Flap lever stuck in the "UP" position ('64 M20D)

[tigers2007]

Well after five weeks of no flying due to IMC, I was blessed with clear skies this morning. I scrubbed my mission after I realized the flap control lever is stuck in the up position. It will not push down. When I pump the flaps, they both go down but creep back up. When I pump greater than four times, I feel a pressure restriction but it still lets me pump. I just taxied back and I'm gonna look up under the dash in a moment with my light and take some photos. These were working fine when I last flew; only like 7hrs since annual...

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[DXB]

Mine did something similar once - not really stuck up but could not push down enough to keep the flaps down. Lubing the heck out of the cable fixed the problem.

[tigers2007]

I suppose I'll pull the inspection plate and try to visualize this better. I just noticed how the flap up/down lever controls a cable. I'm assuming that goes to a lever below? Do you know which inspection plate the end is accessible with?


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[Andy95W]

42 minutes ago, DXB said:

Mine did something similar once - not really stuck up but could not push down enough to keep the flaps down. Lubing the heck out of the cable fixed the problem.

What Dev said.  I'm thinking the colder temps are the cause.  And with the amount of moisture we've had in Michigan the past few weeks, some might have condensed on the steel shaft and spring sheath and may have frozen.

[tigers2007]

Winter Stormageddon is approaching. I'll try to get hold of a kerosene tube heater and my snowmobile suit and tackle this tomorrow morning. I am in my own hangar. Meanwhile I'll bust out the service manuals and take a peek. I noticed that when it's cold, all of the cable operated things are difficult to operate especially the retractable step.


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[Aviationinfo]

Thanks for posting this---please be sure to let us know what you find out.  I agree that it probably has to do with cold temps.   What is the approx. temp in your hangar?

[tigers2007]

Cold enough that my infrared temp reader wouldn't turn on. Like 20F I bet. OAT is -08C right now.


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[TTaylor]

See if you can put the plane in a heated hangar for a few hours.  I agree that the cable likely has some moisture on it and is frozen.  Use a lubricant to displace the moisture once it is warmed up.

[MBDiagMan]

My impression is that it is a hydraulic leak.  Either at the cylinders or the valve.

Edited February 2, 2017 by MBDiagMan

[MooneyMitch]

My 2 cents is it's a temperature/lubrication issue........burr!

I would think if it were a hydraulic issue, one might see the fluid on the belly or on the floor.  

Yes, please let us know outcome on your D model.

[TheTurtle]

this is what the cable attaches to.

[carusoam]

Nice photo Turtle!

simple control arm at the end of the valve connected by a wire to the cockpit...

If the cable has stopped short of closing the valve the oil/pressure will seep back out...

The pump will continue to supply pressure while you are pumping.  The valve allows the pressure to leak back out to the reservoir.

Temperatures don't usually affect this system that much.  It should work well even after hours of flight above 10,000' where it gets extremely colder....

Temperature does affect the desire to go work on things parked outside....

How much belly panel has to come off just to see the cable and control arm?  Sending a camera in to see the valve's operation may save a lot of work.

there are two choices, the pump is leaking back, or the valve is leaking back.  Most likely, the valve isn't closing completely.  See if the control wire is not working as expected...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

[TheTurtle]

there is a small oval access hole at the flap pump actuator (picture above).  Its just barely enough to be able to set the screw which sets the retraction speed.  To actually work on the cable that belly pan needs to come off.  Only like 50 screws...  A video snake would get in there enough to be able to see whats not working though.

[Yetti]

I vote stuck check valve. Heat should help

[tigers2007]

I'm just coming to realization that the only way I can get to a "heated hanger" is if I buy a $400 175,000btu kerosene tube heater. I could fly with no flaps to a nearby airport about a five minute flight away. I'm very new to this aircraft so an INOP flap controller is a good enough reason to not go airborne. Just a bummer it was so beautiful out all day actually. Clear right now too

[Yetti]

No flaps is no big deal.  As some will say the formation people do no flap landings all the time.  You might want to be flying off and on some longer run ways.

[TTaylor]

It will take off and land without flaps just fine.  You will hardly notice the difference. I actually preferred landing my C with take-off flaps.   

[tigers2007]

My neighbor let me borrow his old kerosene heater; said I could keep it forever lol.

 

 

I opened up the two small oval inspection panels and you guys are right - not much room there.

Starboard side:

 

Center:

 

I'm going to let this get toasty and if I survive the carbon monoxide then maybe I'll pull the billion little screws to access this properly to inspect it. On the other hand, maybe I'll wait a few days until I receive the Milwaukee power screw driver. My wrist hurts already from just those little panels.

 

***UPDATE (2min later)***

 

Flap control works great now. Must have been frozen! And of course, it's a beautiful sunny day with heavy snow squalls at 100AGL blowing through...

 

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[tigers2007]

Any advice on how to get lube into the cable?

https://www.amazon.com/dp/B000GZQNC8/ref=cm_sw_r_cp_awdb_36nLybR14X6AT



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[DXB]

4 minutes ago, tigers2007 said:

Any advice on how to get lube into the cable?

https://www.amazon.com/dp/B000GZQNC8/ref=cm_sw_r_cp_awdb_36nLybR14X6AT



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yep that's precisely what I used from the pump side - never tried from the panel side but am sure its doable with a little contorsion

[FloridaMan]

I've had the flaps take more than four pumps after flying in -10 degrees for hours on end. And of course, my spinner bulkhead cracked on that flight too. Go figure. 

[tigers2007]

I just watched an EAA video with Brian Carpenter at Rainbow Aviation demonstrating how that works. I'll order that stuff off Amazon now then. Maybe I can inject some brake cleaner down it to blow out any old lube and then blow in fresh stuff.


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[tigers2007]

Armed with my new screw gun, I thought I had this.

 

 

 

Apparently the cable there is for the indicator only. It certainly looks goofy all wrapped around like a kid did it. Which panel hides the hydraulic control valve?

 

 

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[TheTurtle]

the panel forward of that one. 

the release cable is on the pump.  The indicator cable is on the actuator (its called the hydraulic cylinder in the service manual..

Edited February 10, 2017 by TheTurtle

[tigers2007]

Thank you TheTurtle for clearing that up for me. I did go ahead and yank the main belly panel. Wasn't as dramatic as I thought it would be. I used the lube tool and it clearly shot some up in there but it didn't go out the end in the cockpit. I think I'll leave it as is and see how it performs in the coming days. At the next annual I'll have the A&P dismantle the cable at the lever and have him try to blow cable lube down from there. I'm curious if it is full of 53yo grease. I took photos before I touched anything and you can see some black nastiness at that cable. I did see some moisture drops too at the low point of the edge of the belly pan.








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