Page 55 - CARILEC CE Industry Journal_Oct_2019

Comprehensive diesel engine analysis and monitoring
allow for the early detection of faults utilizing both
vibration and ultrasonic detection, albeit in a slightly
different manner from traditional vibration techniques.
When components in an engine degrade, their mechanical
behavior changes which can easily be detected with these
technologies when implemented correctly.

Another graph that illustrates the economic benefit of
comprehensive engine analysis as part of a condition
monitoring program is the Bathtub Curve (Fig. 6). With
Preventative Maintenance (PM) strategies in place, these Fig. 8 - Misfiring Cylinder
will only “catch” or mitigate the age-related failures which
represent 11-22 % of failures (Allen-2006). Whereas
Condition Monitoring (CM) or Advanced Engine Analysis
can be applied to identify 21% -77% of the random or
unexpected failures (Moriarty and Chauvin, 2016)
indicated in the Useful Life section of the curve. Further,
with a CM approach, post-maintenance testing is
performed to identify improper maintenance and reduce
the failures from maintenance induced maintenance.

Fig. 9 - Engine Report with dead cylinder

Further analysis of the phased vibration and ultrasonic
data identified late injection as the cause of the low
pressure.

Fig. 6 - Bathtub Curve v
A Maintenance Induced Maintenance Failure

Following a routine maintenance activity and the
subsequent surveillance runs which included the
performance of engine analysis on the Emergency Diesel
Generator (EDG). It was noted that Cylinder 12 had a
peak firing pressure approximately 500PSI lower than
the engine average, however the exhaust temperature for
cylinder 12 was above average.
Fig. 10 - Poor Cylinder

Once an inspection of the fuel pump on Cylinder 12 was
conducted, it was easily identified that the “pant leg
washer” (Fig. 11 and Fig. 12) and retaining bolt were
not properly installed which allowed the pump timing
adjustment retainer to fall off. This led to the pump
timing change, resulting in the fuel pump timing
becoming retarded. Thus, the retarded timing caused
the cylinder combustion to start very late, not reaching
even compression pressure. However, it created a
normal to slightly elevated exhaust temperature 860
Fig. 7 - Good Condition Deg. F vs the engine average of 846 deg. F.

CE INDUSTRY Journal 53