Hello: Does anyone fly their tanks till the engine starts sputtering and then change to a fuller tank? I have been flying till showing 2.5 gallons left and changing but when refilling find I have 5-7 gallons still in the tank. I have a 64 Cherokee 235 fixed prop. Just wondering what is the best way to do this. Don't like the sputtering even tho the engine comes right back in 5 seconds when changing tanks. Thanx JOhn
I never fly beyond the 45 minute rule. For me that means I always land with at least 15 gallons of USEABLE fuel on board. Helps keep me from being on of the largest statistics for off airport landings and crashes. LACK OF FUEL!! I never run one side completly out. Why test your luck?
TOD
4213f
LANCE
Edited 1 time(s). Last edit at 11/21/2008 09:28AM by peavydj.
Some older planes recommend running one tank dry in their POH for maximum range. I believe the manufacturers have since changed their position. There are lots of things that could go wrong when you run a tank dry. For instance, what if you vapor lock? What if the selector breaks, or the valve breaks? Assume a non-visible leak in the other tank, thus leaving you with no way out of the situation. Is it really worth the risk for the additional range? I think not.
Depending on the trip and the terrain, I like to leave at least 15 minutes of fuel in "tank a" in the event of just such an emergency. If I'm flying at night, or over unfamiliar or unforgiving terrain, that number is adjusted accordingly.
I've got a 235 also, and although I have done it on occasion I don't make a habit of it because my gauges are well calibrated and I can tell within the last gallon of when it's empty. When I did empty a tank in flight, I was close to the strip and had plenty of altitude.
Found this thread interesting since it is a question I have asked myself. I prefer to change tanks when near a decent place to land in case something goes wrong and so far have never run any tank dry. I have found that my gages are pretty accurate when getting near the bottom and I can guess within a gallon of what is left. I think that this is one of the nice things about low wing planes since the dihedral creates a natural sump, also good to separate water.
When fuel look tight I switch away from one tank when there is still 30 minutes or so available in it, and run on the other tank(s) until they go dry. Usually they don't, but at least I know that every drop of fuel will be used. I switch back to the known-good tank on approach to avoid any unpleasant suprise.
Well, I do it regulary. Our PA28-235B has four tanks, and switching them just before running dry would leave some 2 to 3 gallons per tank. Well, I don't like the idea of beginning an approach with just 2 to 3 gallons in the selected tank. But having those 2 to 3 gallons all together in the last tank, would make a comfortable reserve of 8 to 12 gallons.
Here is how I do it: I fly one tank for 30 minutes, then switch to a tank of the opposite side - I follow the minute hand of the clock: if it points to the right, I use a tank of the right side, and vice versa. Keeping track of the switching scheme, knowing the fuel consumption of the bird and checking the fuel gauges I'm aware when one tank will run dry.
I will then closely monitor fuel pressure, and when I see it drop, it's time enough to switch to one of the other tanks. Sometimes I miss it (distraction because of ATC, for example), so I switch tanks as the engine sputters.
As I also don't like the engine going quite, I do this only when en route, at least at 3000 feet AGL.
Fuel leaks ar no big concern: I ones took of with a very full tank. By looking out of the window, I could see the excess fuel coming out of the vent line - and believe me, it's a real remarkable fuel flow. So fuel leaks might be easily detected by the outside scan.
Not to be rude, But am I the only one that has a problem with this thread? Vfr rules 45 minutes of fuel, IFR 1 hour of fuel. Now I know it doesn't say you can't run a tank dry. By I can't find a single reason in the world to risk injury to me, my passengers and those on the ground, or my fellow pilots (bad PR) for running a tank dry and pushing my luck. To many things can go wrong. If you need more range ..... schedule a fuel stop.
Running a PA28 main tank dry when you have plenty of fuel in the other is a non-event. Mine doesn't make the engine sputter at all, it just simply stops making power and begins windmilling abruptly, just as though you pulled the mixture back to idle cutoff. Kicking on the boost pump and switching to the other tank and the engine lights right back up immediately.
Those who said above about what happens if the selector breaks? Well what are you gonna do if the selector breaks while switching from one tank to another when there's fuel in both? If it's gonna break while moving the knob, it'll probably shut both tanks off and break in the middle of being halfway between left and right and you're screwed anyway. I say the worry about the fuel selector valve being more likely to breaking when you have run one tank dry is extremely far-fetched. If you're that untrusting of your fuel selector valve, you should never leave the ground with the plane until you've had the valve repaired of replaced and positively known to be in perfect working condition.
