The International Cessna^® 170 Association

I have a dipstick which came with my plane, but the numbers don't add up.

When full, the dipstick reads 16.8 us gal. The dipstick is specific to the plane as it has the ident on it.

I thought the tanks were 37 gal total? 16.8 + 16.8 = 33.7.

Is this accurate or am I missing something?

Actually each tank on an A or B can hold 21 gal, 42 total. 37 of that is usable.

No telling how someone marked the stick. Or how they placed it in the tank to get consistent readings. The stick could have been marked very conservatively and the stick owner didn't care to measure his reserve fuel for example.

The 19 gal FuelHawk below, modified by shortening it, is a popular dip stick used by 170 owners and thought to be fairly accurate when used consistently and the same by the user. You will notice even it can't read all 21 gal in the tank it was designed to read cause some of that fuel is in the back
Here are other threads talking about using a FuelHawk

viewtopic.php?f=24&t=14279
viewtopic.php?f=5&t=11932&p=111915&hili ... ck#p111915

Make sure you get the Fuelhawk C-172/19 gal dipstick (not the 26.5 gal one), and then cut the bottom off at the zero mark. A/C Spruce also sells another clear tube fuel dipstick labeled "Direct Fuel Indicator C-170/172." Despite its label, that is NOT the one you want for this.

Bruce Fenstermacher wrote:Actually each tank on an A or B can hold 21 gal, 42 total. 37 of that is usable.

No telling how someone marked the stick. Or how they placed it in the tank to get consistent readings. The stick could have been marked very conservatively and the stick owner didn't care to measure his reserve fuel for example.

The 19 gal FuelHawk below, modified by shortening it, is a popular dip stick used by 170 owners and thought to be fairly accurate when used consistently and the same by the user. You will notice even it can't read all 21 gal in the tank it was designed to read cause some of that fuel is in the back

1175.jpg

Here are other threads talking about using a FuelHawk

viewtopic.php?f=24&t=14279
viewtopic.php?f=5&t=11932&p=111915&hili ... ck#p111915

I've seen this thread and mod, and plan on doing this—cheers

Is there a chance my 170 has different size tanks, or is it more likely my dipstick is incorrect?

reecewallace wrote:
Is there a chance my 170 has different size tanks, or is it more likely my dipstick is incorrect?

The best way to find out is to keep track of your fuel when filling. The next time you fill up to full, make sure you dip the tanks first, then compare the amount added to the amount below full before filing. The best way to confirm fuel tank size would be to fill an empty tank.

Reese...you might be assuming we know which model 170 you own. WHAT model and serial number?

For the 170A and 170B the 19-gal 172 Fuel Hawk, with it’s lower end cut off at the Zero mark.... inserted directly below the fuel filler neck, lower end slid aft against the internal baffle below that filer neck.... will give accurate reading.

GAHorn wrote:Reese...you might be assuming we know which model 170 you own. WHAT model and serial number?

1955 170B Serial #25074

Oh Oh Reese, I am no coniszer of serial numbers but my 1953B (or there abouts) is 25501.

reecewallace wrote:

GAHorn wrote:Reese...you might be assuming we know which model 170 you own. WHAT model and serial number?

1956 170B Serial #25074

johneeb wrote:Oh Oh Reese, I am no coniszer of serial numbers but my 1953B (or there abouts) is 25501.

And my ‘1953 B-model is 25713... so your serial number makes little sense.

It MAY be possible that your year-of-manufacture and your serial number and your logbooks are not ALL talking abou the same airplane?

According to the info in “The 170 Book” (which may not be considered an “authority”)... serial number 25074 does not exist....but FAA registry shows it to be N8222A living in California.... a registration identified as a PIPER.... because the PREVIOUS owner of a 170-B with that registration number has been DE-registered.

Clearly things are ...not very clear.

And my ‘1953 B-model is 25713... so your serial number makes little sense.

It MAY be possible that your year-of-manufacture and your serial number and your logbooks are not ALL talking abou the same airplane?

According to the info in “The 170 Book” (which may not be considered an “authority”)... serial number 25074 does not exist....but FAA registry shows it to be N8222A living in California.... a registration identified as a PIPER.... because the PREVIOUS owner of a 170-B with that registration number has been DE-registered.

Not sure what to say here, haha. I believe it's all 170 parts.

EDIT - I just got off the phone with a previous owner who owned it for 30 years, and he always had the same problem identifying the exact year. He also had discrepancies with serial numbers. He said it's either a 1953, 54, or 55. Guess we'll never know! TC has it registered as a 56

I’ll bet it flies GREAT!

I’m glad you’ve joined up, and look forward to enjoying your airplane with you!

I’m pretty sure sn25074 is a 1952 model (not necessarily the year of manufacture), as John Pugliese’s ‘52 model is sn25077, N8225A. This jives with your serial number, which was N8222A before it was exported around 1970.

https://registry.faa.gov/aircraftinquir ... rTxt=8222A

Make a new stick yourself!

Drain the tanks thru the gascolator with the tail on the ground (which will leave very close to unusable) and refill 5 gal at a time on each side so no cross-feed and calibrate the stick for both tanks. Then you will have an accurate and repeatable usable gauge for your airplane.

I did that on my C-180A in 1993 and have been using the dip tube and calibration card ever since.

Here's a question -- probably a stupid question -- for you engineers. When working on one tank that requires it to be emptied could one transfer fuel from one less than half full tank to the other tank, also less than half full? Reading about the recent issue with the '48 with the probable fuel cap leak made me think about this possibility. My thought was to place the fuel valve on "both" and then either pressurize the tank to be emptied or place a vacuum on the tank to be filled. This would eliminate the safety and avgas armpit issues that accompany draining fuel. The issues one would face might include deforming tanks with too much pressure or vacuum. I would think one would have to pressurize to something like two psi. Creating a vacuum by sucking fuel vapor into a Shop Vac would be an explosive experience so that would not be good. I have a vacuum tool for getting air out of auto coolant system that might work in an application such as this. It uses shop air to create the vacuum. Capping the overhead vent lines would probably make this idea impractical. Thoughts?

Gary,
while doing your experiment wouldn't you have to raise the wing with the tank you want to empty so as to not un-port the cross cabin vent line?