Incident Overview
On 12 July 2015, an Airbus A320-214 experienced a hydraulic fluid leak in the green hydraulic system after landing at Katowice/Pyrzowice Airport (EPKT). The leak was discovered by maintenance organization A, who determined that the leakage exceeded the limit specified in AMM 29-00-00-790-001-A.
Initial Maintenance Attempts
Maintenance personnel from organization A first replaced seals on the fittings and valve (positions ②, ③, ④, ⑤ in the report's Figure 1). The leak persisted. They then ordered and replaced the manifold body, fittings, and valve (positions ① through ⑤). After installation, the leak continued. At this point, organization B was called for assistance.
Findings by Organization B
Mechanics from organization B discovered that one fitting was overtightened and another was undertightened. Additionally, seal residues were found on the internal threads of the manifold body. After cleaning the threads and replacing the seals, they reassembled the components according to AMM 29-11-14/401. Hydraulic fluid was topped up and no further leaks were detected. The aircraft was released for flight.
Recurrence of the Leak
After the aircraft returned from its next flight, the leak reappeared in the same area. Organization B inspected and found that the pressure transducer (Figure 2) had been incorrectly installed by organization A: two of the three mounting bolts were under-torqued. Organization B correctly installed the transducer and verified no leaks. The aircraft was again released for flight. No further leaks occurred on subsequent flights.
Corrective Actions
A Safety Action Group (SAG) meeting was held to discuss the maintenance errors by organization A. Following the SAG decision, a meeting with the management of organization A addressed the quality of maintenance work, noting previous instances of poor workmanship. A deadline for implementing corrective actions was established. Ongoing supervision of organization A's work was initiated, and no further errors were identified. Collaboration with organization A continued.