Installed in over half of the Airbus A320’s globally operating aircraft, the V2500 engine—or the “V”, as it’s called by the specialists at MTU Maintenance in Hannover—is a regular visitor to the shop. Its high-pressure compressor should ideally withstand 16,000 to 20,000 cycles, in other words that many takeoffs and landings. However, maintenance staff soon noted that they were replacing the front part of the compressor’s rotor drum, which is a very valuable component, after roughly 8,000 cycles.
The problem was traced to relatively inconspicuous components, namely sealing wires made of a cobalt-based alloy and just millimeters wide. They serve as vibration dampers for the compressor blades in stages six to eight to ensure the stator blade ring and rotor do not wear each other out and the blades do not fracture. While in use, the wire ends were eating into the titanium alloy of the retaining grooves directly in front of and behind the blade roots where the six damping rings sit. They would damage the groove to such an extent that the rotor could not operate after around 8,000 cycles.