A321
Flight Crew Air Transport Pilot (ATP)
Human-Machine Interface
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Maintenance
Flight Crew Diverted; Flight Crew Landed in Emergency Condition; General Maintenance Action; General Declared Emergency
Aircraft; Human Factors; Procedure
Prior to departure Contract Maintenance had removed some fluid from [the previously] over serviced Green and Yellow hydraulic systems. Approximately 2 hours into the flight an ECAM Alert indicated Green System Pressure Low. ECAM hydraulic page indicated lower than normal Green System quantity and pressure. All ECAM procedures and checklists were completed and system references were checked. ECAM subsequently alerted of Green System low quantity. Dispatch and Maintenance were contacted. The situation was discussed in detail and the decision was made to divert to a nearby airport. ATC; passengers and cabin crew were advised and an emergency was declared. Dispatch and Operations were advised that the flight would need Customs Service at the diversion airport and possibly a tow off of the runway. Due to loss of Green System; ECAM and QRH procedures were followed in order to manually lower the landing gear. The successful gear extension was followed by a normal landing. Nose wheel steering was effective and the aircraft cleared the runway. After emergency responders inspected outside of aircraft for hot spots; aircraft was taxied to a gate to clear customs and undergo repairs. Mechanical irregularities were written up in the log book.Contract Maintenance had failed to notice that; after they had completed their maintenance action; fluid was leaking from the Green System Reservoir. Contract Maintenance would be instructed to observe hydraulic lines for some time period after maintenance to ensure that no leaks are occurring.
An A321 flight crew were confronted with low yellow and green hyrdualic system quantities enroute following maintenance action at their departure airport. After draining excess fluid from the systems; Maintenance personnel had failed to insure that there was no leakage from the reservoirs.