Category Archives: Aeronautic

THERMOCOAX Turbines Solutions Long-life Thermocouples

Thermocoax announces a new thermocouple generation :

  • 24 000 operation hours in heavy duty gas turbine
  • Exceptional resistance to vibration, thermal stress, corrosion…
  • Already demonstrated in air-cooled 446MWatt machine
  • 37 gas turbine  already equipped
  • 18 currently under operation
  • 1.2 Million hours cumulated
  • 699 starts


Technical application of long-life thermocouples

The gas turbine frames market is a challenging business. On the one hand, the frames are more and more high-tech and expensive and on the other hand, the energy producer is driven by low electricity production prices. To make them both compatible, gas turbine frames have to be reliable to minimize operation disruption and to offer longer periods without maintenance. Therefore, providing thermocouples with an increased lifespan decreases the downtime of the turbine, thereby significantly reducing the maintenance costs.

Required Benefits

One of the key aims of the OEM GT is to find high-accuracy thermocouples on the market that are able to perform in harsh environments and work for 24,000 operating hours without failing.

Thermocouples installed in exhaust gas lines are exposed to corrosion, vibration, thermal expansion and much more.

Thermocoax’s Solution: Design a thermocouple that is out of the excitation bandwidth

Based on the capitalized cumulative return of experience in several fields, such as aeronautical, nuclear and oil & gas, THERMOCOAX has developed a vibration absorber that is secured to the thermocouple to avoid premature breaking when the thermocouple is subject to vibrations and thermal expansion. This solution is protected by a patent.

The invention with the patent number 63638FR/CZ/BB – 17 58061 is a vibration absorber that is secured to the thermocouple cable and is made to fit inside the screen/thermowell.

The number and size of the absorbers depend on the gas turbine specification in terms of vibration, acceleration and thermal cycles.

To demonstrate the advantage of this new design and its ability to reach 24,000 operating hours, THERMOCOAX has undertaken simulation and experimental testing:

1.1 Simulation: Comparison between a thermocouple with and without a vibration absorber

Input data:

  • Ø ≈ 3mm Type K thermocouple with 316L SS sheath
  • Length ≈ 500mm insertion length in SS316L thermowell
  • Temperature 870°C
  • Frequency range: 0 to 250Hz, mean value 100Hz
Long-Life TC Standard TC
Resonant Frequency of the TC 174Hz 68 Hz
Stress produced by the Resonant Frequency of the TC 11.1MPa 450MPa
Number of cycles made before Breaking of TC at its Resonant Frequency 9×109 40
Life-span at the Resonant Frequency of the TC 2.1×109 days 10 days

1.2) Field test results: Comparison between a thermocouple with and without a vibration absorber

  • Ø ≈ 3mm Type K thermocouple with 316L SS sheath
  • Length ≈ 300mm insertion length in SS316L thermowell
  • Temperature 900°C
  • Frequency range: 0 to 1000Hz,
Long-Life TC Standard TC
Resonant Frequency of the TC 68Hz 174Hz
Life-span during the Endurance Test Still works after


Stops working before 3000h


The test is still ongoing. We can already say that the field results demonstrate the extraordinary positive impact on the reliability of the gas turbine. This new long-life thermocouple lasts 7 times as long as a standard thermocouple.

For the powerplant operator, the cost saving is at least 150,000 euros in thermocouples for every 20,000 hours of operation because there are no costs incurred from the frame shutting for unexpected maintenance.



For 60 years THERMOCOAX has been a worldwide key player in designing, developing and manufacturing thermocouple temperature sensors for industrial and aircraft gas engines.

With our custom-made Mineral Insulated Cable, we are providing our customers with solutions for:

  • Development applications:
    • R&D programs with institutes
    • Ground, aero & industrial test equipment
  • Production models:
    • Thermocouples in harsh environments with an installed base of over 300,000 thermocouples:
      • Heavy duty gas turbine
      • Stroke engine
      • Steam turbine
    • Thermocouples for helicopter engines with 15,000 units installed
  • Thermocouple characteristics:

Thermocouples are produced with Class 1 custom-made cables with a diameter from 0.25mm up to 6mm.

Single (2 wires) or duplex design (4 wires)
Types K and N are the most used in the industry.

Thermocoax recommends type N thermocouples for a working temperature of between 600°C and 1100°C, which offer a smaller drift compared to type K.

