Jet engines were incorporated in commercial aviation back in the late 1940´s, when the de Havilland Comet airliner entered service powered by two jet engines. Since then, jet engines have followed a sustained evolution, increasing in size, thrust, reliability and performance.
Briefly described, a typical jet engine is composed of 5 main components: the fan compressor (including low- and high-pressure stages), combustor (or combustion chamber), turbine (high- and low-pressure stages), and exhaust nozzle. The external air enters the engine through the engine inlet, the air is highly compressed in the compressor section, and it is then forced into the combustion chamber, where the compressed air is mixed with fuel and ignited. As a result of this combustion, the mass of air is heated immediately, increasing it temperature and pressure even more. The high-temperature, high-pressure mass of air is now forced into the turbine stages and makes the turbine wheels turn (causing for example a propeller to move) and is leaves the engine through the engine nozzle (providing thrust that will impulse the aircraft flight).
A key factor to obtain the most out of this process is the turbine temperature, as it is a representative of the energy available to be transformed into movement. However, the turbine temperature is limited by several factors, beginning with the capability of the material of the chamber, the turbine, and the exhaust nozzle to withstand remarkably high temperatures before degrading or even melting.
Therefore, engine manufacturers develop their designs with special attention to the turbine temperature operating value and critical limits, to get the maximum possible performance out of the engine, and at the same time guaranteeing it will work safely if it is operated within limits and maintained according to manuals and standards.
The turbine temperature of an engine is monitored by an arrangement of temperature sensors installed on the engine. The temperature sensors are normally thermocouples that transform the temperature they sense into electrical voltage, normally in the range of millivolts. This electrical voltage is then transmitted through transductors to the cockpit to show the temperature value on a display for pilot information
Turbine temperature test equipment allows the maintenance personal to verify the condition of the temperature sensor (thermocouple) and determine how accurate the reading of the temperature is in the cockpit compared with the temperature in the turbine.
To do so, the test equipment measures the resistance and isolation of the thermocouple and verifies the indication system response by simulating the thermocouple output (electrical voltage) and comparing the indication on the cockpit display or instrument with the test equipment simulated temperature.
Nowadays, turbine temperature test equipment is engineered to reduce human workload during maintenance activity, and therefore the maintenance personnel rely and depend on the good condition of the test equipment to assure the safety of the aircraft, meaning this that the test equipment must be operative and calibrated.
The calibration of test equipment is not only recommended status of the equipment, but also a mandatory rule according to aviation regulations.
For example, FAR 145.109 indicates: “(b) A certificated repair station must ensure all test and inspection equipment and tools used to make airworthiness determinations on articles are calibrated to a standard acceptable to the FAA.”
The manufacturer of test equipment also recommends the periodic calibration of the test equipment. Typically, a one-year certification is indicated in the test equipment manual.
This precise and key calibration must be performed at a certified and accredited calibration laboratory that will be able to perform the test according to the highest standards, provide the calibration records and certificates that meet the aviation authority requirements, and transmit confidence to the aircraft maintenance organization and aircraft operators.
At e2b calibration, our laboratory provides calibration services for a variety of turbine temperature test equipment, including Barfield TT1000, Barfield TT-1200, Barfield 2312G-8.
e2b calibration is an ISO/IEC 17025:2017 accredited laboratory, ANSI/NCSL Z540-1-1994 certified and registered with ANAB. Please contact e2b calibration with your test equipment calibration requirements and we will provide you an immediate response.