Fluid level sensors for aerospace

Wide range of fluid gauging systems for aero engines and aerospace fluid systems.

Helping to reduce system maintenance costs

Decades of in-service experience with both float/reed switches, capacitance probes and our state-of-the-art Time Domain Reflectometry (TDR) system. Meggitt's aerospace fluid sensors provide accurate and reliable fluid readings.

The sensors are installed in the fuel or hydraulic fluid reservoirs or inside the gearbox. We also design and manufacture the signal conditioners that can interface with any avionics requirement.

Features and benefits of our Time Domain Reflectometry (TDR) system

  • Improved accuracy

    Our latest breakthrough TDR sensor utilises RF-based technology to measure fluid level with a 2.5 mm (0.1”) accuracy.

  • No need for calibration (or re-calibrations) after installation or replacement.

    The TDR is not sensitive to capacitance of interconnects (In comparison, capacitive probes are very sensitive to cable/connector capacitance and their variations including ageing).

  • Technologically advanced, field-proven and mature system.

    Greater reliability over capacitive or float-type probes (i.e. reed switch based).

  • Lower maintenance costs and enhanced dispatch reliability.

    The TDR has a high degree of diagnosis and fault detection (Enhanced BIT) beyond what can be achieved with magnetic (reed) or capacitive probes (i.e. detection of interconnect faults). The TDR signal conditioners use Power up (PBIT) and Continuous (CBIT) built-in tests.

  • More accurate than capacitive sensors.

    The TDR directly senses the surface of the fluid (whereas capacitive probes measure capcitance to indicate fluid level). This gives a fixed 0.38 cm (0.15″) accuracy giving an advantage in deeper tanks, allowing for more “usable fuel”.

  • Measures lower fluid levels than capacitive probes.

    A TDR-based system allows for more usable fuel, as it measures near-empty conditions more accurately. (TDR probes are not sensitive to variations of dielectric constant, but capacitive probes depend on accurate dielectric constant measurement to provide accuracy)

  • Smaller diameter and lighter probes

  • Easily measure free water.

    By adding some additional firmware, you can also measure free water at the bottom of the fuel tank (no extra hardware needed).

  • Save money on aftermarket spares.

    Our TDR system is insensitive to fluid type. In comparison capacitive probes require accurate internal dimensions and a reference capacitor.

More information on TDR sensors

Applications for fluid level sensors

Our fluid level sensors are trusted by aerospace OEMs around the world including Bell, Beechcraft, Boeing, Cessna, CFMI, GE, Lockheed Martin, Pratt & Whitney, Sikorsky and Rolls Royce. They are used on commercial and military, fixed wing or rotary wing aircraft for:

  • Fuel systems measurement
  • Engine lube oil measurement

How does a float/reed switch work?

The magnetic float passes a reed-switch ladder.

When the switch is closed, it indicates the fluid level and sends a signal to either the avionics or a dedicated gauge.

  • Our float/reed switches are not affected by changes in the fluid property and can tolerate temperatures up to 232 C/450 F making them ideal for engine lube applications.

How does a capacitance probe work?

The sensor consists of two metal tubes inside a housing.

As the fluid level changes, the capacitance between the two metal tubes varies and sends a signal to either the avionics or a dedicated gauge.

At Meggitt, we can provide you with a fluid sensor that is specific to your aerospace application and can be further customised to your particular requirements. To discuss what you need in more detail, contact us.