PA28 Fuel management

[TotalBeginner]

The longest leg that I have ever flown a PA28 was 1hr 30min in each direction. For this, I used 45min of fuel from each tank.

Recently I've been thinking about manageing fuel in this aircraft on longer trips. Considering that it is not possible to consume fuel from both tanks at the same time, knowing exactly how much fuel (or time) remains in each tank becomes more critical.

I would be interested to know how pilots go about planning fuel consumption on longish routes. I like to consider worst case scenario with regard to fuel consumption and so normally plan to have 1hr 30min fuel available in each tank with a 30 min reserve each side?

[BackPacker]

The POH actually contains very sensible advice plus a practical method on this. Did you read that?

The other methods I've heard were (all based on full tanks):

Fly half an hour one tank, then switch tanks every hour.

Fly on left tank if the big hand on your watch is on the left side of the dial, right tank right side.

Me personally, I just incorporate things in my FREDA check and fly on the fullest tank all the time. But I'm not making trips to the limit of the endurance in a PA28. Oh, and if I have a weight inbalance in the aircraft (flying solo or with a real heavy bloke in the RHS) I try to compensate for that with fuel management, for what it's worth. Not sure if it actually makes a difference though.

[TotalBeginner]

The POH actually contains very sensible advice plus a practical method on this. Did you read that?

No, I must confess I don't remember reading that :(

[BackPacker]

Look in the Normal Procedures; Cruise section. It's a bit too long to copy it here verbatim.

[TotalBeginner]

I'll have to look it up next time I'm at the airfield. The copy that I am looking at must be abbreviated. It only says:

In order to keep the airplane in best lateral trim during cruising
flight, the fuel should be used alternately from each tank. It is recommended that one tank be used for one hour after takeoff, then the other tank be used for two hours: then return to the first tank, which will have approximately one and one half hours of fuel remaining if the tanks were full at takeoff. The second tank will contain approximately one half hour of fuel.

[FougaMagister]

The outfit I did PPL with had a PA28 checklist (which I use to this day) that instructs to start engine on the fullest tank, then change tanks for the power check, take-off and the first 30 minutes of flight. Thereafter, change tanks every 30 minutes (noting the time at which you do it, or doing a FREDA check every 30 minutes). Obviously, that procedure can be amended as necessary if collecting an aircraft with less than full tanks and/or a fuel imbalance :*

That's an easy way to prevent fuel starvation while having a full tank on the other side (yes, it has happened before)!

Oh, and when changing tanks, always set fuel pump "ON", then change tanks, then switch pump "OFF" and check whether the fuel pressure holds. If it doesn't, then revert to the other tank - and amend your endurance accordingly.

Cheers :cool:

[mark sicknote]

There's you answer them:}

Sicknote

[B2N2]

This is my trick for long flights;

First leg, 2 hours, refuel and calculate fuel burn
Second leg 3 hrs, same power setting and leaning technique, refuel and calculate fuel burn.
Should should now have a good average.
Let's say that it's 7.6 gallons/hr, round up to 8 and you can now safely fly long legs and have an hour reserve.
Keep in mind that you absolutely positively have to use the same technique's as in power settings and leaning to make this work.
I have (safely) flown 5 hr legs in a Pa 28-161 with 48 gallon tanks using this trick.
Same altitude, same everything, same day even.....:ok:


Keep in mind that fuel gauges will look pretty scary (empty) when you do this.

[IO540]

To manage fuel properly, one must first find a reliable way of setting the engine to a known operating point for cruise. This means leaning the mixture correctly. For a non-engine-instrumented plane like most PA28s, you would lean until the RPM just drops, and then go a tiny bit rich again. Then check the carb heat still works. Obviously this would be done at a given engine RPM (and MP if VP prop).

Next, determine actual cruise fuel flow. Do two flights, identical profile except for a 30min or 1hr difference in the cruise section length. Start each with exactly full tanks, and compare the refill required. This will give you the fuel usage per hour at that power setting. Never rely on book figures for fuel flow!

If possible, repeat the exercise for two different power settings; one at max cruise power (probably 75% power) and another at about 60% power. The 2nd should yield a much improved range.

