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Have been eyeballing Maules for float work.

aktango58 said:
Mine only has Left, Right and off, no both.

Transfer pumps only transfer from tips (Aux) tanks to mains. Gravity and engine pump I believe pump in normal operations, but if pressure drops the electric pump will increase pressure between gascolater and the carb.

My fuel line from right tank runs under the seat, but up and out of the way of the flap handle. I will look again, but seems it is well out of the way.
Click to expand...

Thanks for the reply. What year and model is yours?

There must be a reason Maule installed an electric backup pump for the engine. Like when switching tanks if the engine temporarily burps due to fuel supply interruption, or the main mechanical pump looses function or leaks due to diaphragm problems like the second accident Maule did to the previous owner according to the FAA's records. The electric pump emergency activation procedure and fuel tank selection evolved in the Flight Manuals over time. Just a thought for prospective owners to note any change orders or revisions.

A previous SB should have covered that fuel line near the flap. Mine got dented and replaced before the SB.

Gary
 
Gary, It's possible that the pump was installed because of the steep angle of climb with the bigger engines to ensure that they have adequate fuel flow when the tanks are at minimum fuel.
 
Electric pump is only used as a back up for mechanical failure.

Mine is a M-5-235, 1978 with 1300 hours on it now.

I don't fly it enough yet to be good with it, was flying full time until this winter and got other stuff going. Will get better with it this spring when I can fly for fun and be ready for fall.
 
aktango58 said:
Electric pump is only used as a back up for mechanical failure.

Mine is a M-5-235, 1978 with 1300 hours on it now.

I don't fly it enough yet to be good with it, was flying full time until this winter and got other stuff going. Will get better with it this spring when I can fly for fun and be ready for fall.
Click to expand...

POH went with the sale of my last Maule. If memory serves me, electric fuel pump "as required" (?). Pretty sure a faulty mechanical pump will still allow fuel to gravity flow to carb. Maybe not 24 gph as required a sea level wot operation though.


Maybe mentioned earlier, Jeremy Ainsworth, "maules.com" is a walking encyclopedia of all things Maule, a great resource if you are in need of info. He was involved with the company for a number of years, up thru the development of the turbine M9. Now independent, brokers Maules on his own.
 
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skywagon8a said:
Gary, It's possible that the pump was installed because of the steep angle of climb with the bigger engines to ensure that they have adequate fuel flow when the tanks are at minimum fuel.
Click to expand...

Well then the Flight Manual is pretty weak on purpose and emergency procedures. We know that from other planes with fuel injection and engine upgrades that require an aux pump to feed the beast within. But someone flying heavy on a low tank and climbing, maybe turning a bit uncoordinated with the selected tank down without a header tank, especially on floats, might not grasp the significance of the panel switch in time to restart. It's in my muscle memory from 185's but it has to get there first for others.

Gary
 
I have no idea of how the flight manual for the Maule is written. As to Oliver's comment of "as required", the pilot ought to know his engine has a fuel pump and that if the engine pump fails the electric pump is "as required". Judging by the way the Maules are simply put together and the regulations which were in effect at the time of the original certification, this is likely all that is said in the manual.

For certification purposes adequate fuel must flow for the engine to operate when carrying minimum fuel. On low wing airplanes with fuel in the wings, generally a pump is needed. On high wing airplanes in most cases gravity does the job. If the plane has a high powered engine which holds the nose high in the air above the fuel tanks (such as Maule's famous hangar take off picture), an engine driven pump would be required. If there is an engine driven pump required then there will also be an auxiliary emergency pump of some sort installed. It could be a hand wobble pump or more preferably in modern times an electric pump with a toggle switch.

If the engine is fuel injected a pump would be required in either a high or low wing installation for a different reason than a carburetor engine.
 
For reference the various Maule Flight Manuals are available online at Maule's site: http://mauleairinc.com/flight-manuals/ Have a look at the standard and emergency procedures. I read some starting with the M-5's then later M-6 and -7's to learn about their recommendations. They mention using the aux fuel pump if the engine fails (when switching tanks I assume to maintain or boost fuel line pressure) but don't suggest applying carb heat if carb equipped. They may in later or current Manuals.

Over the years there have been Revision Levels for some (http://mauleairinc.com/pdf/flight_maint_rev_level.pdf). For the M-5-235C the Revisions are also shown on page ii early in the Manual. They can be significant. Then the question becomes how does the owner or subsequent owners keep track? Guess they'd have to go where I linked.

The overall manuals and Documents link is here: http://mauleairinc.com/maule-air-technical-manuals-and-documents/

Gary
 
mvivion said:
..That is indeed the report for the accident in question. That said, the fuel lines between the mains and tip tanks contained water, both fuel transfer switches were energized, the engine was not running, and the pilot was attempting a restart with the key switch. We could only assume that the gascolator had been purged of water, but not in time to complete a restart. ...
Click to expand...

So, water detected between the aux & main tanks, but none detected where the rubber meets the road-- the gascolator and more importantly the carb.
The FAA / NTSB tore into the airplane, and do this investigation stuff for a living, but despite their findings
you seem convinced that it was water in the fuel.

