blow from a child passenger as he adjusted his position in the seat.
- The window detached according to its design specifications, as the mechanism is triggered by pressure on the lower corners.
- The safety briefing procedures were found to be insufficient, as the safety cards and videos did not explicitly address the dangers of hitting the emergency windows or provide adequate instructions for the typical passenger demographic.
- There was a lack of a secondary locking mechanism to prevent accidental in-flight opening in compliance with FAR 29.809 regulations.