What happened
On 21 July 2017, a Boeing 767-30 and registration D-ABUK was performing a non-revenue positioning flight from Kangerlussuaq, Greenland, to Frankfurt, Germany. During the initial climb, the flight crew detected an unusual odour. Although the smell had temporarily dissipated by the time the aircraft reached its cruising altitude, it reappeared approximately ninety minutes later and remained constant.
While the crew were evaluating their options, smoke was observed emerging from the area of the right windscreen (Window 1R). In response, the crew donned oxygen masks and declared a MAYDAY. The flight was diverted to Newcastle Airport, where the aircraft landed safely. There were no injuries to the four crew members or four passengers on board.
The investigation
Following the incident, the operator performed troubleshooting which revealed damage to the right windscreen, specifically involving a burnt terminal block, a burnt terminal lug, and damage to the cable loom. The aircraft was subsequently ferried to Frankfurt with the window heating system isolated to allow for component replacement.
A detailed inspection of the removed parts revealed that the terminal lug was not positioned parallel to the terminal block. This misalignment created a risk that the mounting screw could loosen, leading to a high-resistance electrical connection and subsequent overheating. The investigation could not determine the specific cause of the incorrect alignment.