Availability: Another critical factor that can lead operators and service providers to opt for an REP is that the OEM part(s) simply may not be readily available. Legacy gas turbines are problematic for sourcing new OEM components. Over time, the supply-chain (vendors and sub-contractors) may change hands, may go out of business, or even misplace tooling). OEM’s stock lower levels of inventory for legacy turbines. The result is that OEM parts may become very difficult to source (sometimes impossible) or the lead-time to deliver a part may not support customer demand. Suppliers of REPs are often relied upon in the market to fill this “availability” gap. Another dynamic that may be an “availability” issue is that often OEM’s have a policy they will only sell parts to “authorized service providers” or to the gas turbine owner/operators. Or the OEM may have a discount policy on parts that put a non-authorized service provider at a disadvantage. These policies in effect create an “availability” gap, which may encourage the use of REPs.

Independent REPs. Several companies offer GE and Siemens “F-Class” REP parts. Photo Courtesy of Chromalloy.

Proven REPs. Score Energy has been providing proven REPs, both as direct replacements and upgrades for the Rolls-Royce Avon

and the TB5000. Photo Courtesy of Score Energy Ltd.

Component performance: A major factor in
considering OEM versus REPs as a part of your
maintenance program is the expected performance
of the components under consideration. In this
context performance considerations include
output, efficiency and life expectancy.


As we have said, REPs are designed as “form, fit,
and functional” equivalents to the OEM. However,
when choosing the REP option, it is very important
to gain a full understanding of the history of the
REP manufacturer, their track record of success

and failure, and experience on a particular part
number. One should ask for customer references,
information on how many engines the REP has
been used on, and an estimate of the running
hours experienced on the REP.


Other considerations: To address the challenge of
REP parts in the marketplace, OEMs may deny the gas turbine operator technical support subsequent to an REP being installed in a gas turbine. The OEM may consider the use of REPs as evidence of misuse and affecting any future warranty claims. These factors are mitigated for legacy gas turbines, leading to increased use of REP components on older units. Another key consideration is that it may be necessary for the operator to discuss the use of REPs with the insurer of the target equipment.

It is not necessarily normal procedure, but some insurers may deny coverage when a non-OEM component is utilized. Many operators are self-insured.















Components and GTs utilizing REPs

While thousands of individual parts make up a gas turbine and gas turbine package, not all will need to be replaced. Many components such as fuel metering valves, actuators, pumps, casings, and others may never need to be replaced, but there are recommended maintenance practices for them. Clearly, most rotating components and all hot-section components must be replaced.


OEMs have the burden (but also the opportunity) of providing a full suite of replacement parts for the gas turbines they produce, both the highly infrequent replaceable components and the frequent. Independent/3rd party service companies almost always focus their REP development on the frequently replaced components.


Gas Turbine World

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Southport, CT 06890  USA


Telephone: 203.259.1812


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