FAILURE OF FUEL CUT OFF CYLINDER :
Engine - sulzer RND, 7 cylinders :
Incident - While maneuvering in harbour, engine did not stop. Astern kick was given to brake the momentum. But the air went in, with the fuel, causing heavy firing. Engine was stopped locally, but by then all 7 relief valves burnt off, and 3 air-start v/v seats damaged.
4 relief valves renewed with spare and 3 plugged with stainless steel plugs made on board. 2 cylinder heads removed & one unit cut out and vessel sailed out.
Cause of accident: fuel cut-off cylinders had a long bolt at the bottom, which was in place with a hex-sleeve. Apparently the piston inside turned, causing the bolt to come down and got snagged at the rim of the hexagonal sleeve, preventing the fuel cut off from operating.