The interview process took about 3 months in total, despite the company advertising a very quick interview process.
I had two initial interviews with one of the company's internal recruiters. I had a second interview with the director of airframe. I had a third interview with one of the director's structures engineers.
I had a fourth interview with a panel of 6 engineers. The fourth interview was about 2-3 hours in length (with one 15 minute break). This consisted of the panel interview and then 4 one on one interviews.
They gave me their decision 2 days post interview that I was not their ideal candidate. Their company policy is to not provide feedback as to why you were not selected.