Fuel Stick

I've installed Aerospace Logic fuel indicators with new MacFarlane transmitters and a JPI FS-450 fuel flow instrument in my plane. Helpful gauges, no doubt, but the fuel indicator I trust most is my stir stick that I marked myself. I use it before every first flight of the day.
 
denverpilot said:
Yeah, I'm trying to figure out if the specifics are correct.

What model variant of the Skyhawk had 21.5 gallon tanks?

Anyone have that massively cool, but not yet in my collection of books, Cessna maintenance manual compilation book handy?
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It's a 1981 Cessna 172P. Here is a picture of the POH. I'm thinking for its intended use, the 19 gallon one should be close enough.

2q8xag1.jpg
 
flyingron said:
No, I didn't say that, but it's far from a non-problem. If you're going to go to the effort of sticking a tank to the gallon you should do it right. Rather than starting from bone dry and going up (which is going to count unusable fuel), start from the decared usable fuel (Full tanks) and go down. Ain't going to take more than a few minutes more to do it right. In your average skyhawk, there's 1.5 gallons of unusable fuel in each tank. If you don't account for it, why bother sticking the tank. Just use the fuel gauge.
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Ridiculous. If starting from bone dry just take the unusable fuel volume into account. At any rate there is absolutely no need to run the tank dry or drain it. Run it low then follow the instructions for calibrating the generic fuelhawk stick. It isn't difficult and it works just fine.
 
I have made fuel sticks for two planes. They cost nothing and work wonderfully. Go on the enthusiast forum for your plane and pose the question for your particular model. I bet you will get measurements from several people. Use a sharpie to mark a paint stir stick or other stick not so short that it can fall into the tank. Then fill the tank, and start checking the values when refueling. IOW use the stick before fueling, then see if it took the expected amount of fuel when topped off.

Hope this helps.
 
Shepherd said:
In some Cessnas, if you get too low (my 172M POH says < 1/4 of a tank) the engine could stop running dn your descent to the runway.
Had it happen on a steep approach going into Wurtsboro a number of years ago.
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I'll have to look for that... I don't recall anything to that effect in my M's owner's manual.
 
I go with the opinion if you've got 21.5 gal tank, 20 usable, and you aren't happy with the 19 gal stick, perhaps something is wrong with your decision making. If you plan to run the tanks to 20 gal each, that means you're either genius at flight planning and weather, or someday, CAP may get a call to find the wreckage. For starters, your CFI should have taught you

1) not only to read the FARs about fuel but also
2) explained required reserve fuel and mentioned
3) that fuel gages are notoriously unreliable. See #1

Have you considered the reason it's a 19'gal stick with a 20 gal usable tank?

Go with the 19" stick and stop trying to deal with things that are more trouble than they're worth.
 
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murphey said:
I go with the opinion if you've got 21.5 gal tank, 20 usable, and you aren't happy with the 19 gal stick, perhaps something is wrong with your decision making. If you plan to run the tanks to 20 gal each, that means you're either genius at flight planning and weather, or someday, CAP may get a call to find the wreckage. For starters, your CFI should have taught you

1) not only to read the FARs about fuel but also
2) explained required reserve fuel and mentioned
3) that fuel gages are notoriously unreliable. See #1

Go with the 19" stick and stop trying to deal with things you cannot change
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Haha I'm with you, and that was my backup plan to just get this stick, I was just hoping for one that was exact for the plane. If I could reduce the error of 2 gallons by going with another brand or calibrate it based off a knowledge table that'd be my preference. I think I have my answer though, thanks!
 
Skid said:
Haha I'm with you, and that was my backup plan to just get this stick, I was just hoping for one that was exact for the plane. If I could reduce the error of 2 gallons by going with another brand or calibrate it based off a knowledge table that'd be my preference. I think I have my answer though, thanks!
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Hm....why doesn't the school have one in each airplane? Most of the schools (and CAP) around here have one as required equipment along with fuel tester.

Ya know who buys fuel sticks?
And why there's really only one company?

That's right - most of the time, students flying high wings.

I did the same when I bought the cherokee. Then realized that a wood paint stirrer marked at the tab line was sufficient. Then realized that a fuel hawk is irrelevant for a low wing airplane. I think I still have the generic one in the basment. I use it to stir paint.
 
