What happened
On January 29, 2012, an Embraer E170-100 operating a flight from Budapest (OTP) to Warsaw (WAW) was on approach to Warsaw Chopin Airport with 57 passengers, two pilots, and two cabin crew members. At a radar altitude of 1,800 feet, the crew moved the landing gear lever to the DOWN position. This action triggered a "LG LEVER DISAG" (Landing Gear Lever Disagree) warning, as the right main landing gear strut failed to extend immediately.
In response to the warning, the crew decided to execute a missed approach at 1,575 feet. Approximately four seconds after the initial gear lever movement, the right main gear strut extended. The crew notified Air Traffic Control (ATC) of the situation and subsequently performed a second approach with the gear fully extended. The aircraft landed at 14:41 UTC without an emergency declaration. Following the landing, maintenance crews performed extension and uplock roller tests, which yielded positive results, and the aircraft returned to service on January 30, 2012.
The investigation
The investigation examined the mechanical performance of the landing gear and noted a secondary occurrence involving the same aircraft type. On January 31, 2012, during a flight from Budapest to Warsaw, a similar malfunction occurred where the left main landing gear strut extended with a five-second delay. In this second instance, the pilot, aware of the previous event, waited for the delay before continuing the approach. Maintenance performed lubrication of the main landing gear extension mechanisms and conducted extension and retraction tests, which were successful. The aircraft returned to service on February 1, 2012, and the issue did not recur.
Findings
- The primary cause of the delayed gear extension in both instances was increased resistance on the uplock rollers of the left and right main landing gear struts, which resulted in the uneven deployment of the gear legs.