Running a PA28 main tank dry when you have plenty of fuel in the other is a non-event. Mine doesn't make the engine sputter at all, it just simply stops making power and begins windmilling abruptly, just as though you pulled the mixture back to idle cutoff. Kicking on the boost pump and switching to the other tank and the engine lights right back up immediately.
I guess this just begs the question: Why would you want too?
I'm not endorsing the practice, and don't make a regular habit of it, but I have done this on occasion. I've found that you can generally watch the fuel pressure gauge, which will drop suddenly prior to the engine being starved for fuel. If you time it right, the engine will never miss a beat. This is not to discount the potential risks of doing so that have already been discussed here.
Is running out of fuel before switching hard on the fuel pump? I know that for some if not all trucks with multiple tanks drivers have been cautioned to not run the tank dry for this reason.
Here we go again............
I've had the fuel selector fail while switching tanks, and like "NoProb" suggested, it stopped between positions. By it's nature, the valve is most likely to fail when being moved, no surprise there. Safe practice dictates moving it under the most favorable conditions (altitude/ proximity to a strip) every time unless it's just not possible. I think everyone here knows (or should know) If we want to fly we can't eliminate risk and the best we can do is manage/minimize it.
Frank L, There aren't many reasons why anyone would but here were mine. One was to know how what "Advance notice" I might expect and how much time and altitude would be lost recovering should it ever happen sometime other than when I was circling the airport at 5,000 AGL. (It didn't help much when the valve stopped between positions in the incident above but at least I knew right away what was happening). The other was because I installed a full set of new gauges and senders. As careful as I was to set them up during installation, I wanted to verify the gauges were as accurate as I could make them when the tanks were running low. I ran all the tanks dry in flight (not the same flight), 3 of the 4 needed a tweak to make the engine die just as the needle lined up with the empty marking. I have the only plane I know of that has gauges that accurate, and the only way I knew to get them that way involved running the tanks dry in flight.
You could have easily calibrated your gauges without running tanks dry in flight. You could have run them dry on the ground. You could have drained them and then added fuel to calibrate them. I don't see why you'd think that the ONLY way to accomplish the task is to run the tanks dry while in the air, please explain.
If that valve had failed on you when you had fuel in both tanks, do you think the engine would have starved? Would fuel from the tank that you had just run dry not have been able to move through the system? What if the selector knob broke, and the valve stuck on tank A? There are lots of contingencies that get awful hard to manage when one tank is dry.
There is only one reason to run a tank dry in flight, and that is to maximize the range of the airplane. As the initial poster suggested, to make sure that you're not leaving gas un-burned when you land, in an attempt to stretch the range, you burn tanks dry. To me and many of the other posters on this thread, that seems too risky for the minimal reward. Leaving two or three gallons in there isn't going to hurt anyone.
Rob Wrote:
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> For IFR, it's
> a bit different. You have to have enough fuel to
> fly to your intended destination, then to your
> alternate, then continue for 45 minutes. Worth
> mentioning that the VFR flight can not begin
> unless the conditions are met, the IFR flight
> can't continue.
So you miss the approach at your destination and proceed to your alternate which was forecast to have alternate minimums all day long. You arrive at your alternate and there is a snow squall over the field bringing the field to 100 and an eighth conditions that is expected to last 15 minutes. You elect to hold over your alternate airport for those 15 minutes because there is no suitable second alternate within range. You shoot the approach when the weather improves and you land with 30 minutes of fuel remaining. You are perfectly legal to use that reserve fuel and in this circumstance it is unavoidable. That is why you are carrying it.
In this day and age with the added costs of carrying more fuel than necessary, there are times when many air carrier flights are flying just that tight.
Romeo Yankee, I propped the empty tanks in a position that should have mimicked as they would be in flight, then added fuel 1 pint at a time for the first gallon, then one gallon at a time until full, and adjusted the float arm accordingly. I picked 1 pint increments for the first gallon because little as it seems, that's what my manual says is unusable. I wanted "Perfect" and would have bet my life that's what I was going to get but it didn't quite work out that way. These are not the factory Stewart Warner Dog Sh*t units the factory stuck us with and although they were close, I wanted "Perfect" and was willing to spend a little more time to have it. When the width of the gauge's indicator needle completely covers the empty line on the gauge's face in smooth, level flight, the plane sputters to a stop. (I may be wrong but I don't think it gets any better than that).
