Running a tank dry in flight

[Shadrach]

Quote: Jsavage3

Shadrach, please explain the how & why one needs not worry about contaminants being pulled into the fuel lines when running a Mooney's fuel tank dry.  Does the fuel tank design "filter itself" somehow prior to the fuel pickup point?

[DaV8or]

Avoid the whole problem and get a fuel totalizer system of some kind. I have one and it is reasonable accurate, therefore no reason to ever run tank dry. Keep some of your researve in each tank.

[Shadrach]

Quote: DaV8or

Avoid the whole problem and get a fuel totalizer system of some kind. I have one and it is reasonable accurate, therefore no reason to ever run tank dry. Keep some of your researve in each tank.

[RJBrown]

There are times when utilizing the maximum range of a aircraft is helpful.

One such flight was from Brownsville TX (BRO) to Denver's Centennial (APA). The distance is 900.5 Nautical and the still air, no reserve, range of the plane was 1000.

To increase my safety I chose to run off one tank Knowing my full 45 min reserve was in the other. At 14500 MSL, 9500 AGL I flew along with one hand on the fuel lever waiting for a stumble. Felt the stumble and switched over. Landed with 10 gallons.

Centennial suspended arrivals with me 30 miles out. KNOWING my fuel situation allowed me to spend fuel holding over cassi (VFR) instead of rushing off to a different airport, or declaring an emergency.

That plane had a fuel totalizer I trusted but I still felt more comfortable getting it all out of one side before switching over.

I never want to be in a situation where I have the "some" fuel in the "other" tank but don't really know how much and am forced to use it.

One time years ago I had a low oil situation. The plane was down to 2 quarts having blown 5 over if less than an hour. Once over an airport 5000+ AGL I attempted to shut down to protect the engine. It would not stop rotating no matter how slow I got. One thing this showed was that air was still pumping through the engine and past the turbo. Any restart did not include running the starter.

Before using this method I recommend it be tried comfortably above the airport of you choosing to get the feel of what YOUR plane will do. As for me my 231, same plane as a Rocket and the current J all performed this type of exercise faultlessly. 

If you PLAN to do it the swap only takes seconds and is a non event.

[Magnum]

I've ran a tank dry once, it was the first time flying a Mooney together with a CFI. When he saw the fuel pressure fluctuate he switched tanks and I switched the fuel pump on. A couple of seconds later the engine went out and came back to life two or three times and then ran continously. The problem was every time the engine went out and came back the RPM went over the redline as the prop governor was not fast enough to react. Sure, we should have reduced power immediately but I didn't think of that before. For me that is reason enough to NOT run a tank dry.

[Shadrach]

Quote: Magnum

I've ran a tank dry once, it was the first time flying a Mooney together with a CFI. When he saw the fuel pressure fluctuate he switched tanks and I switched the fuel pump on. A couple of seconds later the engine went out and came back to life two or three times and then ran continously. The problem was every time the engine went out and came back the RPM went over the redline as the prop governor was not fast enough to react. Sure, we should have reduced power immediately but I didn't think of that before. For me that is reason enough to NOT run a tank dry.

[Magnum]

That flight wasn't in my own Mooney and I haven't flown it since so I don't know about condition of the governor. I think we stayed below 2900 and IMHO that is the maximum allowed for a short period of time.

It was like pushing the throttle from idle to full power in a split second - IMHO every engine will overspeed in this case. I don't want to do that to my engine, even if it won't hurt. It is just the way how I want to treat it.

The next time I'd first reduce power to idle, and then switch tanks. But I'd only do it if it is necessary to prevent an emergency.

[tablor]

Old thread but one that I had missed, sorry to revive it if anyone minds - I've never done it, but have read the POH regarding using a tank "until depletion" and often wondered.  I guess I've never looked for info on this topic.  It's very comforting to know that should I ever inadvertantly run a tank out of fuel, just switching over the the tank with juice in it should bring my engine back to life.

