The first Qantas turbo-fan 707-138B VH-EBH City of Darwin undergoing an engine change at Mascot. Although the date is unknown, it is possible that this could be the first engine change involving a fan engine. It was a common practice to change engines for "stagger" purposes so that all four engines did not fall due for overhaul at the same time. However, engine failures usually produced the same result. Picture: Peter Gates Collection