Engine failure today and forced landing.

[FlyingMonkey]

11 hours ago, CTMI said:

I had to drill into my head that the site tubes are not fuel gauges.  Again, the site tubes are not fuel gauges. they couldn't be fuel gauges because depending on the attitude of the aircraft they can read anything between zero and 10 gallons and doesn't tell me if there's more than 10 gallons. What fuel gauge do you know of that's wildly inaccurate and only works when the tank is 1/2 empty or less?

 

While I don't disagree, the FAA requires fuel gauges in all aircraft to be accurate in exactly one condition: when the tank is empty.

Many certified aircraft have wildly inaccurate fuel gauges; that is why you should really know how much fuel you start with and think about that in terms of hours of flight time.  Sight tubes have an advantage over mechanical gauges in that you can VISUALLY VERIFY the condition of fuel within the tanks.  You might not know an exact amount in a tank, but you can confirm that the fuel is there.

And I personally believe that the sight tubes can be very accurate for fuel estimation if used properly.  I recently made a flight from Winder, GA to the Florida border, about 250 miles.  I stayed for a while, then departed another 250 miles back home.  I knew I'd be stretching the range capabilities of the airplane, so I watched the sight tubes very carefully and kept them pretty well balanced.

I estimated on landing that I had 8 gallons remaining, and wanted to test my accuracy and the calibration of my sight tube markings.  Back in the hangar I immediately drained all the fuel from the airplane from the gascolator, which shows all the fuel the engine could use.  I drained 7.8 gallons.  That is as accurate as I could possibly expect any fuel gauge to be. 

BTW, I don't have a Dynon EMS, and don't feel under-equipped without it.  The BEST fuel gauge is probably a stopwatch.

[FlyingMonkey]

10 hours ago, ctfarmer said:

I think this point needs to be reiterated over and over.

The fuel pickup and the fuel sight tubes are both located on the inside of each tank. There is an important concept to understand here. If you have fuel showing in any one or both sight tubes, unless you are flying inverted, you must have fuel to the engine. If you have fuel in one sight tube, you can be sure there is fuel to the engine. This however is not a good condition to find yourself as, any increase in your un-coordinated state, can, very quickly, un-port or uncover the fuel pickup in the tank that was showing fuel leading, possibly quite quickly, to fuel starvation.

So the condition of fuel starvation in this manner is as follows - you are flying for a period uncoordinated; all fuel in one tank transfers to the other; you continue to fly uncoordinated; all fuel remaining in the other tank, having an outward force component from uncoordinated flight, pushes outward until there is no fuel covering the fuel port. This condition also pushes fuel away from the sight tube, so, in this steady state condition, both tanks will show no fuel in either sight tube. There is fuel in one tank but you cant see it.

Summarizing this condition - 

#  you have no fuel in one tank (and obviously no fuel in that sight tube)

#  you have fuel in the other but it is moved outward uncovering the fuel delivery port (and you have no fuel in this sight tube either as it is moved to the outside of the tank).

Under such steady state conditions, if only for a very short period, you will quickly use up fuel in the delivery lines and float bowl and fuel starvation is likely.

The more fuel in the tank, the more uncoordinated you can be without starvation occurring in this manner.

Bottom line - fly coordinated and the problem is no more. Fly with more fuel and the likelihood of fuel starvation resulting from un-coordinated flight lessens.

 

 

Beautiful post.

[FlyingMonkey]

10 hours ago, Buckaroo said:

Wow this post is kinda like really pragmatic, non nerd and really important and clear! For me my right site tube during my alfalfa field landing in retrospect may of had 8 oz of fuel in the tube only or 8 to 10 gallons of fuel in that right tank! L

 

I think your idea that you can have 8oz of fuel in the tube and no other fuel in the tank is pretty much impossible.  The tube is open at both ends.  The fuel *will* flow out of the tube to seek equilibrium with the the level of fluid in the tank.  The only way this could happen is for you to be in a near 90° bank, where any residual fuel could pool in the tube.  Otherwise, I think it's just not possible.  

You can have fuel in the tank and show an empty sight tube, but I don't think you can have an empty tank and still show fuel in the tube.