I was surprised that no one mentioned the wing access panel fuel gauges.  The gauge is not at the root of the wing so when it's float quits floating I know there's about 7 gallons left in the tank.  It's obvious when the needle quits bouncing around and if I catch this event within a couple of minutes I can time 30 min from then and know that there is very little fuel left in the tank without ever running it dry.  If you don't have these gauges, I'd highly recommend getting them.  I find them terribly useful - it should be noted that they are intended to be accurate on the ground, in level cruise they read lower than actual.  The most fuel I've ever purchased to top off is 44 gallons and I can't see *wanting* to need to buy more than that -

- but should I ever need to...  Thanks for the thread!

[Cruiser]

I have had the low fuel light come on in the annunciator panel. That was enough to get my heart rate up, I know my guages are accurate but.............

I put 57.8 gallons in to fill her up and she still had another ¾ hour flight time left in the tanks.

[MARZ]

No need here... 64 gallons - 12 for my personal end of flight reserve, I switch tanks every hour.

54 gallons at 11 per hour worst case = about 5 hours flight

Chances that one of the three people in the plane will go 5 hours without a bio break - 0%

If I'm going that far and will be stopping anyway - fuel up - one less thing to worry about.  In my mind GA doesn't have to cut fuel to the bare bones like the big carriers do.  The idea of actually planning to arrive somewhere with the requisite 30 or 45 minute reserve in the tank (guys that's 5 to 7 gallons - at least in my bird) is flirting with the chance to make the 5 o'clock news at best and become a statistic at worst. 

Another thought - 5 gallons in the left wing - landing in left traffic flow - uncoordinated turns - how far away from the pickup tube is that 5 gallons now?

my 2 cents.

 

[Shadrach]

Quote: LT4BIRD

 The fuel system will collect trash at the lowest point. The Gaskolator. 

[Shadrach]

Quote: maropers

Another thought - 5 gallons in the left wing - landing in left traffic flow - uncoordinated turns - how far away from the pickup tube is that 5 gallons now?

my 2 cents.

[Barry]

The routine I use is to run the 1st tank 1 hour and switch to the 2nd while noting the time. Fly the other tank till it's out of gas ( I don't wait for the engine to die, you can see the fuel pressure bouncing around when it gets close). Switch back to the 1st tank and note the time. Time left on the last tank is 2nd tanks time minus 1 hour.

I also have a fuel totalize that is within 0.9 gal of actual (in my favor) which really keeps peace of mind.

[Hank]

Barry is actually doing what my Owner's Manual says to do, but I'm conservative enough that I switch tanks pretty much every hour. Don't have to remember to "note the time" since my wind-up clock in the yoke has the movable red hands, and it's on my Run-Up checklist to set them to match the moving white hands. Every time the minute hands are close, I look for an airport and when I'm near enough to it, I lean down and switch the lever.

But anyway, when using the "book" method above, the extra fuel burned in the climb just gives you additional margin of safety to not run out of fuel as soon. Making a cruise-power descent will also increase your ground speed, buying more margin yet against the time-based method.

[201er]

That's why I switch based on gallons used (fuel totalizer) and not time. I make the first switch after 10 gallons used but subsequent switches are every 20 gallons. It's kind of a big deal to keep track of this with 100 gallons. When I'm at a point where running on a certain tank will leave anything less than 10 gallons, I prefer to run it dry in flight and then work on a single tank for landing and go around if need be. I much rather have 20 gallons left in one tank than to have 10 in each not knowing when exactly it will cut out. The low fuel indicator light is nice but I can usually run a good 30-60 minutes before the engine quits so I almost forget about it and by the time it does quit I'm a little surprised at first. All it takes is switching the tanks though to keep it going. If not, first instinct would be to throw the fuel pump on.

[jetdriven]

+3

thats what I do too.  For those of you who leave 5 gallons in each tank, thats an hour to 45 minutes of fuel in each  tank.  Leaving it all in one tank gives you the 1 hour to 1:30 in that tank. Or, if 7 gallons, which is up to an hour of cruise flight, in one tank you still have a safe reserve. A totalizer obviously makes this easier.  

Some aircraft have as many as 6 tanks, and leaving 45 minutes in each of them would sound absurd.

