Performing under pressure
Mobile vacuum tool to replace conventional cabin pressure tests
If you hear a whistle in the aircraft cabin, it may not be a cheery fellow passenger or a hydraulic pump that is serenading you. Even the tiniest leaks on windows and doors can result in unusual noises in the pressurized cabin of a passenger aircraft. They are extremely difficult to identify on the ground without the pressure difference that is present during flight. Until now, the seals on windows and doors have been inspected visually and with simulated cabin pressure tests on the ground, with replacement when a leak is found. The procedure takes a lot of time and is personnel-intensive – and no other work can be done in the cabin while it is being carried out. This is all set to change with the new "Vacuum Leak Check" developed by Lufthansa Technik.
The "Vacuum Leak Check" is a mobile vacuum procedure which simulates, on the ground, the maximum pressure differences that an aircraft is subject to during flight. This makes it possible to rigorously inspect windows and doors and to trace leaks with precision. The innovative procedure replaces the laborious process of creating a pressurized cabin. It thus avoids placing the fuselage structure under additional stress, and it can be carried out at the same time as other work on the aircraft.
How it works: The windows and doors to be inspected, including their seals, are thoroughly cleaned and then closed. Then, from the outside, a special fiber fabric ("Air Weave Flies") is placed over the door or window, and over this an airtight latex sheet with hose connections; they are fixed in place with adhesive tape. Once this is complete, the two vacuum and air pressure hoses are attached and connected to the vacuum pump. The vacuum can now be created. Within the cabin, a leak detector can precisely localize any leaks.
The vacuum procedure makes it possible to exclude any other sources of error. The time for inspection is significantly reduced, thus shortening the ground time for the aircraft being tested. Work hours are also saved, reducing costs, because only two employees are required on site instead of four. The testing equipment can be stored in an easy-to-handle toolbox, so that the vacuum procedure can be deployed quickly and easily at any location to identify and repair faults as part of troubleshooting work.