 

[Buckaroo]

1 minute ago, FlyingMonkey said:

I think your idea that you can have 8oz of fuel in the tube and no other fuel in the tank is pretty much impossible.  The tube is open at both ends.  The fuel *will* flow out of the tube to seek equilibrium with the the level of fluid in the tank.  The only way this could happen is for you to be in a near 90° bank, where any residual fuel could pool in the tube.  Otherwise, I think it's just not possible.  

You can have fuel in the tank and show an empty sight tube, but I don't think you can have an empty tank and still show fuel in the tube.

 

The day after my field landing I propped a two inch board under the right tire to see if the right tank would flow out left. It did and with the stick was empty but the right tube still showed 8 or so gallons.?

[FlyingMonkey]

9 hours ago, CTMI said:

And if there's no turbulence, and if your ball is mounted level, and if your mushroom is mounted level, and if the fuel in the tanks is not sloshing back and forth. That's 9 "ifs." That's a lot of ifs.

i do not rely on the sight tubes to tell me how much fuel I have onboard, I just use them to tell me WHERE the fuel is. The dynon, with simple arithmetic as a backup is a far more precise instrument. 

That might be true but as I noted, not all CTs are equipped with whiz-bang EMS fuel flow computers.  And those can fail as well.  What happens when the fuel flow transducer takes a dump?  You either have to fallow the gizmo to a smoking hole, recognize the failure and revert to the sight tubes, or unnecessarily discontinue the flight.  

I have one fuel management option on my airplane, the sight tubes.  I have learned to use and read them very well, and can operate my airplane very safely down to low fuel levels.  The EMS is nice and I would like to have one, but like any automation you have to be careful how much you rely on it, and always question the information it's giving you.

[FlyingMonkey]

8 hours ago, sandpiper said:

It has always been my opinion that the CT line of aircraft should have had a left, right, both and off fuel selector. FD argued that such a system would invite fuel mismanagement, that it was better to have the system we have. FD finally changed this with the fuel injected system to include a header tank. 

This does not mean the non injected system is unsafe. But it does mean that check out in the aircraft should be from someone who actually has experience in it. Just as should happen with any aircraft you are checking out in. And, in a perfect world, this should apply to administration of the Biennial Flight Review.

My two cents - worth exactly what you paid for it.

I agree.  The POH could have a disclaimer saying something like "in most circumstances the valve should be left in the BOTH setting, but one tank or the other can be selected temporarily to balance fuel tank flow rates"

Now that I'm ELSA, I thought about adding a left/right/both valve, but another CT pilot talked me out of it.  Now that I've flown the airplane 400+ hours I'm very familiar with its fuel system and there is not much need to change it. 

[FlyingMonkey]

1 hour ago, ls6pilot said:

Eventually I will be able to figure this for myself but what is an estimate of fuel burn per hour doing touch and goes. 

 

 

Low.  You will spend a lot of time at low power in the pattern, it's probably something like 3.5gph.

[Buckaroo]

9 hours ago, CTMI said:

And if there's no turbulence, and if your ball is mounted level, and if your mushroom is mounted level, and if the fuel in the tanks is not sloshing back and forth. That's 9 "ifs." That's a lot of ifs.

i do not rely on the sight tubes to tell me how much fuel I have onboard, I just use them to tell me WHERE the fuel is. The dynon, with simple arithmetic as a backup is a far more precise instrument. 

It's worth noting however that mr baker knows about 1000 times more than I do about these planes. But I do have fresh experience with being new to this, and the reduction of variables affecting my accurate understanding of fuel quantity and management reduces my workload and increases accuracy and my safety. Preference only

I have the Dynon can you brief me how to set up the fuel monitor system?

 Thanks 

Dave

[FlyingMonkey]

13 minutes ago, Buckaroo said:

The day after my field landing I propped a two inch board under the right tire to see if the right tank would flow out left. It did and with the stick was empty but the right tube still showed 8 or so gallons.?

Yeah, you raised the right wing and the fuel sloshed inboard on that tank.  You probably didn't actually have 8 gallons since the wing was raised and presenting more fuel inboard than what you had, but if you transferred fuel to the left you had a lot more than 8oz.