We have several sheath alloys available:

  • Stainless Steel
  • Inconel
  • Haynes
  • Platinum
  • Tantalum



THERMOCOAX Calibration Lab

100% of the mineral insulated cable and finished thermocouples are controlled in the calibration lab.

  • Capabilities

Fixed points

TEMPERATURE -Thermocouple
Calibration purpose Mesurand Measurement range Best calibration uncertainty Measurement principle/Method reference (*) Calibration tools (reference, Equipement) Activities in Lab and/or on site
Thermoelectric couple Temperature                                                                              Electromotive Force Signal Voltage Melting ice point 0,00°C ±0,3°C Method by comparaison at a fixed point / PP200D010 Rev06 Water triple, Sn, Pb, Zn cells Platinum resistance thermometer multimeter                                                  Melting ice point Lab
Water Triple point 0,01°C ±0,3°C
Sn Melting point 231,928°C ±0,5°C
Pb melting point 327,46°C ±0,5°C
Zn melting point 419,46°C ±0,5°C
Sb freezing point 630,62°C ±0,9°C Sb Cells                                              Thermoelectric couple S Type Multimeter                                              Melting ice point


By comparison

TEMPERATURE -Thermocouple
Calibration purpose Mesurand Measurement range Best calibration uncertainty Measurement principle/Method reference (*) Calibration tools (reference, Equipement) Activities in Lab and/or on site
Thermoelectric couple Temperature                                                                                                                                                                        Electromotive Force Signal Voltage -40°C to 0°C ±0,4°C Method by comparison / PP200D022 rev 08 Ethylene/Glycol constant temperature bath                           Platinum resistance thermometer Multimeter                                     Melting ice point Lab
0°C to 80°C ±0,3°C
50°C to 200°C ±0,4°C Oil Constant temperature bath Platinum resistance thermometer Multimeter                                                 Melting ice point
150°C to 400°C ±0,5°C Bath of melted salts Platinum resistance thermometer multimeter
400°C to 500°C ±0,6°C
500°C to 700°C ±1,3°C Tubular furnace                                    S type thermoelectric couple Multimeter                                             Melting ice point
700°C to 1100°C ±1,4°C
1100°C to 1200°C ±1,6°C
1200°C to 1300°C ±2,1°C
1300°C to 1500°C ±2,4°C


THERMOCOAX has reached a major milestone this year. The company is celebrating its 60th anniversary.

60 years of service to our customers, 60 years of innovation in the nuclear, aerospace, semicon, and industrial markets meeting the expectations of these sectors through their constantly evolving applications.

To celebrate this event, the teams undertook the crossing of the bay of Mont Saint-Michel last month.  Braving the cold, the mud, and the rivers (sometimes full), we managed to chase the clouds and together we reached the finish line of this jewel of architecture, The Mont Saint-Michel, also called the “Wonder of the West”.  It was a very beautiful day revealing the mutual effort, team spirit, strong human values of THERMOCOAX.




THERMOCOAX Aeronautic Products : Grey Water Drain Mast Equipped with Electrical Anti-Icing System

Thermocoax Pedigree

THERMOCOAX is a worldwide key player and has been designing, developing and manufacturing heating solutions for aeronautic market for 20 years.

Based on the 60 years homemade Mineral Insulated Cable, we provide our customers with solutions for:

  • Ground applications:
    • R&D programs with institutes
    • Ground aero test equipment
  • Flying models:
    • Anti-icing system for pitot tube, Angle of Attack, Total Air Temperature Sensor
    • Wire Cutter (WSPS) on helicopter equipped with electrical anti-icing devices.
    • Anti-icing screen for helicopter engine air inlet.
  • Specific Application:
    • Shower Heating system for VIP business Jet


Technical Application of Grey water drain mast

To save weight, the grey water from the washbasins is ejected to the outside of the plane.

Function of the configuration, most planes are equipped with two drain masts, one at the front and one at the rear where the washbasins are.

Drains are fixed at the bottom of the fuselage exposed to the outside air.

The major risk with a drain mast is the production of ice at the tip and risking a potential impact with the fuselage or it getting sucked into the engines.


Technical Description of Drain Mast Anti-Icing

In accordance with the specification, the drain is equipped with one or two water pipes.

The shell is made using the resin-moulded method.

For optimal efficiency of the anti-icing system, THERMOCOAX technology warms up the water pipes instead of the shell.

