Mixture Control Creep

[kiwibob]

The mixture control on my FX-3 has started to creep rich in the cruise (I lean LoP using Fuel Flow per the manual).

Anyone know if there's a simple fix to this?

[Andy]

The mixture control on my FX-3 has started to creep rich in the cruise (I lean LoP using Fuel Flow per the manual).

Anyone know if there's a simple fix to this?

Would you please give a reference to any CubCrafters recommendation or procedure for LOP operation. All AFM settings are for 50 deg F ROP

By "creep" do you mean the mixture control actually moves or that the mixture changes for a fixed mixture control position? I have never seen the mixture control move, or the fuel flow change, from what I have set.

[kiwibob]

Would you please give a reference to any CubCrafters recommendation or procedure for LOP operation. All AFM settings are for 50 deg F ROP

By "creep" do you mean the mixture control actually moves or that the mixture changes for a fixed mixture control position? I have never seen the mixture control move, or the fuel flow change, from what I have set.

Hi Andy, I follow Superior XP360 Operators Manual (XPOM360) 4.10 Leaning to Flowmeter, there's a bunch of graphs for different power settings. Aero Sport Power supplied me with the manual.

By creep it's the mixture control gradually moving in (more rich).....

[Andy]

Hi Andy, I follow Superior XP360 Operators Manual (XPOM360) 4.10 Leaning to Flowmeter, there's a bunch of graphs for different power settings. Aero Sport Power supplied me with the manual.

By creep it's the mixture control gradually moving in (more rich).....

Thanks for the reference. My FX-3 (serial 0100) has the Lycoming built engine so I assume that explains the difference. My mixture control has multiple fixed detents and there is no way it could slip or creep. I understand that a vernier mixture control was offered as an option. Was there an earlier, non vernier, mixture control that had no detents?

[kiwibob]

Thanks for the reference. My FX-3 (serial 0100) has the Lycoming built engine so I assume that explains the difference. My mixture control has multiple fixed detents and there is no way it could slip or creep. I understand that a vernier mixture control was offered as an option. Was there an earlier, non vernier, mixture control that had no detents?

That's interesting, the CC website still talks about the CC363i, is this no longer Aero Sport Power's engine?

My mixture is a simple pull knob, it does have detents in the sens that it clicks but there's no vernier.

I'll PM you about the manual.

[Andy]

That's interesting, the CC website still talks about the CC363i, is this no longer Aero Sport Power's engine?

My mixture is a simple pull knob, it does have detents in the sens that it clicks but there's no vernier.

I'll PM you about the manual.

CC363i is the CubCrafters engine designation but it doesn't indicate who built it. At one time CubCrafters was using two suppliers but all recent FX-3 registrations seem to show engine as Lycoming. Mine is Lycoming built and came with Lycoming test documentation. The AFM and Lycoming documentation suggest leaning to 50 deg F rich of peak which is a much disputed technique.

Sound like you have the same mixture control as I do. I don't understand how it could slip unless it is defective. The detents in my mixture control are very positive.

[Andy]

Hi Andy, I follow Superior XP360 Operators Manual (XPOM360) 4.10 Leaning to Flowmeter, there's a bunch of graphs for different power settings. Aero Sport Power supplied me with the manual..

Well I tried to find that document but couldn't. Superior seems to combine installation and operation of the O-360 and IO-360 in this document - https://www.superiorairparts.com/fil...42/SVIOM01.pdf.

I only found one reference to LOP operation "Do not lean beyond 50°F lean of peak on fuel injected engines" and no fuel flow plots for LOP operation. Did I miss something or has Superior changed their recommendations?

BTW I have no intention of opening a discussion on the merits of LOP operation. I am well aware of the conflicting advice on the subject.

[Daveembry]

In this post on my forum thread, I have several attached files at the bottom you can download.

http://forum.cubcrafters.com/showthr...ll=1#post23102

This is the correct manual they said to use for the 363i that was made by Superior and assembled by Aerosport. The newer engines being shipped now (which I haven’t run yet) are done by Lycoming.

file:///Users/davidembry/Downloads/Superior%20O360%20Engine%20Manual.pdf

Note..... their manual (page 39 & 40) says to NEVER run engine between peak EGT and 75 ROP. 50 ROP is the WORST place for an engine and they state this in the manual. For more info, research Savvy Aviation, Mike Busch articles and videos on the RED BOX. Here is one link to an article but go to savvy aviation and Youtube for many more articles, etc on the subject.

https://resources.savvyaviation.com/...ox-red-fin.pdf

For performance cruise at or above 75%; 75 ROP. For economy cruise at 75% or less...... lean to peak EGT or -50 LOP.