 

[Buckaroo]

4 minutes ago, FlyingMonkey said:

Yeah, you raised the right wing and the fuel sloshed inboard on that tank.  You probably didn't actually have 8 gallons since the wing was raised and presenting more fuel inboard than what you had, but if you transferred fuel to the left you had a lot more than 8oz.

 

The stick showed empty but the tube showed 8 gallons so was the inner right wing still with fuel or was the tube showing fuel not supported by any fuel in the tank?

[Buckaroo]

11 minutes ago, FlyingMonkey said:

 

Low.  You will spend a lot of time at low power in the pattern, it's probably something like 3.5gph.

That kinda surprises me as 1/2 the job is at full power! Who woulda thunk!

[Tom Baker]

8 hours ago, sandpiper said:

It has always been my opinion that the CT line of aircraft should have had a left, right, both and off fuel selector. FD argued that such a system would invite fuel mismanagement, that it was better to have the system we have. FD finally changed this with the fuel injected system to include a header tank. 

The change to the left/right/both fuel selector in the new fuel injected airplane was primarily because of the engine set up. The return fuel flows back to the header tank, and then to the left wing tank. Because of the return path it is possible to have the left tank completely full and the return fuel being pumped overboard. By being able to select the left wing only you can keep that from happening.

[Tom Baker]

19 minutes ago, Buckaroo said:

The stick showed empty but the tube showed 8 gallons so was the inner right wing still with fuel or was the tube showing fuel not supported by any fuel in the tank?

If you were to look at the airplane from the front, wherever the top of the fuel was in the tube, that will also be the top of the fuel in the tank. Visualize this if you take a 2x8 board that is 6 feet long. Take and make a mark 6 inches up the end and then 5 foot along the bottom from that end. Now draw a line between those 2 points making a long skinny triangle. That triangle represents the fuel in the tank. The filler cap is on the end away from the triangle. This is why when you stick the tank you don't get any fuel.

[FlyingMonkey]

28 minutes ago, Buckaroo said:

The stick showed empty but the tube showed 8 gallons so was the inner right wing still with fuel or was the tube showing fuel not supported by any fuel in the tank?

The fuel you were seeing was inboard of the tank filler so it didn't show on the dipstick, filling the inboard lower corner of the tank.  You probably had 2-5 gallons if I had to guess.

[Tom Baker]

10 hours ago, CTMI said:

And if there's no turbulence, and if your ball is mounted level, and if your mushroom is mounted level, and if the fuel in the tanks is not sloshing back and forth. That's 9 "ifs." That's a lot of ifs.

i do not rely on the sight tubes to tell me how much fuel I have onboard, I just use them to tell me WHERE the fuel is. The dynon, with simple arithmetic as a backup is a far more precise instrument. 

It's worth noting however that mr baker knows about 1000 times more than I do about these planes. But I do have fresh experience with being new to this, and the reduction of variables affecting my accurate understanding of fuel quantity and management reduces my workload and increases accuracy and my safety. Preference only

I have been around enough of the Dynon equipped airplane to know that the fuel totalizer can also be inaccurate. At a glance, if you have fuel in both sight tubes you can average the levels to get a total, even if the mushroom is not level or you are in rough air. Just remember that you are judging fuel based on the position in the sight tube only, and not comparing it the sticker that is placed beside the sight tube. You can not take the level of fuel in the sight tube and draw a line over to the sticker and say I have this much fuel in the tank!

Personally I would much rather know I have fuel because I can see it in the sight tube, Than to think I have fuel because the Dynon totalizer says I should.

[FlyingMonkey]

Does this illustration help?

 

[FlyingMonkey]

50 minutes ago, Buckaroo said:

That kinda surprises me as 1/2 the job is at full power! Who woulda thunk!

You are at full power up to pattern altitude, which only takes a minute or two in the CT when solo.  I then go to ~3800rpm for downwind, and idle abeam the numbers for landing.  The amount of time at full power is probably 25-30% of the total time.  The rest is very low power or idle.

