Hi all,

For those of you that hung on my every word, I apologize for being quiet for so long. Happy to say I've been busy flying and learning.

Our '63 182 is supposed to be back on EDO 2790 amphibs as of this afternoon. I'm going to post about my journey learning to fly amphibs on the float flying forum but it raises an issue that probably fits better under campfire (or maybe maintenance?).

Since we bought the plane last year I've been pretty religious about flying with lots of fuel but that will change with heavy amphib floats hanging underneath. Cessna fuel gauges are notoriously crappy but I've found my engine monitor (EDM900) to be very accurate. When I refill I simply hit 62 gallon refill and the indicated fuel burn is remarkably close to what it takes to refill the tank. Problem is, I won't be able to accurately measure how much I'm adding when I fill part way so I'll have to dip the tanks.

I don't think anyone sells one pre-calibrated so I'll need to build something myself. I've been told that a stick with a float side and a pavement side is the way to go but I can't figure out how to calibrate it.

Is the only way to start with empty tanks and slowly add fuel and mark the stick accordingly?

Is your attitude much different on floats vs wheels Al? I'd think it's probably pretty close so you could use the same side of the stick. Especially if you dip before and after to measure how much you added.
As far as calibrating goes, the only way I know how to do it is by starting empty and add calibrated amounts. I did 5 gallon increments on the 180.

I encourage you to determine the exact amount added, each time. The fuel flow instruments available are very accurate, but they depend on an accurate starting point. We use this meter, found at Tractor Supply. Or you could use 5 gallon cans with a defined "5 gallon" mark.

Most of the summer we're adding 10, 15 gallons at a time and inputting that in the fuel flow gauge. For the 2 or 3 long trips when we fill it; it's usually within 1-2 gallons of what the fuel flow gauge had computed.

Also, we have made a dipstick. However, with any wave action it is hard to get an accurate reading with the fuel sloshing around those big flat tanks.

Enjoy the floats!

https://backcountrypilot.org/images/ori ... 02ed32.png

I seriously doubt the depths of various fuel quantities is very different from wheels to amphibs.

If you have a stick calibrated for wheels, I’d use that, should be close enough. Unless of course, you’re one of those who runs fuel load down to near zero in flight.....

MTV

Mike, I don't have a stick for wheels. I changed the wheels/tires when I bought the plane so the original one was useless.

David, what is the smart way to drain the tanks? Is that something I'm wiser to let my mechanic do? I really wrestle with my tendency to do everything myself but I know getting in over my head on my truck is a different thing than making a mistake turning wrenches on my plane.

I like the idea of a flow meter for my fuel dispenser, even if I do get a good dipstick going. Not sure why that hadn't occurred to me already.

a little trick, start with one full tank. drain 5 gallons a time into a calibrated fuel container (think sharpie lines, not the molded ones). Dump this one into the empty tank tank. Measure both. This way you can calibrate both at the same time. You can level your wings with a 2x4 and a pad.

I have one, well actually 2 (anybody want one cheap?) of the universal fuel dip tubes, you put your finger over the end and it pulls out fuel which you can read the level on the scale etched in the plastic tube. There is a supplied chart you can fill out from your calibration to give you exact amounts.

albravo wrote:Mike, I don't have a stick for wheels. I changed the wheels/tires when I bought the plane so the original one was useless.

David, what is the smart way to drain the tanks? Is that something I'm wiser to let my mechanic do? I really wrestle with my tendency to do everything myself but I know getting in over my head on my truck is a different thing than making a mistake turning wrenches on my plane.

I like the idea of a flow meter for my fuel dispenser, even if I do get a good dipstick going. Not sure why that hadn't occurred to me already.

Th best way to drain I've found is pull the cowling and disconnect the fuel line at the carb or strainer. Insert end of line into barrel and open your fuel valve.
Fuel meters work very good, but aren't cheap...

I drained the tank the fun way... Fuel selector on Right, fly until she quits, fly home on the Left tank and do your filling calibration on the Right tank

Zzz wrote:I drained the tank the fun way... Fuel selector on Right, fly until she quits, fly home on the Left tank and do your filling calibration on the Right tank

Oh I like it!

