Not a bad idea, should also have a warning light telling you you're on reserve otherwise people will accidentally switch to reserve and fly around until they run out [like on a motorbike :D]

As mentioned a PA34 with less than full fuel means you cannot see any fuel. As one instructor told me, "If you can see fuel, you have loads"......Still better to be safe than sorry in my....experience:D

Knobby,

The problem with that idea is that if the fuel in this "reserve" tank is never used, it will go stale, and by the time you need it, it won't work.

The only aircraft I know of that uses this type of design is the Europa. In this case, the reserve fuel tank is on the right hand side of the aircraft, the main tank on the left and centre. The filler cap is on the right. As new fuel is added, it displaces the old fuel out of the reserve tank and into the main tank, thus ensuring that the fuel in the reserve tank is always fresh. It really needs to be designed in from the start, I can imagine it would be a real pain to add it on afterwards.

FFF
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strafer,

Do I teach my students what?

That a fuel miscalulation is stupid and careless, which is what I said?

That they'll be prosecuted for it, and that in SOME cases I'd disagree with that?

Anyway, I teach on the R22, which actually DOES have accurate fuel gauges,or so I've always been told. It also has a fuel warning light, which comes on when you have five minutes of fuel left, and the light is checked before each flight. And five minutes is enough to land a helicopter safely - we don't need runways.

So your point is??

As many have pointed out, the geometry of the Seneca fuel tanks make a visual inspection prior to flight practically impossible if the aircraft is less than full.

However, the aircraft is fitted with fuel flow indicators and from memory at about 24/24 and leaned, the fuel flow will be about 10 USG per side making a total of 20USG per hour consumption.

Thus unlike the C172 or C150 or similar types, the pilot has a direct readout of the actual fuel consumption as the flight progresses.

Not having enough fuel to divert is absolutely no problem - Shoreham has several independent runways. However, that does not remove the 45 min final reserve.

As to accurately knowing how much fuel is in the aircraft before departure - Weight is the answer. The aircraft has a certified empty weight. If simple electronic scales are available at the aerodrome then simply weighing the aircraft without people or baggage will reveal how much fuel is on board and 6 pounds per US Galon is a nice round figure to keep things simple.

How about putting a weight platform on front of the pumps?

Regards,

DFC

Whirlybird - My point (as I'm sure you are well aware) was to do with your blase, 'anyway can make a slip-up' comments
No - but when it comes to fuel calculation, yes! People who have are not 'foolish', they are criminally negligent.

BTW, if someone has told you that the fuel guages on a R22 are always accurate, then no problem! And checking the fuel lights before each flight - well then there's no way they can fail during flight! Anyway, as you said, 5 minutes is enough to land a helicopter. However, I presume that one day you'd like to travel more than 5 minutes from the airfield? Over water say, or forests, or indeed, people's houses.

Fine, if there's no towbar, cockpit covers, liferafts, baggage, mud, rainwater, etc. etc. etc. to falsify the weight.

And, from my experience of dealing with manufacturers of weighing equipment, they would never certify the weights recorded by a device that was left outside and was available for public use.

And nobody could really blame them for that.

On some motorbikes the "reserve tank" is just a tap lower down the one and only tank, ie is a little bit of fuel in the bottom (and it'll get mixed in each time you refuel). I'd always assumed it was there as a cheaper alternative to providing a fuel guage - are there bikes with fuel guages, and if so do they have "reserve tanks"?

On the subject of auxillary tanks it should probably be noted that the Cessna twin series are equipped with just that and have been well presented in the accident stats due to mismanagement of the tanks.

Common threads on there are:

1. Failure to select a tank with fuel in it and making an off field landing with fuel on board;

2. Selecting an auxillary tank with the main tank still full. Excess unused fuel by the engine is then pumped back into the full mains and promptly vented overboard.

Nah, the system used for the Seneca and Seminole is quite good as it is not necessary to fiddle with the fuel selector other than in an engine failure when you want to cross feed or emergency when you want to shut the valve.

FD

Just a couple of points following up all the interesting points raised.

Aztecs join the group of aircraft whose tanks appear to be dry when plenty of fuel remains, but how much exactly lurks in the tank is unknowable because you don't know how much more fuel was used after the initial 'dry' point, and who trusts aircraft gages to tell you.

Fuel flow gages are fitted to injection engined aircraft, but like all other gages they are not reliable within a couple of gallons per hour, so not suitable for fuel planning.

They can be cross checked by keeping a fuel log, and compared in a twin by referring to the EGT, however any gage can play up during the course of a flight, and leakage and theft can upset the log.

Reserve fuel tanks. We all have reserve tanks, they are that portion of the fuel load that should be reserved for in fuel planning, and that sort of reserve doesn't go stale.

Head winds, strong enough to throw marginal fuel planning out the window, can be overlooked, I was highly surprised at 90 kts ground speed in the Rhone valley one time, and that was with 160 kts airspeed.

strafer,

My comment was not intended to be blase, more a case of "There but for the Grace of God...", "Let he who is without sin..." etc.