[Buckaroo]

57 minutes ago, FlyingMonkey said:

You are at full power up to pattern altitude, which only takes a minute or two in the CT when solo.  I then go to ~3800rpm for downwind, and idle abeam the numbers for landing.  The amount of time at full power is probably 25-30% of the total time.  The rest is very low power or idle.

That's you I'm 290 lbs!????

[Buckaroo]

1 hour ago, FlyingMonkey said:

Does this illustration help?

 

Yes sir! Thanks 

[CTMI]

2 hours ago, FlyingMonkey said:

Many certified aircraft have wildly inaccurate fuel gauges; that is why you should really know how much fuel you start with and think about that in terms of hours of flight time.  Sight tubes have an advantage over mechanical gauges in that you can VISUALLY VERIFY the condition of fuel within the tanks.  You might not know an exact amount in a tank, but you can confirm that the fuel is there.......

......

BTW, I don't have a Dynon EMS, and don't feel under-equipped without it.  The BEST fuel gauge is probably a stopwatch.

To be clear, i do use the sight tubes to corroborate what the dynon says. I agree that the BEST fuel guage is stopwatch, which, by the way, is all that the dynon really is. It just also does the simple multiplication for you. Even with the Dynon, i use a stopwatch (flight timer on the dynon) and mental math to verify the dynon, in case the fuel flow rate is erroneous.

The tools for determining fuel levels and distribution are:

1. the stick

2. the dynon

3. the tubes

4. the watch

i use all of them in one capacity or another, i just happen to prefer to use specific ones as my primary, "at a glance" tool. 

 

1 hour ago, Tom Baker said:

I have been around enough of the Dynon equipped airplane to know that the fuel totalizer can also be inaccurate. At a glance, if you have fuel in both sight tubes you can average the levels to get a total, even if the mushroom is not level or you are in rough air. Just remember that you are judging fuel based on the position in the sight tube only, and not comparing it the sticker that is placed beside the sight tube. You can not take the level of fuel in the sight tube and draw a line over to the sticker and say I have this much fuel in the tank!

Personally I would much rather know I have fuel because I can see it in the sight tube, Than to think I have fuel because the Dynon totalizer says I should.

just to play devils advocate, how would you determine how much fuel you had if: amount of fuel > 21 gallons? How do you determine whether you have 22 gallons or 32 gallons? If you had a headwind you didn't anticipate, and had a long stretch in front of you with no airports, knowing if you have 22 or 32 gallons could be the difference between landing on a runway or in a forest. The tubes wont tell you. That's not a great primary fuel gauge. To continue that scenario, if your destination is in the GPS the dynon will tell you how much you'll have left when you get there. That's a pretty valuable resource. 

Maybe its just a personal preference or a generational thing (under 30 here) but i'd rather use a precise instrument (computers are precise) to gather precise numbers, and use the rough tool (cuz hey, you aren't getting down to the decimal point with the fuel tubes) to get a rough verification, rather than vice versa. i really don't want to do a bunch of mental math while staring at the tubes to determine what the mean point that the fuel is bouncing above and below is to figure out how much gas i got. i'd rather get the number off the screen and just check if the tubes are consistent enough with that to rule out a computer malfunction. Then when i'm looking at them i'm just primarily (not solely) concerned with whether they are roughly EQUAL.

the only reason i brought this up actually is because this thread is peppered with statements like "the tube said i had 8 gallons" and i just want to highlight that the fuel amount that the tube indicates is highly conditional. The dynon is much less conditional. (still fallible however)

i also would note that Buckaroo had to put his plane down in a field because of fuel starvation and he was NOT using the fuel management computer that his plane is equipped with. He is clearly an OUTSTANDING pilot and his ability to fly his plane is beyond phenomenal, but that doesn't mean he, and other pilots, shouldn't be aware of and have every tool available to him/them at their disposal. Would Buckaroo have had a different result if he had had his fuel levels presented to him down to the decimal point, available at a glance throughout his flight? Would he have refueled? Or perhaps would the decreased workload, (no staring at the tubes and doing mental math) allowed him to focus on coordination of the plane for the sake of fuel distribution? Who knows. What i do know is that i just cant justify NOT using this resource.

