EMS-D120 Alarms Enhancement Request

[Marc_J._Zeitlin]

I'm a new owner of a D120 EMS system in a COZY MKIV. I've got all of 45 minutes of flight time on it so far. Everything seems to work well and I like it a lot, although I still need to tweak some of the alarm limits.

At any rate, I notice that the oil pressure alarm (as well as a few others) goes off as soon as I shut the engine off after a flight. While I certainly want the alarm to go off if the oil pressure drops during a flight, it seems that it should be possible to have some logic that says that if the RPM's are below some limit after having been higher, such as 200 (since no Lycoming idles below that limit) then the oil pressure, CHT Low, and possibly some other alarms to be determined shouldn't actuate. I know the pressure's low - I just shut the engine off .

Howzzat?

--
Marc J. Zeitlin marc_zeitlin@alum.mit.edu
www.cozybuilders.org

 

[jaba-who]

I'll add my vote to that as well. Same reasons.

Jaba-who

 

[PilotKris]

I like this idea too. I'm tired of having to silence the oil pressure alarm every time I power up my D180.

So many kewl things can be done with computers and multiple sensors...

Along the same idea, how about the low temp alarm not coming on unless the RPMs are above take off levels (like 4000RPM on the Rotax)? Currently, the alarm comes on at power-up and must be silenced. Since the alarm is silenced, it won't "remind" the pilot to check that the temps are up to the proper levels prior to takeoff.

PilotKris

 

[dynonsupport]

PilotKris - does the "power on alarms" setting under SETUP>GLOBAL>ALARMS not get rid of that for you on initial D180 powerup?

 

[PilotKris]

Haven't tried that yet.

Will that silence the low temp alarms too? If so for how long?

I'd like for the alarm to still come on if you try to take off before the coolant and oil temps are warm enough (even if you've "silenced" or "ACK" the alarm previously).

PilotKris

 

[dynonsupport]

From the pilot's users guide:

Set this parameter to “ON” to enable alarms before engine startup. With this parameter set to “OFF”, all alarms are suppressed whenever ALL of the following conditions exist:
•RPM less than 400
•Oil pressure less than 20 PSI
•First five minutes after master instrument power applied

All alarms are initialized when any of the above conditions are exceeded.

 

[Marc_J._Zeitlin]

From the pilot's users guide:....All alarms are initialized when any of the above conditions are exceeded.

Assuming this works, it should be trivial to do the same at the other end - have it not alarm when the engine is shut down, too. That would be great!

 

[dynonsupport]

Marc,
Let's assume a bad situation.

I'm flying along and I have an engine fire that kills my tach wires. No alarm, since the tach doesn't alarm when low. Then it eats the line to my oil cooler, and my oil pressure goes to zero. No alarm, because, well, you've landed, right?

Any time you start playing tricks with hiding alarms because we guess you don't want them, you introduce real ways that they can get blocked in an emergency.

We have the 5 minute timeout on startup for this very reason, so that if something is wrong, we'll at least throw an alarm after a few minutes. There's no way to do that on the shutdown side. The only indication we have the engine is spinning is the tach signal, and if you rely on this fully as the block to all your other alarms, that's a lot of trust in one wire.

 

[Marc_J._Zeitlin]

We have the 5 minute timeout on startup for this very reason, so that if something is wrong, we'll at least throw an alarm after a few minutes.

I agree, and that's a good thing.

There's no way to do that on the shutdown side.

Here, I don't agree. I think that there is a way.

The only indication we have the engine is spinning is the tach signal, and if you rely on this fully as the block to all your other alarms, that's a lot of trust in one wire.

You're correct - relying on only one signal would not be a good idea. However, there are (at least) TWO signals that indicate a stopped engine - RPM and Oil Pressure (there's MP and FF as well, but they've got some lag in their readings). If BOTH went to zero within a couple of seconds, it's pretty clear that the engine has stopped or that there's been some amazing confluence of coincidences that killed both wires at exactly the same time.

If the engine stops in the air, it's hardly going to be the flashing red light on the EMS that's going to alert me - I'll have figured it out soon enough . But if it stops on the ground because I brought the mixture back to idle cutoff, I don't need the EMS flashing and yelling at me about it.

I'm not saying that this should necessarily be the default, but at least give me the option of choosing to turn off shutdown alarms if the OP and tach go to zero within a second or two of each other. Some folks would like this - maybe some wouldn't - but at least it would be up to the user. You already give them the option of shutting off alarms altogether - this could hardly be as drastic as that .

 

[aceflyingservice]

Maybe a compromise would be that if the tach, oil pressure and whatever else indicates the engine has been shutdown, the EMS would just kill the audio portion of the alarm and still flash the warning messages on the screen. This way we wouldn't have to listen to an unnecessary alarm and have to explain to our passenger they shouldn't worry about all that beeping. However, if the alarm was truly valid, the pilot would still get a visual message.

