Rolls-Royce 1004227 - Manual (Page 44)

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Reliability, Availability and Maintainability
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RAM Statistics: Avon, RB211 and Trent - All Duties
Data from the Operational Reliability Analysis Program (ORAP) was utilized to provide
statistics on Rolls-Royce engines. The following table summarizes the characteristics for the
Rolls-Royce fleet as represented by the units reporting to ORAP. The statistics are for all units
reporting that meet SPS criteria for inclusion in the database for a particular year. As such, they
are a subset of Rolls-Royce entire operating fleet. 2005 is the first year in which Rolls-Royce
data is available in ORAP; therefore trending over time is not available.
Table 3-1
RAM Statistics: Fleet Characteristics for Avon, RB211, and Trent
Avon RB211 Trent
Time Period 1 Year: 2005 1 Year: 2005 2 Years: 2004, 2005
No. of Units 6 10 4, 8
Unit-Years 4.2 8.1 11.1
Period Hours 36,790 70,960 97,240
Fired Hours 29,700 45,250 18,860
Service Factor 81% 64% 19%
Units that report for less than 100% of the time period result in partial unit-year data. Units
reporting less than 70% of a calendar year are typically excluded from the data set. Note that
this data set represents a limited sampling of engines in each model type and therefore the RAM
statistics may not accurately represent the larger fleet.
The following table summarizes the combined duty RAM statistics for the Rolls-Royce fleet
reporting to ORAP.