To use the fuel computer hit one of the 3 center soft keys on the EMS, navigate to fuel, and use the selections to ZERO out your fuel amount and ADD fuel to the total as needed, the amount you add you gather from dipping the tanks. Enter waypoint on the GPS to see how much fuel you'll have when you get there at your given burn rate. 

 

[Tom Baker]

17 minutes ago, CTMI said:

just to play devils advocate, how would you determine how much fuel you had if: amount of fuel > 21 gallons? How do you determine whether you have 22 gallons or 32 gallons? If you had a headwind you didn't anticipate, and had a long stretch in front of you with no airports, knowing if you have 22 or 32 gallons could be the difference between landing on a runway or in a forest. The tubes wont tell you. That's not a great primary fuel gauge. To continue that scenario, if your destination is in the GPS the dynon will tell you how much you'll have left when you get there. That's a pretty valuable resource. 

I have made it quite clear in earlier post that the sight tubes are only of value when the fuel is within the range that they show.

You must have a Skyview. Not all Dynons are created equal. The D100/120 airplanes show fuel usage, fuel remaining, and tell you how long it will last at the present usage. It doesn't tell you how much you will have left when you get there. you will have to figure that out on your own. I have flown a bunch of different CT's from the CTSW's to the CTLSi. I have seen fuel flow numbers anywhere from 0.0 (a faulty transducer), to spikes over 10 GPH, and everywhere in between. The Dynon fuel totalizer is a useful tool, but I would never bet my life on it. I stick the tanks before flight. I check the amount on board to see that it agrees with the Dynon. I keep track of time, and I watch the sight tubes.

Now my turn to play devils advocate. You are 1 hour away from your destination. The Dynon says you have 15 gallons remaining. This also goes along with the fuel you measured before takeoff. You look up at the sight tubes and the are both below half in the tube. Which one are you going to trust?

[FlyingMonkey]

31 minutes ago, CTMI said:

just to play devils advocate, how would you determine how much fuel you had if: amount of fuel > 21 gallons? How do you determine whether you have 22 gallons or 32 gallons? If you had a headwind you didn't anticipate, and had a long stretch in front of you with no airports, knowing if you have 22 or 32 gallons could be the difference between landing on a runway or in a forest. The tubes wont tell you. That's not a great primary fuel gauge. To continue that scenario, if your destination is in the GPS the dynon will tell you how much you'll have left when you get there. That's a pretty valuable resource. 

Maybe its just a personal preference or a generational thing (under 30 here) but i'd rather use a precise instrument (computers are precise) to gather precise numbers, and use the rough tool (cuz hey, you aren't getting down to the decimal point with the fuel tubes) to get a rough verification, rather than vice versa. i really don't want to do a bunch of mental math while staring at the tubes to determine what the mean point that the fuel is bouncing above and below is to figure out how much gas i got. i'd rather get the number off the screen and just check if the tubes are consistent enough with that to rule out a computer malfunction. Then when i'm looking at them i'm just primarily (not solely) concerned with whether they are roughly EQUAL.

the only reason i brought this up actually is because this thread is peppered with statements like "the tube said i had 8 gallons" and i just want to highlight that the fuel amount that the tube indicates is highly conditional. The dynon is much less conditional. (still fallible however)

i also would note that Buckaroo had to put his plane down in a field because of fuel starvation and he was NOT using the fuel management computer that his plane is equipped with. He is clearly an OUTSTANDING pilot and his ability to fly his plane is beyond phenomenal, but that doesn't mean he, and other pilots, shouldn't be aware of and have every tool available to him/them at their disposal. Would Buckaroo have had a different result if he had had his fuel levels presented to him down to the decimal point, available at a glance throughout his flight? Would he have refueled? Or perhaps would the decreased workload, (no staring at the tubes and doing mental math) allowed him to focus on coordination of the plane for the sake of fuel distribution? Who knows. What i do know is that i just cant justify NOT using this resource.

To use the fuel computer hit one of the 3 center soft keys on the EMS, navigate to fuel, and use the selections to ZERO out your fuel amount and ADD fuel to the total as needed, the amount you add you gather from dipping the tanks. Enter waypoint on the GPS to see how much fuel you'll have when you get there at your given burn rate. 