Depending on eye-witnesses to figure out what happened isn't always an exact science.
We had a fatal Seabee crash near here years ago,
there were three eyewitness accounts -- none of which agreed with the others.

FWIW maybe it had nothing (or everything) to do with the accident,
but it seems to me that monkeying around with the aux tank pumps when taking off and/or early in the climb-out is a poor idea.
I know of several airplanes that were force-landed / crashed due to (shall we say) fuel mismanagement because the pilot switched tanks at an altitude which was too low to allow a re-start when the engine quit. At least one switched tanks on climbout, and several while approaching to land.
​
 
Hotrod,

The NTSB did NOT tear into the plane. In fact, they did a quick examination at the accident site, then released the wreck to the owner. The NTSB never looked at the plane again, other than the engine. In addition, there were clear skid marks leading downhill, caused by the aircraft's floats, leading to the wreckage. The airplane apparently slid, skipped, slid, then tumbled. Yet, the proximate cause of the accident was listed as:

"Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's inadvertent stall of the airplane during an unknown phase of flight."



MTV
 
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Remember the Anchorage NTSB office was the subject of a short lived series on Discovery (Or one of the cable networks). While I am NOT disparaging them or their work, watch an episode or two and see what you think of their investigative process.
 
mvivion said:
"Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's inadvertent stall of the airplane during an unknown phase of flight."



MTV
Click to expand...

From that I will consider the 'skip' to be a phase of flight:evil:

Aux tank pumps can run at any time. I have turned mine on in taxi, and left them on until cruise. Sounds funky, but I use fuel to balance the plane on trips when alone, as my light 120 lb :wink: body tends to want to tip the plane left. (maybe I weigh more;-))

Electric fuel pumps seem fairly standard for the big six cylinders. The 180 is one of the few that doesn't use one, but as said above all injected motors have the back up.

I believe all of us can benefit by sitting in our plane and running through the emergency procedures a couple of times- reaching with our eyes closed; no matter what airplane you are flying.

I have no idea how long the O-540 would run with fuel off, (popped tank), or how long to get fuel back into it. Maybe I will check that out one of these days when I have some runway in front of me... Do a fuel shut off at 10 feet over Yakutat runway and see how long it runs, then how long it takes to come back. I wonder if it would get off the ground if you turned off the fuel and went full power?

How many of us know our plane well enough to answer that question? Add water into the mix and it would not be good.
 
I used to request the check instructor make it part of a Flight Review. To actually do the fuel starve and switch maneuver. At least review the muscle procedure, and on occasion selecting Off then back On with whatever goes with that. At altitude it's informative and time slows during the quiet time.

Cold drilling (and especially at night) emergency procedures works but only if the pilot wants it to. Same deal with Cubs in continuous wing down turns feeding mostly off header tanks...how long before THAT happens? Better yet don't turn then too long and practice a 90-270* series instead of a continuous 360*.

If I had a Maule again I'd know the answer to all this before the question came up.

Gary
 
I have no idea how long the O-540 would run with fuel off, (popped tank), or how long to get fuel back into it. Maybe I will check that out one of these days when I have some runway in front of me... Do a fuel shut off at 10 feet over Yakutat runway and see how long it runs, then how long it takes to come back. I wonder if it would get off the ground if you turned off the fuel and went full power?

First I would suggest running that experiment at, oh, say several thousand feet........agl.

Don't know about the Maule, but I can tell you about a stock C-185. With fuel shut off before starting the engine, it will not only take off but keep running at 25 squared for 45 seconds because of the header tank. Turning on a tank and going to high boost will restart it in about 2 seconds.

I have it on good information the cub will restart after popping a tank in a couple seconds even with a header tank and no boost pump.
 
I know the 207 has header tanks under the front floor, but don't have one in the Maule.

185 I don't believe has one either, so that makes a difference.

If I do try an 'off' fuel position I will be sure to have lots of room in front of me!
 
Why it is important to review every so often to confirm you remember what you are flying!!!

Do all models of 185 have headers? I don't have access to the books right now and can not recall.
 
BC12D-4-85 said:
...but it's in the floor
Click to expand...
It's actually between the lower part of the control column and the firewall. It serves two purposes. One to keep an amount of fuel available for the electric fuel pump and the other is as a fuel/air separator. Excess fuel in the fuel control unit flows into this tank. Any air in the fuel and excess fuel is then returned out of the top back to the right wing tank. Air mixing with fuel flow creates a rough running engine. Air in the fuel lines and fuel injected engines is not a happy engine.

You can see it if you look under the instrument panel.

On hot days when your fuel injected engine is running rough while at low or idle power there is air in the fuel injection lines. Turning on the electric pump pressurizes the lines squeezing out the air bubbles. This is more common with the Lycoming engines than the Continental perhaps due to the "header" tank acting as a fuel/air separator. The Lycoming system doesn't flow back to the main tanks.
 
That tank in a Cessna is called an accumulator tank. It's required with the Continental fuel injection, which has a fuel return line to manage line pressure. I don't believe fuel supply is it's primary purpose. Fuel collection from the return line is.
 
