M4 Fuel selector Valve.

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stick_rudder
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Re: M4 Fuel selector Valve.

Post by stick_rudder »

plowboy wrote:
Sun Oct 25, 2020 12:53 pm
what do you do with the in dash fuel off business, when you change to the new valve with off in the kick panel?
Are you referring the panel mounted fuel shut off on the -210 models? In that case, the fuel selector would not have an OFF position.

Wingman12
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Re: M4 Fuel selector Valve.

Post by Wingman12 »

Great to discover these posts on the fuel valve selector, but a bit confused at times through lack of detail. I have a 1966 Maule M4-210C with the Continental IO360 210 hp engine. The fuel selector valve has been removed and it is a Weatherhead two-position type, with the long part of the handle pointing to the desired tank, as indicated on the kick-panel plate: LEFT tank is UP, RIGHT tank is FORWARD (thus a 90 deg possible range). The handle was actually able to rotate past each of the 'UP' and 'FORWARD' positions, for a total rotation of about 130 deg. Having inadvertently moved past the 90 deg rotation during a flight over the mountains, the engine lost power after a minute and I quickly switched to the other tank and regained power. Later, over more open territory, I switched tanks again and deliberately went past the 90 deg position, which resulted in the same one-minute delay to engine power loss, corrected by moving the fuel selector handle to the proper 90 deg position. Later, on the ground, the fuel selector valve handle rotated 180 deg, leaving the opposite side of the handle pointing to the desired tank! Subsequent running of the engine would last only one to two minutes before power loss, with fuel pressure drop as the leading indicator. This was preceded, during engine start, by erratic electric boost pump fuel flow indications accompanied by apparent cavitation of the boost pump with fuel pressures only 1-2 psi most times, until a solid, continuous boost pump sound and 4 psi indications allowed for a normal engine start and running. This indicated to me that the fuel selector valve was not allowing sufficient or any fuel flow to the header tank and boost pump, depending on the various positions of fuel selector valve placement, including the reversion to the 'proper' long-handle indicating the desired tank. There was never any 'detent' or other means to confirm the actual fuel-flow situation while positioning the fuel selector valve handle. Disassembly of the valve showed serious wear of all components and a crack at the valve-end of the shaft where the short pivot-pin holds the delrin valve item to the shaft. The fact that the valve could go past the (supposed 90 deg) stops to rotate 180 deg and then 360 deg indicated failure in any case. The valve was always sticky/squeaky to move, though the handle had lots of 'slop' in it, leaving a question as to the precise positioning for full full fuel flow through the valve.
Seeing the non-FAA approved Weatherhead valve on Aircraft Spruce and reading other comments here, I am confused about the 'Maule modification' of the valves and the mention of the 'off' position, which my old one does not have.
Questions:
1) Can I get a direct replacement valve for my old original valve? If so, where?
2) Is a modification to a new/different valve type mandatory? If so, which valve and where do I get it?
Thanks to all.

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Mog
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Re: M4 Fuel selector Valve.

Post by Mog »

I recommend buying the Maule valve for your plane. Yeah it more than the cheap one on aircraft spruce but to me it was worth knowing I 100% had the correct part. I also do enjoy the extra positions available with the new valve. Anyway, just my 2¢

Wingman12
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Re: M4 Fuel selector Valve.

Post by Wingman12 »

Thanks Mog,
I entirely agree about having the right part, regardless of cost (most times!), especially in this critical instance of fuel flow! Without having contacted Maule about it yet, I wonder if the replacement is the exact fit (albeit with some small internal modification to the valve), or if it will be an entirely different valve with accompanying dimensional, mechanical, fuel-line or indicator-plate problems or lengthy modifications/adaptations? I'm far from my home base right now, so I'm hoping it's a simple, direct replacement. Do you know if that is the case? Is Maule a source for this? I'm not seeing it on any other aircraft parts sites.

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Goomba
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Re: M4 Fuel selector Valve.

Post by Goomba »

Maule furnished replacement I received for my M4-220 had left, right,both, and off positions with a sort of detent or perceptable click at each position. Bolted right in place. Fyi.
"Bucket lists RULE!"
1972 M4-220C

Wingman12
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Re: M4 Fuel selector Valve.

Post by Wingman12 »

Thanks Goomba! Being a Sunday, I've just been doing online research, but will contact Maule tomorrow. I had Stinsons with the 165 hp engine. How do you like the 220? Franklin was always good to me, just getting tough to find mechanics who know them/will work on them.

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Mog
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Re: M4 Fuel selector Valve.

Post by Mog »

Assuming your existing fuel selector is stock or close enough then the new Maule part just bolts right in. Takes 20min give or take.

Wingman12
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Re: M4 Fuel selector Valve.

Post by Wingman12 »

Thanks Mog, will check with Maule tomorrow.

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Goomba
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Re: M4 Fuel selector Valve.

Post by Goomba »

Wingman,
I’ve about 1200 hours on my PZL Franklin and done most all maint myself with oversight, paying attention to the specifics of the engine. Yes not too many Franklin familiar a and ps around so it pays to study up and be involved with work done.kk
"Bucket lists RULE!"
1972 M4-220C

Wingman12
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Re: M4 Fuel selector Valve.

Post by Wingman12 »

Yeah Goomba, great to enjoy that Franklin - and the necessary study and experience to deal with it and A&P to work with!
I was able to order a replacement fuel selector valve from Maule this morning. However, my long original post here expressing my concern and confusion resulting from my online research, photos and info dealing with different Maule models was justified: For the 1966 Maule M4-210C, they had to make (modify) a replacement fuel selector valve. Recall that mine is Up=Left tank, Forward=Right tank (no "Off" or "Both" positions). The new valve will be Up=Left tank, Forward=Both tanks, Down=Right tank. This, of course, will necessitate marking the new positions on the valve selector plate. I was assured that there will be no mechanical, mounting or plumbing differences. From what I gathered in my research, I suspect that Maule drills an extra hole in the Delrin valve barrel for the "Both" position. The other possible Maule valve includes an additional "Off" position, but that is not called for in the M4-210C due to the panel-mounted emergency fuel shut-off (red knob) that uses a push-pull cable attached to a valve at the bottom of the header tank instead of a Fuel Selector Valve "Off" position.
I'm sure that my experience with stiff/sloppy fuel selector valves is not uncommon, in many different types of aircraft. But I'm glad that this final malfunction occurred on the ground. Below is a link to an NTSB article (with pics) about this universal maintenance problem. Very recognizable to myself and, I'm sure, others. Perhaps others may be able to use some of this info I've learned about.
I'll post here again to confirm that the new valve installs and operates as advertised.
As an aside, I'm very glad that Maule is still a family-run outfit. The people I spoke with were conscientious, efficient and very well-informed about the specifics involved. The shop manager that I discussed this with has been working for Maule since 1980 and knew about all the fuel selector valve differences. He was flying at Maule Field, Napoleon, MI in 1978, just after I got my PPL checkride from Ray Maule there in 1977. Small world, filled with lots of great experience!

NTSB Safety Alert:
https://mail-attachment.googleuserconte ... nUYY3u3aLA

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