Accident
On 4 December 2014, an ATR 72-202 commercial aircraft, registration D-ANFE, was landing on runway 14 of Zurich Airport (LSZH). During the landing, the nose landing gear was not centered, preventing the two nose wheels from rotating freely. Consequently, control of the nose landing gear was lost, and the gear sustained significant damage.
Investigation
The Swiss Transportation Safety Investigation Board (STSB) conducted the investigation. Examination of the nose landing gear revealed that the valve input lever of the differential control selector valve (DCSV) had been connected rotated by 180°. This misalignment prevented proper steering function. Additionally, the investigation found that maintenance of the nose landing gear had been inadequate.
Probable Cause
The STSB determined that the accident was attributable to the nose landing gear not being centered during landing, which prevented free rotation of the nose wheels. The most likely cause was the interaction of two factors: a valve input lever of the differential control valve connected rotated by 180° on the nose landing gear, and inadequate maintenance of the nose landing gear. A contributing factor was the design that allowed the valve input lever to be installed incorrectly by 180°.
Other Findings
During runway inspections conducted a few hours after the accident, small aircraft parts were found on the runway. While these parts did not influence the occurrence or course of the accident, they were considered a safety risk.