 

To play devil's advocate to your devil's advocacy...

You are correct, you can't tell your fuel level much above 20 gallons (maybe 22) with the sight tubes.  But...does it matter?  That amount of fuel is four hours of flying, and equal to full fuel on an RV-12.  I'd submit that if a pilot's flight planning is not accurate to within FOUR HOURS, or if he places himself in a situation where he will not encounter a refueling opportunity within four hours, then one or both of the following are true:

1)  The flight planning sucks and the pilot needs more training.

2)  The pilot has far exceeded the intended mission of the CT family of aircraft.

When I plan long legs I plan either two hours (10 gal, which is actually a little more) of reserves and/or to pass multiple refueling opportunities.  With the big tanks the CT has, there is no need to ever really sweat over fuel.

And I take some issue with you stating that the tubes cannot be accurate.  I told you of just one event (among many) where my reading of the tubes was within 0.2g of the true amount in the tanks.  How much more accurately you do want to slice it?  Your planning should never leave in doubt whether you will run out of fuel, and if the situation changes so should your flight plan.

I understand if you want to use the Dynon system instead of the tubes.  It's there to be used after all, and just seeing a number without doing any interpretation is simpler.  But just because that is your preference, don't make it seem like it can't be done with just the sight tubes and a watch.  That's all I've had for over 400hrs and it works great if you take the time to learn how to interpret what you are looking at.   

 

[ausctls]

https://youtu.be/TuEdU_lrtZk

 

[Buckaroo]

5 hours ago, CTMI said:

To be clear, i do use the sight tubes to corroborate what the dynon says. I agree that the BEST fuel guage is stopwatch, which, by the way, is all that the dynon really is. It just also does the simple multiplication for you. Even with the Dynon, i use a stopwatch (flight timer on the dynon) and mental math to verify the dynon, in case the fuel flow rate is erroneous.

The tools for determining fuel levels and distribution are:

1. the stick

2. the dynon

3. the tubes

4. the watch

i use all of them in one capacity or another, i just happen to prefer to use specific ones as my primary, "at a glance" tool. 

 

just to play devils advocate, how would you determine how much fuel you had if: amount of fuel > 21 gallons? How do you determine whether you have 22 gallons or 32 gallons? If you had a headwind you didn't anticipate, and had a long stretch in front of you with no airports, knowing if you have 22 or 32 gallons could be the difference between landing on a runway or in a forest. The tubes wont tell you. That's not a great primary fuel gauge. To continue that scenario, if your destination is in the GPS the dynon will tell you how much you'll have left when you get there. That's a pretty valuable resource. 

Maybe its just a personal preference or a generational thing (under 30 here) but i'd rather use a precise instrument (computers are precise) to gather precise numbers, and use the rough tool (cuz hey, you aren't getting down to the decimal point with the fuel tubes) to get a rough verification, rather than vice versa. i really don't want to do a bunch of mental math while staring at the tubes to determine what the mean point that the fuel is bouncing above and below is to figure out how much gas i got. i'd rather get the number off the screen and just check if the tubes are consistent enough with that to rule out a computer malfunction. Then when i'm looking at them i'm just primarily (not solely) concerned with whether they are roughly EQUAL.

the only reason i brought this up actually is because this thread is peppered with statements like "the tube said i had 8 gallons" and i just want to highlight that the fuel amount that the tube indicates is highly conditional. The dynon is much less conditional. (still fallible however)

i also would note that Buckaroo had to put his plane down in a field because of fuel starvation and he was NOT using the fuel management computer that his plane is equipped with. He is clearly an OUTSTANDING pilot and his ability to fly his plane is beyond phenomenal, but that doesn't mean he, and other pilots, shouldn't be aware of and have every tool available to him/them at their disposal. Would Buckaroo have had a different result if he had had his fuel levels presented to him down to the decimal point, available at a glance throughout his flight? Would he have refueled? Or perhaps would the decreased workload, (no staring at the tubes and doing mental math) allowed him to focus on coordination of the plane for the sake of fuel distribution? Who knows. What i do know is that i just cant justify NOT using this resource.

