Fuel tank timer

[OgieOglethorpe]

I know there's an overall timer. But as an owner of a 4 tank pa32, i think it would be a really neat way to cross check not only the sender but my own notes if there was a way to have a timer shown above the quantity for each tank. Plus not having the expensive cies senders and not being able to install the ei senders, I'm stuck with 1960's boat gauge resistive gauges I tend to not trust.

 

[airguy]

You're looking for a timer for the fuel remaining in each tank? That's going to be highly variable depending on your fuel burn rate, not really dependable.

 

[OgieOglethorpe]

No no. A timer that would show total time I've pulled off of each tank. Not a countdown of fuel remaining.

 

[PaulSS]

How would it know which tanks you've selected? Surely you'd need some sort of electrical contact on the fuel selectors to signal the timer to start counting.

 

[OgieOglethorpe]

How would it know which tanks you've selected? Surely you'd need some sort of electrical contact on the fuel selectors to signal the timer to start counting.

You could manually start the timer for the tank you were on. Fuel pump on. Switch tank. Tap fuel gauge for that tank, start timer. Fuel pump off.

Wasn't trying to reinvent things.

 

[GalinHdz]

If you have fuel flow, then set an alarm for every X amount of gallons used. Since fuel burn depends on condition of flight (during the same amount of time a full power climb burns a lot more fuel than a low power descent) this is significantly more accurate. I set my alarm for every 5gallons but you can set it to any amount you want.

 

[OgieOglethorpe]

If you have fuel flow, then set an alarm for every X amount of gallons used. Since fuel burn depends on condition of flight (during the same amount of time a full power climb burns a lot more fuel than a low power descent) this is significantly more accurate. I set my alarm for every 5gallons but you can set it to any amount you want.

Good idea. Didnt know I could set an alarm that way.

 

[MikeD]

The alerts don't work across flights.

I fly a tandem aircraft with 21 gallons in each wing and I switch tanks frequently to keep them in balance. I use a pad of paper and pencil to keep track and wanted to try using the alarm. I set the alarm to alert me every 6 gallons so I can switch tanks. Unfortunately, Dynon does not preserve the math across engine starts. If you land after consuming 4 gallons, when you restart, the counter goes back to zero. So effectively, when you restart, you get notified after consuming 10 gallons, not 6. I stopped using the timer.

 

[GalinHdz]

Yes the alarm resets after every engine shutdown, but that is exactly what you want. Fuel consumed during the flight you are conducting.

Your fuel remaining indication will show how much total fuel you have since it subtract the fuel consumed during that flight from the fuel amount at engine start. The fuel tank quantity from the fuel level sensor won't match but that is due to the fuel level sensor not being anywhere as accurate as fuel flow. THAT is why you should be physically checking the fuel amount in each tank prior to engine start so you know which is the fullest tank to take off on and by how much fuller it is than the other tank.

With this method my SkyView has been accurate to about 1gal per 100 gallons used. This is how I have had it since 2013 and it works great.

 

[MikeD]

Yes the alarm resets after every engine shutdown, but that is exactly what you want.

I respectfully disagree, that is not what I want.

As you noted, the SkyView Fuel Computer will accurately keep track of "Gallons Used" and "Gallons Remaining". "Gallons Used" does, and should, reset after every shutdown. The Fuel Computer will be as accurate as the "K" factor of your fuel flow transducer. I have had to tweak my K factor a few times over the past 13 years and the Skyview fuel consumption calculations have always been accurate within a few tenths when I check it at fill up.

If you fly a tandem aircraft you can easily tell when the tanks are not balanced. My use case is a simple one, I want to keep the tanks balanced. I do that by switching tanks every X gallons and keep a manual tally on a pad of paper in the cockpit. This method has served me well for 13 years. At any point in time during flight I know how much fuel I have in each tank, within a tenth of a gallon. My manual calculations are crossed checked with the Fuel Computers calculations. I only occasionally look at my fuel tank sensor readouts

In it's current state, the alarm does not maintain the integrity of the math across engine starts. If the alarm alerted every "X" gallons, independent of engine starts, I could use it to balance my tanks. Unfortunately, that is not the case.

 

[GalinHdz]

For safety of flight that is exactly what it was designed for and what it does very well; to accurately calculate fuel used during the flight. It is NOT designed to "maintain the integrity of the math across engine starts" nor to "use it to balance my tanks". System are to be used within their capabilities and design.

BTW, My airplane has the same requirement as yours for switching fuel tanks.

 

[MikeD]

For safety of flight that is exactly what it was designed for and what it does very well; to accurately calculate fuel used during the flight. It is NOT designed to "maintain the integrity of the math across engine starts" nor to "use it to balance my tanks". System are to be used within their capabilities and design.

BTW, My airplane has the same requirement as yours for switching fuel tanks.

Apologies for the confusion but I don't think we are talking about the same function. I agree with you 100% regarding how the Fuel Computer currently calculates fuel used during the flight and resets that count across engine starts. I don't want that to change.

What I am referencing is the Skyview "Switch Tank" countdown timer. This function was designed to help you balance your tanks. You get to pick what to use, gallons or minutes, you set a target, and you get a visual and audible alert to "Switch Tanks" when the timer expires. In it's current state, it is a safety issue since it resets a timer set by the pilot at engine start.

My position is if a pilot sets the "Switch Tank" countdown timer, (gallons or minutes), only the pilot should be able to reset it.

 

[GalinHdz]

The Skyview "Switch Tank" feature is only to advise when you have consumed a specific amount of fuel during the flight you are currently in which helps you decide how to balance your tanks during that flight and that flight only. It is considerably more accurate than using a clock/timer to do the same function. If you want to use the feature for something else, YOU must know how to use it based on its design capabilities and limitations, otherwise it become a safety of flight issue.

If you think an additional feature (pilot reset vs engine-off reset) is a good idea, submit it to DYNON and they might incorporate it in a future software release. User recommendations are how many current features were added to Skyview over the years. IMHO additional capabilities are a good thing and I doubt anybody uses every available Skyview feature, I know I don't.

In the mean time; use the system based on its design capabilities and limitations.