Never rely on what anybody previously claims there is in the tank. ALWAYS fill up yourself to the top, or do a physical check to tabs, etc. If the fuel is too low to be physically checked, do not fly - EVER. Even if an instructor tells you there is plenty in there. I have twice walked up to a plane declared by an instructor as having X amount of juice, and it was virtually empty (either because somebody did not log a flight, or maybe fuel theft during the night).

Best thing is a fuel flowmeter (Shadin Microflo etc), especially linked to the GPS. Then you get a constantly recomputed FOB (fuel on board) at the planned destination. Obviously you have to accurately enter the starting FOB into one of these.

[172driver]

There's a very simple trick to this: switch tanks according to the minute hand on your watch. In other words, if the minute hand is in the left hemisphere fly on left tank, if on right, right tank. Doesn't give you the amount of fuel used or remaining, but avoids running one tank dry while having plenty in the other.

[DB6]

On a slightly different tack, if you fill up a PA28 and have two people up front, you will very likely be out of the forward CofG limit, which is why it can need quite a heave in the flare sometimes. Bung 50 kg or so in the back luggage compartment and it gets much easier :ok:.
Fuel balance - look at the gauges every now and then and when one gets visibly lower than the other, change tanks. If you're a fat bastard like me you might want to keep the right tank a bit fuller to balance the belly out.
The only real problem you will have is if you never look at the gauges and let one tank run dry :eek:, otherwise you'll just wonder why the aircraft keeps wanting to roll.

[dublinpilot]

Fuel balance - look at the gauges every now and then and when one gets visibly lower than the other, change tanks.

I've flown plenty of aircraft where doing that would result in a very significant fuel imbalance. Guages on light aircraft are totally crap, and noone should ever rely on them for anything.

Changing tanks based on time is a much better system.

dp

[FougaMagister]

IO540 - that's a very professional and involved way of doing it! Do 2 flights, identical profile etc... all very good when you are an FI, or own your own a/c - much less practical when you rent a club aircraft once/twice a month! I'm not too sure most people would want to repeat flights just to assess the fuel burn. I know I wouldn't.

As for leaning the mixture, it's always highly recommended (certainly on longish trips), but there isn't much point doing it up to 3,000 ft or so; you won't get a significantly lower burn.

I totally agree though about checking the tanks, and if possible, flying with full tanks if airfield performance/mass & balance allow. As I've said before, there is hardly any performance penalty for doing so, and on a PA28 with an engine in reasonable nick, you'll have about 4.5 hours endurance. Incidentally, a new PA28-161 is meant to burn slightly less than 9 US Gallons/hr, but an older engine will use up to 20% more. I do my fuel planning using a 10 USG/hr figure (including power check, take-off and climb), and when checking tanks against fuel gauges afterwards, there is slightly more left than my calculations show. The number of different PA28-160/161 airframes I have flown over the years had a fuel burn varying between 8.5 and 10 USG/hr.

But I agree that a fuel flowmeter is ideal; I have "snagged" PA28s a couple of times due to one fuel gauge becoming u/s in flight and showing empty. If the a/c has no tendency to roll and the engine still feeds OK from that tank, it's obviously a gauge problem and not a fuel leak; having no fuel indication on one side is another good reason for proper fuel management (and to calculate fuel remaining at each waypoint).

Cheers :ok:

[Captain Jock]

When I was a student I was taught a very simple means of fuel management on Pipers. Know your endurance before you start and change tanks with fuel pump on at each FREDA check. It is excessive but you will at least burn each tank evenly.

[mm_flynn]

As for leaning the mixture, it's always highly recommended (certainly on longish trips), but there isn't much point doing it up to 3,000 ft or so; you won't get a significantly lower burn.

While that 'might' be true in a PA-28 (which after all is what this thread is about), it certainly isn't true in other aircraft. At 70% power and 1000 ft, I burn 21 gph full rich and 14.5 gph leaned. That percentage difference on a 3 hour flight in a PA-28 is the difference between arriving with 1:30 of reserves and being a glider!

[Julian]

I use the clock face method in ours, its simple and works.

12-6 Right Tank
6-12 Left Tank

J.

[TheOddOne]

I did a long over-water trip with a friend in his PA28 last Summer, to the Faeroes (great destination!)

