What happened
On January 30, 2011, a Boeing 757-200 PCF, registration TF-FIH, arrived at the cargo apron at Keflavik Airport (BIKF) from New York. During ground operations, the aircraft commander opened the main cargo door, noting that the reported wind conditions were within the manufacturer's operating limits. While the aircraft was parked at stand 20, the wind was gusting up to 42 knots.
As the cargo loading crew approached the aircraft, the main cargo door began to sway significantly. The loading crew reported hearing several loud bangs, after which they observed that the door had moved past its fully open position and was resting on top of the fuselage. The door' and its supporting structure were severely damaged. The maintenance technician attempted to close the door, but it fell uncontrolled to its closed position during the process. No injuries were reported during the incident.
The investigation
The RNSA examined the structural integrity of the cargo door conversion and analyzed local meteorological data. Wind monitoring stations at the airport recorded gusts of up to 42 knots at the time of the incident. The investigation focused on the relationship between the wind speed, the manufacturer's 45-knot operating limit, and the required safety factors for transport category aircraft.
Investigators analyzed the drag loads exerted on the door and compared the failure point to the regulatory requirements of the FAA and EASA. The investigation also looked into the local wind conditions at the cargo apron, noting that wind channeling between nearby buildings can cause local speeds to differ from official airport readings.
Findings
- The main cargo door support structure failed while the aircraft was subjected to a 42-knot gust.
- Calculations indicated that while the 45-knot limit represents the maximum operating load, the structure should have been able to withstand up to 55 knots before reaching its ultimate failure condition.
- The cargo door support structural design does not meet the requirements set forth in FAA and EASA structural regulations regarding safety factors for ultimate loads.
- There was no evidence of corrosion or underlying damage that contributed to the failure.
Safety action
Following the incident, the operator implemented new procedures in its Flight Crew Operation Manual. This includes a requirement to consult maintenance or load control if winds exceed 35 knots at the Keflavik hub, and a stricter limit of 40 knots for opening the door at the cargo ramp. Additionally, a new wind monitoring station was installed at the cargo ramp to provide more accurate local readings.