Hydraulic flap problems

[skydvrboy]

I have two flap problems that tell me they aren't working right.  First, it takes exactly 8 pumps to go from no flaps to full flaps, always has since I got the plane.  Second, it takes about 1 second on the ground to retract the flaps, in the air this is less than 0.1 seconds.  My A&P and IA just finished adjusting the set screw all the way in and it made no difference on the retract time.  Any ideas on what may be causing this?

Is it possible for the flaps to still work, but exhibit this behavior if one of the two balls is missing?  What if they were switched?

[Dream to fly]

I have two flap problems that tell me they aren't working right.  First, it takes exactly 8 pumps to go from no flaps to full flaps, always has since I got the plane.  Second, it takes about 1 second on the ground to retract the flaps, in the air this is less than 0.1 seconds.  My A&P and IA just finished adjusting the set screw all the way in and it made no difference on the retract time.  Any ideas on what may be causing this?
Is it possible for the flaps to still work, but exhibit this behavior if one of the two balls is missing?  What if they were switched?

The springs that retract them might he stretched. Also prop wash helps push them to retract. As for the pump I had lasar rebuild mine. Works great 4 pumps and no drips.

Sent from my E6810 using Tapatalk

[Prior owner]

Lasar has the kits for the master and slave- they are pretty cheap, just o-rings. A long time to pump them down coupled with a really Fast retraction time, even after adjusting them, might indicate air in the system? Regarding weak springs- I think that weak springs would have the opposite effect of what you are experiencing  (it would be quick to pump them  down and slower during retract).

Did you pressure bleed them from the bottom?

Edited November 28, 2018 by PilotCoyote

[N201MKTurbo]

There is a screw on the pump that controls the retract time. When it is screwed all the way in the flaps should not retract at all. If this doesn’t happen then something is wrong. The adjustment is very sensitive. 

Adjust the rate to be about 10 seconds on the ground to get a good rate in the air.

The way yours are adjusted the plane must feel like it is falling out of the sky when you put them up.

[Shadrach]

32 minutes ago, skydvrboy said:

I have two flap problems that tell me they aren't working right.  First, it takes exactly 8 pumps to go from no flaps to full flaps, always has since I got the plane.  Second, it takes about 1 second on the ground to retract the flaps, in the air this is less than 0.1 seconds.  My A&P and IA just finished adjusting the set screw all the way in and it made no difference on the retract time.  Any ideas on what may be causing this?

Is it possible for the flaps to still work, but exhibit this behavior if one of the two balls is missing?  What if they were switched?

Your system needs to be bled. 8 pumps is no bueno, should be 4. There is no point in trying to set retraction speed until the other issue is worked out.

Edited November 28, 2018 by Shadrach

[skydvrboy]

15 minutes ago, PilotCoyote said:

Did you pressure bleed them from the bottom?

Yes, we pressure bled them from the bottom.

6 minutes ago, N201MKTurbo said:

If this doesn’t happen then something is wrong.

Agreed, there is definitely something wrong, but what?  And yes, in the air it feels like the back end drops about a foot instantly when I retract the flaps.  It was a bit alarming at first, but I found if I give the yoke a slight forward push as I retract them it's not so bad.

6 minutes ago, Shadrach said:

Your system needs to be bled.

I don't think air in the system is the problem since it's been like this for over a year.  Always consistently 8 pumps and I get very positive response with each pump.  I had a leak last year and got air in the lines when the fluid got to low.  When that happened, it took a few pumps before they started moving and felt mushy.

I guess I didn't mention in my initial post, we did find the leak in the actuator and rebuilt that with the kit from Lasar.  That fixed the fluid leak, but no change to the retraction speed or # of pumps.

[Shadrach]

Just now, skydvrboy said:

Yes, we pressure bled them from the bottom.

Agreed, there is definitely something wrong, but what?  And yes, in the air it feels like the back end drops about a foot instantly when I retract the flaps.  It was a bit alarming at first, but I found if I give the yoke a slight forward push as I retract them it's not so bad.

I don't think air in the system is the problem since it's been like this for over a year.  Always consistently 8 pumps and I get very positive response with each pump.  I had a leak last year and got air in the lines when the fluid got to low.  When that happened, it took a few pumps before they started moving and felt mushy.