Quote: 201er

That's why I switch based on gallons used (fuel totalizer) and not time. I make the first switch after 10 gallons used but subsequent switches are every 20 gallons. It's kind of a big deal to keep track of this with 100 gallons. When I'm at a point where running on a certain tank will leave anything less than 10 gallons, I prefer to run it dry in flight and then work on a single tank for landing and go around if need be. I much rather have 20 gallons left in one tank than to have 10 in each not knowing when exactly it will cut out. The low fuel indicator light is nice but I can usually run a good 30-60 minutes before the engine quits so I almost forget about it and by the time it does quit I'm a little surprised at first. All it takes is switching the tanks though to keep it going. If not, first instinct would be to throw the fuel pump on.

[Hank]

Quote: JimR

[DrBill]

I've yet to be on a trip long enough to do this in my Mooney. Those long trips in my Beech Sundowner are now much shorter (timewise) however, back then.. I'd switch after the first 30 mins then run that tank dry. When it's dry, you know it fast and I can have the pump on, tank switched and motor barely skips a beat. Now it's run until my destination or the bladder indicates otherwise which is ALWAYS before I run out of fuel.  I might have tanks that can go for 4-5 hours but my bladder says TIME TO STOP ALWAYS in less than 4.

Dr Bil '65 M20E  8A6

[dgrami]

Several yars ago I was flying 30 NM west of Taos NM running very low on the left tank.  I decided to switch tanks just before climbing to cross a mountain range.  The fuel selector jammed in the OFF position.  Fortunately was able to return to the left tank.  I tried 1 more time to no avail, returned to Taos, could not find any mechanic, fueled up the left tank and continued safely to my destination on the left tank.  Lesson learned was never to run a tank compeltely dry unless I am within gliding distance of an airport.  The culprit as explained to me was the fuel selector o-ring had worn and "crimped" while in the OFF position as I was switching tanks.  

[aviatoreb]

Quote: Barry

The routine I use is to run the 1st tank 1 hour and switch to the 2nd while noting the time. Fly the other tank till it's out of gas ( I don't wait for the engine to die, you can see the fuel pressure bouncing around when it gets close). Switch back to the 1st tank and note the time. Time left on the last tank is 2nd tanks time minus 1 hour.

I also have a fuel totalize that is within 0.9 gal of actual (in my favor) which really keeps peace of mind.

[gregwatts]

I don't know, but I think you guys deliberately running a tank dry have some enormous balls....not sure how you even fit them into a Mooney! Once that tank is dry, you have absolutely no backup plan if something happens with the other tank of fuel, such as a clogged line or contaminated fuel, etc. Whatever happened to having "reserves"?

[scottfromiowa]

I have a fuel totalizer.  I plan for one hour reserve or ten gallons remaining.  I don't see the need to run a tank dry (unless you are in a huge hurry and on a long cross country and don't want to stop) or to carry extra weight in fuel that I am not going to use...except my one hour reserve.  I sump and know based on time and totalizer to + or- a gallon what's been used.  If people want to run a tank dry or fly with full tanks works for me.  I just don't do either-unless on a long cross country where I will be re-fueling or get into my 1-hour reserve used allotment.

[Shadrach]

Quote: dgrami

Several yars ago I was flying 30 NM west of Taos NM running very low on the left tank.  I decided to switch tanks just before climbing to cross a mountain range.  The fuel selector jammed in the OFF position.  Fortunately was able to return to the left tank.  I tried 1 more time to no avail, returned to Taos, could not find any mechanic, fueled up the left tank and continued safely to my destination on the left tank.  Lesson learned was never to run a tank compeltely dry unless I am within gliding distance of an airport.  The culprit as explained to me was the fuel selector o-ring had worn and "crimped" while in the OFF position as I was switching tanks.  

[Shadrach]

Quote: gregwatts

I don't know, but I think you guys deliberately running a tank dry have some enormous balls....not sure how you even fit them into a Mooney! Once that tank is dry, you have absolutely no backup plan if something happens with the other tank of fuel, such as a clogged line or contaminated fuel, etc. Whatever happened to having "reserves"?

[jetdriven]

People are so concerned about percieved risk when the real risk goes unnoticed.