Engine Management Alarm Settings

[ChuckGant]

Hello all,
I am trying to minimize the number of nusacence alarms I get with my GRT EIS4000 set-up, so I was wondering what values are common for:
EGT
CHT
Cylinder Head cooling rate
Max fuel flow
Max fuel pressure

Thanks,
Chuck

[Kwright]

Your settings depend on engine and fuel system. However, in general there is not a max for EGT. MAX for CHT is generally 400 degrees because of the physical property of aluminum losing 50% of its strength at that tempeture.

[Kyle Boatright]

Originally Posted by ChuckGant

Hello all,
I am trying to minimize the number of nusacence alarms I get with my GRT EIS4000 set-up, so I was wondering what values are common for:
EGT
CHT
Cylinder Head cooling rate
Max fuel flow
Max fuel pressure

Thanks,
Chuck

The fuel related settings are be determined by your engine choice - engine size determines flow, injected or carbureted determines pressure.

EGT is a relative measurement that I use for information, not warnings. Mine is set such that I am unlikely to get a warning.

CHT, I would use Lycoming's red line if I was in flight test, and would lower the setting later once you have a handle on your engine's behavior. I think my CHT warning is set at 425, which is far below Lycoming's red line.

I do not have a warning enabled (or I have the parameters set very loose) for cylinder cooling rate. Given that I treat my engine pretty well, if I'm ever doing a rapid power off descent, I'm doing it for a reason and don't need a flashing light to distract me.

My personal philosophy is that I don't want to be warned (distracted) by blinking lights and buzzers until something is a problem. My scan will (hopefully) identify looming problems in time to manage the problem(s). Other philosophies are viable too...

[az_gila]

More reading here -

http://www.vansairforce.com/communit...195#post669195

[flightlogic]

I think knowing the menu process for those limit settings is a good thing operationally... so go in and just bump them all up a bit. You will find settings for your engine and cooling flow that eliminate the normal range alerts... but are still there for an unusual occurrence. It might take a few tries. Then, the alarm going off will get the correct reaction and you can pull the power back and level off if something spikes.

[rightrudder]

I also like a CHT alarm at 425 F for my Lycoming, as that's the highest recommended for continuous operation. I rarely exceed this value (and only for a few seconds) on steep climbout on a hot day. When it flashes red, I know to reduce climb and go full rich mixture, if I'm not already there.

Other limits are set to pretty generous values, to avoid unnecessarily blinking lights. I'm pretty strict on the instrument scan, and it's so easy with an EFIS that displays all pertinent info in a strip along the bottom of the display.

[BobTurner]

If you also have a GRT EFIS, the EFIS and the EIS can be set to different alarm values. e.g., CHT over 410, EFIS flashes, I should do something. CHT over 420, red light (EIS) flashes, I must do something NOW.

[RV10inOz]

Here is the APS recommendation and you can read John Deakins articles for more background info if you wish.


EGT No limit, however realistically if you want a spark plug failed alert, set it to go at about 1580dF and that will give you an indication.
CHT Set this to 400dF, if you have a two stage YELLOW/RED make it 400 for yellow and 410 for red. NO HIGHER. If something nasty happens you want as much advanced warning as you can get.
Cylinder Head cooling rate This is a junk feature, set the number as high as you can so it does not ever annoy you
Max fuel flow Set this at 20GPH on a 4 cylinder and 30 on a 6, if you get a big enough leak to trigger it you want to know about it
Max fuel pressure Refer to the manual but off the top of my head it is 45PSI for injected engines, I have never seen one get past 27-30

Remember realistic alarms should not give nuisance alerts, but they must alert you as soon as reasonably possible.
Hope that helps.