Incident Details
On 5 May 2015, shortly after takeoff from Warsaw Chopin Airport (EPWA), the flight crew of an Embraer 170 attempted to raise the landing gear but found the gear lever could not be moved to the UP position. The crew informed air traffic control of their intention to return to the departure airport; no emergency was declared. They performed the GEAR LEVER CANNOT BE MOVED UP checklist and the 3.15 p.6 WOW SYSTEM FAIL procedure. The aircraft subsequently executed a safe landing on runway 15 at Warsaw.
Maintenance History
Approximately three and a half months prior, during a maintenance check on 22–23 January 2015, an Engineering Order was accomplished on the aircraft to replace the Proximity Sensor Electronic Module (PSEM) with a new, modified unit. The purpose of this modification was to reduce occurrences of the LG NO DISPATCH caution. Following the modification, fault history records indicated that LG NO DISPATCH messages appeared repeatedly, starting during the same maintenance check.
In response, maintenance personnel replaced, in sequence: the CTR LEVER LANDING GEAR, the LDG SELECTOR VALVE, and the SPDA1 LRM13 MODULE. The fault persisted, and on 7 February 2015 it recurred. Maintenance then replaced the Proximity Sensor Electronic Module No. 2. A subsequent flight test confirmed the fault was resolved.
Investigation and Cause
The investigation determined that the most probable cause of the incident was a failure of the Proximity Sensor Electronic Module that had been installed on 22 January 2015 during the modification.
Outcome
After returning to the airport, the aircraft was withdrawn from service. The SPDA1 LRM13 (Secondary Power Distribution Assembly Line Replaceable Module, DC Power Module in SPDA 1 slot 13) and the EMERGENCY EXTENSION OVERRIDE SWITCH were replaced. System tests were successful, and the aircraft was returned to service.
No safety recommendations were issued by the investigating commission, as the event was recorded in the Safety Management System and will be included in air safety indicators for the area of continued airworthiness management under the SMS.