What happened
On February 21, 2012, during the climb phase shortly before reaching cruise altitude, an Embraer E170 departing from Warsaw Chopin Airport (EPWA) experienced unexpected illumination of several buttons on the lower panels. The illuminated controls included the L/H and R/H reverse thrust, water dump, ground proximity terrain inhibit, and landing gear warning inhibit panels. After consulting with the operations center, the commander decided to execute a return to the departure airport.
This incident was part of a series of similar malfunctions involving the same aircraft. A similar fault had occurred on the previous day. Following the initial return to base, maintenance crews replaced three lower button panels in accordance with the Aircraft Maintenance Manual (AMM). However, during a subsequent flight from Milan (MXP) to Warsaw (WAW), the illumination issue recurred. After landing in Warsaw, technicians replaced the panels with components from another aircraft. Despite being unable to replicate the fault during ground testing, the aircraft was cleared for service.
On February 23, 2012, during a flight from Zurich (ZRH) to Warsaw (WAW), the malfunction manifested for a third time, necessitating the aircraft's removal from service for hangar inspection.