An engineer I worked with was steady state testing a Diesel engine on the dyno (from a semi truck). He was in the test cell while it was running. He was checking some stuff out while leaning over the twin turbos. Unfortuanetly the pressure releif vavle that was changed to manual control closed. With in one step from the door, the hose between the twin turbos blew off. Which could have taken his head off!!