I use the same fuel tank dipstick on wheels and floats even though I’m flying a taildragger! Honestly, there isn’t much difference in the calibration. Don’t worry about it between amphibs and tricycle configuration changes.

Probably someone mixed up the dipstick story with the oil dipstick, and on a 180, or 185, there is a lot of variation depending on floats or wheels.

Create a table. Every time you dip your tanks, record the fuel totalizer and tabulate the readings. Once you have a good sized data sample, graph the data, discard the eratics, and you’ll have reliable numbers for future use.

Even on floats you’ll occasionally fill your tanks and reset your totalizer. Burn some off and that’s the time to get your best data.

mtv wrote:I seriously doubt the depths of various fuel quantities is very different from wheels to amphibs.

The A185F I just finished for a customer had LR tanks. This bird has a float kit and the owner goes on and off floats. He likes to go north into Canada for some extended trips and really packs the 185 full. I weighed the bird on wheels, but was really concerned that the fuel may be different when on floats. The last thing I wanted to do was give him a W&B and a usable load guide that wouldn't be accurate when it was on floats.

To do a proper W&B, one must drain the usable fuel, not fill it full then subtract the usable. I did this, then weighed the bird on wheels. While still on scales, I filled the tanks until they were visibly full. (this is a good exercise so you can see if the "usable" is close to the book.) After it was full, I brought the bird back into flight attitude to simulate it being filled while on floats, and then began adding more fuel.

I was surprised when I was able to get another 7 gal of fuel in. That's 42 lbs!

Having a proper WB on wheels, and then going on floats may put you over gross in some cases. This was a good exercise.

Bigrenna wrote:

mtv wrote:I seriously doubt the depths of various fuel quantities is very different from wheels to amphibs.

The A185F I just finished for a customer had LR tanks. This bird has a float kit and the owner goes on and off floats. He likes to go north into Canada for some extended trips and really packs the 185 full. I weighed the bird on wheels, but was really concerned that the fuel may be different when on floats. The last thing I wanted to do was give him a W&B and a usable load guide that wouldn't be accurate when it was on floats.

To do a proper W&B, one must drain the usable fuel, not fill it full then subtract the usable. I did this, then weighed the bird on wheels. While still on scales, I filled the tanks until they were visibly full. (this is a good exercise so you can see if the "usable" is close to the book.) After it was full, I brought the bird back into flight attitude to simulate it being filled while on floats, and then began adding more fuel.

I was surprised when I was able to get another 7 gal of fuel in. That's 42 lbs!

Having a proper WB on wheels, and then going on floats may put you over gross in some cases. This was a good exercise.

Allan has a 182 though. Hence why MTV and I are saying there qont b much difference. On a TW I agree that there definitely a difference and 42 lbs is considerable.

Yes, when you’re calibrating fuel gauges, the 185 is level, and there is a measurable difference between when the airplane is leveled for calibration or just sitting on ramp, fuelling at the pump. I also agree that it holds more fuel when levelled than when it’s in tailwheel configuration. Thanks BigReena for quantifying it, because I’ve had evidence for this, but no proof.

For the purpose of pre-flighting my airplane, I use a Fuelhawk universal dipstick that I calibrated tail low while fueling on wheels. I calibrated it for use on both the inside and outside fillers. I use the same stick and calibration chart for when I’m on floats or amphib floats, and I’ve found that it makes no significant difference.

For Albravo, I recommend a universal dipstick from Fuelhawk, and because his fuelling attitude changes very little compared to what a 185 does, I’m confident advising him that it’s safe to trust that same stick whether he’s on wheels, on a runway with amphibs, or floating at a dock. You can calibrate this stick by completely draining your tanks, adding back the specified quantity of fuel listed as un-useable, and then add fuel in increments, recording the dipstick readings as you go. Alternately, you can follow the directions that are provided with the Fuelhawk universal dipstick, and calibrate from the top down. That is, each time you intend to fill up, measure your fuel first. Then record how much fuel it takes to fill. Total capacity minus the amount added to fill equals the initial fuel quantity. Build a data set over time and this becomes very reliable. The scatter on your data will tell you just how reliable.

This method may not be satisfactory to everyone, but there are some who are good at collecting data, good at recording it, and good at analyzing and implementing it.

Bigrenna wrote:

mtv wrote:I seriously doubt the depths of various fuel quantities is very different from wheels to amphibs.

