ISA 107: Advanced Instrumentation Techniques for Gas Turbine Engines

Under the auspices of the International Society of Automation (ISA), the above Standards Committee was created to develop standards to ensure the measurement accuracy of the various parameters necessary to safely and reliably operate a gas turbine engine.

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Scope of work:

This Standards Committee will organize, provide for sufficient participation, and manage subcommittees (writing/working groups) to support the projects it selects. Initially it started with two sub-committees (working groups) to develop new standards for two sensing technologies which address critical turbine engine measurement needs, Blade Tip Timing and Thermographic Phosphors. Since then an additional sub-committee was added in October 2010 to develop Standards for Blade Tip Clearance, and another sub-committee was added in June 2011 to set Standards for Wireless Data Transmission in the Test Cell Environment. Additional future standards topics regarding gas turbine engine instrumentation will be identified by this committee as the need arises.


To organize, manage, and coordinate all ISA Standards and Practices Department activities specifically related to gas turbine engine instrumentation.

While our purpose is to prepare ISA standards, this committee will have members from multiple countries and may eventually work with international standards bodies like the IEC.

ISA107 will do much of its work electronically, but also plans to holds face-to-face meetings twice annually (in conjunction with ISA’s International Instrumentation Symposium (IIS) in the spring, and in conjunction with the Propulsion Instrumentation Working Group’s Fall Meeting. For more information on ISA107, contact Carol Cash at OAI (

ISA 107.1 Tip Timing for Use in Gas Turbine Engines


The purpose is to develop a standard for gas turbine instrumentation used to measure blade tip deflections during engine operation.


The scope is to standardize the application of tip timing instrumentation including the acquisition and data processing of tip timing data. The object of the specification is to provide common tools and agreed methods for testing different systems to the same standard.

107.2 Thermographic Phosphor Temperature Standard

Purpose and Scope

The higher temperatures of the latest engine designs require the use of Thermal Barrier Coatings (TBC) to allow the cooling air being pumped through the blades to be minimized and thereby improve the efficiency of the engine. The use of TBCs however virtually prevents the use of pyrometry to measure blade and vane temperatures, since the TBCs are approximately 4 times less emissive than metal surfaces, and about 4 times more reflective of the fireball radiation being emitted immediately upstream of the turbine in the combustor.

Thermographic Phosphors have been used in a number of other high temperature applications and hold significant potential for solving our component temperature measurement problems in the engine. Again, no measurement standards currently exist for the use of Thermographic Phosphors. Through the use of Thermographic Phosphors, temperatures can be determined from pulsed-illumination-induced fluorescence of thin phosphor coatings applied to turbine engine surfaces of interest. In a similar fashion, suitable composites of Thermographic phosphors integrated with thermal barrier coatings (TBC) can fluoresce and yield temperature and other indications of TBC health.

The basic components consist of an excitation source (usually a laser or an LED), an optical probe that provides for illumination of the coating and collection of the fluorescence, the coating and the method for applying it, a data acquisition system, and a data analysis protocol.

Standards for comparing the various approaches and defining appropriate benchmarks are needed. Standardizing the definitions of coating durability, fluorescence efficiency, temperature range, temperature sensitivity and methods for establishing these characteristics, as well as establishing, a set of standards or best practices for the other components of a system are needed. Establishing Standards for Thermographic Phosphors will be a major benefit to both aircraft and power generation engine manufacturers and to sensor vendors alike.

107.3 Non-Contact Clearance Measurement Systems for Use in Gas Turbines


The purpose is to develop a standard for gas turbine instrumentation used in the measurement of blade tip to engine casing clearance during engine running.


This specification provides guidance on the standardization of the specification and qualification testing of high bandwidth, non-contact clearance measurement systems for use in gas turbines to measure blade tip clearances at high temperatures.

The specification makes some references to the capacitive based technology. However, many parameters are generic. Future updates of this specification will include details to the other emerging technologies like optical and radar (micro-wave).

The object of the specification is to provide a common language and agreed methods for testing different systems to the same standard.

107.4 Wireless Standards for Turbine Engine Test Stands


The Subcommittee’s focus is to define scalable architectures, system components, and protocols that allow secure reliable wireless connectivity for test cell based turbine engine measurements. The subcommittee will address multi-tier wireless technologies including but not restricted to wireless mechanisms for data transmission and passive wireless sensing or technologies required for harsh environments as found in the operating power turbine test environment. The results of this Subcommittee may serve as a basis for future on-wing engine health monitoring or control systems. This subcommittee will leverage the efforts of existing committees (e.g. ISA84, ISA99, ISA100) and contribute to these committees as necessary.


The Subcommittee’s purpose is:

  • To identify where shall the wireless interfaces need to be?
  • To define the surrounding environment (inside or outside engine)
  • To identify the radio frequency (RF) environment
  • Multi-vendor interoperability support for various applications on the test stand
  • System integration support for critical and non-critical measurements
  • Common application interfaces
  • Common network management
  • Enhanced security management
  • Co-existence support
     –With other network standards
     –Other proprietary networks – not addressable

107.x Dynamic Pressure Standards for Turbine Engine Testing



This Standards Subcommittee is in the early stages of development. The purpose and scope below are open to comments and suggestions. The first meeting of this subcommittee will be held at the IIS/PIWG meeting in La Jolla, CA June 4-7, 2012. Subcommittee Chair Adam Hurst is seeking subcommittee participants and comments prior to formal application to ISA as Standard 107.5. Contact Adam at


Measuring dynamic pressures within the varying environmental conditions of gas turbines is extremely complex due to the high-level understanding of the numerous pressure sensor technologies available, fluid mechanics and data acquisition and analysis required in order to collect accurate, reproducible dynamic pressure data. Selecting the appropriate pressure transducer to measure the desired dynamic pressure complicates the matter as there are numerous pressure sensor technologies available, such as piezoresistive, piezoelectric, optical, capacitive, resonant, etc., all of which have different advantages and limitations. The purpose of the Dynamic Pressure Standards Subcommittee is to establish a standard to compare gas turbine dynamic pressure instrumentation and a set of best practices for making accurate dynamic pressure measurements within gas turbines.


  • Standardize the specifications and validation testing methods used to define the dynamic performance of the various pressure transducer technologies to improve industry wide understanding of underlying technologies and capabilities.
  • Provide an objective review of the fundamental sensor technology used in the numerous dynamic pressure transducers available.
  • Compile a set of best practices for making accurate, wide-bandwidth dynamic pressure measurements, including transducer packaging, installation, signal conditioning, data acquisition and analysis.
  • Determine common problems encountered when making dynamic pressure measurements on gas turbines and recommend design changes to overcome such industry problems.