Heating cable technology available:

  • Self-regulated cable
  • Or fixed power cable coupled with switches
  • Inconel or nickel sheath cable
  • Ø 5 up to 3mm
  • Power supply 28 or 115Vac 400hz
  • Dissipated power from 20 to 250 Watts
  • Pipe Temperature up to >40°C at -55°C environmental conditions

Each heating cable is produced with cold ends.

The cable is then wrapped onto the tube.

The cable is flexible enough to increase the volume of cable and get more heat for areas exposed to coldest conditions.

Cable is brazed on the tube for:

  • Conduction pipe/heater for more thermal efficiency
  • Robustness
  • Reliability
  • Longevity
  • Production repeatability



Thermocoax Drain Mast Final Assembly

Drain masts are developed, produced and checked in Thermocoax facilities

Acceptance Test Criteria of Drain Masts:

  • Dimensional
  • Weight
  • Line resistance
  • Insulated resistance under 500Vcc
  • Dielectric 1mn 1500Vac


Test for Qualification Program of Drain Mast

THERMOCOAX conducts the qualification test program in accordance with our customers’ specifications.

Our engineers write the QTP for customer approval prior to running the tests.

Most of the tests (thermal, humidity, electrical etc.) on the drain mast are performed in THERMOCOAX’s test lab facilities.

These require heavy equipment (vibration, acceleration, impact etc.) and are sub-contracted to external laboratories or provided by our customers with the complete water system.

-Typical Qualification Test Schedule for Drain Mast

  • Vibration
  • Acceleration
  • Impact & Crash Safety
  • Vibration
  • Pyrotechnic Shock
  • Load Test
  • Temperature & Altitude
  • Temperature Variation
  • Explosive Atmosphere
  • Waterproofing
  • Sun & Dust
  • Fluid Susceptibility
  • Salt
  • Audio, induced signal, radio frequency
  • Lightning
  • Icing
  • Fire and Flammability
  • Combined Temperature, Altitude, Humidity
  • Dielectric Test
  • Corrosion
  • Engine Blade Out
  • X-Ray Examination
  • Thermal Cycling Test



Lightning test


THERMOCOAX supplies the following platforms:

  • Dassault Falcon Jet
  • Bombardier C Series
  • Embraer EJet 1 & 2


THERMOCOAX is a key player for anti-icing systems on board aircraft platforms and is proud to participate in challenging international aero programs.

THERMOCOAX focuses on high quality heating products for the best stability and repeatability in operation. For 15 years, we have witnessed the challenges faced by our customers to manufacture aircraft and to improve the safety and comfort of passengers.


New large programs are taking shape, THERMOCOAX is ready for production ramp up and supporting the market with cost-effective drain masts.

THERMOCOAX Aeronautic Products : Carbon Brake Temperature Monitoring & Aircraft Brake Monitoring System

Thermocoax Pedigree :

THERMOCOAX has been a worldwide key player for 20 years in designing, developing and manufacturing with thermocouple sensors for the aeronautical market.
Based on the 60 years Mineral Insulated Cable produced in-house, we are providing our customers with solutions for:
– Ground applications:
 R&D programs with institutes
 Ground aero test equipment

– Flying models:
 Thermocouples and RTDs for air cabin management system.
 Thermocouples for helicopter engines with 15 000 units installed
 Alternator Bearing temperature measurement on twin aisle and double deck platforms

– Scientific tasks:
 Skin temperature on supersonic frame
 Engine Space launcher



Technical Applications of the Brake Temperature Sensor :

New technologies are rapidly developing and the brake industry is working hard to make aircraft operations safer and offer passengers more comfortable travelling conditions.

A new generation of brakes has been installed on modern aircraft. Carbon brakes developed by key brake manufacturers is the result of a long and costly program of investment in research and development.

The new carbon disk generation provides more power braking during landing but also during braking in an emergency.

Firstly, the brake thermocouple gives the brake temperature in real time and can be transformed in a “hot brake” alert to the pilot when the value goes over a predetermined temperature threshold.

It gives valuable information to the cockpit on the temperature of the right and left brakes. If these differ too much, an asymmetric friction on the brakes can cause difficulties when maintaining heading and keeping speed under control.

Thanks to this system, the pilot receives a “Go/No Go” clear message for takeoff authorization. The brake thermocouple indicates that in case of a braking emergency event during takeoff, the brake will have his full capacity to stop the aircraft on time for the safety of all passengers.

