Testing an actuator: Article in Lufthansa Magazine 11/2013

What's that you're doing, Mr. Jahnke?

Avionics technician Lars Jahnke, 38, has been working for Lufthansa Technik in Hamburg since 1991. "I'm testing an actuator, the type you will find in all Airbus models, although the number varies according to the size of the aircraft. Actuators are an important element in the cabin's temperature control circuit; a complex system designed to keep the cabin temperature at the required setting. The actuator triggers the trim air valves, which let in the ideal mix of prewarmed fresh air and filtered hot air from engine. The actuator controls the opening angle of these valves with great precision - it takes a maximum of 3600 impulses to open or close the valve, each impulse opening or closing the valve by roughly 0.02 millimeters. This means that the cabin temperature can be regulated quickly an precisely. Each section of the cabin and the cockpit has its own separate circuit, making individual temperature settings possible in each area. In the image, I'm holding the actuator motor in my left hand and attaching the connector cable to the test box on an adapter plate with my right. What I'm going to do is run through all of the parameters, checking whether the actuator overcomes the required loads, how many amperes the motor draws, the time periods, whether the angles are correct an a lot besides. Our latest-generation test bench is worth over 100.000 euros and saves us a good deal of time on maintenance. Besides, it can be easily modified for use with devices from the aircraft of the future, such as the A350 and the Dreamliner."