Incident Overview
On May 19, 2017, a Boeing Company B 747-400 F freighter experienced an in-flight separation of the outer landing flap actuator cover on the right wing. The incident occurred during the final approach to Munich Airport (Landebahn 26R). The German Federal Aviation Office (BFU) investigated the event under case number BFU17-0540-TX and concluded it as a disturbance with minor aircraft damage and no personnel injuries.
Flight Details and Crew
The aircraft, operated by a British airline and registered in the United Kingdom, was on approach from Frankfurt at 07:48 local time. The crew consisted of two pilots and one mechanic. The captain, aged 61, held an ATPL(A) license with 23,978 total flight hours, including 6,578 on the B747-400. The copilot, aged 44, had 6,981 total hours, with 3,621 on the type.
Sequence of Events
As the aircraft extended its landing flaps to 30 degrees at a distance of 12 km from the runway threshold, the crew reported hearing a noise. The indicated airspeed was 146 knots. Despite the separation, the flight continued without further issues, and the aircraft landed safely on Runway 26R.
Investigation Findings
Post-landing inspection revealed the missing cover for the outer flap actuator (No. 8) on the right wing. The cover was recovered from a field near Wartenberg, approximately 12 km east of the runway threshold. Examination showed broken and bent holders and connecting rods in the flap guide rail area. Both front bolt fastenings were missing, with scratch marks indicating friction. The rear support fitting was twisted nearly 180 degrees and torn. No fire occurred.
Maintenance History
The aircraft had undergone a C-Check prior to delivery to the operator on April 22, 2017. During this maintenance, the cover in question was removed and reinstalled for inspection, as documented by job cards. The manufacturer had previously issued service letters regarding potential causes of such cover losses.