Secondly, during takeoff in hot climates, this temperature monitoring avoids a too early landing gear retraction. This avoids a risk of tyre explosion in the wheel compartment.

The brake thermocouple is now a key piece of equipment that airlines use to reduce turnaround times (TAT) in short-haul operations to around 30 minutes.


This new generation of carbon brakes replaces the old metallic brake.

Each brake manufacturer develops their own carbon technology. Specialists agreed to give carbon technology products a longer life, more braking cycles and much higher efficiency of braking especially for heavy airliners.

But carbon brake technology produces high amounts of heat energy during braking and the temperature can get very hot if the dissipation of kinetic energy is not optimum. This temperature rises to nearly 1000°C during normal braking. In case of emergency braking at full power during takeoff at full weight, the friction off the carbon disks is so powerful that the energy produced causes the temperature to rise to 2000°C.

Temperature monitoring is implemented on every aircraft platform, commercial and military. One thermocouple per brake/wheel is the rule. A typical single-aisle aircraft is equipped with 4 thermocouples, a twin-aisle aircraft 8 to 12 thermocouples, double-deck aircraft 16 thermocouples and military fighter 2.

This is an opportunity for THERMOCOAX to contribute to this program and improve the safety of the airframe and passengers every day around the world.


Technical description of brake thermocouple

When measured at nominal temperature, the thermocouple typically has the following properties:

  • K type thermocouple
  • Single-circuit, 2 wires


  • Class 1 in accordance with IEC and ASME
  • Ceramic insulator
  • Dielectric under 500V
  • Insulation resistance:
    • 1011Ω.m at room °T
    • 107 Ω.m at 600°C
  • Inconel 600 sheath
  • Ø 2.5 to 4.75mm
  • Hermetic connector EN2997
  • Hermetic connector D38999
  • 2 compensated pins


  • Oval base or mesh for easy removal from the torque tube when replacing


  • Mass: <100g
  • Environmental and safety of flight tests
  • Impact: RTCA/DO160 Sect 7 cat B, D
    • Cat B
    • Cat D
  • Vibration: RTCA/DO160 Sect 8
    • Cat R curve W
    • Cat T curve E
    • 2000 hz, 200G


  • HALT Tests


Acceptance Test Criteria of the Brake Thermocouple :

  • Temperature calibration
  • Helium leak test
  • XRay by sampling
  • Time constant
  • Visual and mechanical inspection
  • Overvoltage
  • Line resistance
  • Polarity
  • Insulation resistance
  • Dielectric 500Vac, 60Hz/60s
  • Mass
  • Final manufacturing report


Packaging and Cleanliness :

THERMOCOAX focuses on high quality Brake thermocouple products for the best stability and repeatability while in operation.

We understand our customers’ challenges to manufacturing braking systems and to make the aeronautical industry reliable and the millions of passengers safer.

At THERMOCOAX, we are working hard to contribute to these incredibly challenging programs.

THERMOCOAX has supplied many commercial programs and military platforms.

THERMOCOAX designs, develops, qualifies and produces in accordance with aircraft specifications such as :

  • Airbus 350
  • Embraer EJet
  • Mitsubishi Regional Jet
  • Irkut MC21
  • Sukhoi Super Jet100
  • COMAC C919


THERMOCOAX is the major player for brake thermocouples and is a proud contributor to great aeronautic programs.



Thermocoax joins in Europe’s NIPSE project which targets the novel integration of system equipment on next-generation aircraft engines

Press Release    logo NIPSE



26 November, 2015

The challenges of equipment integration on future aircraft engines – particularly next-generation Ultra-High Bypass Ratio (UHBR) powerplants – is the focus of a three-year European Union-funded technology project now underway with 10 companies and organisations.

Called nipse (Novel Integration of Powerplant System Equipment), this programme addresses installation limitations expected in such future engines, including the thinner nacelles and larger fan modules ; along with architectures that require more functionality and provide extra thermal constraints through lower ventilation capability and reduced volume availability.

In this context, the NIPSE project seeks to find better placement options for equipment, using locations in the engine, the nacelle and the aircraft itself. NIPSE also addresses the need to improve thermal management of integrated powerplant systems (IPPS).