The A185F I just finished for a customer had LR tanks. This bird has a float kit and the owner goes on and off floats. He likes to go north into Canada for some extended trips and really packs the 185 full. I weighed the bird on wheels, but was really concerned that the fuel may be different when on floats. The last thing I wanted to do was give him a W&B and a usable load guide that wouldn't be accurate when it was on floats.

To do a proper W&B, one must drain the usable fuel, not fill it full then subtract the usable. I did this, then weighed the bird on wheels. While still on scales, I filled the tanks until they were visibly full. (this is a good exercise so you can see if the "usable" is close to the book.) After it was full, I brought the bird back into flight attitude to simulate it being filled while on floats, and then began adding more fuel.

I was surprised when I was able to get another 7 gal of fuel in. That's 42 lbs!

Having a proper WB on wheels, and then going on floats may put you over gross in some cases. This was a good exercise.

Greg,

My point which you quoted was in reference to the OP’s airplane, which is a TRICYCLE gear model.

And, yes, there can be a significant difference in both fuel and oil in taildraggers when going from wheels to floats.

I’m now the owner of a 175 with a tailwheel conversion, and it’s interesting (and a pita) to fuel because the fuel ports are so far aft on the wings. Designed for tri gear.

MTV

I bought a "fuel stick" from www.fuelstick.com and calibrated it for my 108-3, it's pretty sweet. I drained the tanks and added 1 gallon at a time to create the fuel index. IMO you should always check the fuel levels, mechanically, every pre-flight, there is always the possibility you are short some fuel via some leak you aren't aware of, it takes less than a minute to check two tanks to prevent becoming another fuel exhaustion statistic...

My oil level can read two quarts higher sitting on the water at my dock than it does with the gear down in my hangar. 182-G with IO550 on Aerocet 3400's.

I don't know how that compares to when it is on 8.50's or 29" ABW's. I'll try to remember to check before and after next time I swap back to wheels.

Anyone know or have an informed opinion on which oil level is "more correct": floats on water or floats on wheels?

Pierre_R wrote:...Anyone know or have an informed opinion on which oil level is "more correct": floats on water or floats on wheels

That seems pretty easy to ascertain--
check the dipstick in both situations immediately after an oil change,
when you (should) know exactly how much oil you put in.
I always figure about a half quart of oil lingers in the internal nooks and crannies of the engine.
So putting in 10 qts, I figure I probably have about 10-1/2 on board.

The Cessna dipstick was calibrated on wheels and on 2960 edo straight floats, as appears on the type certificate. I’d trust the dipstick more on floats than in shopping cart configuration. 2790 amphibs are also on the type certificate, so it’s probably valid on those in either configuration too.

I find that on water with my IO-550 and Aerocets, the oil level reads a bit higher than on land with the Aerocets. It’s only a part quart, so I don’t sweat it much. It definitely sits a bit tail low in the water, and nose down on the runway.

I just keep enough oil in it that I never see the bottom X dry. Yes, it might blow a bit of oil out the crankcase vent, but it’s working hard on amphibs, and more oil = more cooling.

I think I figured out how to calibrate the dipstick without draining the tanks and adding a few gallons at a time.

If I dip the tank and mark the dipstick before filling up, then take note of how much fuel the wing takes until full it should give one solid data point. Subtract new fuel from 31 gallons and voila, an accurate mark. Doing that a few times should give me a useful range.

It might not be as linear as draining the tank and adding a few gallons at a time but I think over time it will provide accurate info.

Any flaw in my logic here?

Nothing wrong with your method at all. Matter of fact, just 6 posts above, I tried to detail this method. Sorry my explanation didn’t cause the light bulb to illuminate. I tried, but my writing doesn’t always hit the target.

Alternately, you can follow the directions that are provided with the Fuelhawk universal dipstick, and calibrate from the top down. That is, each time you intend to fill up, measure your fuel first. Then record how much fuel it takes to fill. Total capacity minus the amount added to fill equals the initial fuel quantity. Build a data set over time and this becomes very reliable. The scatter on your data will tell you just how reliable.

This method may not be satisfactory to everyone, but there are some who are good at collecting data, good at recording it, and good at analyzing and implementing it.