To use the fuel computer hit one of the 3 center soft keys on the EMS, navigate to fuel, and use the selections to ZERO out your fuel amount and ADD fuel to the total as needed, the amount you add you gather from dipping the tanks. Enter waypoint on the GPS to see how much fuel you'll have when you get there at your given burn rate. 

 

Thanks CTMI for the valuable information and my flying accolades! ??

[CTMI]

5 hours ago, Tom Baker said:

I have seen fuel flow numbers anywhere from 0.0 (a faulty transducer), to spikes over 10 GPH, and everywhere in between. The Dynon fuel totalizer is a useful tool, but I would never bet my life on it. I stick the tanks before flight. I check the amount on board to see that it agrees with the Dynon. I keep track of time, and I watch the sight tubes.

 

Quote

The tools for determining fuel levels and distribution are:

1. the stick

2. the dynon

3. the tubes

4. the watch

i use all of them in one capacity or another, i just happen to prefer to use specific ones as my primary, "at a glance" tool. 

 

Quote

Now my turn to play devils advocate. You are 1 hour away from your destination. The Dynon says you have 15 gallons remaining. This also goes along with the fuel you measured before takeoff. You look up at the sight tubes and the are both below half in the tube. Which one are you going to trust?

 

6 hours ago, CTMI said:

To be clear, i do use the sight tubes to corroborate what the dynon says.

I agree that the BEST fuel guage is stopwatch, which, by the way, is all that the dynon really is. It just also does the simple multiplication for you. Even with the Dynon, i use a stopwatch (flight timer on the dynon) and mental math to verify the dynon, in case the fuel flow rate is erroneous.

Quote

....... i'd rather use a precise instrument (computers are precise) to gather precise numbers, and use the rough tool (cuz hey, you aren't getting down to the decimal point with the fuel tubes) to get a rough verification, rather than vice versa. 

 

I would identify that the sight tubes did not corroborate what the dynon or my watch said, and I would act under the assumption that the worst indicator was the correct one and land my plane. I would hope that's what anyone would do, even if the roles were reversed (sight tube says 10 but watch/dynon says 1.

 

5 hours ago, FlyingMonkey said:

To play devil's advocate to your devil's advocacy...

You are correct, you can't tell your fuel level much above 20 gallons (maybe 22) with the sight tubes.  But...does it matter?  That amount of fuel is four hours of flying, and equal to full fuel on an RV-12.  I'd submit that if a pilot's flight planning is not accurate to within FOUR HOURS, or if he places himself in a situation where he will not encounter a refueling opportunity within four hours, then one or both of the following are true:

1)  The flight planning sucks and the pilot needs more training.

2)  The pilot has far exceeded the intended mission of the CT family of aircraft.

When I plan long legs I plan either two hours (10 gal, which is actually a little more) of reserves and/or to pass multiple refueling opportunities.  With the big tanks the CT has, there is no need to ever really sweat over fuel.

Agreed, it was just an illustration.  I'm just saying there are limitations to the sight tube functionality as a tool for total quantity.

 

Quote

And I take some issue with you stating that the tubes cannot be accurate.  I told you of just one event (among many) where my reading of the tubes was within 0.2g of the true amount in the tanks.  How much more accurately you do want to slice it?  Your planning should never leave in doubt whether you will run out of fuel, and if the situation changes so should your flight plan.

They CAN absolutely be accurate. Im just saying they rely on alot of variables being in control to be accurate.

Quote

I understand if you want to use the Dynon system instead of the tubes.  

Didnt say that.

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It's there to be used after all, and just seeing a number without doing any interpretation is simpler.  But just because that is your preference, don't make it seem like it can't be done with just the sight tubes and a watch.  That's all I've had for over 400hrs and it works great if you take the time to learn how to interpret what you are looking at.   

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I agree that the BEST fuel guage is stopwatch, which, by the way, is all that the dynon really is. It just also does the simple multiplication for you. Even with the Dynon, i use a stopwatch (flight timer on the dynon) and mental math to verify the dynon, in case the fuel flow rate is erroneous.

 

 

 

wowsers. Hey who here uses the AOA function on their Dynon EFIS?