What happened
On January 7, 2017, during a scheduled maintenance inspection (750/1200/9500FH+ROU) at the maintenance organization's technical base at Warsaw Chopin Airport (EPWA), technicians identified a discrepancy regarding a component on an Embraer ERJ-195 operated by PLL LOT SA. While performing task 27-31-001, which involves checking the control column disconnect, personnel discovered that the identification plate on the Elevator Disconnect Device displayed the incorrect part number. The plate showed part number 170-24297-407, whereas the Embraer Aircraft Illustrated Parts Catalog (AIPC) specified that the correct part number should be 170-24298-407.
Upon discovery, the component with the incorrect identification was removed from the aircraft and replaced with a new unit bearing the correct part number.
The investigation
The investigation focused on determining how the incorrect part reached the aircraft. Investigators examined the maintenance organization's inventory and IT systems, finding that the part with the incorrect part number was not present in the organization's warehouse stocks, nor was it assigned to any other aircraft under their care. Furthermore, no digital records indicated that any Elevator Disconnect Device had been withdrawn from stores for aircraft SP-LNC.
Records within the organization's SI MERLIN system indicated that the aircraft should have been fitted with part number 170-24298-407 (serial number 0000668639) as of August 19, 2011. Given that the aircraft was delivered to the operator on August 24, 2011, the investigation noted that the lack of traceability in the maintenance organization's systems suggests the incorrect part may have been installed by the manufacturer during the initial assembly in 2011.
Findings
- The primary finding was the presence of an Elevator Disconnect Device with an incorrect part number on the aircraft.
- There was no evidence of recent part withdrawals or inventory discrepancies within the maintenance organization's internal systems.
- The discrepancy likely originated from the initial manufacturing process at Embraer, as the part was present on the aircraft since its delivery in 2011.