Release 9 Insiders - Anyone can post - Suggestion

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Suggestion - Low Fuel

Printed From: Avidyne
Category: Entegra Release 9
Forum Name: Release 9 Insiders - Anyone can post
Forum Description: Release 9 Insider Members
URL: http://forums.avidyne.com/forum_posts.asp?TID=106
Printed Date: 27 Apr 2024 at 12:44pm
Software Version: Web Wiz Forums 12.01 - http://www.webwizforums.com

Topic: Suggestion - Low Fuel

Posted By: rdawson
Subject: Suggestion - Low Fuel
Date Posted: 24 Aug 2010 at 4:25pm

There must be a place on this site for suggestions, but I cannot find it so here is mine ---

I can’t be the only guy with this problem.

First, let’s acknowledge that fuel gauges are essentially worthless; in 40 + years of flying, I have always ignored them and kept track of fuel with fuel flow and time. Nonetheless, the Cirrus has fuel gauges and, worse, integrates them to the R9. The problem is what R9 does with the information. If the gauge reads below a certain level, up pops a warning – a warning that requires at the least an acknowledgement. Then, when the gauge shows a bit more fuel, the warning goes away only to reappear on the next giggle of the fuel sender.

The proper response, it seems to me, would be to latch the warning, or at least design in a bunch of hysteresis. We can be reasonably sure that no fuel is being added to the tank while airborne. (I did not purchase the air-to-air refueling option.) As it is now, I get (literally) dozens of warnings on a given flight – some of which require attention at busy times such as on an approach.

Am I the only guy with this problem?

Replies:

Posted By: AviMike
Date Posted: 25 Aug 2010 at 11:29am

I agree with your assessment of the fuel gauges and them being used as fuel 'planning' devices. The fuel tanks in a Cirrus have discrete outputs back to R9 that indicate a low and a zero fuel level. Those inputs are what we use to trigger the Low Fuel caution and warnings that used to go to the annunciator panel.

R9 handles the discretes just like they were handled in the annunciator panel except that we delay the display of the message until it is received continuously for 5 seconds. It is especially problematic when there is extended high pitch or roll of the aircraft. When the discrete is cleared then we take down alert. We apply hysteresis to other parameters but didn't to this input. We have thought of ways to improve it 'flashing' like latching it when it goes off the first time. We've had some other thoughts, like handling it differently in maneuvers but haven't thought through all the use cases.

You are not the only one who has brought up this issue. Would you like it to be latched after it goes off the first time?

Posted By: rdawson
Date Posted: 25 Aug 2010 at 12:51pm

Latching would be ideal. Fuel in the tank never increases. Therefore "when the discrete is cleared" can be safely ignored.

Posted By: AviMike
Date Posted: 25 Aug 2010 at 12:57pm

I should have been more clear. Latching it would mean keeping the caution or warning visible after the first time it is detected. Taking the alert down would not 'certifiable' or safe since the condition could still be present and the alert is gone.

Posted By: rdawson
Date Posted: 25 Aug 2010 at 2:34pm

It is I should have been more clear. By ingoring "when the discrete is cleared" implies that the warning would remain for the duration of the session. I agree that the alert should not be taken down - it is the alert that would be latched.

Posted By: rdawson
Date Posted: 14 Sep 2011 at 10:23pm

Has Avidyne given any more thought to latching the low fuel warning? There was no mention in the description of the current software release. Will this be included in a future release?

Posted By: AviMike
Date Posted: 15 Sep 2011 at 3:18pm

Hi Rick,

This feature did not make the list in R9.2.3. In fact, this release is a very small update to fix a couple of IFD software issues that were seen in the field. Release 9.3 is the next major functionality release with SynVis. Currently, this low fuel suggestion is not on the R9.3 list either. It will be included in a future release but we need to get through the big-ticket items first.

- Mike

Posted By: rdawson
Date Posted: 15 Sep 2011 at 4:54pm

Thanks for the update. Keep up the great work!