Roger Johnson
LongEZ N34JR

 

[PilotKris]

Personally, it isn't such a big deal to silence the alarm AFTER the flight and I don't think worried passengers (in a stopped/shut down airplane) are a good enough reason to take the chance that the alarm won't go off when it should. I'm 100% with Dynon with this one.


Dynon didn't answer the 2nd part of my question however. I would still like some assurance that the Low Temp alarms won't fail to alarm prior to take off (potentially a BIG problem with a Rotax).

Correct me if I'm wrong,  but with the power-up alarms "OFF" won't the Low Temp alarms go off (beep) as soon as the engine starts? The alarms would have to be silenced and then wouldn't trigger another alarm prior to an attempted take off even if the temps were still to low.

PilotKris

 

[Marc_J._Zeitlin]

Personally, it isn't such a big deal to silence the alarm AFTER the flight and I don't think worried passengers (in a stopped/shut down airplane) are a good enough reason to take the chance that the alarm won't go off when it should. I'm 100% with Dynon with this one.

That's fine - all I'm asking for is that it be MY choice, not the device's (in this case). If it's something that the user can set, then you will have the option to leave things as is, and the alarm will go off. I, conversely, would have the option to decide for myself whether or not I want that to happen, and I would choose to have it NOT happen, if the unit determined (via RPM/oil pressure readings) that the engine was off.

I think I've posited a logic system that minimizes the chance of a missed important alarm, while ensuring that false alarms will not occur. Leave it up to the user - that's all I'm asking.

 

[Simn_Smith]

From the pilot's users guide:

Set this parameter to “ON” to enable alarms before engine startup. With this parameter set to “OFF”, all alarms are suppressed whenever ALL of the following conditions exist:
•RPM less than 400
•Oil pressure less than 20 PSI
•First five minutes after master instrument power applied

All alarms are initialized when any of the above conditions are exceeded.

Is it possible to have the choice as to which alarms are suppressed? There is one that I have that I consider very important (it alarms if the turbo control unit on my Rotax 914 is not powered) but it gets lost too easily among the oil px etc. It would be nice to be able to suppress all the others until start.

 

[PilotKris]

Still didn't get an answer to my 2nd question. To repeat:

I would still like some assurance that the Low Temp alarms won't fail to alarm prior to take off.

Correct me if I'm wrong, but with the power-up alarms "OFF" won't the Low Temp alarms go off (beep) as soon as the engine starts? The alarms would have to be silenced and then wouldn't trigger another alarm prior to an attempted take off even if the temps were still to low.

PilotKris

 

[dynonsupport]

Kris, we don't have low oil temp or low coolant temp alarms. Which alarms are you worried about?

Low coolant temp or low oil temp are not inherently alarms. If that was true, you'd never be allowed to start the engine. They limit your RPM range, so we limit your RPM range.

On the Rotax, what we do is throw a RPM alarm if you rev up the engine before the oil is warm enough. This will still work, and it works well. You will get an alarm when you throttle up to take off if the oil is not yet warm enough. From what we know, Rotax tells you to watch the oil temp as the indicator of when you can take off.

 

[dynonsupport]

A few clarifications:

It is not possible to inhibit individual alarms. It's all or nothing. You can, however, completely shut alarms on individual sensors you don't want chirping at you ever.

Also, once rpm comes alive, your other alarms will be re-enabled. If you dismiss other alarms, they will remain dismissed unless the parameter exits the alarm condition and re-enters it. But, the indication will still show the alarm condition through the red flashing textual item, even after you've dismissed the alarm.

I'll note that there isn't currently an oil temperature redline on the low end of the scale (but there is a yellow caution band). This was designed, in part, precisely because of the nuisance alarm that would be caused by such a redline everytime you started a cold engine.

 

[PilotKris]

There is however, a lower, upper RPM redline (and alarm) when the oil temp is <120, when "rotax" is selected...right?

I plan on renting out my LSA and I'd REALLY like a noisy alarm if a renter attempts to take off with the oil below 120 degrees.

For those reading this who might be wondering what the big deal is, The Rotax dry sump oil system relies on positive crankcase pressure to get the oil out of the crankcase and into the oil reservoir where it can be pumped by the oil pump. If the oil is too cold (and thick), the oil may not make it to the reservoir and cause oil starvation.

 

[PilotKris]

Just an update.

Up uploaded the new operating system and selected "rotax" for type.

It works just as advertised. The RPM alarm does indeed go off if you try to take off with the oil too cool.

Well Done Dynon!

PilotKris

 

[Simn_Smith]

A few clarifications:

It is not possible to inhibit individual alarms. It's all or nothing.

Just to be sure, I know that this is the case at the moment but are you saying that this will never be possible (due to system design etc)?

thanks

 

[dynonsupport]

Pretty much anything is possible in software, but there are no plans to allow individual inhibiting of alarms.

Again, individual alarms can be permanently inhibited in the individual sensor setup. The only thing that is not possible today is the individual inhibition of an alarm before engine start.