He has a clockwork hour-timer rigged up in front of the passenger seat and briefs the pax that it's their duty to keep an eye on it and holler when it does an hour. Then he changes tanks. Works well when you're using the limits of endurance of the a/c. Incidentally, at the power setting he normally uses, we wouldn't have had an alternate if we'd been unable to land at Vagar. At my suggestion, we used about 150 RPM less and would have made it back to Scatsca with reserves...

TheOddOne

[IO540]

I agree fuel gauges are crap and cannot be trusted - except for very few like the 28V TB20GT ones which are super accurate.

IO540 - that's a very professional and involved way of doing it! Do 2 flights, identical profile etc... all very good when you are an FI, or own your own a/c - much less practical when you rent a club aircraft once/twice a month! I'm not too sure most people would want to repeat flights just to assess the fuel burn. I know I wouldn't.

This may sound a useless comment but you pays your money and you takes your choice.

If you want to fly on the cheap, you should not expect the same mission capability.

Put it another way, if you cannot afford to do a couple of flights, total time say 3hrs, and you cannot afford to do them even with 3 people cost sharing the flights and going somewhere for four burgers, then your only option is to fill right up every time and treat the fuel endurance as 3 hours when in reality it might be 5 hours.

The advantage of knowing the fuel endurance is say 5hrs is that you can now do longer flights, and plan your alternates intelligently. Whereas PPL graduates have usually got no idea what the real endurance is - not least because they have never been taught to lean the engine - so they stick to 1hr-2hr trips. This is OK but it cuts out a huge chunk of utility/fun value out of GA, which in turn results in so many people chucking it in very early.

The difference between 3hrs and 5hrs is that you can do a long trip into France; somewhere beyond Le Touquet :)

[PompeyPaul]

When I was a student I was taught a very simple means of fuel management on Pipers. Know your endurance before you start and change tanks with fuel pump on at each FREDA check. It is excessive but you will at least burn each tank evenly.I was taught this, but every OTHER freda check you change. Works for me, come back balanced almost every time.

It still makes me shudder when I check and aircraft and see a full tank on one side, but fuel almost dry on the other. Some student has done the QXC and not been changing tanks.

[Gargleblaster]

Agree, fuel gauges useless, should be taped INOP from the factory. Funny thing is that where I live, they're on the MEL list ! The most useless instrument on the aircraft !

My method is: Change tank everh 30 mins. That way you won't get too heavy on either side.

Piper vs. Cessna fuel strategy can be discusssed ad nauseum, both potentially dangerous in it's own way. My first PPL lesson , I asked "Shouldn't I change tanks ?" "Yup, good idea" said instructor. I turned it to "off". 30 seconds went in silence. Then: Never seen any one react so quicky.

[FougaMagister]

IO540: I use commercial reserves - even when flying a PA28. I.e, 5% contingency fuel, plus enough for a go-around, 30 minutes "holding" fuel, and a diversion to a suitably planned alternate. A bit like an airliner's Computed Minimum Reserve if you will. It usually ends up at around 7.5-8 US Gallons (depending if it's a Cadet, a Warrior or an Archer) leaving about 4 hours' endurance (even without leaning). That still allows to fly beyond Le Touquet.

Cheers :cool:

[IFMU]

OK the 20 billion dollar question, why doesn't a PA-28 have the option to select both? Was it just cost or does anyone know if there is a good reason for it?
G-EMMA,

I don't know about the PA28, but the PA25 (pawnee) comes in a couple configurations. One is a single cowl tank, the other is two wing tanks. Our pawnee with the wing tanks is plumbed to take fuel from both tanks, with no selector. There is a fuel shutoff which is downstream of the tanks. We typically fly for 1.5 hours, and the fuel is never balanced between the tanks. Sometimes the left tank will be very low and the right tank will be nearly full. What bugs me about that is what happens if one tank runs out first? Seems like the fuel pump would rather pull air than fuel, as it is much less work. This is a lot different than a high wing, where gravity wants to push the heavy fuel downhill, and leave the light air in the tank. But when I fly a PA28 I can ensure that I don't run a tank out of gas, by managing the fuel selector.

