I started working as a ground engineer on 747s in Iran in 1977 and retired in 2010 after 33 years on them. It was an easy aircraft to maintain - relatively simple systems compared to the likes of Tristars or Airbus. The MEL was such that you were rarely grounded for a defect. I flew flight mechanic on several contracts. When based in Manila in the late 80’s I frequently did round trip to London without leaving the aircraft - 42 hour duty period! I loved the aircraft and always regarded my work as a well paying hobby.