One cylinder was missfiring which started a runaway condition. Engineers tried to shut it down but couldn’t.
the ticking sound likely was a sticking hydraulic lash adjuster, which functioned to maintain the timing of the opening and closing of the exhaust valves on the cylinder head.
But also this:
the number seven fuel injector was stuck in the full-open position, and the fuel rack arm was in the off position.
If I have it right the engineers were running the at idle to listen to the ticking sound. How did the #7 get stuck on full-open?
Neither of the engineers interviewed had any formal training; they stated that their training
was typically “on the job.” They did not have any Coast Guard-issued credentials, nor were they required to have them.
The National Transportation Safety Board determines that the probable cause of the engine
explosion and resulting fire aboard the towing vessel The Admiral was a misfiring cylinder that
ignited lubricating oil in the sump of the engine.
The emergency shutdown button on the governor did not stop the engine when the engineer
pressed the button. Also, the engine did not stop when the engineer attempted to shift the fuel rack arm to the off position. Furthermore, the overspeed trip device did not shut down the engine once the speed of the engine exceeded the setpoint, even though the overspeed trip device was found in the tripped position. Post accident inspection of the damaged engine by the port engineer revealed that the number seven fuel injector was stuck in the full-open position, and the fuel rack arm was in the off position. Despite attempts to shut off the fuel supply to the engine, the engine accelerated in an uncontrolled manner, indicating that an external fuel supply outside its normal diesel- injection system was present.
After the accident, the company hired a forensic engineer to determine the cause of the
engine explosion. He concluded that the engine had been in a runaway condition and likely used its own lubricating oil as an uncontrolled fuel source for combustion. The white smoke that the pilot saw was an indicator of lubricating oil combustion. The forensic engineer determined that the ticking sound likely was a sticking hydraulic lash adjuster, which functioned to maintain the timing of the opening and closing of the exhaust valves on the cylinder head. The engineer’s report concluded that a misfiring cylinder, with pressurized exhaust gases andcombustion productsentering the airbox, could have caused the lubricating oil in the airbox to reach a combination of pressure and temperature necessary for an explosion to occur.