-- IFMU

[mm_flynn]

There are two different questions being asked here (and a third not being addressed)

1 - How do you make sure you do not accidentally run a tank dry on a longish flight in an aircraft that feeds from only one tank at a time.
- Lots of good answers in the thread

2 - How do you Actually know how much fuel is left at any time
- Fewer good answers (IO's definitely, FougaMagister seems to fly the same or similar aircraft multiple times so uses a close approximation of IO's)

On many aircraft, fuel burn is highly dependant on leaning technique which is one of the reasons pilots are often taught not to trust the book numbers. FMS commercial technique applied by a less experienced pilot without accurate leaning could easily wind up as a glider on a flight that actually had to execute the diversion

3 - (The one not asked yet) How do you operate a maximum range flight. Ie. How much usable fuel is really in your tanks (more important for bladder than integral tanks) and what fuel configuration do you want on landing.

Deakin has an article on Pelican's perch (AvWeb) where he advocates running each tank dry (on separate flights!) so on refilling he can establish exactly how much useable fuel there was, He then advocates, if you have to stretch every drop out (i.e. an emergency) running one of the tanks dry so you have all of your fuel in one tank on landing and minimise the risk of un-porting or being on the slightly less full tank and accidentally running it dry in the pattern. Finally of course as usual, he recommends a full engine analysis and a known calibrated fuel totalizer. And finally, there is an implied caution to make sure you have plenty of enroute diversion options

[IO540]

IO540: I use commercial reserves - even when flying a PA28. I.e, 5% contingency fuel, plus enough for a go-around, 30 minutes "holding" fuel, and a diversion to a suitably planned alternate. A bit like an airliner's Computed Minimum Reserve if you will. It usually ends up at around 7.5-8 US Gallons (depending if it's a Cadet, a Warrior or an Archer) leaving about 4 hours' endurance (even without leaning). That still allows to fly beyond Le Touquet.

This still requires accurate fuel flow information. All the planning in the world will not help if this is not known. Any modern airliner has accurate flowmeters (of the order of 1% accuracy) and I believe most modern ones also have accurate fuel level gauges.

Incidentally, the fuel flow difference between a) full-rich and b) leaned to peak EGT, is about 30%..... a LOT. Most UK PPL training is done full-rich, which robs the plane of a large chunk of its useful range for going places.

[A and C]

I agree with almost all that IO540 has to say on the subject, however if you know the aircraft well you don't have to have any more than an EGT indicator to get accurate fuel flow numbers.

On both the Robins that I have owned (same engine as the PA28) I could get the fuel flow numbers to the nearest litre, I fly (by UK GA standards) long flights direct to northern Spain and the far south of France from Oxfordshire and have never had a fuel management problem.

To achive this I make sure that the power and mixture are accuratly set and at the end of a flight check that the fuel uplift matches the plog fuel burn (to monitor engine performance).

As for fuel planning I use the basic commercial reserves as outlined above however on the longer flights I use the en-route alternate system. this cuts the contingency fuel down to 5% overhead the destination airfield and gives about 30 Nm more range but requires carefull fuel monitering
at each waypoint along the route.

The biggest problem with the average PPL holder is poor education when it comes to fuel management, most clubs treat the mixture lever as an "on-off switch". I have found when doing recency checks for a local flying club that most pilots don't even know how to set 75 or 60% power and this is essental for accurate fuel flow at these are the numbers in the flight manual with the performance graphs.

Can someone please tell me how most new PPL holders have got a licence and never used the mixture lever correctly?

[llanfairpg]

Can someone please tell me how most new PPL holders have got a licence and never used the mixture lever correctly?

For the same reason instructors get ratings without being able to give detailed comprehensive instruction.

My tip is always leave one tank with 15 minutes more fuel in it because thats the tank you want to run on in a fuel emergency landing

[172driver]

Well the problem is knowing what's in the tanks and what comes out.

In a GA context, there really are three scenarios:

a) fly your own a/c, ideally equipped with a good fuel-flow meter. This is the ideal situation, as you know your machine AND have the instrumentation to check what it is actually up to. Great, seems to be IO's circumstance.

b) fly one or two club a/c regularly, therefore get to know them well and develop empirical data. Some may even have a flow meter.... mostly (with exceptions) my situation.

c) fly a wide variety of spamcans w/o flow meters. Now we're down to guesswork or book numbers with all the associated problems. This, alas, probably describes a good portion of GA flying

My personal approach is to err on the side of caution and I usually adopt an approach similar to Fouga's - also because I seem to be in a similar situation, as mm-flynn points out.

