flap handle malfunction

[DXB]

When I got my '68 M20C a few months ago, my flap handle worked nicely - 2 pumps for takeoff setting, 2-3 more for full.  Exactly what the POH says.   The release lever was very stiff, but then a local MSC simply lubed the cable, and it worked perfectly too.  Now suddenly (on first solo after finishing 10 hrs transition training, of course), it takes 3-4 rapid pumps to get any back pressure behind the handle and have flaps start coming down. Then it takes 6-7 pumps to get them down to full.  They seem to stay down ok and will still come up at appropriate speed subsequently. 

 

I've read various stuff on other posts regarding leaks, bleeding the system, including trying to get air out by various strategies.  My questions are (1) Did I do anything to cause this problem?   (2) What, if anything, I should try to do myself here before flying back to MSC. Dealing repeatedly with early squawks is getting old, and I really just want to fly it for a while to get my skills honed.  

[bonal]

Since they stay down once deployed I don't think you have a leak or bad cylinder likely needs bleeding. There is an adjustment that can be made I know it controls retraction don't know about deployment. As for doing some flying IMHO can't see any issues since they do operate and since no one can agree on weather to even use them in the first place unless in more challenging conditions. Go do some flying it will help reduce the sting of all the problems you have encountered...Believe me when I say I know what you mean...

[carusoam]

Sounds similar to having some air in the system...

Try to work the system on the ground to see if the air works itself out.

Pump them down, let them up....

Many times.

If you pump the handle and nothing happens....

Might be time to read up on flushing the system...?

There is plenty written on the topic around here...

Best regards,

-a-

[Andy95W]

Sounds similar to having some air in the system...

Try to work the system on the ground to see if the air works itself out.

Pump them down, let them up....

Many times.

If you pump the handle and nothing happens....

Might be time to read up on flushing the system...?

There is plenty written on the topic around here...

Best regards,

-a-

I agree with Anthony, and to add that you definitely need to make sure the hydraulic reservoir is full of red 5606 hydraulic fluid.

It definitely sounds like you sucked some air into your system. Repeated pumping will, eventually, bleed that air out from the point you are now.

[Jim Peace]

When I got my '68 M20C a few months ago, my flap handle worked nicely - 2 pumps for takeoff setting, 2-3 more for full.  Exactly what the POH says.   The release lever was very stiff, but then a local MSC simply lubed the cable, and it worked perfectly too.  Now suddenly (on first solo after finishing 10 hrs transition training, of course), it takes 3-4 rapid pumps to get any back pressure behind the handle and have flaps start coming down. Then it takes 6-7 pumps to get them down to full.  They seem to stay down ok and will still come up at appropriate speed subsequently. 

 

I've read various stuff on other posts regarding leaks, bleeding the system, including trying to get air out by various strategies.  My questions are (1) Did I do anything to cause this problem?   (2) What, if anything, I should try to do myself here before flying back to MSC. Dealing repeatedly with early squawks is getting old, and I really just want to fly it for a while to get my skills honed.  

Mine did the same thing after I left a paint shop.  What I think happened is they left the flaps down for whatever reason and it was about 120 degrees in the shade that week.  The hose that is on the right side by the copilot right knee (actually near the floor) behind the interior panel was leaking.... I just changed the hose a few weeks ago...the test flight is tomorrow..on the ground with no load I am back to 2 for approach and 4 to 5 for landing...

 

remind me to let you know how it goes.......

[Browncbr1]

I'm still learning about the systems on mine as well, but I think the flaps hydro system is shared with the brakes? Do the brakes work ok?

[Shadrach]

Does anyone know if the Hydraulic flaps changed over the years? I ask because my 67F takes precisely 4 pumps from 0 degrees to full flaps. And I do mean precisely; the handle will come up on the fifth pump but is hydro locked out from pumping. The few times that I've gotten more than 4 pumps it has been due to leaks, low fluid and air in the system.

[carusoam]

I believe they are all the same, Ross.

My 65C did four pumps.

First, was thought to pressurize the system and give a couple of degrees deflection.

Second, 10° Deflection.

Third, 20° deflection.

Fourth, 30° Deflection.

Roughly 'estimating'.

There may be some difference in hardware over the years. I just don't know...

Side note: how's the growing family?

Best regards,

-a-

[DXB]

When I got my '68 M20C a few months ago, my flap handle worked nicely - 2 pumps for takeoff setting, 2-3 more for full.  Exactly what the POH says.   The release lever was very stiff, but then a local MSC simply lubed the cable, and it worked perfectly too.  Now suddenly (on first solo after finishing 10 hrs transition training, of course), it takes 3-4 rapid pumps to get any back pressure behind the handle and have flaps start coming down. Then it takes 6-7 pumps to get them down to full.  They seem to stay down ok and will still come up at appropriate speed subsequently. 

 

I've read various stuff on other posts regarding leaks, bleeding the system, including trying to get air out by various strategies.  My questions are (1) Did I do anything to cause this problem?   (2) What, if anything, I should try to do myself here before flying back to MSC. Dealing repeatedly with early squawks is getting old, and I really just want to fly it for a while to get my skills honed.  

Ok so I made some progress, but things are not quite back to perfect.  With help of folks here, I found the hydraulic fluid reservoir- indeed the level was low (at the level where the line for the flaps comes off on the side).   I topped off, pumped handle a bunch of times, topped off again, pumped some more until minimal drop in the level visible in reservoir.   I then put the flaps down and retracted a number of times as suggested above.   I also inspected all the visible hydraulic lines no obvious leaks from the limited portions accessible behind the panel.  

