Running a tank dry in flight

[201er]

I really don't understand how some people think it is safer to have a little in each tank and risk having to do a tank swap low to the ground (say on a go around) than to have more in one tank and nothing in the other? I would much rather run a tank dry in cruise and leave 2 hours in the remaining tank than to have some arbitrary amount of roughly half in each.

Think about it, if you have 1 hour in each side... you run one of those sides down to what 30 minutes? 20 minutes? Now you get nervous about going dry, perhaps you're in a go around so you swap to the 1 hour tank. Before you know it you have 20 in one tank and 20 in the other. That's not a situation I want to be in.

Now I'd like to ask the guys who run a tank dry in flight. How high and/or in what condition of flight do you want to be in when you do it? Do you have to be over an airport? Do you have to be over a certain height AGL that you will feel comfortable doing it? Or would you run a tank dry during a low cruise at 2000ft?

[John Pleisse]

Reasons NOT to run a tank dry:

1) Lack of redundancy

2) Engine stoppage

3) Screen or bowl clogs

4) Vapor lock

5) Weight distribution offsetting cruise and control  efficiency

6) Clogging from tank sealant

 

You'd think after 8 pages of a thread, there would be deep, compelling, major operational reasons to run a tank dry in flight. Agreed, range is what makes these planes great. With a good Shadin or a Hoskins totalizer, you know where you stand. If you want to do flow or efficiency measurements, do as you wish. I'd do it on the ground. Sorry, bravado run amuck.

 

[carusoam]

201er,

 

The experienced folk here can "feel" an air bubble in the fuel line prior to switching over.  They are so aware of their systems they know what to expect and when to expect it.  They can also comfortably fly to 200' agl minimums in tough meteorological conditions using no digital technology.

 

They drain and change on the fly.   No big deal.  Not unsafe. Not scary.  

 

Certainly wouldn't orbit an airport waiting for the SOP to be completed.

 

Done to the best of their abilities, the engine doesn't cough, just the fuel pressure goes low.

 

It seams there is similar risk in leaning your engine.  

 

Most passengers appreciate knowing that an engine stumble is not unscheduled.

 

Other things I learned....

In my intro flight to the M20C, learned that there is no "both" position.  It took about 20 seconds at idle, to kill the engine on the ground.  Uncomfortably long 20 seconds....memorable experience.

 

Before landing, switch to the tank that is most full.  If you are unsure which one that is...

 

I chose incorrectly, my engine went silent as the descent went steepest.  It was hard to tell.  Is the engine out" or is it just not pulling.  Switch fuel, engine starts pulling in about 20 seconds.

Uncomfortably long 20 seconds....

 

If you are going to run into "reserves" it is good to use the single tank method with all it's required practices including restart procedures for your aircraft.

 

JetD, nobody is going to come forth with data or facts indicating that single tank operations is bad or illegal.  It just might not be a best fit for everyone.

 

Is it debate day in TX?

 

Can we agree to throw this topic on the dead horse pile?

 

Insert smiley here.

 

Best regards,

 

-a-

[jetdriven]

[John Pleisse]

Mamma taught to keep my eggs in more than one basket. She also paid for my first solo.

[201er]

Does no one here fly with 4 people onboard? Perhaps some baggage? That kinda stuff can easily restrict you to be starting out with less than 50 gallons. 3 hour flight, no biggie. 30-35 gallons of fuel used. That leaves 15-20 gallons. It's not bad until you realize it's split between two tanks and who is going to rely on the last 5 gallons in a tank down in the pattern?

[John Pleisse]

Who is going to fly a Mooney 201 with 4 passengers and 15 or fewer gallons of fuel? Have a safe flight!!

[gregwatts]

I think you should run BOTH tanks dry then shoot an ILS down to 200' and 1/2 mi vis......then you're a badass!

[jetdriven]

Do you think that landing with almost two hours fuel is an unreasonable thing?

[RJBrown]

 

[John Pleisse]

Quote: jetdriven

Do you think that landing with almost two hours fuel is an unreasonable thing?

[Shadrach]

Quote: N4352H

 No. Having it all in one tank would be less preferable.

[Shadrach]

Quote: RJBrown

Quote: N4352H

So I just read all 8 pages of this entire thread (includ. my engine out in St. Augustine). Somebody explain to me the benifits of intentionally running a tank dry. Never mind if you are afraid of it, whether or not an engine restart is a SOP, airlines and military do it..etc..............what is the benefit? How does it make flying a Mooney better and safer?

