Main tank Useful Fuel

[Thrashnic]

Can some one help? I have a 1946 bc12d with a 12 gallon main tank, I am wondering what the useful fuel is on that tank?

[N96337]

Re: Main tank Useful Fuel

Pretty much all of it!

[PA1195]

Re: Main tank Useful Fuel

Is fuel line head pressure a factor in determining minimum useable fuel...like in climbs? In level and descent all should be available.

Gary

[Robert Lees]

Re: Main tank Useful Fuel

On some models (F19?) there is a minimum fuel requirement to prevent unporting of the tank in a steep climb. I've suffered that once!

[astjp2]

Re: Main tank Useful Fuel

I thought that was for takeoff only? I have run a few dry...bone dry

On some models (F19?) there is a minimum fuel requirement to prevent unporting of the tank in a steep climb. I've suffered that once!

[Jim Hartley]

Re: Main tank Useful Fuel

This was my experience and only once...steep climb from small lake engine went quiet until I reduced pitch attitude. I had 2 gallons left in tank.

I thought that was for takeoff only? I have run a few dry...bone dry

[White Knuckle Aviation]

Re: Main tank Useful Fuel

My '78 F-19 owner's manual, under "Specifications and Performance" states: FUEL CAPACITY........24 GAL. (21 USEABLE). I'm not shouting here, it's in caps.

A/C is obviously equipped with two, six-gallon auxiliary wing tanks.

Page 2, under FUEL SYSTEM, states: "The fuel system consists of a twelve-gallon fuel tank located in front of the instrument panel in the fuselage. Only nine gallons of this fuel may be safely used. Fuel gauge indicator shows content of fuselage fuel tank only. This gauge is calibrated to read empty when usable fuel of fuselage tank is consumed."

I've never run the fuselage tank dry, but have ventured considerably into the red warning stripe after reaching "E". Approximating here, but fill-up amounts over the years indicate at _least_ three gallons remain available in reasonably level flight once the "E" mark has been reached.

[Robert Lees]

Re: Main tank Useful Fuel

The unusable fuel is negligible from all 3 tanks (in level attitude), maybe a cupful or two. I do not know about the unusable fuel in the aux tank fitted under the baggage sling in some models.

Perhaps the 3 gallons that Rodney (WKA) refers to is a "safety factor" introduced by Ferris and/or FAA?

But do I think Tim & Jim are correct, it's a take-off unporting scenario.

Welcome, Rodney!

Rob

[flyguy]

Re: Main tank Useful Fuel

On the ground, with the tail elevated to a level-flight position the front tank in my 12D-85 will drain down to perhaps a tablespoon or so remaining around the slightly elevated drain fitting "ring." I have drained it several times, always the same. I could see it being a problem in a climb with just a couple of gallons remaining.

Next time I drain it I will check it first to see how far down it will drain with the tail in the down position. That should be informative.
DC

[astjp2]

Re: Main tank Useful Fuel

I don't trust the factory manuals too much, they don't even publish a good parts manual...

My '78 F-19 owner's manual, under "Specifications and Performance" states: FUEL CAPACITY........24 GAL. (21 USEABLE). I'm not shouting here, it's in caps.

A/C is obviously equipped with two, six-gallon auxiliary wing tanks.

Page 2, under FUEL SYSTEM, states: "The fuel system consists of a twelve-gallon fuel tank located in front of the instrument panel in the fuselage. Only nine gallons of this fuel may be safely used. Fuel gauge indicator shows content of fuselage fuel tank only. This gauge is calibrated to read empty when usable fuel of fuselage tank is consumed."

I've never run the fuselage tank dry, but have ventured considerably into the red warning stripe after reaching "E". Approximating here, but fill-up amounts over the years indicate at _least_ three gallons remain available in reasonably level flight once the "E" mark has been reached.

[astjp2]

Re: Main tank Useful Fuel

I don't trust the factory manuals too much, they don't even publish a good parts manual...

My '78 F-19 owner's manual, under "Specifications and Performance" states: FUEL CAPACITY........24 GAL. (21 USEABLE). I'm not shouting here, it's in caps.

A/C is obviously equipped with two, six-gallon auxiliary wing tanks.

Page 2, under FUEL SYSTEM, states: "The fuel system consists of a twelve-gallon fuel tank located in front of the instrument panel in the fuselage. Only nine gallons of this fuel may be safely used. Fuel gauge indicator shows content of fuselage fuel tank only. This gauge is calibrated to read empty when usable fuel of fuselage tank is consumed."

I've never run the fuselage tank dry, but have ventured considerably into the red warning stripe after reaching "E". Approximating here, but fill-up amounts over the years indicate at _least_ three gallons remain available in reasonably level flight once the "E" mark has been reached.

[Nefj40]

Re: Main tank Useful Fuel

My '46 had everything done to it for the 85 upgrade including the F-19 fuel gauge inside. As far as I can tell there's still 2-3 gallons left when it hits "E." I've never been brave enough to flirt with fuel starvation. YMMV

[PA1195]

Re: Main tank Useful Fuel

From what I can gather after briefly reading the various TCDS and CAR certification standards for Taylorcraft, the unusable fuel of 3 gallons first appeared in TCDS 1A9 with the intro of the F19 with its O-200 engine. It apparently doesn't apply (legally at least) for earlier models. However common sense may dictate avoiding steep climbs at full power and abnormal maneuvers with minimum fuel. The 0-200 (and upgraded engines with more hp) may place demands on the fuel tank's level that can't be met below 3 gallons (pressure and demands of fuel flow; see below).

For the BC (and BF and BL) series up through 85 hp:

TCDS A-696. No note for unusable fuel: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/9b3edd87141e70b986257ab800663da9/$FILE/A-696_Rev_25.pdf

Certification per CAR 04 as of 5/1/38 applies per the TCDS. Note page 40 and 04.620 regarding fuel tanks, and pressure and flow requirements 04.625:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgccab.nsf/0/5ff8a7dbdaf904ef86257b2c0060a953/$FILE/CAR_4_1937.pdf

For the Model 19 on:

TCDS 1A9. Note the Model 19 (85 hp) has no minimum fuel requirement, just the F19 (100 hp) and on other certain models (see Note 1):

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/2fd8478843961ff186257ab80066c947/$FILE/1A9_Rev_22.pdf

Certification per CAR 3 as of 11/1/49 applies per the TCDS. Note the Fuel Tanks General 3.440 and 3.672 for indicator marking and panel placarding, and 3.433 through 3.437 for methods of determining the unusable fuel supply. That's likely what led to the "3-gallon unusable" for later Taylorcraft models certified under CAR 3:

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgccab.nsf/0/73377eeb0c2129fb86256dfe005fdf58/$FILE/part2.pdf

Gary

[PA1195]

Re: Main tank Useful Fuel

I might add this link (hopefully with Terry's permission, I didn't ask first) for SB.01 regarding fuel flow requirements for C-85 engines installed per STC # SA1-210: http://dc65stc.blogspot.com/2010/05/...c-sa1-210.html

Good mechanical and common sense info.

Gary

[White Knuckle Aviation]

Re: Main tank Useful Fuel

Welcome, Rodney!



Thanks, Rob, but I've been lurking here since the original webhost was in place (when that was, I can't remember). I just haven't had much to say.