Robin - visual fuel quantity check

[fireflybob]

The club where I instruct is about to get a diesel powered Robin on a 3 month trial.

It has been said that it is impossible to do a visual check on the fuel contents and that also due to the geometry of the filler neck etc it is also impossible to design a "dipstick" to verify the fuel quantity without relying on the fuel gauge. Can anyone confirm this or whether it is at all possible to verify the contents - thanks for any help.

[Rod1]

It is true, however;

I have never flown a DR400 without an accurate fuel gauge on the back tank

If you fill the tank until fuel starts to drip out of the vent, you know it is full.

Rod1

[fireflybob]

Rod1, thanks for your comments - I am not disputing the general accuracy of the fuel gauge but I am asking whether it is physically possible to check the contents of the tank (other than filling it up to full!) in any way.

[Rod1]

The routing of the filler pipe and the positioning of the tank make it impossible to dip the tank. It is also impossible to see any fuel through the filler, so the answer to your question in no. We are talking about just the rear tank which is all that is fitted to this model, the wing tanks are a different matter.

Rod1

[Mark 1]

It is a problem on the rear tanks of the DR series Robin/Jodel models.

If you have wing tanks, then use those for take-off and landing.

The float type gauges are pretty unreliable, but the low quantity warning light is independent, comes on at about a quarter full, and I've found it to be pretty consistent and reliable.
It gives about 20-30 minutes safe flying after it lights up.

[huckleberry58]

In short, no, it's not possible to check the fuel the conventional way, ie. with a dipstick. I used to fly a R2160. I had concerns about the reliability of the fuel gauge also at the time. Reason was that due to weight limitations while doing aeros. Anyway, the concerns I raised to the company were the following:
1. The fuel gauges are calibrated in units of 0,1,2,3 etc where each number corresponded to a given amount of fuel and the interpolation between the numbers isn't linear.
2. The fuel indicator 'needle' is pretty thick and is actually about a quarter the thickness between units.

['Chuffer' Dandridge]

I'm surprised nobody has invented a dipstick like we used on a Victa Airtourer. Same scenario - Fuel tank under the pilots seats with the filler cap on the side of the fuselage and no way of checking the level. Victa very kindly provided a sort of wobbly dipstick that would go round corners and indicate fuel level. The aircraft's fuel gauges were as good as useless anyway!

Happy days!:)

[MayorQuimby]

We use a (self made) dipstick on the HR200. Goes in at an angle, that's all. Indicates within 5 litres of the (accurate) fuel gauge. Presume it would be the same for the 2160, but don't know about the other types.

MQ

[BackPacker]

I fly a Diamond DA-40 TDI and you can't check the fuel quantity in the wing tanks in that aircraft either since the filler is not in the middle of the tank but outboard. Diamond delivers the aircraft with a clever little device. It is basically a flat, hard piece of plastic with a cutout in the shape of the front of the wing. You hang that on a specific place on the wing, probably chosen to minimise the effect of unlevel ground. Attached to this piece of plastic is a length of tube which you push into the drain valve. Fuel flows into the tube and up the piece of tube which is riveted to the piece of plastic, until the fuel level in the tanks and in the tube are equal. A scale printed on the piece of plastic then allows you to read off the amount of fuel in the tank.

Should not be too hard to create something similar for a Robin, I'd say.

Just for the record, our club flies Robins too (DR2-120, DR2-160 w/ long range tanks, DR400) and we only check the fuel level through the fuel gauge in the cockpit. {}-(

Oh, a few tips if you're going to fly diesel, and I assume this is the first diesel in your fleet: Get a water/odorproof box and put a club-issued fuel tester and a bunch of gloves (from a fuel station) in it. Leave that box in the aircraft for pilots to use instead of their own stuff. Diesel and Jet-A1 both smell horribly and because it does not evaporate, the smell will last forever. Not something you will want to have in your flightbag. Also, put a empty jerrycan, weighted down with some stones or something, near the parking place of the Robin to discard the sampled fuel in. I don't know what the custom is at your place, but we normally empty our 100LL fuel which we sampled on the concrete to evaporate. If you do that with diesel, it will not evaporate but will get very slippery very quickly.

[Nipper2]

The 2160s I did my Aeros training in in Australia all had flexible blade type dip-sticks. As I remember they were reasonably accurate.

I'm sure if you contact them at desko at sydneyaerobatics dot com dot au they will give you the details.

[BlueRobin]

Quite, later HR200s and derivatives had a dipstick fitted. What's different about the DR400 filler neck and tank?