Fuel dip stick C172

[WrongWayCorrigan]

Can anyone help me make a fuel dipstick for a C172 with standard 20 g tanks? I really just want a piece of wood with graduations on it, innit. Anyone help?

[abgd]

Empty the tanks. Get a broom handle. Add 1 gallon incrments. Mark each time. Job done, innit?

[James331]

What he said.

Or just order a "fuel hawk"

FUELHAWK CESSNA-172FUEL GAUGE from Aircraft Spruce (http://www.aircraftspruce.com/catalog/pspages/fuelhawkfuelgaugeC172.php)

http://www.aircraftspruce.com/catalog/graphics/13-00442.jpg

[sherburn2LA]

don't forget to order the device for fishing plastic fuel sticks out of the tanks

[roundsounds]

Alternatively, you could do this:
Go to your local hardware and grab a suitable piece of timber. I use 2" cover strip it's profile is flat with rounded edges- I find it stows well and easy to mark graduations. Make sure it's long enough to not fall into the tank if you accidentally let go. When the aircraft is reasonably low in fuel take your dipstick and aircraft to the bowser. Place the dip stick into the tank, remove it and mark the line made by the fuel. Don't let it sit for too long as it draws fuel up the timber. Add 5 litres, dip and mark again, repeat this process until the tank is full. The last addition may be less than the 5 litres, but note the amount. The "high tide mark is obviously full, so mark it with the total useable for that tank, the next Mark down will be a quantity equal to full, less the last odd amount added. Now label the remainder of the marks progressively deducting 5 litres. I've made at least 30 dipsticks this way over the years and found them to be sufficiently accurate and saves draining a tank. Also not a bad idea to crest a template on cardboard or paper and store it away in case the original goes missing. I lost one out of a Piper Dakota 15 years ago and recently located it in the baggage compartment of a Tiger Moth when checking a guy out in it. Someone had "borrowed" the dipstick to I've the Tiger mag a tap to release the impulse coupling.

[squawking 7700]

Forget the plastic thing.

Calibrate a piece of wood as said above but don't forget, on a 172, to set the fuel tank selector to anything but 'BOTH' otherwise the tanks will crossfeed while you fill and give an innacurate calibration.


7700

[worrab]

A wooden spoon is great for this. The thin bit dips the tank and the fat bit won't fit through the hole so it can't fall in.

[VP-F__]

they also crossfeed in the off position......tape a stick across the dipstick to stop it dropping in the tank.....it is as close to religion as I dare get!

[CISTRS]

Uhhh
Someone want me?

[WrongWayCorrigan]

Ah, well what a bunch of helpful clever dicks. We have wooden spoons, broom handles, plastic tubes floating round in tanks, an enlightening but irrelevant tangent about cross-feeding and ... a Dipstick from Hong Kong (where the best dipsticks come from). I was rather hoping someone knew the distances between the marks on a bit of wood and would tell me so I can make one.

[9 lives]

I was rather hoping someone knew the distances between the marks on a bit of wood and would tell me so I can make one

Ooo, I wouldn't touch that with a ten foot dipstick! Pilot runs out of fuel - investigators ask: "How'd you know how much fuel you thought you were carrying?". Pilot answers: "I made a home made dipstick with dimensions I read on an internet chat group, from a person I do not know, for a model of 172 I could not confirm."

Best to make your own. Don't do it with the fuel selector to "both" or "off", and assure that the plane is sitting repeatably level, as that makes quite a difference in the reading. Cut the notches in the handle of the spoon, rather than ink, which will wash off.

[londonblue]

There is, of course, one flaw in all these good ideas. They assume the plane is on flat ground! At Elstree that is rarely the case (both Echo and Bravo are on a slope), so always err on the side of caution.

[tecman]

It's also worth mentioning that, while the assumption of a linear relation between the dipstick scale and the full quantity might be just about OK for a C172, it's dangerous to generalize. Doesn't work in a P2002, for example. But you can get closer to the truth by running the tank very low or dry, then adding known fuel quantities and noting the levels on a ruler until you hit full. A little bit of graph plotting then gets you the curve you need to make the dipstick.

I agree with Step Turn in that I would never trust a dipstick that I hadn't personally made or checked.

By the way, you'd be surprised at the difference you see between two notionally identical tanks (e.g. LH or RH) when you do the plotting exercise for some aircraft.

[worrab]

so always err on the side of caution.


Which tank is on the caution side? :)

.

.

.

.

.

.

I'll be off now.

[Mariner9]

Pilot answers: "I made a home made dipstick with dimensions I read on an internet chat group, from a person I do not know, for a model of 172 I could not confirm."

That would still result in a better degree of accuracy than the installed fuel gauges I suspect ;)

[squawking 7700]

WWC - why was mention of cross feeding whilst trying to calibrate a dipstick 'irrelevent'?
If you're filling at 5ltr measures and one litre or more is cross feeding in to the other tank, what will that do for dipstick accuracy?

I think we all know who's the dipstick if they can't work out how to make and calibrate a dipstick.


7700

[londonblue]

Which tank is on the caution side?

It's in the middle isn't it?

[localflighteast]

I use the exact one pictured by James.
Not a fan of the wooden ones for a couple of reasons:

some bright spark at the flight school I rent from made a whole load from a wood of such a shade that it barely changes hue when the fuel touches it, rendering it near useless. Personally I feel it must have taken a lot of talent to find a wood with these properties and secondly despite having the aircraft reg sharpie markered on them, I keep finding dip sticks for the 152s in the 172s.

Not helpful.

The dipstick itself is marginally more accurate than the gauges. I really just use it to check that we are all in agreement within a quarter of a tank or so, as I don't tend to do long flights that are fuel critical. At least the dipstick doesn't go below zero if someone overfills the tanks as the gauges on one 172 I fly do :confused:

[mikehallam]

FWIW.

