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Reliability, Availability and Maintainability
3-4
Additional RB 211 Operating Statistics
The following table provides average Reliability and Availability statistics for a limited number
of RB 211 engines based on a one-year operational study. Statistical values are from sources
other than ORAP and have not been verified.
Table 3-3
Additional RB 211 Operating Statistics
Type # Number of Units Service Factor Availability % Reliability %
24 A 9 56.4 90.2 98.3
24 C 21 61.07 90.2 98.6
24 G 13 52.26 98.0 99.5
24G DLE 16 71.8 95.9 99.8
Avg. of Fleet 93.6% 99.0%
Avg. of -24G & DLE 97.0% 99.8%
RAM Assessment
The typical benchmark for mature heavy-duty and aero-derivative engines is 99% reliability,
94% availability and 95% starting reliability, on average. The Avon exceeds these minimum
expectations; however, the RB211 and Trent machines, as represented by these particular fleets
reporting to ORAP, do not meet benchmark values. Furthermore, the Trent does not meet
expectations for starting reliability. Since the Trent engines in this sample appear to be in
peaking service, starting reliability is a critical factor as well. Again, caution is advised since the
number of units in the ORAP statistical sample is relatively small, particularly for the Avon and
RB211 engines. The single year operational study data on RB211 engines shows more favorable
availability and reliability statistics, particularly for the later sub-model type G.
Conclusion
The aero-derivatives are generally classified as “under 50 MW”. The industrial Trent breaks that
barrier and is the word’s largest aero-derivative combustion turbine at 51.2 MW. The heritage of
the aero-derivatives leads to the inherent development of flexible, high power density, and highly
efficient industrial combustion turbines. By their very nature they are generally more complex
and more exotic than the frame type (heavy duty) industrial combustion turbine. The frame type
industrial combustion turbine, however, is adopting much of the aero technology to the point that
there is a similarity of the flow paths cooling schemes, coatings, and combustion technologies.
The limiting factor is not the transfer of technology but in the manufacturing of frame size
components from the aero size components.