What happened
On May 20, 2013, an EMBRAER 170-100 was operating a scheduled flight from Gdańsk (GDN) to Frankfurt (FRA). Shortly after takeoff, while climbing through an altitude of 4,000 feet, the flight crew received a FLAP FAIL indication in the cockpit. In response to the malfunction, the crew executed the appropriate flap failure checklist and initiated a return to Gdańsk. The aircraft landed safely at EPGD using a landing configuration of flaps 2 and slats 3.
The investigation
Following the landing, maintenance personnel performed troubleshooting procedures in accordance with the Flight Interruption Manual (FIM). The inspection identified a failure within the left-hand inboard flap assembly outboard actuator. The faulty component was subsequently replaced following the approved Aircraft Maintenance Manual protocols. Post-replacement tests were conducted successfully, and the aircraft was returned to service.
The investigation revealed that the failed actuator (P/N C154811-2, S/N 1020) had been installed on the aircraft since its manufacture on June 25, 2004. While the manufacturer had issued Service Bulletin SB170-27-0037 regarding flap actuator inspection and SB170-27-0025 regarding recommended replacements, the specific failed unit was not listed among the parts identified for mandatory replacement. The operator had implemented the inspection bulletin, but the non-mandatory replacement bulletin was not applied to their fleet.
Findings
- The primary cause of the incident was a mechanical failure of the flap actuator.
- The failed component was an older part that had been in service since the aircraft's production date.
- The replacement actuator installed after the incident met all manufacturer requirements for aircraft updated under the relevant service bulletins.