Thanks guys, I was positive that there were not two headers, and now that the word 'Accumulator' comes out it sparked my memory.

One note in the system about that 1 way valve to feed fuel from the electric pump to the engine: If your 1 way valve goes bad, and there is almost no way to test without disconnecting it, and you lose your fuel pump and need fuel from the electric pump you will only get a couple of minutes of run time before starving the engine.

This happened to our Chief Pilot- took a while for the mechanics to figure out what was going on.

Shucks! Maules back to Cessnas... How about that Grumman Goose?
 
aktango58 said:
One note in the system about that 1 way valve to feed fuel from the electric pump to the engine: If your 1 way valve goes bad, and there is almost no way to test without disconnecting it, and you lose your fuel pump and need fuel from the electric pump you will only get a couple of minutes of run time before starving the engine.
Click to expand...
What type of airplane George? The electric pump in a 185 is in series between the accumulator tank and the engine driven pump.
 
It was the 185. I should ask the mechanic again about it, but the 1 way valve that allows excess fuel to return back failed and that caused the fuel to quit flowing. After the engine would die fuel would gravity feed and the engine would start again and run after a bit... then die again.

Not a great feeling when you are over ocean capes I can tell you that!
 
aktango58 said:
It was the 185. I should ask the mechanic again about it, but the 1 way valve that allows excess fuel to return back failed and that caused the fuel to quit flowing. After the engine would die fuel would gravity feed and the engine would start again and run after a bit... then die again.

Not a great feeling when you are over ocean capes I can tell you that!
Click to expand...

You won't have that problem in a Maule. That's not to say it doesn't have other lesser issues such as it's venting etc. Bottom line is it pays to know your fuel system.

Here is a link to a fuel system 185 accident. It not related to what's said above but gives the schematic routing of the 185 fuel system as it pertains to this discussion. A confusing part for me is the contention that the Cessna 185 will takeoff and run for 45 seconds in a climb with the fuel shutoff closed because of available fuel in the header/accumulator tank. I must be reading that wrong or don't understand the 185 schematic.

The Maule will not run very long at all if you shutoff the fuel because the only fuel between that valve and the engine is the gascolator. I think there is safety in that sort of design. I have not experimented with how long it will run with the fuel shut off because one of the weak aspects of Maule that has not been mentioned is the Muffler system and it's propensity to crap a baffle at the hint of a back fire. Atlee's version of the Maule muffler rectified this to an extent and my baffle life span went from 80 hours to around 500 hours.

Jerry
 
"It was the 185."

Found it! It's between the fire wall and the top of the accumulator tank in the return line from the fuel control. Mine was removed and routed up high to a T into the feed line from the front of the right tank when the turbo system was installed 30+ years ago. At the time I was told that there was sometimes trouble in that return line. I just did not know what it was.

Thanks, I learned something today.
 
cubflier said:
You won't have that problem in a Maule. That's not to say it doesn't have other lesser issues such as it's venting etc. Bottom line is it pays to know your fuel system.

Here is a link to a fuel system 185 accident. It not related to what's said above but gives the schematic routing of the 185 fuel system as it pertains to this discussion. A confusing part for me is the contention that the Cessna 185 will takeoff and run for 45 seconds in a climb with the fuel shutoff closed because of available fuel in the header/accumulator tank. I must be reading that wrong or don't understand the 185 schematic.

The Maule will not run very long at all if you shutoff the fuel because the only fuel between that valve and the engine is the gascolator. I think there is safety in that sort of design. I have not experimented with how long it will run with the fuel shut off because one of the weak aspects of Maule that has not been mentioned is the Muffler system and it's propensity to crap a baffle at the hint of a back fire. Atlee's version of the Maule muffler rectified this to an extent and my baffle life span went from 80 hours to around 500 hours.

Jerry
Click to expand...

I was the pilot. It not have been 45 seconds, but it was over a mile of flight. Reason was an incorrect fuel tank selector valve was installed after an accident. The four-position valve was out of a 182 and the stem was not "keyed". 185 valves have three positions and the stem has three flat sides and a fourth 'half moon'. During a hundred hour inspection the 185 selector handle was removed and replaced 90* out of position. When 'Both' was selected, only one tank fed the engine. The first flight after the inspection (to a remote airstrip) depleted that tank. After landing the aircraft came to a stop sitting one wing low. The selector was moved to another position to prevent cross feed. The valve was then actually in 'both', allowing the depleted tank to empty into the opposite wing tank. At startup, the handle was moved to 'Both' which actually selected the now empty tank and isolated the tank with fuel. There was enough fuel remaining in the line and header tank to get a mile down the valley before engine shutoff. The rest is a long story with a safe ending.
 
According to the Cessna Service Manual on my desktop the fuel selector valve was optional. Don't confuse that with the fuel shutoff that's downstream of the accumulator. The selector is upstream.




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I have flown a 185 with no fuel selector, a 1967 model, that was ordered by the owner without the selector to “keep it light”. Nice airplane, and a real rocket ship indeed. Never missed the selector, in any case.

MTV
 
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