I guess I didn't mention in my initial post, we did find the leak in the actuator and rebuilt that with the kit from Lasar.  That fixed the fluid leak, but no change to the retraction speed or # of pumps.

Then your pump is improperly assembled.  Only half of the fluid is making it to the actuator. I have a 67F.  I have rebuilt and bled every part of this system. 8 pumps is not good. a retraction screw that has no effect means that fluid is leaking back elsewhere.

[Dream to fly]

The springs that retract them might he stretched. Also prop wash helps push them to retract. As for the pump I had lasar rebuild mine. Works great 4 pumps and no drips.

Sent from my E6810 using Tapatalk

My issue. I read that as 10 sec not .1.


Sent from my E6810 using Tapatalk

[Shadrach]

7 minutes ago, Dream to fly said:

My issue. I read that as 10 sec not .1.


Sent from my E6810 using Tapatalk
 

You're referring to the retraction spring on the flaps no?  how would a stretched (unlikely in my opinion) make the flaps retract faster. Stretched springs would exert less force, not more.  If your mechanic told you that your stretched retraction springs caused a fast retraction, he was confused.

Edited November 28, 2018 by Shadrach

[Dream to fly]

5 minutes ago, Shadrach said:

You're referring to the retraction spring on the flaps no?  how would a stretched (unlikely in my opinion) make the flaps retract faster. Stretched springs would exert less force, not more.  If your mechanic told you that your stretched retraction springs caused a fast retraction, he was confused.

I read that as it took ten seconds to retract in the air.  My fault.  That is what I was saying.  

[skydvrboy]

25 minutes ago, Shadrach said:

Then your pump is improperly assembled.  Only half of the fluid is making it to the actuator. I have a 67F.  I have rebuilt and bled every part of this system. 8 pumps is not good. a retraction screw that has no effect means that fluid is leaking back elsewhere.

I think your onto something there, which is why we thought that the two little balls might be swapped.  I have a good understanding of hydraulics and how a hydraulic pump works in general, but no actual experience with this mechanism.  It seems strange that the flaps would stay down if some of the fluid is leaking back, but it must only be leaking back when the flaps are being pumped up or down.

I'll get the pump rebuild kit from Lasar and go through it with my A&P with a fine tooth comb.  The pump itself is not leaking, at least externally.

Edited November 28, 2018 by skydvrboy

[Shadrach]

1 hour ago, skydvrboy said:

I think your onto something there, which is why we thought that they two little balls might be swapped.  I have a good understanding of hydraulics and how a hydraulic pump works in general, but no actual experience with this mechanism.  It seems strange that the flaps would stay down if some of the fluid is leaking back, but it must only be leaking back when the flaps are being pumped up or down.

I'll get the pump rebuild kit from Lasar and go through it with my A&P with a fine tooth comb.  The pump itself is not leaking, at least externally.

The rebuild kit is comprised of seals only. If you're tearing it down ,might as well replace them.  If you have a working understanding of how hydraulics work it will be a simple assembly.  Heres a diagram to give you an idea what your up against.

 

Edited November 28, 2018 by Shadrach

[carusoam]

Updating the pump seals makes it work magically, once the air is flushed out of the system...

Use extreme caution with flaps that can dump lift immediately....

The setting on the ground is about half what the retract speed will be in flight... springs vs air pressure...

Better to be slow on the retract speed, than to be too fast...

The MM covers many of the details...

PP thoughts only, not a mechanic.

Best regards,

-a-

[Captnmack]

Rebuilding is easy, getting it out, harder. Some of the seals are Leather but the Kit has them all. Once installed AND bled it’s easy to adjust the return rate.

Goodluck.

[Shadrach]

I'll just leave this right here. Symptoms are similar.

 

 

[rbridges]

On 11/28/2018 at 6:04 PM, Captnmack said:

Rebuilding is easy, getting it out, harder. Some of the seals are Leather but the Kit has them all. Once installed AND bled it’s easy to adjust the return rate.

Goodluck.

The white Teflon inserts are not. Try not to damage them during the procedure. That was the source of my problems. 

BTW, turning the adjustment screw clockwise slows the dump speed of the flaps. 

[skydvrboy]

Thanks for the heads up guys.  I've been following @rbridges thread and will check the condition of the teflon inserts during the overhaul and stake the balls into them.