Fuel

[Jared]

Excuse my ignorance PPRUNEr's - but I have just started flying the Robinson R44 and can't seem to be able to find out when the aircraft actually runs out of fuel.

Is it when BOTH tanks are empty, or can it be that the aircraft will run empty when the Aux tank, for example, is empty and the Main is on 1/4.

I had a scenario over the weekend when

[The Nr Fairy]

In both the R22 and the R44, the main and aux tanks are connected by a cross-feed pipe - unfortunately I don't know exactly where the cross-feed is (note to self - find out!). Fuel is gravity fed to the engine.

Since the aux tank is smaller than the main - 18 gallons compared to 31 or so for the main - and the bottom of the aux tank is higher than the bottom of the main, in normal operation the aux tank should empty first then the main tank should empty. Theoretically, when both tanks show empty the fuel low light should come on, i.e., you're out of fuel.

Since your post is half-completed, perhaps you could expand on the exact nature of your problem ?

[Helisell]

The robinson R44 has, in common with many other types, a fuel usage tracking system. It consists of multiple pistons operating within metal cylinders.

Fuel is drawn into the cylinders and with the application of heat it is made to combust and transfer the ensuing force onto the pistons which then convert this motion into a rotary one.

This process will generate a fair amount of noise.

So . . . . "no noise" = "no fuel"

Hope this helps ;)

[cyclic flare]

Jared where did you do your conversion on the R44?. Don't you think this is something you ought to know?

Nr Fairly

I think you might find that the Aux tank is actully fed thru the main tank. Take a look


Cyclic

[headsethair]

A 44 consumes around 1 litre per minute at cruise power. So - dip the tanks before take-off, convert US g to litres by a rough multiplication of 4, and turn litres into minutes.

Use your watch, use the guages, and watch for the light. And if that isn't enough, get a fuel flow meter fitted so you can monitor fuel useage in flight more accurately than the guages.

In the nicest possible way, where/who taught you ?

[Grainger]

There is a cross feed between the two, so fuel drains from both tanks at the same time. In normal operation, the reading on both gauges (main and aux) should reduce together as fuel is used up. As has already been mentioned, the aux tank reaches empty first. Once this happens, the reading on the "main" gauge will then start to drop much faster as fuel is being supplied only from the one tank. The aircraft will continue to fly with the aux empty but it's definitely time to start thinking about getting down !

Throughout all of this the rate of fuel usage should be around 15 gph, so you can monitor it that way. Just watch out for the faster progress of the "main" needle in that last 1/4 of a tank.

There used to be a fault on the R22 where the crossfeed tubing could get kinked or blocked, so if you saw the main tank getting used up but a constant reading on the aux that would be the time to get worried. This was fixed several years ago however.

What was your "scenario" ?

[Gaseous]

When does it actually run out of fuel?

Easy one

Just before the rotor horn sounds.

:}

[Aesir]

I think "Helisell" has got it right :D

[Jared]

Thanks for all your help and technical assistance.

I now feel more able to rely on my understanding of fuel consumption in the R44. Some very useful tips.

Scenario (almost mentioned) did not involve low fuel light lighting up, but did leave me with an unnerving feeling that I was not fully cogniscant with R44 fuel consumption facts and figures.

Thanks again.

Jared :ok:

[Vfrpilotpb]

Jared,

Please take this as advice as offered in the kindest and most thoughtfull way I can put it,

Don't fly again until you are really, and I mean really in touch with the full workings and consumptions of the helicopter you intend to fly, Read and check every capacity of oil's and fuels, make yourself totally happy that you know everything about the machine you are going in, makes sure you know how to do the water check also.

To run short of fuel, or run out of fuel means you are not as one with your machine, and that makes you unsafe and a danger to others!

Peter R-B
Vfr

[EMS K-MAX]

When the aux is empty there will still be 1/4 of a tank (30min) of fuel in the main tank. why the f*#k would a helicopter company design a machine that runs out of fuel with 1/6th of the endurance left.

[4ero]

The raven and astro will use 60Lt/h with the raven II it's more like 65Lt/ph

If that light comes on, (and you should only ever see it on the daily) you have sod all time to set down. Like, a couple of minutes if that.

I use a minimum fixed reserve of 40Lt. That 40Lt weighs 29Kg. Makes hardly any difference to ops, but all the difference to health of all involved.


p.s. The only legal requirement for the accuracy of fuel guages is that they read empty in a nil useable fuel situation. Don't trust them. Trust your stick.