 

Now it does take exactly 4 pumps to get the flaps fully down once they start moving, but I still need an additional 2 pumps before they will move.  However, if I have just retracted them in the last minute or so, I do not need the initial two pumps. They still seem to stay down ok and retract at the appropriate speed.   I can live with this, but I don't want to ignore a more serious underlying problem.   Or is this just normal??

[Marauder]

Ok so I made some progress, but things are not quite back to perfect. With help of folks here, I found the hydraulic fluid reservoir- indeed the level was low (at the level where the line for the flaps comes off on the side). I topped off, pumped handle a bunch of times, topped off again, pumped some more until minimal drop in the level visible in reservoir. I then put the flaps down and retracted a number of times as suggested above. I also inspected all the visible hydraulic lines no obvious leaks from the limited portions accessible behind the panel.

Now it does take exactly 4 pumps to get the flaps fully down once they start moving, but I still need an additional 2 pumps before they will move. However, if I have just retracted them in the last minute or so, I do not need the initial two pumps. They still seem to stay down ok and retract at the appropriate speed. I can live with this, but I don't want to ignore a more serious underlying problem. Or is this just normal??

Sounds like you still have air in the lines.

Sent from my iPad using Tapatalk

[carusoam]

Air is one thing...

That oil went somewhere.

Expect that the oil lines are 40+ years old. They swell, crack and dump the oil all over the belly panels...

My C got its low pressure oil lines replaced. These are the lines that return oil back to the reservoir.

Relatively easy and low cost when working with your mechanic. If you have a lot of oily dust and hard to clean belly panels....

Expect that there is a leak in the old tubes...

Best regards,

-a-

[Shadrach]

I believe they are all the same, Ross.

My 65C did four pumps.

First, was thought to pressurize the system and give a couple of degrees deflection.

Second, 10° Deflection.

Third, 20° deflection.

Fourth, 30° Deflection.

Roughly 'estimating'.

There may be some difference in hardware over the years. I just don't know...

Side note: how's the growing family?

Best regards,

-a-

RE: Flaps That's what I figured but I think my 67 is the oldest Mooney I've flown in with manual flaps.

 

RE Family:  Thanks for asking! We celebrated our first year in August.  Talking about additions now...

 

I'm rarely around these parts; it's good to see the activity!

 

Hope you're well!

[Shadrach]

Ok so I made some progress, but things are not quite back to perfect.  With help of folks here, I found the hydraulic fluid reservoir- indeed the level was low (at the level where the line for the flaps comes off on the side).   I topped off, pumped handle a bunch of times, topped off again, pumped some more until minimal drop in the level visible in reservoir.   I then put the flaps down and retracted a number of times as suggested above.   I also inspected all the visible hydraulic lines no obvious leaks from the limited portions accessible behind the panel.  

 

Now it does take exactly 4 pumps to get the flaps fully down once they start moving, but I still need an additional 2 pumps before they will move.  However, if I have just retracted them in the last minute or so, I do not need the initial two pumps. They still seem to stay down ok and retract at the appropriate speed.   I can live with this, but I don't want to ignore a more serious underlying problem.   Or is this just normal??

 

It is not normal and you do have air in the line. Find the leak.  It's likely at the pump or at the actuator.

 

A few years back my actuator started leaking like a sieve.  I removed it (under A&P supervision as always) and took it apart.  Other than ratty looking fluid, I could find nothing wrong. The o-rings and leather were in good shape.  I cleaned everything in solvent and let it dry.  I reinstalled the o-rings and leather and gave it a good soak in hydraulic fluid. After reassembling the actuator, I hooked it to a hydraulic hand pump with a pressure gauge. I stopped pumping at 1200PSI as it held tight. Reinstalled and bled it from bottom to top. No issues since.  Sometime these old things get gummed up or a piece of particulate gets stuck in the works. There are no expensive wear items on the manual system...none. Find the leak, stop the leak, flush and bleed the system, done.  Even if you have to overhaul the actuator and the pump, the parts should be well under $100. The system is truly elegant in its simplicity and reliability!

[DXB]

Finally think I got all the air out, I think, after several rounds alternating vigorous pumping and adding more fluid to the reservoir.   Must be a leak, but hard to know how bad from this one episode.   If problem comes back fast, then off to the MSC.  If not, wait to lump it together with the next problem or two...

[Shadrach]

I have a pressure pot Dev. If you don't get this sorted, you may borrow it if needed.

[DXB]

So...the flap saga continues:

 

The good news: The flaps work perfect now after adding a bunch of fluid and getting the air out.  I checked the reservoir after flying today and saw no drop in fluid level, so system is not leaking like a sieve somewhere and maybe can wait a bit to check out.  

 

The bad news: On today's flight, the flap INDICATOR stuck in the down position (comes up only 1/4 of way upon pushing the tab up).  The flaps come up fine.   I took the indicator faceplate off when I got back and can then manually force the tab back to the up position. It then goes down again appropriately and gets stuck at the exact same spot on the way back up.  The indicator needle itself moves fine so it must be the cable attached to it or past that in the system.     

 

Anyone else have this problem??  Seems like an incredible coincidence to have the indicator cable bind or something right after adding a bunch of fluid and pumping the handle a million times to get the air out.  

[Shadrach]

The indicator cable may be binding. Get out your screwdriver, as the belly panels need to be removed to gain access. I would lube the whole cable if possible (I don't recall if it's sealed or just a coil). I like Kroil or Mouses Milk for cables. You should also [have your mx] look at the the cable attach point on the flap spar and make sure that it's not binding there.

[carl]

The other day , it was a warm 50 degrees and my flaps behaved totally different. The J bar gear did too. Extremely easy . . later that week it was 39 degrees F, and they were stiff again . that one 50 degree day was a quick summer  but I liked it, but the plane felt different . 

 

carl