Engine Oil – Indicating System


vị trí : nằm trên đường vào Scavenge Filter và phía trước Master Chip Detector.

The scavenge oil temperature thermocouple is located in the combined scavenge line between the master magnetic chip detector and the scavenge filter for indication in the cockpit.The oil temperature is sensed by a dual resistor unit. Temperature measurement range:– 60 deg. C to 250 deg. C.

Thermocouple->analog signal->EIU->convert into digital signal->FWCs and DMC send it to lower ECAM.

the oil temperature indication :

+ green khi T<156 Độ C

+flashes green khi T>=156 Độ C.

+Amber khi T>165 Độ C

Warning Message : ENG 1(2) OIL HI TEMP xuất hiện khi T>156 trong vòng 15 phút hoặc T>165.

Có nghĩa là chỉ thị temperature có thể đang flash green vẫn có thể xuất hiện meassage trên.


The oil pressure transmitter is connected to the engine oil system by two steel tube. One tube connects to the oil supply tube (to the engine and gearbox bearings). The other tube connects to the No. 4 bearing oil scavenge tube (to the oil scavenge pump).

The 28VDC supply goes through the electromagnetic interference (EMI) filter to the DC/DC converter which changes the voltage to 15VDC. This decreased voltage goes to the strain gauge and amplifier regulator. In the strain gauge, the voltage causes an excitation of the circuit.Each diaphragm moves by oil pressure from the inlet port. As the diaphragm moves it changes the condition of the attached strain gauge.This causes a change in the associated excitation voltage. Thus the voltage is in proportion to the oil pressure at the diaphragm.The excitation voltage goes from the strain gauge to the amplifier regulator. The amplifier increases the voltage to between 0 and 9VDC (changes as the oil pressure changes). This is the output signal voltage which goes through the EMI filter to the cockpit.The signal voltage of 0 to 9VDC gives a pressure range of between 0 and 400 psi (2720 kPa).


 The low oil pressure switch is connected between the oil supply tube and the No. 4 bearing scavenge tube. Actuation of the low pressure switch is at 60 psid decreasing pressure.The set point range is between 45 psi and 75 psi.

When the oil pressure drops below 60 psid plus or minus 1 psid (decreasing) the low oil pressure switch closes. As a result of this:

-The red MASTER WARN light located on the glareshield comes on.

-The audio warning is activated.

-The ENG page appears on the lower ECAM display unit:The oil pressure indication flashes red.

-These warning messages appear on the upper ECAM display unit:




The scavenge filter differential pressure switch is set to operate when the differential pressure increases and gets to 12 psi plus or minus 2 psi

When the differential pressure through the scavenge filter is higher than 12 psi plus or minus 2 psi, the switch closes.As a result:

  • On the ENG page on the lower ECAM display unit:The amber OIL FILTER CLOG indication appears.
  • On the upper ECAM display unit:The warning message ENG 1(2) OIL FILTER CLOG appears.

Tổng kết có các switch và transmitter như sau :

  • scavenge oil temperature thermocouple.
  • oil pressure transmitter.
  • low oil pressure switch.
  • scavenge filter differential pressure switch.
  • No.4 Bearing Compartment Pressure Transmitter.

Sự khác nhau giữa switch và transmitter :

Pressure Switches

A pressure switch is an active electromechanical device which measures the pressure in a system and when the pressure reaches too high or too low of a given set point, the device will “switch” meaning it will open or close a circuit that powers a certain device (like an alarm system or a shutdown valve).

A pressure transmitter or pressure transducer, is also an electromechanical device which measures pressure but instead of signaling a switch, it merely sends a read-out signal of what the specific pressure value is to a remote location.

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