Incident Details
On July 20, 2013, during a pre-flight inspection of a Boeing 737-400 at EPWR (Wrocław Airport, Poland), the flight crew discovered that a passenger boarding bridge (commonly referred to as a "jet bridge") had made contact with the left angle of attack sensor. The contact occurred due to an error in ground handling procedures. The crew contacted the Maintenance Control Center (MCC) and the operator's Operations Department, and received a one-time approval for licensed mechanics to perform maintenance.
Maintenance Actions
Following the approval, maintenance was conducted under specific MEL (Minimum Equipment List) items. The aircraft was returned to service with operational limitations imposed by MEL items 22.7, which led to additional restrictions under 22.4 (autothrottle system), 27.12 (auto slat systems), and 27.13.1 (stall warning system). On July 22, 2013, the angle of attack sensor was replaced in accordance with Aircraft Maintenance Manual (AMM) 27-32-11. After the replacement, the aircraft was cleared for unrestricted operation.
Cause
The investigation determined that the incident was caused by an error in the handling of the passenger boarding bridge, which resulted in damage to the left angle of attack sensor.