NIPSE is targeting potential engine fuel savings of up to 2-3 percent, gained through a 15-percent reduction of equipment volume for the UHBR engine, along with weight savings and improved thermal management on the more integrated powerplant systems. Additionally, a reduction of development time for the installation of powerplant systems is anticipated.

We, THERMOCOAX, participates to improve fire detection technology and the implementation of these sensors on the engine or nacelle.

Established within the European Commission’s Horizon 2020 Programme, NIPSE is funded at 6.2 million euros and has a three-year duration from its formal kickoff last June. It is managed by the Commission’s INEA (Innovation and Networks Executive Agency), with Aircelle (Safran) as the programme leader in its role as industrial coordinator.

Contact :

Iain Minton, NIPSE project coordinator

The NIPSE consortium :

Safran Aircelle (France) ; ARTTIC (France) ; Thermocoax SAS (France) ; Stichting Nationaal Lucht- En Ruimtevaartlaboratorium (The Netherlands) ; Compañía Española De Sistemas Aeronáuticos (Spain) ; BAE Systems (Operations) Limited (UK) ; Meggitt Aerospace Ltd. (UK) ; Safran Snecma (France) ; Safran Labinal Power Systems (France), Archimedes Center for Innovation and Creation (Greece).


This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 636218


THERMOCOAX Aircraft Products – Bleed Air Leak Detector – NEGACOAX©


The THERMOCOAX Bleed Air detector is designed to detect leaks in an aircraft’s pneumatic duct system by sensing the temperature of the overheated air surrounding the leaking duct.

The NEGACOAX technology gives the location of the overheat condition, annunciates the overheat to the aircraft’s crew warning system.

The NEGACOAX consists in a homemade Mineral Insulated Cable, doped with eutectic salts. When the NEGACOAX detects an overheat (air leakage) the cable Impedance value will drop down and the capacitance value will increase very fast.

03-08-2015 16-37-35

Example of curve with NEGACOAX NG124 :

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The THERMOCOAX’s current technology uses the Binary compound within Eutectic as described below, in others words, liquidus and solidus will melt entirely at the same temperature.

This specificity gives the high accuracy of this technology :

03-08-2015 14-16-09

Insulated Cable homemade manufacturing, this technology offers a high reliability and nearly no maintenance.

The maximum length of each NEGACOAX detector is 5 meters. We have no length limitation regarding the number of detector connected together to make a complete loop.

THERMOCOAX’s NEGACOAX detectors are typically installed at heat critical points throughout the aircraft structure. Typically, these are located in the wings, engine pylon, fuselage, empennage and tail cone (APU compartment).

This technology can be applied to military, commercial transport and general aviation aircraft.

The electronic control system associated will get 2 separated electrical parameters :

  • Impedance

03-08-2015 14-48-03


  • Capacitance

03-08-2015 14-47-00

By connecting both ends of the NEGACOAX loop with the electronic system, the leakage location can be determined by current ratio.


NEGACOAX Detector Characteristics

  • Nickel Sheath
  • Insulant: Al2O3 + eutectic salts
  • Constantan conductor
  • Line resistance at 20°C: 2,15±0,05Ω/m
  • Diameter Ø2,2mm +0,2/-0,4
  • Length L<300cm ±6mm
  • Length 300cm<L<460cm +19/-0
  • Max detector Length 460cm
  • Mass=25gr+(27*L)gr with L= length in meter
  • Service Life: 20 years
  • MIL and RTDO 160 standard
  • 100 000 Flight hours
  • MTBF > 300*106 hours
  • FMEA 1.954*10-7 Failures/FH



03-08-2015 15-45-58

NEGACOAX Product Ranges :

  • NG124
  • NG154
  • NG180
  • NG204
  • NG215
  • NG232

Thermocoax has a large experience on aircraft platform with :

  • McDonnel Douglas MD90
  • Airbus A340
  • Dassault Falcon F5X
  • Embraer KC390
  • Bombardier Global Express
  • Airbus Helicopter


Thermocoax supplies a large range of accessories to fix the detectors on the aircraft structures

Mechanical System for :

1 or 2 loops :

303 925    303 925 (3)

Electronic System

NEGACOAX is compatible with any electronic system with the following characteristic :


Thermocoax is working in partnership with aircraft industry electronic specialist.


06-10-2015 17-05-06


Test Loop

Thermocoax offers as option an upgrade of the detector with integrated shunt resistor in the connector. This shunt (>30KΩ) is connected between the core and the sheath.


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