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FlyingMonkey

Slow Flaps Cycling

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Hey all, I have been having a minor but slightly perplexing issue with my flaps:

I park my airplane with the flaps set at 0°.  When I first start the airplane and taxi out, the first time I cycle to the flaps down to 15°, they are slow and the motor sounds a little strained.  After that they are fine.  In the air there does not need to be any issue with flaps operation, just that first cycle of the day.  I have applied Inox to the flap mechanism as Roger Lee suggests, but the behavior doesn't change. 

I don't think this is electrical, since it's just that first deployment that is slow.  Any thoughts?  The flaps jack screw?  The motor?  How should I proceed in diagnosing the issue, and is it really even an issue? 

Thanks!

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The exact same thing happens to my 2009 CTLS, exatly as you described it. Happens almost every time on the first flap movement of the day on the ground. I have also tried the Inox with no success. I have been perplexed for months. Ill keep an eye on this thread. If you find anything out please let me know, and I will do the same. 

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Sorry - not of any help here except that i have also noticed "weak" motor but usually only when i extend the flaps in flight.  When i switch 0 to 15 degrees,  it will take a few moves and maybe 30 seconds before reaching 15 degrees.   (not one smooth movement)  Note; im not extending flaps at faster than recommend speed.   

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11 hours ago, Aaronp07 said:

The exact same thing happens to my 2009 CTLS, exatly as you described it. Happens almost every time on the first flap movement of the day on the ground. I have also tried the Inox with no success. I have been perplexed for months. Ill keep an eye on this thread. If you find anything out please let me know, and I will do the same. 

Sorry you have the problem, but glad I'm not alone!  Maybe it's not even a problem so much as a "quirk"...I guess time will tell.

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7 hours ago, cdarza said:

Sorry - not of any help here except that i have also noticed "weak" motor but usually only when i extend the flaps in flight.  When i switch 0 to 15 degrees,  it will take a few moves and maybe 30 seconds before reaching 15 degrees.   (not one smooth movement)  Note; im not extending flaps at faster than recommend speed.   

That sounds a little more serious than what I'm experiencing.  Sounds like you have something binding up, or a failing motor.

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8 hours ago, cdarza said:

Sorry - not of any help here except that i have also noticed "weak" motor but usually only when i extend the flaps in flight.  When i switch 0 to 15 degrees,  it will take a few moves and maybe 30 seconds before reaching 15 degrees.   (not one smooth movement)  Note; im not extending flaps at faster than recommend speed.   

That sounds like an adjustment to the current limiter on the board, or you need to slow down a little more before dropping the flaps.

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Is there a spec for the current limiter?  I might buy a clamp-on DC current meter just to diagnose this. My flaps are also slow airborne.

I'm about to check all the connectors on the regulator board, and maybe put in my spare battery. Engine crank is working fine, so probably not battery.

 

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It's an issue with the actuator design. I have to regrease the jackscrew with a molybdenum grease every once in a while (3-4 years).

There's no official documentation for how to perform it though, and disassembly of the motor gearbox is tricky, lots of small parts.

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Thanks Anticept. So yours did the same thing before you dissasembled and regreased it? I am not mechannically inclined, and that sounds beyond my abbilities.

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It is a reoccurring problem that shows up in several CTs i have dealt with, all solved with the same solution.

It is especially a problem in the cold.

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On 12/9/2019 at 1:59 AM, Anticept said:

It is a reoccurring problem that shows up in several CTs i have dealt with, all solved with the same solution.

It is especially a problem in the cold.

Can you provide an overview on how to perform this?

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Obvious legal thing: I'm not responsible for what you do to your flaps even if you follow this overview.

 

This guide applies to the vertical flap actuator system, if you have the horizontal one... you'll have to wing it i guess, most of this stuff still applies.

Find a molybdenum grease. Yeah it's gonna be EXPENSIVE. Don't cheap out.

Flaps need to be in their lowest position. If you don't do this, parts are going to fly everywhere and you'll probably damage something.

Again, lowest possible position. Use the manual down on your flap controller.

Did I say lowest possible position yet? Just in case I didn't....

 

Put a towel under the flap actuator and make sure it covers everything. These parts are not replaceable. You need to catch them if they fall out.

Start by disconnecting the two terminals on the motor. Leave the wires to the potentiometer alone, you're just taking the motor off.

Are the flaps in the lowest position? Last chance!

 

Using a screwdriver, look for the 4 philips screws where the heads are facing down on the motor to assembly flange. Remove them carefully, keeping a hand on the motor.

Once removed, slowly lower the motor, taking photos so you can see how it was assembled. There are, as I can best remember, 2 free floating gears, itty bitty teeny weeny spacers for those gears, 2 roller bearing assemblies with a removable track that comes with it, and a guide pin positioning spacer (plastic, looks like a sickle, pay attention to how it is fitted in, this is critical!). Pay attention to how it was assembled, *ALL* of this is required or your motor will likely self destruct because it's all meant to hold things in place with the *enormous* forces felt in operation.

With all of this removed, put your finger up into the jackscrew and rotate it counterclockwise. You shouldn't have to use much force. The jackscrew will lower, take it out as far as it will allow you to. There may be bearings and races attached, make sure you don't lose them!

Proceed to clean parts and wipe down the jackscrew, and put in molybdenum grease in the actuator gearbox, and a coating on the jackscrew. Run the jackscrew up and down and reapply once or twice.