On the 363i (once broken in) I have found it best to use the LEAN ASSIST function (or just watch EGT's) and just lean while watching EGT's. Once they peak and start to fall again, continue leaning to 20-30 LOP while watching the CHT's. Continue LEANING until you get the CHT's where you want them. The more you lean, the more the CHT's will drop (once you are lean enough for the CHT's to start to drop). I like to keep them 370-390ish. I've never had a problem with these engines running very LOP. The carburetor engines (like 340) can get touchy running LOP and go rough many times before you can get them lean enough.

Contrary to old wives tale, you can't hurt an engine going lean. Rough maybe and loose power.....but you can't hurt it (otherwise we wouldn't be shutting it down going lean).

Once I start up, I immediately lean back to where it will just idle at 1,000 - 1,200 rpm so that if I give it more power (like to taxi) it might stumble. Then I enrichen only enough to taxi. These plugs can foul when idling at full rich for very long.

Also by being VERY lean.....if you happen to forget to enrighen before run-up or take-off......you'll know it quick when it won't run up! (safety factor)

Well I tried to find that document but couldn't. Superior seems to combine installation and operation of the O-360 and IO-360 in this document - https://www.superiorairparts.com/fil...42/SVIOM01.pdf.

I only found one reference to LOP operation "Do not lean beyond 50°F lean of peak on fuel injected engines" and no fuel flow plots for LOP operation. Did I miss something or has Superior changed their recommendations?

BTW I have no intention of opening a discussion on the merits of LOP operation. I am well aware of the conflicting advice on the subject.

[kiwibob]

On the 363i (once broken in) I have found it best to use the LEAN ASSIST function (or just watch EGT's) and just lean while watching EGT's. Once they peak and start to fall again, continue leaning to 20-30 LOP while watching the CHT's. Continue LEANING until you get the CHT's where you want them. The more you lean, the more the CHT's will drop (once you are lean enough for the CHT's to start to drop). I like to keep them 370-390ish. I've never had a problem with these engines running very LOP. The carburetor engines (like 340) can get touchy running LOP and go rough many times before you can get them lean enough.

Contrary to old wives tale, you can't hard an engine going lean. Rough maybe and loose power.....but you can't hurt it (otherwise we wouldn't be shutting it down going lean).

Once I start up, I immediately lean back to where it will just idle at 1,000 - 1,200 rpm so that if I give it more power (like to taxi) it might stumble. Then I enrichen only enough to taxi. These plugs can foul when idling at full rich for very long.

Also by being VERY lean.....if you happen to forget to enrighen before run-up or take-off......you'll know it quick when it won't run up! (safety factor)

Thanks Dave, A most helpful post.

I don't have a lean assist function (or if I do I don't know about it, I have the EI engine monitor) and have been leaning to fuel flow. This results in CHT around 320-360F, cyls 2&4 are always 20-30F hotter for some reason. I pretty much always run economy cruise 23"x2300 as the performance cruise only give an extra 5-10kts and burns a lot more gas.

The tip about leaning for idle is most welcome, I've been running full rich until after t/o as I've been concerned about accidently "giving it the gravy" without going to full rich.

[Pete D]

The mixture control on my FX-3 has started to creep rich in the cruise (I lean LoP using Fuel Flow per the manual).

Anyone know if there's a simple fix to this?

The detent friction is from a spring on the housing that rides on the bumps you see on the center part when it is all the way out. The spring is located right on the back side of the instrument panel. It sounds like the spring may have been displaced out of the slot or it is possibly broken. If it is displaced you may be able to access it and push it back into the slot, if it is broken then you would need to change the cable out.

An alternate method if the spring is broken would be to put a slight bend in the cable and housing by hand to add some friction. Do a little, try it, add more if needed. Sneak up on it, it is tough to un-do. This was the method used before the de-tented cables were spec'd out.


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