Leaves us with the question on how to plan a maximum-range flight. My - short - answer would be: don't with an unfamiliar a/c unless it is equipped with a good (and working) fuel flow meter. I've had to do this a number of times, and my approach is to do a couple of short(ish) hops and see what really happens. Most of the time you can start a long journey by doing a few short legs first, figure out what's what and then go about the long-haul (well, in GA terms) planning.

Now seriously drifted from PA28 fuel management :)

[IO540]

I think that's exactly it: you cannot do a max-range flight with an unknown aircraft, working on POH data.

The two test flights I referred to earlier can be easily done in the context of two trips somewhere.

[Julian]

I agree that fuel management is something that woofully inadequately taught on the PPL, in fact when I look back on mine I dont think they spent more than 5 mins on the subject! It was only when I really started flying regulary in the club/group atmosphere you start to pick up on things and supplement your PPL - as keeps getting said "Its a licence to learn"

I like to keep it simple so hence the clock face approach, I think doing it every FREDA check is a bit excessive but it works for you then stick with it. You also dont need a fuel flow meter, just look at how many litres they put in on your return and you can easily work out your gallons/hr, again keeping it simple, not 100% accurate but good enough.

Leaning again is something I really got my teeth into post PPL and I think something which wasnt stressed enough on my PPL. A mate (from our group) and myself did an experiment in our PA28, 2 flights upto about 4500, first without leaning and second with. We got from 11 USG/hr down to 7.8 USG/hr, so quite a saving on a long trip and also quite a range improvement (hate the phrase "mission capability" - makes it sounds like I am going to bomb someone :) ). These are approx figures as we worked it out from the uplift of fuel back on thre ground, but as pay a dry (not wet) rate for the aircraft its all money that stays in our pockets not Mr Browns.

My 2p worth.

J.

[Final 3 Greens]

Deakin has an article on Pelican's perch (AvWeb) where he advocates running each tank dry

I know of one guy who did this in a PA28 and went to the fuel selector, which ithen jammed requiring an immediate forced landing :mad:

[mm_flynn]

A mate (from our group) and myself did an experiment in our PA28, 2 flights upto about 4500, first without leaning and second with. We got from 11 USG/hr down to 7.8 USG/hr, so quite a saving on a long tripOn a four hour flight it is also the difference between 1:45min of reserve and 0:06 minutes :ooh:

[TotalBeginner]

OK the 20 billion dollar question, why doesn't a PA-28 have the option to select both? Was it just cost or does anyone know if there is a good reason for it?

I think it has something to do with the low wing. Because the fuel tanks are below the engine, fuel is "sucked" from the tanks by the engine driven pump (or electric pump). The problem of running on both tanks is that if one were to run dry, the pump would no longer be able to "suck" from the remaining tank.

It's hard to explain but try this...

Get 2 cups, each with a straw. Fill one cup with water and leave the other empty. Now put both straws in your mouth and suck. You should find that it's almost impossible to draw water from the cup that is full. Fill them both, and you have no problems!

[llanfairpg]

Two fuel systems provides additional safety, the fuel in one tank could be contaminated,( I have known private owners fill one side with avgas and the other side with automobile fuel) there could be a blockage or leak in part of the system in that side. Having the ability to run on the other system allows the engine to continue running in these circumstances.

[Keef]

Leaning makes a difference at any altitude. I normally fly an Arrow III, and at 1500 feet, 23 ins/2300RPM/fully rich, the flow gauge indicates 14.5gph. if I lean it to just rich of peak, it drops to about 11 gph. The cruising speed is slightly higher when leaned (the actual speed depends on loading).

Fuel management - I use the "clockface/half hourly" method.
The only reliable fuel gauge is to look into the tanks before takeoff. I work on "full" and "tabs". I also stick to the same "fuel reserves" as mentioned above by FougaMagister. If it's below 1½ hours, I should have landed already.

Over several years, I find that the fuel burn is very consistent. Leaned to an indicated 11 gph, it does indeed burn 11 gph. That's not to say yours will, but it works for me.

[Tinstaafl]

Similarly to '540, I check the fuel consumption in each of the aircraft I fly - and I fly in general aviation for a living.

The aircraft I fly have multiple tanks (up to 6) but my method is similar to '540s: On a typical trip that allows full tanks - and there's always one, soon enough - I do from start to top of climb on one tank. After setting cruise power & leaning I change to the other tank and note the time interval since start.