Wind the jackscrew back in. Reassemble and test. Positioning that plastic sickle spacer was by far the biggest pain, a little coating of grease on it should hold it in place.

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Excellent write up - Thanks!

What are you seeing with the "old" grease when you open the gear box up? Is the oil separating from the Moly? Does it seem to be hardening? Moly is a great product for high shear force applications, but I have heard it might not be the best product where the device is only used occasionally. Just curious if there is something else that would work better for this application.

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It's a jack screw that internally has a pretty decent load on it. The moly grease is what I put in both the gearbox and the jackscrew.

This is also why I said don't cheap out. The carrier grease is important too.

I am not sure why this works, because I can still clearly see the grease on the jackscrew (though barely), I just know that the moly grease I use lasts a long time.

Aeroshell 33 is another that I have used.

I have also learned that non synthetic greases are terrible for this application. I ended up having to regrease less than 6 months later when I tried one of the single digit aeroshell greases, can't remember which. The grease did not stay in place at all.

I started using moly because this is also what is used in a lot of other jackscrew applications in airlines.

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Looks like there are/were two Aeroshell 33 greases. One version is a synthetic lithium grease that is used on most places on an airframe, the other is Aeroshell 33MS (now called Aeroshell 64) which contains molybdenum.  I assume it is the last grease or similar that you prefer?

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Thanks for the write up Corey.  Maybe at my next annual over the winter I will screw up my courage (pun intended) to do this maintenance.  I definitely worry about losing a bunch of (I'm sure very expensive) tiny parts, or getting something wrong on the reassembly.

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2 hours ago, BravoFoxtrot said:

Looks like there are/were two Aeroshell 33 greases. One version is a synthetic lithium grease that is used on most places on an airframe, the other is Aeroshell 33MS (now called Aeroshell 64) which contains molybdenum.  I assume it is the last grease or similar that you prefer?

It was standard 33. 33MS/64 was out of my price range.

The big point, again, is the synthetic base.

Greases with clay thickeners actually separate under high pressure and don't reintegrate very well, which is probably one reason why grease reapplication is so common, it's probably a carry over.

Lithium based greases are significantly less prone to that problem. There's other types of greases too, but a Lithium or moly grease is fine.

I actually switched to using lithium based grease for the nosewheel assembly too, it lasts significantly longer. 

This became my go to for pretty much all my grease applications except the jack screw but it works pretty well for that too (tried it before switching to moly) .  https://www.aircraftspruce.com/catalog/eppages/exxongreaseshc-100.php

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Also remember to clean those parts best you can.

You are not supposed to mix greases. They may interact and destroy lubricating properties.

Especially don't mix greases with different thickening agents. It completely changes, and not always immediately.

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On 12/13/2019 at 4:37 AM, Anticept said:

Obvious legal thing: I'm not responsible for what you do to your flaps even if you follow this overview.

Thanks for the guidance on this.  Im gonna attempt servicing it this weekend.  Just wanted to double check;   2 screws on the bottom and 2 screws on the top (as per pics).  The jackscrew,  that stays in as i pull down the motor yes?    Then rotate the jackcrew to lower it .. Does the jack screw eventually come off ?  or just lower it enough to be wiped down and regreased?   (thanks for all the details as i am likely to mess this up - thus wanna make sure i know im not missing something)

And YES i will make sure flap is at lowest position before starting the procedure !! LOL

Flap 1.jpg

Flap 2.jpg

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 The jack screw is inside the assembly. That's a cap, probably so they can inject grease during manufacturing.

There are 4 screws if I recall correctly. Two of which are near that cap.

Keep flaps at lowest position before you do this or you'll have parts going everywhere... and again, you should still be laying out rags and such to catch the parts.

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Im attaching some photos for those interested in the flap motor removal and the parts within: 

Picture 1.  Note; When I removed the motor,  the small whitetish plastic part and the round metal pc didn't come off -so it took me awhile to figure out that this also had to come off to get access to the jack screw

 

IMG_4701.thumb.JPG.53e604c17c2d4a404c6f8fc17e4b86ff.JPG

 

Picture 2

IMG_4694.JPG

Picture 3

IMG_4718.JPG

 

Picture 4.      This is pic 3 disassembled.   Don't lose the white plastic part (forgot to include it this photo)

IMG_4717.JPG

Picture 5

IMG_4711.JPG

Picture 6

IMG_4716.JPG

Picture 7. Cleaned and ready to grease 

IMG_4722.JPG

Picture 8  - the small plastic piece  that can barely be seen in seen in picture 1

1773915965_PlasticSickle.jpg.5592a008e6906528a89d6956f47eb07e.jpg

When re-installing - make sure the plastic is inserted correctly - I was having a difficult time inserting the motor/gear back in as the plastic was installed wrongly...  

102763701_FlapMotorInstalation.thumb.jpg.8665a2d691ea3212bf9c80c58afdf4ac.jpg

Flap Motor Instalation.jpg

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On 2/9/2020 at 2:44 AM, Anticept said:

 The jack screw is inside the assembly. That's a cap, probably so they can inject grease during manufacturing.

There are 4 screws if I recall correctly. Two of which are near that cap.

Keep flaps at lowest position before you do this or you'll have parts going everywhere... and again, you should still be laying out rags and such to catch the parts.

Do you mean lowest setting physically (40°) or lowest numerically (-6°)?  Complete opposites, would hate to get it wrong!  :D

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