Fuel reserve?

[DKirkpatrick]

Hello. Bought a c172 with 180 ho Lycoming that has had 52 gallon fuel tanks installed. Looking for an estimate for what may be fuel usable w these tanks.
Coaching appreciated. Thanks

 

[Morgan3820]

Wouldn’t that be in the POH. Or the STC if these are installed under an STC?

 

[Domenick]

https://wayman.edu/files/Cessna-172N-POH.pdf

Short version:
Long Range Tanks: Total Capacity: 54 gallons. Total Capacity Each Tank: 27 gallons. Total Usable: 50 gallons. To ensure maximum fuel capacity when refueling, place the fuel selector valve in either LEFT or RIGHT position to prevent cross-feeding.

 

[DKirkpatrick]

Thanks Domeneck. Got into an incredible headwind in a cross country flight and only one fuel gauge kinda sorta working. No good place to refuel and ended up putting in 47.2 gallons. Your numbers and tip w the fuel selector management are most helpful.
-dan

 

[Magman]

The slide-in tip tanks are labor intensive to install.

If doing it for the first time the hours are not even close.

 

[Hang 4]

Thanks Domeneck. Got into an incredible headwind in a cross country flight and only one fuel gauge kinda sorta working. No good place to refuel and ended up putting in 47.2 gallons. Your numbers and tip w the fuel selector management are most helpful.
-dan

Starting from full? either way, Yikes! Assuming full tanks and 10gph, that's almost 5 hours in the air and landing with basically empty tanks.

 

[Morgan3820]

A fuel totalizer installed, and properly calibrated would’ve gone along way towards preventing this. Just an idea.

 

[DKirkpatrick]

yes, started from totally full, but w 49 knots in the face and an all day flight ahead, one trlends to fly balls to the wall.. the last fifty miles were totally lean and about 2100 rpm… took about an hour of looking for short field landing spots.
And yes, fuel totalizer going in next week…

 

[asicer]

yes, started from totally full, but w 49 knots in the face and an all day flight ahead, one trlends to fly balls to the wall.. the last fifty miles were totally lean and about 2100 rpm… took about an hour of looking for short field landing spots.
And yes, fuel totalizer going in next week…

Ouch! That's the right way to fly into a headwind. But if anyone asks, be prepared to say that you declared an emergency to yourself. The regulations aren't very clear that someone has to be listening when you declare.

 

[kyleb]

Ouch! That's the right way to fly into a headwind. But if anyone asks, be prepared to say that you declared an emergency to yourself. The regulations aren't very clear that someone has to be listening when you declare.

It was the long taxi in and extended idle before shutdown that caused him to *appear* to be below VFR reserves. ;-)

 

[Let'sgoflying!]

Wow what a story!
What was the route?

 

[Dan Thomas]

Got into an incredible headwind in a cross country flight and only one fuel gauge kinda sorta working.

That gauge is not in compliance with FAR 91.205, is it?

(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:

(1) Airspeed indicator.
(2) Altimeter.
(3) Magnetic direction indicator.
(4) Tachometer for each engine.
(5) Oil pressure gauge for each engine using pressure system.
(6) Temperature gauge for each liquid-cooled engine.
(7) Oil temperature gauge for each air-cooled engine.
(8) Manifold pressure gauge for each altitude engine.
(9) Fuel gauge indicating the quantity of fuel in each tank.
(10) Landing gear position indicator, if the aircraft has a retractable landing gear.

If it's not indicating the quantity of fuel in the tank, it's not legal. And it's not deferrable.

And yes, fuel totalizer going in next week…

Still doesn't fix the non-compliance of that fuel gauge. As quirky as these gauges are, and not very precise at all, they're still useful when they are operating as they should be.

"Useable fuel" is not reserve fuel. Reserve is whatever the FARs specify for the type of flight, such as 30 minutes for day VFR. That would mean maybe five gallons in addition to the unusable fuel that must be remaining in the tanks at the end of the flight. Eating into the reserve when you could have turned around and landed somewhere close by would go against you if you ran out of fuel.