I then burn only from that tank until I have to reduce power during the descent & approach. Prior to reducing power I change back to the main tank and note the time interval.

After shutdown I note the interval again & have the tanks filled. The fuel consumption from the cruise tank gives me cruise power fuel flow. Using that FF for the intervals where fuel was consumed for the departure & arrival gives me the figure that would have been burnt if that entire period was in the cruise. The difference between that amount and the amount that was consumed from the departure & arrival tank gives me the additional departure & arrival fuel for required for a typical flight.

Next time I need to plan fuel consumption I need only to plan the entire leg at the measured cruise fuel flow and add the calculated departure & approach allowance.

Until I can do that for an aircraft I plan fuel consumption conservatively. In all cases I always check fuel uplift against time flown to get a block fuel flow for that aircraft. Periodically I revisit the extended method to check accuracy.

When I was flying air ambulance between the Shetlands & Scotland I would not have been able to do some trips without an accurate fuel consumption. The availability of alternates would be so limiting that a rough & ready fuel rate wasn't sufficient.

[llanfairpg]

A lot of the above cant help you if you have a fuel leak in flight, gauges are the only real means of detection until it all goes quiet. Some have mentioned that the gauges on some aircraft are very inaccurate but what they really mean is that they tolerate flying unservicable aircraft.

Being a professional pilot dosnt make for better fuel planning(as suggested) all the low fuel emergencies I can remember involve professional pilots.

[IO540]

A lot of the above cant help you if you have a fuel leak in flight, gauges are the only real means of detection until it all goes quiet. Some have mentioned that the gauges on some aircraft are very inaccurate but what they really mean is that they tolerate flying unservicable aircraft.I agree, but beggars can't be choosers.

A renter can't walk into a school and demand they rip out the crappy 30 year old gauges and replace them with new ones.

Duff fuel gauges are an integral part of general aviation - tolerated along with all the other crap we put up with.

The only "escape" is to rent from one of the very few schools that have modern fleets, or scrape up enough money to buy something decent like a TB20GT with a 28V system whose capacitive fuel gauges are accurate to a few percent. But the TB20 will probably have a flow totaliser anyway.

Of all the planes I have ever rented, not one had gauges usable to the extent of being worth reading for any fuel management purpose. This includes PA38, various PA28s, C150, C152. I have never trained in any plane whose fuel gauges were useful.

That's why one has to either play very conservatively (starting from a physical check) or establish the fuel flow experimentally and then basically work on timing the flight.

Being a professional pilot dosnt make for better fuel planning(as suggested) all the low fuel emergencies I can remember involve professional pilots.

That's because professional pilots think they know how close to the line they can go :) But ultimately you are only as accurate as your equipment, and an awful lot of "professional" flying, at the piston end of things, is done in old wreckage, which is just the same as the wreckage used for training, only bigger and with more engines. The pilots of the ancient clapped out Trislanders for example have no better idea how much fuel they really have than a GA renter.

[llanfairpg]

Some have mentioned that the gauges on some aircraft are very inaccurate but what they really mean is that they tolerate flying unservicable aircraft.

[Julian]

Isn't a fuel gauge required technically to be accurate at only one point - that when its reading empty?

J.

[Tinstaafl]

Depends on the rules of the country. Under FAR, yes. In Oz there must be a fuel guage calibration card that gives the correct** quantity for the gauges divisions.

Even so, most GA gauges measure [i]volume[/] but fuel consumption is by weight. That in itself affects how accurate the gauges can be to determine endurance.

As for the accuracy of a fuel gauge, the certification requirements aren't that high a hurdle to jump. What might seem rather poor can still be within requirements without necessarily being faulty.

**But then ground attitude doesn't have to equate to flight attitude. Oops, another contributor to fuzzy accuracy.

[PompeyPaul]

OK the 20 billion dollar question, why doesn't a PA-28 have the option to select both?Nope, that would be where on earth has G-Emma been for several months ?

[BackPacker]

I only post on PPrune whilst sat here revising for exams.. had a break for a while now started on Nav the last PPL exam for me other than the RT practical!!!. It makes a nice change from getting annoyed with trying to get the right answer from the devils wheel.

Does that mean that your current series of postings is going to be the last ever, assuming you pass the upcoming exam? That would be a shame!

Good luck with the nav exam though.

