EMS-D120 Enhancement requests

[Marc_J._Zeitlin]

As a follow on to my previous alarm requests:

1) With the fuel flow calculator, we get a nice estimate of fuel remaining at the next waypoint, updated realtime. This is very useful. However, it's perfectly happy to report negative fuel amounts, with no yellow or red alarms popping up, and no buzzing in the headset . It would be very useful to be able to set alarm limits for "fuel remaining at waypoint", so that the unit would alarm in the amount dropped below some limit (like zero, at the very least) . Or at least VFR/IFR reserve amounts.

2) Some of the systems monitored (volts, amps, oil pressure, fuel levels, etc.) can have very short term spikes/drops in values. The electrical systems, in particular, can indicate and alarm due to spikes created when high current items (electric landing gear, etc.) are switched on or off. Rather than changing the alarm limits, it would be nice if there was a 4 second (or some appropriate time limit) moving average of the value that was used for alarms (and display, actually).

3) When calibrating the fuel levels in 2 gallon increments (a very nice feature - creates very accurate readings), the unit asks for the maximum fuel volume, but doesn't use this volume as the "Full" level - it seems to extrapolate from the last reading. Due to this, I show 26.89 gallons on the left tank and 27.10 gallons on the right tank, rather than 27 gallons on each. Not a big deal, but if it's going to ask me how much fuel is in the tank when full, then it should display that much when I tell it that the tanks are "Full".

4) The meaning of "Time Remaining" (in the fuel computer) is unclear - is that "Time Remaining" to "VFR Reserves", "IFR Reserves", or "Empty"? It's not obvious (at least to me) which it's attempting to indicate. This should be user settable - I should be able to pick which of the three I'm interested in having it display, and it should also have the ability to indicate a yellow and red alarm at user settable points. It would also be nice if there was a reasonable way to tie the actual fuel level readings from the tank level senders in to the fuel computer for these indications.

5) The fuel levels are inaccurate when on the ground and turning, due to fuel sloshing. Not a big surprise, but if the fuel levels are low, they can cause alarms to go off inappropriately. There's already a time based filter on the fuel levels, but maybe there's some way to tie in the GS from the GPS, so that if the unit knows that it's only going 20 kts (or some user settable limit) or less (but more than zero), to ignore fuel level changes over some relatively short time span.

6) If, for whatever reason, the unit is shut off in flight and then turned back on, the timers reset themselves. I think it would be nice to have the ability for the unit to ASK whether or not the timers should be reset every time the unit is turned back on. One choice could be to automatically reset them, as it now does, but the reset should be at the users discretion if desired. Otherwise lots of information is lost.

Thanks for listening!

 

[dynonsupport]

1) With the fuel flow calculator, we get a nice estimate of fuel remaining at the next waypoint, updated realtime.  This is very useful.  However, it's perfectly happy to report negative fuel amounts, with no yellow or red alarms popping up, and no buzzing in the headset .

This would cause lots of nusiance alarms. During climbout, you are often burning fuel so fast and going so slow that you are hundreds of miles short of having the range to get to your next waypoint. Same is true when you decide to climb while in cruise. I doubt many people want a range alarm every time they takeoff or decide to go up 2000 feet.

3) When calibrating the fuel levels in 2 gallon increments (a very nice feature - creates very accurate readings), the unit asks for the maximum fuel volume, but doesn't use this volume as the "Full" level - it seems to extrapolate from the last reading.  Due to this, I show 26.89 gallons on the left tank and 27.10 gallons on the right tank, rather than 27 gallons on each.  Not a big deal, but if it's going to ask me how much fuel is in the tank when full, then it should display that much when I tell it that the tanks are "Full".

We only show fuel in full gallon increments. How are you seeing "26.89"?

Besides that, we can't show what you told us was your tank size. Many airplanes can't read the last few gallons of fuel, so while they have 19 gallon tanks, the sender stops at 16. We're not going to say "19" when we don't know anything more than 16, and we're not going to make people pre-measure where their sender stops. Because of this, yes, we extrapolate from the last reading. You always have at least as much fuel on board as we indicate. Since we show fuel in full gallon increments, it sounds like your system shows "27" when it's full on each tank, which is what you want.

4) The meaning of "Time Remaining" (in the fuel computer) is unclear - is that "Time Remaining" to "VFR Reserves", "IFR Reserves", or "Empty"?  It's not obvious (at least to me) which it's attempting to indicate.

It's time until empty. We leave it up to the pilot to add 30 or 45 minutes to it in their head depending on their situation.

 

[Marc_J._Zeitlin]

This would cause lots of nusiance alarms. During climbout, you are often burning fuel so fast and going so slow that you are hundreds of miles short of having the range to get to your next waypoint. Same is true when you decide to climb while in cruise. I doubt many people want a range alarm every time they takeoff or decide to go up 2000 feet.

That's true, but the high fuel burns (higher than in cruise flight) only occur for short periods of time, and are a special case. It would be simple to have a setting for fuel flow, above which the alarms would not occur, but below which, they would. You could call it "Climb Fuel Flow", make it user settable (in my case, it would be anything above 12 gph for an O-360), and the alarms would only be active if the fuel flow was LESS than this limit, although you could still display "fuel at waypoint" as is done currently.

We only show fuel in full gallon increments. How are you seeing "26.89"?

Maybe it's 26.9 - I don't have the unit in front of me - but IIRC, the fuel level for each tank is shown in tenths of gallons - I think it was an old firmware version that only showed in gallon increments. Going by memory, here.

Besides that, we can't show what you told us was your tank size. ... Since we show fuel in full gallon increments, it sounds like your system shows "27" when it's full on each tank, which is what you want.

Well, it would be if it showed 27, but it doesn't - one shows 26.9, and the other shows 27.1. Like I said, not a big deal, but a little strange, since I told the unit that the tanks hold 27 gallons, and I then told it that the tanks were full. Clearly, it's USING the extrapolated numbers for full, because I didn't tell it that the tanks held 26.9 or 27.1 gallons - it came up with those #'s by itself during calibration, with the last gallon put in each tank.

At any rate, the logic used for indicating full tanks (from the fuel LEVEL senders, not the fuel FLOW computer), should be coupled to the "Full" setting when adding fuel. Not to "Preset", and not to an incremental add, but only to the "Full" setting. Once the level reaches a point where the fuel senders CAN be accurate, then, obviously, they should be used.