A319
Maintenance Powerplant; Maintenance Airframe
Maintenance Inspector 15; Maintenance Technician 12
Training / Qualification; Troubleshooting; Situational Awareness; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance
General Maintenance Action
Incorrect / Not Installed / Unavailable Part; Human Factors
After discovering we were going to install our 3rd Hydraulic Reservoir Pressure Manifold; I decided to figure out why the 2nd and Original Equipment Manufacturer (OEM) Pressurization Manifolds were not pressurizing the Blue Hydraulic Reservoir to 50 PSI. In fact; both [previous Pressurization Manifolds] Units did not pressurize Blue System at all. After a few hours of troubleshooting the problem and verifying on another Airbus aircraft [in adjacent] Hangar Dock; I found that the left engine [Pneumatic] Supply line in the Left-Hand (LH) wheel-well on the Forward (FWD) Bulkhead (BLKHD); was connected to a Tee [fitting] which is the line that supplies all three Hydraulic Reservoirs; bypassing the [Pressurization] Manifold completely and probably over-pressurizing the reservoirs. And; I found the Blue System Pneumatic supply line (going to the Hydraulic reservoir) was connected to a (Union) [fitting]; which is the Manifold supply connection from the LH Engine. Thereby never supplying pneumatic pressure to the Blue Reservoir. So the lines were criss-crossed. Yes; both ['B'] nuts will fit on either connection and there is plenty of room for the lines to criss-cross and not chaff on anything. To me; neither line has been replaced that I could tell. And the Engineering Orders (E/Os) that were accomplished in the same area should not have had the need to remove these lines. Please note; this condition was [found] on our inbound C-Checks; [while] checking head pressure for the Hydraulic reservoirs.
Reporter stated when an Airbus comes into the hangar; they perform a Low-Pressure Check of each Green; Yellow and Blue Hydraulic Reservoir's head pressure using ground service air. Although the Blue Reservoir's head pressure was above the 22 PSI that sets off warnings in the cockpit; he could not increase the head pressure by applying service air to see if the Reservoir Pressurization Manifold was functioning. When the Blue head pressure did not respond; the thought was the Manifold was again at fault. The Pressurization Manifolds are made of metal aluminum; often plug-up with debris; have corrosion and heavy metal pitting. Airbus Manifolds are not a rotable recovered component; basically disposal. Boeing B757 aircraft Manifolds are made of steel and repairable.Reporter stated the A319 had been flying for some time with the lines crossed; but since the Blue Hydraulic Reservoir head pressure never went below 22 PSI; no discrepancies were ever noted. Maintenance history showed the aircraft did have hydraulic issues with the Green and Yellow Systems oozing hydraulic fluid. He suspects those discrepancies were driven by Reservoir high head pressures from the crossed pneumatic supply lines. The Engineering Orders (E/O) that were accomplished in the area of the Hydraulic Reservoir Pressurization Manifold; involved installing Anti-Vibration clamps on hydraulic lines and a pneumatic supply line.
Mechanic describes what he found while trouble shooting for the cause of two previous replacements of an A319 aircraft's Hydraulic System Reservoir Pressurization Manifold; that allegedly had failed to pressurize the Blue System Hydraulic Reservoir from the left engine.