Occurrence
On 21 January 2016, while performing a pre-departure check (PDC) at Vilnius Airport (EYVI), the flight crew of a Bombardier DHC-8-400 operated by LOT Polish Airlines (SP) observed that the lock nut safety wire on the left main landing gear forward right door pushrod was broken. The crew reported the finding to the airline's operational technical engineering (LOT OTE).
Investigation
A certified mechanic dispatched to Vilnius examined the pushrod and determined that the bolt had been turned 26 full rotations in the threaded sleeve. To complete a full adjustment of the landing gear door mechanism, the aircraft was operationally ferried to Warsaw Chopin Airport (EPWA). The aircraft manufacturer was informed, and the responsible fleet engineer filed a Ground Safety Report (GSR).
Cause
The investigation established that the safety wire securing the lock nut, which locks the pushrod bolt in a fixed position, had ruptured. The reason for the wire failure could not be determined.
Preventive Actions
The incident was recorded in the airline's Safety Management System (SMS) database and classified according to LOT's criteria. It was included in monitored safety performance indicators (SPI) as outlined in the Safety Management Manual. The Polish Civil Aviation Authority (KBZL) initiated a preventive action directing an inspection of main landing gear door pushrods across the entire DHC-8-400 fleet. On 29–31 January 2016, Engineering Order ELOT/Q40/0004/16 was issued and executed, mandating a one-time inspection of the locking safety on the main landing gear forward rod (MLG FWD ROD).
Recommendations
No safety recommendations were issued by the investigation commission.