We check the fuel before each flight, and the lights. Also, checking the gauges is part of the cruise checks, ie making sure you are burning fuel at the rate you think you should, and at the same time, that the gauges are working. You should never - unless it's completely unavoidable - be flying over large areas of forest anyway, unless at a height at which you could glide (autorotate) clear; if I did so during training I'd get given a PFL. Ditto if flying over towns;though most of them do have flat areas where you could land in an emergency, it's something that's always born in mind. Over water? Well, lots of people won't fly single engined helicopters over water; I'm not one of them, but it is indeed a calculated risk...but I'm talking of engine failure here, not fuel mismanagement.

Would I like to travel more than five minutes from the airfield? Helicopters, as I said, don't require an airfield. "Fuel light coming on" is an emergency I've practised; you land as soon as possible, ie in a field, preferably close to a road. "Someone" hasn't told me the gauges are accurate; virtually everyone says they are. I don't believe it 100%, and always check as I fly, because that's the way I am, and that's what I was taught to do(and teach).

The only point I'm making is that I'm a helicopter instructor, and helicopters are different in some ways. Now let's not highjack this very important and interesting thread.

I think it was the Triumph Herald which had a 'reserve' cock on the fuel tank. Problem was, it was in the boot. So not much use in an aeroplane! Personally, I've no idea whether the 'low state' fuel caption works in my Prelude as I've always diverted to the nearest fuel station when I'm down to 1 segment on the LED fuel gauge.....and I apply the same logic in aeroplanes.

Surely there must be someone out there who can design an accurate, reliable fuel gauging system for light aeroplanes? The best one for a PA28 is a calibrated piece of wood to dip the tanks - the manufacturer's gauges are utterly useless.

My Dad's old P5 Rover 3 litre had a reserve switch. There was a second fuel pump, with a lower inlet than the main one.

It worked fine.

Do you really think that incidents due to fuel starvation will be a thing of the past with reliable gauges?

Come on........

Aviation's history is littered with incidents and accidents which occured despite people knowing exactly were they were in relation to limits and performance of their machines.

What is suggested next? Weight sensitive squad switches whcih determine whether the aircraft is within weight and balance limits? And if not you can not start the engine?

Did you use to stick your pet in the tumble dryer before they issued advice against such practice in the manual?

FD

I can think of very few aeroplanes where, if it was considered important enough, a small panel / filler-cap where a dipstick could be inserted into the deepest part of the tank couldn't be inserted with very little trouble at-all. Also a reasonably cheap totaliser could be inserted in the main fuel line very easily with a cockpit readout - so long as you know how much fuel you had to start with there's no particular problem. The CAA mod fees would probably be more than the device itself.

Incidentally, in a previous life I used to do flight testing on a British light twin called a Jaguar. That had an obscene number of tanks, and a largely automated fuel system. Fuel gauging was through a totaliser which worked on everything except the tailtank. Drill was not to take-off until it started going down because until it had, you were out of aft CG. If you've ever seen a Jag sat at the start of a runway for longer than seems sensible in reheat before taking the brakes off, that's probably why!

G

All this talk of invisible fueltanks - how about the DA-40 then? This has four tanks in total, two in each wing, joined by tubes so the outboard tank always drains into the inboard tank automatically. The outboards only hold 3USGal each... so anything beyond 6USGal (out of 40USGal) burnt makes the tank look completely empty.

Diamond thought this was stupid too - so they provided a fuel gauge which works like a manometer. Attach it to the fuel drain and you can SEE the fuel in a clear calibrated pipe. Works a dream, albeit a little soggy when you remove the gauge from the drain as the fuel in the pipe has to go somewhere! With a little practice you can make it "on the floor" rather than "up the sleeve" :D

I'm sure a similar system could be made for the other aircraft mentioned with "invisible" fuel tanks.

MD.

are there bikes with fuel guages, and if so do they have "reserve tanks"?

My Honda Blackbird has an analogue fuel guage with a 'low fuel' light within the guage, just like my car. The Honda VFR I recently owned had a digital LCD fuel guage, and the last 'segment' would flash as a low fuel warning.

I think it's a while since bikes had a physical 'reserve' tap.

SSD

I think it's a while since bikes had a physical 'reserve' tap.

It's a while since I've driven a bike. I just got too scared by all the car drivers pulling out in front of me "oh sorry, didn't see you". Plus I once had a girlfriend who was a speech therapist at a rehab unit - she said they never really managed to teach the motorcyclists who came in with head injuries to talk again.

SSD - bikes still have physical reserve taps... at least, mine do! Good idea, although how well they would function on an aeroplane where a spluttering fuel-starved engine could cause more than a bit of embarressment at the traffic lights?!

A thought on some of the comments above about how the operator liked their aircraft returned and what equipment the operator provided - not wanting to sound pompous, but who gives a monkey's?

If you are not happy with the state of the aircraft before flight (eg. you've been pressured into going with less fuel than you'd like or haven't been able to verify fuel levels to your satisfaction), don't take the aircraft at all, surely?

Yes, this is a textbook utopia and yes, we all succumb to outside influences in the real world, but surely it's a fear for your own life that should stop you taking off in an aeroplane you are not happy with or sure of the condition of?

Hersh

SSD,

Yeah mbike bike has an amber warning light but no analogue guage, I never trust it, for one thing I would think its only accurate when the bike is in a straight line as otherwise the fuel is sloshing about. Unfortunately I dont have a reserve so I am ******ed if I run out. I use the milage method and refuel between 100-120 miles done.

Julian.

As reported by the Beeb:
http://news.bbc.co.uk/1/hi/england/s...es/3201561.stm