What happened
On September 6, 2017, an Embraer ERJ-175 was performing an approach to landing at Munich Airport (EDMM). During the approach, the aircraft's flaps became stuck in position 2, and a FLAP FAIL message was displayed in the cockpit. In response to the malfunction, the crew executed a missed approach.
The crew followed the procedures outlined in the Quick Reference Handbook (QRH) for a flap failure. The aircraft subsequently landed using flaps in position 2 and slats in position 3. The landing was completed without further incident, and technical services and the Maintenance Control Center (MCC) were notified immediately following the arrival.
The investigation
Following the incident, the operator canceled the aircraft's subsequent flight. Maintenance personnel from Lufthansa, stationed at Munich, inspected the aircraft and identified the cause of the malfunction. The investigation revealed that the flap actuators and torque tubes in the left wing lacked necessary lubrication.
Records indicated that a maintenance task for lubricating the actuator mechanism had been scheduled and confirmed as completed by maintenance technicians on September 2, 2017, just four days prior to the incident. However, upon further inspection and correspondence between the operator and the Approved Maintenance Organization (AMO), it was discovered that while the right wing mechanism showed evidence of lubrication, there were no traces of grease on the left wing flap mechanism.