so how much will a 75 F model hold fuel wise

[Yetti]

33.8 gallons.  Although the hose handle was leaking a bit

Had to edit that it's 33.8

 

Edited May 24, 2022 by Yetti

[Mooney Dog]

per tank? wouldnt that be listed in the POH? 

[Yetti]

8 hours ago, Mooney Dog said:

per tank? wouldnt that be listed in the POH? 

Well it is placarded at 31.   I had to empty it to calibrate a fuel sender.

[Mooney Dog]

4 hours ago, Yetti said:

Well it is placarded at 31.   I had to empty it to calibrate a fuel sender.

Oh i see. I wonder if some of that is going into the fuel line itself. Either way nice to know there's a little extra just in case. 

[Yetti]

11 minutes ago, Mooney Dog said:

Oh i see. I wonder if some of that is going into the fuel line itself. Either way nice to know there's a little extra just in case. 

I remember reading there was 3 gallons of fuel to cover the fuel pickup.   So I would not plan on the just incase amount at 2.5 gallons per 15 minutes

[ArtVandelay]

Same for the J, although I hope never to need the extra.

[Ragsf15e]

15 hours ago, Yetti said:

Well it is placarded at 31.   I had to empty it to calibrate a fuel sender.

My ‘68 poh says “fuel capacity is 64 gallons…”.  Interesting your ‘75 is placarded at 31/ side.  Mine says 32, but I doubt they changed the tanks?

Interestingly, my jpi930 is set to 62 gallons as full fuel.  It was put in by previous owner, so I’m not sure the details, but maybe he and jpi used the later models poh to determine the tank capacity?

[RobertGary1]

5 minutes ago, Ragsf15e said:

My ‘68 poh says “fuel capacity is 64 gallons…”.  Interesting your ‘75 is placarded at 31/ side.  Mine says 32, but I doubt they changed the tanks?

Interestingly, my jpi930 is set to 62 gallons as full fuel.  It was put in by previous owner, so I’m not sure the details, but maybe he and jpi used the later models poh to determine the tank capacity?

First I’ve heard of that. I’ve only seen 32/side placarded F’s.  

[Ragsf15e]

1 hour ago, RobertGary1 said:

First I’ve heard of that. I’ve only seen 32/side placarded F’s.  

Well the op said his ‘75 F is placarded at 31/ side.  Anyone got a ‘75 poh handy?

[Ragsf15e]

16 hours ago, Yetti said:

Well it is placarded at 31.   I had to empty it to calibrate a fuel sender.

Now I’m curious, why is yours placarded at 31/ side?  The ‘75 poh in the download section says 64 gallons useable.

[MikeOH]

FWIW, my '70F is placarded 32/side, 64 usable.

[ArtVandelay]

Now I’m curious, why is yours placarded at 31/ side?  The ‘75 poh in the download section says 64 gallons useable.

Bladders?

[Marauder]

My 75F POH:




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[Marauder]

My guess is that someone placarded it this way because they could never get 32 gallons of usable.

When I installed the new senders and caps for my bladder system, I had to calibrate the JPI gauges. There was no way I had 27.4 gallons per side usable.

Both tanks can only provide 26 gallons usable.




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[Marauder]

Did I break my daily photo allotment?


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[RobertGary1]

1 minute ago, Marauder said:

My guess is that someone placarded it this way because they could never get 32 gallons of usable.

When I installed the new senders and caps for my bladder system, I had to calibrate the JPI gauges. There was no way I had 27.4 gallons per side usable.

Both tanks can only provide 26 gallons usable.




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32 is usable. There is something like 2.5 additional not usable. 

[Marauder]

32 is usable. There is something like 2.5 additional not usable. 

I understand that. My point was that the previous owner probably flew the tanks dry a few times and figured out that they could never get the full 32 usable back in it. I saw the same thing with my bladders. Although the bladder supplement shows a total 2.5 gallons of unusable for both tanks, it really is closer to 2.5 gallons of unusable per tank.


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[RobertGary1]

4 hours ago, Marauder said:

I understand that. My point was that the previous owner probably flew the tanks dry a few times and figured out that they could never get the full 32 usable back in it. I saw the same thing with my bladders. Although the bladder supplement shows a total 2.5 gallons of unusable for both tanks, it really is closer to 2.5 gallons of unusable per tank.


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With bladders I could see room for variability. Without bladders I’d be surprised. I’ve heard people say they get closer to 34 gal/side run dry but that could also be straight and level fuel vs certification. 

[Fly Boomer]

9 hours ago, Marauder said:

daily photo allotment?

Lifetime

[icurnmedic]

67f. Placard at 64, actual from A&P 66.5. Must have a few unusable. Not that I will be flying that far anytime soon, or ever. 

[RobertGary1]

10 minutes ago, icurnmedic said:

67f. Placard at 64, actual from A&P 66.5. Must have a few unusable. Not that I will be flying that far anytime soon, or ever. 

64 is usable. The manual says how much is not usable but I think it’s 2.5/gal. I’ll have to look it up in my service manual. 

[carusoam]

Often lost in the calculation…..

How is full defined?

1) Bottom of the fuel neck…

2) Top of the wing skin…

3) A drilled calibrated hole in the fuel neck….

Find the filling procedure in the POH… see if it mentions it anywhere….

There is a few gallons that can be fit in at the top, with careful filling, and time for air to escape….

The vent hole is usually uphill from the fill neck…. So it is unlikely, on a level surface, that fuel will get dumped out the vent….

+1 for knowing your useable fuel, in your plane, today…..

PP thoughts only, not a mechanic…

Best regards,

-a-

[Yetti]

The Operators Manual which is serial number correct to the plane.   says usable fuel of 64 Gallons.   The original placards on the wing say 31 gallons.   This was on level ground.   Not sure how to deal with the missing 2 gallons.   Maybe a gallon in the fuel lines?  Heck I don't know.

[Marauder]

The Operators Manual which is serial number correct to the plane.   says usable fuel of 64 Gallons.   The original placards on the wing say 31 gallons.   This was on level ground.   Not sure how to deal with the missing 2 gallons.   Maybe a gallon in the fuel lines?  Heck I don't know.

You got a picture of the placard?


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[carusoam]

There is probably a specific procedure used to drain and measure useable fuel….

Which probably includes all of the fuel that is available to be pumped out of the tanks using the electric fuel pump….

It may be specific to being level in two dimensions….  Because you can get more out of a tank by raising the nose… and lifting the wing…. Which may not be viable in all regimes of flight…. So, not useable…

expect fuel lines and the upper part of the water separator to be included in the number…. And if carburetor equipped… the carb’s bowl carries a few ounces too…. 

PP thoughts only, not a mechanic…

Best regards,

-a-