Skid said:
Haha I'm with you, and that was my backup plan to just get this stick, I was just hoping for one that was exact for the plane. If I could reduce the error of 2 gallons by going with another brand or calibrate it based off a knowledge table that'd be my preference. I think I have my answer though, thanks!
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2 gallons at 10 gal/ hour is less than the required reserves. Again, decision making question.
 
murphey said:
Hm....why doesn't the school have one in each airplane? Most of the schools (and CAP) around here have one as required equipment along with fuel tester.

Ya know who buys fuel sticks?
And why there's really only one company?

That's right - most of the time, students flying high wings.

I did the same when I bought the cherokee. Then realized that a wood paint stirrer marked at the tab line was sufficient. Then realized that a fuel hawk is irrelevant for a low wing airplane. I think I still have the generic one in the basment. I use it to stir paint.
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I haven't asked, but of all the places I've flown I always get a snarky remark of "you know how hard those things are to fish out!!?!". I'll see what they have to say though. I think my quest for accuracy comes from flying the R22, which always seemed to be over gross with 2 normal sized adults, and the solution was to tap on the tanks to get a feel of the level. Didn't care for that much.
 
Always wondered why the fuel tanks didn't simply have a little angled metal strip in there to show the level. Seems like it would cost about $0.16 in sheet metal to do so. Something like this.

Just another thing that would make "Tantalum-Aircraft" an awesome company. lol

upload_2017-4-27_11-6-39.png
 
Skid said:
It's a 1981 Cessna 172P. Here is a picture of the POH. I'm thinking for its intended use, the 19 gallon one should be close enough.

2q8xag1.jpg
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It just odd that FuelHawk doesn't have the right one.

Buried in that POH somewhere, are there a couple of gallons of fuel between the tanks and the engine? (Not necessarily unusable, but elsewhere in the system...) That seems too high for a Skyhawk. But I wonder... if they've figured that out and that's why it's a stick for 19.

Could contact them. I did that with a pre-printed checklist card place after something in one of their checklists didn't make sense, and after they looked at the POH, they agreed and changed ALL of their 182-P cards and offered free upgrades to other 182-P owners to the newest version.

Skid said:
I haven't asked, but of all the places I've flown I always get a snarky remark of "you know how hard those things are to fish out!!?!". I'll see what they have to say though. I think my quest for accuracy comes from flying the R22, which always seemed to be over gross with 2 normal sized adults, and the solution was to tap on the tanks to get a feel of the level. Didn't care for that much.
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We've fished one out of our tank. Coat hanger wire fits into the hole in the FuelHawks. Can't speak for the size of the other solutions presented or any of the wooden sticks, but it's probably not a bad idea to drill a hole in the sticks for that purpose. Both the dowels and the paint sticks would be a bear to get ahold of at the bottom of a tank. Some folks drill a hole and put a little loop of something at the top. Just be careful fishing with a coat hanger if you have bladder tanks! :)

(No, I wasn't the one who dropped it, or fished it out.)
 
A homemade dipstick can be made long enough that it is impossible (or nearly so) to fall in. I know several people who have dropped Fuelhawks into the tank.
 
dmspilot said:
A homemade dipstick can be made long enough that it is impossible (or nearly so) to fall in. I know several people who have dropped Fuelhawks into the tank.
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You make the dipstick in a T shape. The leg of the tee goes into the tank, the crosspiece rests on the filler neck. Make the leg so it doesn't quite touch the bottom of the tank, saving it from being scratched up and saving rubber bladder tanks from being chafed. That dipstick cannot be dropped into the tank.

I make them of aluminum, riveted together, and paint them with green epoxy aircraft primer. The primer, being a flat finish, shows the fuel level clearly and the fuel can't eat it. For the 180/185, I make them in a banana shape, with the curved leg reaching toward the back of the tank to get at the lower fuel levels. You won't be able to measure much of the fuel otherwise, with the airplane in the three-point attitude.

Calibrate it in useable fuel. You don't want to get bitten by an engine stoppage when you thought you had a little left after you had to burn into your reserve due to weather or something. Unuseable fuel is defined as the fuel that will not flow out of the tanks when the aircraft is in the attitude most critical for flight. So a VX climb can unport in a tank with a single outlet in the inboard middle of the tank, and a full-flap power-off descent can do the same thing. I have seen it happen at least twice. Not to me.
 
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