What happened
On July 7, 2016, during a periodic inspection at the LOTAMS technical base at Warsaw Chopin Airport (EPWA), ground personnel identified damage to the flap mechanism of an Embraert ERJ-175 operated by PLL LOT SA. While performing a required inspection for wear on the right inboard main flap track 2A, the crew extended the flaps and discovered structural damage to two linkage pushrods within the flap mechanism fairing. Specifically, the upper pushrod (PN 171-03779-901) was bent, and the lower pushrod (PN 171-03778-901) had suffered a fracture and the loss of its end fitting (joint).
The investigation
The investigation examined the aircraft's operational history to identify potential triggers for the component failure. The review of flight data and maintenance records highlighted three notable events prior to the discovery of the damage: a hard landing recorded on April 1, 2016; an exceedance of flap speed limits recorded on May 16, 2016; and a significant longitudinal deceleration during braking accompanied by a sharp left turn during flap retraction on July 6, 2016. Additionally, the investigation noted that the maintenance team did not take photographs of the fairing and damaged pushrods immediately upon discovery, which prevented a verification of the original installation state before disassembly.
Findings
- The upper pushrod was found to be bent.
- The lower pushrod was fractured, resulting in the detachment of the end joint.
- The exact cause of the damage could not be definitively established.
- While a hard landing and speed exceedance were recorded in the months preceding the incident, detailed analysis determined that none of the identified operational events were sufficient on their own to cause the observed damage.
- A similar incident involving pushrod damage occurred on aircraft SP-LIE in July 2015, which was attributed to the malfunction of a lateral landing gear damper.