Remote Oil Level Sensing (ROLS)

ROLS:  FCI Solution for Remote Oil or Liquid Level Sensing

The presence or absence of oil in a gearbox sump of the lubricating system of Auxiliary Power Units (APU), is critical to know, preflight and in the air for optimum operation as well as routine scheduled maintenance. Low lubrication level can cause parts to seize and result in system failure. Using a sight glass may not be an option. FCI’s liquid level sensor works like an “electronic dipstick” to provide data that allows for the wet/dry notification of key oil-wetted components, such as gears, bearings, and seals, well before a run dry condition occurs and without unnecessary teardown inspection. APU oil level is measured using a Remote Oil Level Sensor (ROLS) which is located in the APU oil tank that provides level indication to the interface.  The sensor sends an input to the aircraft FADEC for low and high oil level and temperature protection. When oil indication increases to a high, or drops below a low, predetermined value for a preset number of seconds, the entire APU (on ground only) can be programmed to shut down automatically. Electrical failure of this sensor can be detected during a BIT check. The level indication will change to annunciate an Oil Low message when the APU has not been operating for 10 minutes and/or level drops below the expected rate.  

Illustration of AS-LLE liquid level element measuring tank levels

Key Criteria For Remote Level Sensor Selection

  • Precision point level measurement, right where you want it
  • Dual function, measures both level and temperature
  • Flight proven on over 40,000 units
  • Ultra small and light weight design ≤ 1.6 oz [45 grams]
  • Rugged, corrosion resistent titanium wetted parts
  • Temperature service -67°F to 400°F [-55°C to 205°C] RTCA/DO-160
  • Qualified for fluid compatibility, temp cycling, vibration and endurance testing
  • mA output signal customized to actual fluid and operating conditions
  • ISO9001 and AS9100 certified quality system standards

The AS-LLE is an easy to install, hermetically sealed, safe, liquid level indicator that delivers lowest life of acquisition costs for truly demanding airframe mounted solutions. Aerospace Engineers will find the AS-LLE series provides optimal, highly repeatable indication and performance in hard to reach liquid level applications, including all the necessary features required for accuracy and reliability in critical liquid level applications.

To learn more, contact an application expert or request a quote from FCI Aerospace today.