Oil/Fuel pressure external light

[A321Flyer]

Hi Dynonavionics

In addition to the EMS D-120 I want to install a warning light for oil and fuel pressure (in case EMS is u/s I still want to be able to continue flight to an appropriate airport with sufficient engine monitoring).

The idea is to use the same VDO sensor, but take the voltage at the sensor to a simple electronic circuit with a LM311-comparator.

What is the voltage and inner resistance of the EMS D-120 for oil and fuel pressure sensor excitation?

Did anybody installed similar warning lights in his/hers aircraft?

Kind regards
Martin

 

[dynonsupport]

Your circuit would only work if the EMS was still powering the sensor. Since you are looking for redundancy, that isn't very effective. The EMS processor must be up and running before it will power sensors, so any failure of the EMS has a very high chance of not powering the sensor.

The only way to get redundant information is to install separate senders on the engine. You can't power the sensor yourself since that will mess up the EMS reading.

 

[A321Flyer]

You are absolutely right! I just didn't think about this.

Well, perhaps I will add a second sensor then...

Thx and regards
Martin

 

[PilotKris]

http://www.egauges.com/vdo_indS.asp?Sender=150PSI_10Bar&PN=360-025

VDO makes a combination Oil Press Sender/Warning Light Switch.

PilotKris

 

[uk_figs]

In my RV-7 I installed the oil pressure sender switch with circuit normally closed, this lights a master caution light on the panel. When the oil pressure is greater than 15 psi the switch changes to NO and the light goes off, the other side of the switch now controls the hobbs. In the NC side I have also wired the EMS external warning light switch which switches to ground on any warning. This combination works as follows:
1. Warning light ON when MASTER ON and engine OFF (good method to ensure the master is not left on)
2. Warning light OFF when oil pressure exceeds 15 psi (good check for oil pressure rise within 30 secs after engine start)
3. Warning light ON for low oil pressure or any other programmed EMS alert.

Simple circuit but seems to work very well (only three flights so far but with some alarms)

You have to remember also that if you do not set alarms to be self clearing (i.e you set them to be latched) then if the latched alarm goes off the light will stay lit until you reboot the EMS.
Hope this helps, I have the circuit diagram if it will help.
Dave

 

[PilotKris]

In my You have to remember also that if you do not set alarms to be self clearing (i.e you set them to be latched) then if the latched alarm goes off the light will stay lit until you reboot the EMS.
Hope this helps, I have the circuit diagram if it will help.
Dave

I do not believe that is correct. The light should go off when you acknowledge the alarm (press the ACK button on the EMS).

 

[SammyQ2]

Bob Knuckolls, at the AeroElectric Connection, has a schematic for this:
www.aeroelectric.com/PPS/Engine/Oil_Pressure/Oil_P_Warn.pdf