I made a wooden dipstick long enough not to tilt/fall into my Rans S6 wing tanks.
I paint mine with gloss black paint. Then the fuel wetting shows up clearly, but quickly dries off again as it doesn't soak into the wood, so repeat depth checks are easy.

The S6 tanks when filling have different cross sectional areas as they approximate to the wing profile, so for me the best setting up method has to be fill and mark in 5 litre steps. It's now served me safely for 1/2 dozen years

mike hallam

[WrongWayCorrigan]

squawking 7700 - I may be a dipstick but you're an Ignorak (ignorant Anorak). Thank you Round Sounds.

[TRPGpilot]

Squawking 7700 is in fact correct after all. Sigh.

[phiggsbroadband]

I'd go for the commercial plastic tube, for several reasons...

*** How do you measure BOTH SIDES with a piece of wood, if the first side you measure holds more than the second side, and has wetted the wood?
*** Surely the wood absorbs a lot of fuel and either smells, or is a fire hazard in the cockpit.


However if you really want to be accurate with the wooden dipper, then just compare it with your mates plastic gizmo....


btw.. I think each model 172 is different, especially the SP version.

[DeeCee]

Gawd, just buy one. I bought a plastic one years ago and I'm fairly sure it can't be dropped in the tank. Stick it in the tank and put your thumb over the hole in the top. Lift it up and take the reading. Take your thumb off the top and the fuel goes back in the tank. Simples.

[subsonicsubic]

Try this link (http://www.sportys.com/PilotShop/product/16946). :)

Best,


SSS

[Big Pistons Forever]

A plea from an instructor. After you have dipped the tanks compare the dipstick value to what the fuel gauges say.

[tecman]

I second that. Of all the things to pay attention to, fuel management is a genuine imperative. There's a regulatory requirement here in Oz for the PIC to use multiple sources to establish the fuel status of the aircraft and I guess there are similar requirements world-wide. Regardless, using all the information you have in terms of dip-stick readings, fuel gauges, bowser totals and (if available) know fuel burn for the aircraft is really basic. Having and using redundant information is of course basic to verifying individual sources - such as a new or unknown dip-stick.

In the case of any light aircraft I fly regularly failure to predict, e.g. fuel needed to fill the tanks to within a couple of litres per tank, is enough to ring the alarm bells, and to cause a bit of angst while I figure out what's happened. The "that's odd" realization is important for any pilot.

[londonblue]

*** How do you measure BOTH SIDES with a piece of wood, if the first side you measure holds more than the second side, and has wetted the wood?
*** Surely the wood absorbs a lot of fuel and either smells, or is a fire hazard in the cockpit.

The petrol actually evaporates pretty quickly, so when you get the to other wing during your checks you can be pretty sure a wooden dipstick will be dry.

I've only ever used wooden ones, and never had a problem, although I do agree that you shouldn't leave the dipstick in too long if you want to get an accurate reading.

[ChickenHouse]

Pihutze, first of all - there is no "C172" correct dip stick! You have to specify which, as a SP will have different scales from a G. Dip stick measurements, always on both(!) tanks at prefilght check, are a good way to get to know your gauges uncertainty ... Btw, the markings are not linear on most 172s. ... and do not, I repeat do not, use a wooden stick. In old times when Avgas was all mineral that was ok, but with increasing bio-**** it is not advisable to grow nasty bacteria and other stuff on a wooden soil. This especially applies for those with Mogas/Autofuel STC! Go for a non biological usable substrate, i.e. a PTFE or PEEK sticks.

[Meldrew]

Hey guys , just trust the fuel guages, they are never wrong. Kick the tyres and light the fires.
Fly Safe!
(Tongue firmly in cheek)
Meldrew.

[ChickenHouse]

just trust the fuel guages, they are never wrong.

LOL, did you ever sit in an old 172 with these wooden floater devices "measuring" quantity? The old "gauges" are an ancient incarnation of binary - as long as the indicator needles in normal flight wave to you, there is probably some fuel in the tank, if they don‘t and the engine is still running something is wrong.

[9 lives]

We know that we should operate the aircraft in accordance with the procedures specified in the Flight Manual. Has anyone ever seen a modern Flight Manual which states that the pilot should use a dipstick to determine fuel quantity?

A Cessna or Piper wheelplane on the ramp is pretty straight forward, but an amphibious high wing plane will require a tall ladder, and a floating floatplane is a real challenge.

Fuel quantity indication is required by the type design, and therefore must work. If the pilot suspects it is not working, the aircraft is not airworthy. Now, how the pilot "suspects" the accuracy of the fuel quantity indicating system could take us back to the use of dip sticks.

Happily, some types, like my Teal, have the dip stick permanently installed in the tank, and easily visible through the filler neck...

[thing]

A Cessna or Piper wheelplane on the ramp is pretty straight forward

A 182 ain't. Big ladders out for that one.

I've always found estimating the fuel burn a useful exercise. I can get it down to a litre or so error an hour on the stuff I fly. Just fill say a 28 to tabs, do a flight out somewhere an hour or so away and come back. Say to your mate 'We have used x litres of fuel' and fill it back up to tabs. Then either look smug or stupid; you soon start getting it right.

[VP-F__]

I know what the OP was and have read the responses to it and it strikes me that someone has little experience of measuring fuel here.

The most sensible option would of course be upright tanks with capacitance gauges rather than flat and float to make dipsticks (and dipsticks) obsolete.

This not being the case in a 172 however it is probably worth buying a plastic dipstick for the same price as a few minutes in the air and then measure, mark, chisel and sand a stick until fulfilment arrives......and then of course keep wings level fore and aft and don't let it crossfeed wile dipping your stick.