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CASE 11<br />
The Engine That Ran Away<br />
Narrative<br />
A passenger vessel carrying 151 people made<br />
heavy contact with a pier when control of one<br />
of its two engines was lost and it ‘ran away’<br />
(i.e. it suddenly increased to full speed).<br />
Although the pier and the vessel suffered<br />
significant material damage, the crew had<br />
instructed the passengers to sit down and<br />
brace themselves before the impact and none<br />
suffered serious injury.<br />
A bottom end bearing bolt on one of the<br />
engines had failed, resulting in the connecting<br />
rod and piston assembly being ejected through<br />
the side of the engine casing. The engine’s<br />
governor’s fuel control linkage was broken by<br />
the flying debris, causing the fuel racks to be<br />
set to their maximum position. The engine<br />
began to ‘run away’, despite the absence of one<br />
piston. The skipper was unable to control the<br />
vessel with the other working engine, resulting<br />
in the accident.<br />
The engine room was unmanned at the time<br />
of the accident. The first indication of trouble<br />
was the sounding of several machinery alarms<br />
in the wheelhouse. The engine speed was<br />
then seen to be rising uncontrollably. When<br />
the engineer went to the machinery space to<br />
check, he found that the engine room<br />
had filled up with smoke. He also found<br />
a piston, connecting rod and gudgeon<br />
pin of one unit on the floor plate near<br />
the engine.<br />
Due to its age, the vessel was not<br />
required to be fitted with a fire detection<br />
system and the engine’s technical<br />
manual included no instructions<br />
regarding the fatigue life of bottom end<br />
bearing bolts.<br />
Figure 1: Crankcase damage caused by<br />
connecting rod/piston assembly<br />
24<br />
MAIB Safety Digest 1/2017
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