[IO540]

most GA gauges measure [i]volume[/] but fuel consumption is by weightThat is an interesting point.

For a liquid, the two are practically the same. Avgas expands only 0.1% per degC. The biggest change one is likely to see (GA) is say +35C on the ground, down to -25C at FL200. That is a volume shrinkage of 6% - too little to see even on an accurate fuel gauge.

I believe you can see this on a flowmeter though. The standard Floscan 201 turbine flowmeter used with nearly all fuel totalisers in GA measures volume flow, I believe. So at the above FL200 example, the fuel mass flow will be underestimated (i.e. the error is on the dangerous side) by 6% but does this matter? You are still working in volume units; well I am - in USG.

If however your flowmeter was set to read lb or kg then you would have a real error because at low fuel temperature the flowmeter is under-reading because the fuel is heavier. This means the "FOB at destination" projection (from the standard flowmeter-GPS functionality) will be optimistic - if the flowmeter is set to read lb or kg.

Interesting!

Not that one should sail quite so close to the wind for this to matter...

[TheGorrilla]

Some of the few things I've learn't about GA fuel planning when flying the likes of a PA28 on a longish cross country.

Plan your fuel based on time and don't get too smart calculating it to the litre using miles per gallon or gps functions. Don't assume you'll be flying in a direct line to your destination either!

Look at the weather and look at alternative airfields and consider how much fuel it'll take to get there from your destination. Don't just say, use your usual 45 mins reserve all the time (fine for your back yard local flying).

Keep the ball in the middle and change tank every half hour or so first checking for suitable fields and turning the electric pump on before messing about with the selector.

Never think "it's ok, I've got lots of fuel".... Especially when you're lost!

Don't smoke at the pumps.

Don't run with scissors.

Stay in school.

Do as your mummy said.

[IO540]

Don't smoke at the pumps.

How did you learn that one? ;)

[Mungo Man]

The outfit I did PPL with had a PA28 checklist (which I use to this day) that instructs to start engine on the fullest tank, then change tanks for the power check, take-off and the first 30 minutes of flight.

I too was taught to start up on one tank then change tank before power checks, but I always start up on the lowest and take off on the fullest tank. I don't think its the smartest thing to take off on the lowest tank as implied above.

[tp555]

Back on my time on the PA28 I was taught to start on the RIGHT Tank then switch to the LEFT during taxi / checks.

Sole reason being in the event of an EFATO, the action of moving the fuel tank selector from LEFT to OFF is easier than RIGHT to OFF.

Always think worst case ;)

[dublinpilot]

Sole reason being in the event of an EFATO, the action of moving the fuel tank selector from LEFT to OFF is easier than RIGHT to OFF.

I can't see that! There is **** all difference! :}

dp

[tp555]

Make life as easy as you possibly can for yourself before something goes wrong. 6P's and all that.

Just an airmanship thing I do, only a suggestion.

[IO540]

Sole reason being in the event of an EFATO, the action of moving the fuel tank selector from LEFT to OFF is easier than RIGHT to OFF

I would rather concentrate on doing a half decent landing in an EFATO. Turning off the fuel cock will do no good if the wing tank is ruptured, and if the plane is undamaged then it doesn't matter anyway.

It is only for the specific (and I suggest very rare) case of both wings undamaged but the engine fuel hoses damaged that turning off the fuel cock is relevant.

[crispey]

AT MSF(Manch) we were taught your method Mungo Man.Take off on the full one.

[FougaMagister]

I agree with the above comment re. taking off on the fullest tank. Let me elaborate; the outfit which checklist I refer to had our PA28s fully refuelled between each and every flight, so we always had full tanks on start-up anyway (AVGAS is cheaper Stateside :ok: ).

Cheers :cool:

[ArcherCol]

I always do fuel planning for our Archer II at 40l/hr (giving 264 mins endrnc) and lean out in flight. Our motor has 50 hrs to run before replacement and on a 3 hr flight came back at 33.5l/hr burn rate. So better to plan at upper rate.

Another thing I was taught was to take off and land on the left tank so if you had to change tanks quickly it is easier in the PA 28 from the left hand tank, whether shutting off or changing to RH.

I agree with IO540 I'd rather walk away from a landing not having shut down properly than stuff up completely. Remeber every landing you walk away from is a good one.

Cheers