Summary
On 29 January 2012, an EMBRAER E170-100 aircraft operating a scheduled passenger flight from Bucharest (OTP) to Warsaw (WAW) encountered a landing gear anomaly during approach to Warsaw Chopin Airport (EPWA). The flight had 57 passengers, 2 pilots, and 2 cabin crew members. The aircraft was carrying out a normal approach when, at a radio altitude of 1800 feet, the crew selected the landing gear lever to the DOWN position. Immediately, a "LG LEVER DISAG" (Landing Gear Lever Disagree) caution message appeared, indicating that the right main gear had not extended. The crew decided to abort the approach at 1575 feet radio altitude.
Event Details
Approximately 4 seconds after selecting the gear down, the right main gear extended. The crew informed air traffic control of the situation and performed a second approach with the gear down. The captain did not declare an emergency. The aircraft landed safely at 14:41 UTC. After landing, maintenance personnel conducted a Landing Gear Extension Test per AMM 32-33-00 and AMM 32-34-00, as well as a Landing Gear Uplock Roller Jammed Test per AMM 32-00-03. Both tests had satisfactory results, and the aircraft was returned to service on 30 January 2012.
Similar Occurrence
During the investigation of this incident, the operator's safety department noted that a similar anomaly occurred on 31 January 2012 on a flight from Budapest (BUD) to Warsaw. In that instance, the left main gear extended with a 5-second delay. The captain, aware of the previous incident, waited 5 seconds and did not abort the approach. After landing, the aircraft was again handed over to maintenance, who lubricated the extension mechanism components on both main gear legs per AMM 32-00-03-600-803A. A Landing Gear Extension and Retraction Test per AMM 32-33-00-05 and AMM 32-34-00-05 was performed with satisfactory results. The aircraft was returned to service on 1 February 2012, and the issue did not recur.
Probable Cause
The Polish State Commission on Aircraft Accident Investigation determined that the cause of the incident was delayed landing gear extension due to uneven extension of the right main gear (first occurrence) and left main gear (second occurrence), resulting from increased resistance on the UPLOCK ROLLER mechanism on both main gear legs.
Preventive Actions
The operator implemented preventive measures including the development of an information bulletin for the ERJ 170 fleet regarding the event and the distribution of the investigation report to the maintenance organization for use during periodic technician training. The commission did not issue any safety recommendations.