[John Pleisse]

Quote: Shadrach

 No. Having it all in one tank would be less preferable.

[jetdriven]

thats to keep all the sand, tank sealant, grass, sediment, debris, and sludge out of your fuel screen

Quote: Shadrach

Randy, I agree with you in theory, but I need to say that it is not possible to burn all of the unusable fuel out of a Mooney. The pick up is elevated ~1.5" to 2" off of the tank bottom. No way, no how... you're not going to get it..

[RJBrown]

Quote: jetdriven

 

[danb35]

Quote: N4352H

You'd think after 8 pages of a thread, there would be deep, compelling, major operational reasons to run a tank dry in flight.

[201er]

Quote: N4352H

 No. Having it all in one tank would be less preferable.

[201er]

Quote: N4352H

Who is going to fly a Mooney 201 with 4 passengers and 15 or fewer gallons of fuel? Have a safe flight!!

[GeorgePerry]

Quote: jetdriven

A challenge to all of those "run a tank dry it won't restart" believers.   Can anyone find an accident report where a pilot ran  a tank dry and could not restart the engine on the other tank containing fuel? This seems to be a big fear of the pilots who have never ran a tank empty. 

 Byron, while I appreciate your position, being the person that speaks the loudest and the longest, doesn't make you the "correct-est".  Its a foolish practice and an unnecessary risk for just about any mission profile in a Mooney. 

Earlier I posted the MAPA accident statistics showing fuel exhaustion accident percentages.  Since you seem unconvinced as to the data and facts behind others assertions to the contrary, I'll now post the fuel mismanagement accident numbers that cover the years 1982-1991.  Although the information is somewhat dated, it is still germane to the discussion.  You can't really mismanage your fuel, unless you intentionally run your tanks extremely low...Something that's required to run a tank dry as you advocate.  The readers can form their own opinion as to whether or not running a tank dry is a smart thing to do. Your mileage might vary.

[FlyDave]

Quote: GeorgePerry

[jetdriven]

George:

  You are confusing the practice of running a tank empty with fuel mismanagement. THEY ARE NOT THE SAME THING.  Virtually every NASA ASRS incident report about fuel mismanagement begins with the tank running empty inadvertently and this startles the pilot.  They then either switch tanks (continuing on), fail to switch tanks, or goof the procedure.  The ones who conscientiously run tanks empty aren't the problem.  The same pilots who practice stalls arent the same group of pilots who stall their aircraft inadvertently.  It's the inadvertent running tank dry or wing stall that is the problem.  You are applying the label of "fuel mismanagement" to the practice of intentionally running a tank dry in cruise.  This is no more a mismanagement of fuel than a practice stall is a mismanagement of airspeed. 

The link the the MAPA pilot proficiency program said that "fuel mismanagement caused 7% of accidents. This accident invariably involved failure to switch tanks, or running borth tanks dry."  I am not advocating running both tanks dry, nor an I offering advice to fail to switch tanks.   The second photo you posted again, says fuel mismanagement.

In every piston twin with aux tanks it is SOP to run the aux tanks dry, and then continue on to destination on the mains.  Piper PA-31-350. Twin Cessna 402, 421, etc. Some essna 310's dont even have aux fuel tank guages! 

I am not advocating it if you are not nearing the range of the aicraft. I am not advocating running a tank dry to the point of engine stoppage.  It can happen, yes, but the point of the technique is to get all the available fuel, and you can do that by watching the fuel pressure guage.  Some aircraft give you a whole minute of warning.

If my position and experience level isnt enough, well listen to John Deakin. Yes they ex-747 captain for JAL with 35,000 hours and (before his stroke) held FAA pilot examiner status on 43 different types of aircraft. Issued type ratings.  He also advocates such crazy things such as running oversquare, LOP, and things like that.  He also takes my side on running a tank dry.   http://www.avweb.com/news/pelican/182044-1.html

of note from Deakin:

Is there a problem restoring the fuel flow? In a word, NO. The FAA certification rules require testing in this area. For example:

 

FAR 23.955(e)

Multiple fuel tanks. For reciprocating engines that are supplied with fuel from more than one tank, if engine power loss becomes apparent due to fuel depletion from the tank selected, it must be possible after switching to any full tank, in level flight, to obtain 75 percent maximum continuous power on that engine in not more than -

(1) 10 seconds for naturally aspirated single engine airplanes;

(2) 20 seconds for turbocharged single engine airplanes, provided that 75 percent maximum continuous naturally aspirated power is regained within 10 seconds; or

(3) 20 seconds for multiengine airplanes.