Perhaps You didn't understand but in both of my other posts on the subject, I said I have only run tanks dry under controlled conditions. I don't know how much more clear I could have been than by saying "Close to the strip and had plenty of altitude" & "Circling the field @ 5,000 AGL". I don't believe light-loading is worth the risk, I don't condone or recommend it, and never empty a tank during a normal flight. I probably land with more reserve fuel than 99% of the pilots at any given field, the least I ever remember having on board after a flight was almost 30 gallons. (more than 2 hours in cruise)
I wasn't working on new gauges when the valve malfunctioned so there was fuel in both tanks. (That pesky little valve shaft roll pin problem that was unique to 235's and Cherokee sixes). I was almost 10 miles from the strip and I did all the in-flight diagnosis I needed to know the selector lever was no longer attached to the valve and prepared to make an off-field landing. I had just flown over the top of the Big Bear California area and had lots of extra altitude, and the small amount of fuel that was getting past the valve allowed the engine to run at a slightly fast idle (About 800-850 on the ground) so as it turned out, I got to land on the strip instead of one of the local dairies. (Just barely, but who could ask for more under the circumstances)
as posted before: 4 times 2 to 3 gallons remaining in the tanks don't make me feel very comfortable. I honestly prefer to have those 8 to 12 gallons total located in one (the last) tank.
I like to know where my fuel is, which implies to know also where it NOT is. And this implies to run the tanks dry - of course NOT the last one!
So I do it on the long hauls, and I run the tank(s) dry with comfortable altitude and near convenient places.
Like NoProb and JimR have stated: it's an non-event.
I have gone up to altitude and ran the tips empty to watch all of the gauges react so I know what they should look like if I was staring at them at the specific time I ran the tanks empty. But I dont like to make a practice of that sound or lack there of. Also if your tank selector broke while switching tanks I think you better go back to your Mechanic and tell him he is an big trouble for signing off your annual because if that thing goes that bad in one year of last inspection you have bigger problems.........my 2 cents
BKF1968, Amen to that! The fuel selector incident was a massive learning experience for me but unfortunatly the parties responsible for it never got thiers. That happened about 6 mounths after I bought the plane, and was the event that taught me I better start thinking a little more for myself rather than roboticaly following the manual's instructions. The plane had belonged to the same person for the last 40 of it's 42 year life and the same mechanic had done the annuals since the early 70's. Although The first for that problem had been complied with, the second (the one that really fixed the problem) had been overlooked by everyone. The owner, his mechanic, and the person I paid for a pre-purchase inspection. I suppose if I would have had an accident there may have been reprocussions for one of them but the general consensus around here was nobody at the FAA would be interested otherwise, so I wrote it off to education and good fortune. It also taught me that I shouldn't just switch to the fullest tank before landing when the one I'n on has plenty, and if I'm going to swith them anytime, I should remember that event and have a good "Plan B" in mind.
I am sure the fuel pump sucking vapors while the tank was run dry,and no aviation fuel going through the pump, probably isn't the best thing for the fuel pump seals.
NoProb Wrote:
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> Those who said above about what happens if the
> selector breaks? Well what are you gonna do if the
> selector breaks while switching from one tank to
> another when there's fuel in both? If it's gonna
> break while moving the knob, it'll probably shut
> both tanks off and break in the middle of being
> halfway between left and right and you're screwed
> anyway. I say the worry about the fuel selector
> valve being more likely to breaking when you have
> run one tank dry is extremely far-fetched. If
> you're that untrusting of your fuel selector
> valve, you should never leave the ground with the
> plane until you've had the valve repaired of
> replaced and positively known to be in perfect
> working condition.
This is actually a good point. When I first bought my aircraft I felt the fuel selector valve was hard to move. My previous GA experience in smaller aircraft went back many years but the valve just didn't feel as I remembered. I replaced the valve outright with a new one. It turns out the valve also had a couple of drops of fuel seepage with movement and the fuel pump on. After replacement there is no more seepage and no effort required to move it. The new one slides effortlessly to its detent, just as I remember when I flew new Pipers.
A tight or difficult to move valve is not normal and flying with one is the only way you are going to shear the pin or break off the valve handle. Some valves can be overhauled with a fresh lubricated o ring and some need to be replaced outright. As years slowly pass you may not actually realize the valve has become more difficult to turn.
When you have a bad one and you install a new one it's night and day.
I am amazed that we have such differing levels of risk when it comes to fuel management. Take a couple of hours and read through the 235's accident database and you will find that fuel starvation is a common problem.
After a 400nm trip I needed 55 gallons to fill up, that is the most I have ever put in on a refuel. One of the reasons I purchased a 235 was it's ability to carry a large quantity of fuel....I never want to run out. Why take chances and run a tank dry with 4 tanks and 84 gallons? You can eliminate the fuel starvation issue with this plane why not do it?
Regards,
Justin
PP ASEL
66 PA-28-235
Edited 3 time(s). Last edit at 11/23/2008 09:03AM by jaholder.
