As you look to interview with the British Airways engineering team, you can certainly expect some technical questions like this to pop up. Whether you have the direct experience working with an IDG or not, your interviewer will at least be looking to hear that you are familiar with the fact that they are used on large commercial airplanes to help supply electrical power. They'll also look to hear that you have knowledge of the IDG's requirements for maintenance on the oil within the system as a regular part of the work that you'll perform. If you do have direct experience, be sure to talk about that as you answer this question.