FAR 25.951(a) Each fuel system must be constructed and arranged to ensure a flow of fuel at a rate and pressure established for proper engine and auxiliary power unit functioning under each likely operating condition, including any maneuver for which certification is requested and during which the engine or auxiliary power unit is permitted to be in operation.

(

Each fuel system must be arranged so that any air which is introduced into the system will not result in -

(1) Power interruption for more than 20 seconds for reciprocating engines; or

(2) Flameout for turbine engines.

Have you actually ever ran a tank dry, and refilled it to verify the actual fuel capacity of the aircraft?  Sure, you may never run below 15 gallons but are you sure there is really 15 galllons in there?  All these years you might have been landing with 15 gallons but it might have only been 10. 

Here is the AOPA, "dogfight" column.  Hirschmann, (who is against the practice)  entire argument is "what if the engine doesnt come back to life".  Thats a weak argument.     http://www.aopa.org/members/files/pilot/2011/march/feature_dogfight_tank_dry.html?WT.mc_id=ebrief

So, fine, you don't feel comfortable doing it, and I respect that. But your opinion is based on feelings and unfounded fear.   Making operational decisions based solely on bad data, hangar talk, and feelings is "foolish".  If you would find some sort of accident or NASA report showing where a pilot intentionally ran a tank dry, and then selected to a tank containing fuel and it would not restart when following the POH, I may change my mind.  I would like some data points, because so far the only ones I have seen says its safe.  Here is the link for the NASA ASRS search.

http://www.37000feet.com/

here is some discussion on VAF   http://www.vansairforce.com/community/showthread.php?t=40875

I supose I go on the longest because I never give up.  I think the facts and about 80 years of operational practice are behind me as well.

Quote: GeorgePerry

[RJBrown]

On this subject I agree with Byron. His last post pretty much says it all.

I am not and I don't think Byron is recommending running a tank dry as part of any normal procedure.

There are many variables in flying. The variable we don't control is the wind and weather.  Weather predictions often are no more than guesses. The range of our planes can easily exceed 1000 nautical miles. I once rented a vintage 180HP Mooney that had long range tank that held 100 gal of fuel. That bird could stay airborne for over 10 hours and travel close to 1500 miles. Traveling those distances requires in flight decision making. I usually plan an hour minimum fuel reserve. In the Rocket that was 20 gal. in the MSE 10. The flexibility surrounding speed range payload and gross weights are variables we all deal with. If you fly enough at some point you will find you self with less fuel than you had planned for and you will need to manage the situation. If you say "No it can never happen to me" you are either lying to yourself or limiting the capabilities of your plane and tankering fuel. You can carry a 2 hour reserve but I think that can be wasteful. As you approach a minimum fuel situation there are numerous tools at your disposal. Slowing down to extend range or landing short of your destination are options. Safely getting the most from the fuel onboard can be the objective. Running one tank empty is a safe option. It is not something I would ever plan for at take off but it is a tool I would use if the vagrancies of flying combine to infringe on my fuel reserve. Emptying one tank in straight and level cruise flight so there is more in the other while maneuvering to land may actually present a safer choice. Our fuel reserve is more than just a planning exercise. It is there to be used and used safely when needed. Some day running one tank dry may be the safest option you have. Don't let fear and inexperience rob you of that tool. 

[John Pleisse]

Quote: 201er

How does having 4 passengers or not having 4 passengers (3 excluding pilot) change whether or not to fly a Mooney with full confidence of there being 15 gallons usable fuel onboard (especially if it's all in one tank so you can use all 15 of it) when you are arriving at your destination? I was just trying to point out earlier that running it tight on fuel is far more likely in a 4 person scenario than flying solo because of weight/balance.

I don't get gas at my home field. I fly over to a nearby airport less than 10 minutes away to get gas. What would be the big deal to take off with 20 gallons and arrive with 15+? I can go back and forth between the two more than 5 times on the remaining fuel. How would this be any different with 4 passengers onboard and picking up gas before an xcountry flight?

[John Pleisse]

Quote: RJBrow

I am not and I don't think Byron is recommending running a tank dry as part of any normal procedure.

Well, yes he his. RJ, What is the title of the thread?

Don't let fear and inexperience rob you of that tool. 

Thank you...what do we owe you?