Checking Fuel Contents in Light Twins

[loftustb]

I hire a variety of light twins from a variety of FTOs and feel some unease over the way fuel contents are "checked". Some twins are supplied with a calibrated fuel dipstick, but find me one operator who hasn't broken it in the first week of use and not repaired/replaced it. Generally, you can't visually check the contents and fuel gauges are notoriously unreliable.

Some places rely on the paperwork sums - remember the crash on the south coast attributed to this method? There was another incident recently of fuel starvation over the Channel - the Captain had asked for the a/c to be refuelled and assumed it had been done, but the faxed request hadn't printed out in the refueller's office.

I worry when the person behind the Ops Desk says he thinks the a/c was refuelled before the last flight and Joe Bloggs only flew an hour so it should be ok.

It's the PIC's responsibility to ensure sufficient fuel, but how exactly are we all doing that?

[flyhardmo]

Usually I use 2 independant methods such as fuel guages, dipstick or visual checking. Some aircraft like the duchess have calibrations inside the tank. Its also always a very good idea if you visually check the fuel in the pre-flight to check caps and fuel contents. Have heard of a few accidents where this wasnt done.
Also a good idea to make a dipstick. Drain the tank and add 20lts then mark it at every 20lts.... easy but effective and reassuring.

[Tinstaafl]

If you're going to do that, you're better off adding the published unuseable fuel to the drained tank THEN putting in calibrated amounts. You have to wonder about the unuseable fuel that may or may not be included in XYZ Flying School's home made dipstick

[whatunion]

tech logs should really include a fuel diary so that loaded fuel can balance with fuel on board etc(mandatory for public transport).

filling the tanks up full before flight is a sensible option if weight permits, unless you were the last pilot also, thats what i did when flying charter.

its amazing how relaxed some operators are in regard fuel.
never trust fuel gauges remember the aztec were the gauge contents were being indaicated by the internal tank liner pushing against the transmitter.

i flew a cessna recently were the right tank guage was u/s and had been fo awhile but there was no tech log mention of it but the a/c was taken out of service because the turn co ordinator didnt work?????

[englishal]

I think your best bet in a light twin like the Seneca, where you cannot visually check the fuel when its below 3/4 tank or whatever it is, is to insist the A/C is topped up until you can see fuel. In a Seneca, if you can see fuel, you know you have more than a couple of hours.

Tech logs are all very well, but I don't trust them after seeing many people fill them out after a flight and guestimate the figures, usuallyn in a hurry to get home, and what if they make a simple mistake....

EA

[Chilli Monster]

With the Seneca II I use the 'rib' that's visible through the fuel filler. With that just covered the tank has 140 litres.

With that in mind if you're worried about weight and balance then you can fill it in terms of "Rib plus xx litres".

On the Aztec - if in doubt fill the inners, it doesn't hurt. If you've got the wingtip fuel gauges on the outers I find them quite accurate. If not then treat visible fuel as half tanks and go from there.

[Flyin'Dutch']

Seeing is believing, not just for light twins.

So visual check or dipstick.

Anything else and on your head be it.

FD

[rustle]

Anything else and on your head be it.The third most useless thing in aviation:
Runway behind you
Fuel in the bowser
Fuel on your head ;)


Visual check. Always.

It doesn't take too much effort to make a reasonably accurate dipstick so's you know you have enough...

[Flyin'Dutch']

It doesn't take too much effort to make a reasonably accurate dipstick so's you know you have enough...

Not for Senecas which have long shallow tanks (TBs are similarly equipped and their gauges are the worst I have ever encountered)

FD

[IO540]

My post year 2000 TB20 has the most accurate gauges I have ever seen. More accurately, it has the only usable gauges I have ever seen :O The gauges are accurate within 1mm on the needle position i.e. about 3% of the tank capacity.

So it is technically feasible.

I would never trust any paperwork on principle, having seen errors personally and having seen the blind faith which some instructors have in them.

[whatunion]

never trust one man, one engine, one gauge. best advice i was ever given.

[fireflybob]

Pretty appalling state of affairs when the a/c manufacturers cannot provide a reliable way of measuring the fuel quantity on board. Why cannnot the manufacturers supply calibrated dripsticks?

Big a/c have capacitance types guages which are much more accurate - are they so much more expensive that they cannot be fitted to light aicraft?

Not surprising that the commonest cause of engine failure on light aircraft is lack of fuel and /or mismanagement of the fuel system. We have guages in US gallons in a country (UK) which has been brought up on imperial gallons and then we fill up in litres - a recipe for disaster if ever there was.

[TonyR]

I fly a lot of different aircraft, Our TB20, we know it will burn 52 liters ph taco time and it can always be filled so no real problem.

My Rallye has a sight glass tube in the cockpit, easy to see.

Seneca II can be filled to visual and will give at least 2 1/2 hours when you can see fuel, you would never want to fly with much less anyway.

The Cessna 340 with 6 tanks gives me the most trouble, fill it and you must fly alone. so I like to see some fuel in each tank. and I know I can work it out from there

You must know the aircraft well, the exact fuel burn, and not listen to anyone about how much fuel they say they have in it.

Tony

[Tinstaafl]

Most accurate fuel gauges I've ever experienced were in a 1970or '71 A36 Bonanza I used to operate.

[IO540]

fireflybob

Capacitive gauges do exist (I have them) and aren't particularly expensive but I don't think there is a legal retrofit option available for most older aircraft, and if there was, few owners would want to pay for it, presumably on the grounds that a) they can't afford it and b) flight planning should be done such that fuel gauges are superfluous.

The last one I agree with; one cannot fly a plane the way one drives a car... stop and fill up when the red light comes on.

It is an interesting argument... if taken literally, there would be no use (in GA) for fuel flowmeters of any sort, never mind ones linked to GPS that give you a constantly updated "fuel at destination" figure.