M20 Hydraulic Pump Flap Diagram

[Shadrach]

1 hour ago, Andy95W said:

I get movement on the first pump, but more on pumps 2, 3 and 4.

That’s weird given the pump should be moving the same amount of fluid with every pump.

[Tcraft938]

The timing for this thread is selfishly perfect for me.  In annual so today the IA and I examined the system.  It is taking 8 pumps to get the flaps all the way down, 10 seconds to retract them.  After many times of cycling and doing so while under the plane checking the actuator, pump and lines (not a drop of leak noted) it got to 6 pumps if pumped fairly fast.  The IA observed that not the full stroke of the handle feels like it is translating into pumping.  Only about 1/2 of the throw of the handle moves the flaps, which makes sense, 1/2 of 8 is 4, about the same as POH.  He is assuming this is due to air in the system, but how did air get in?  The only anomaly I can think of was about two months ago I went to the hangar and found a plate size puddle of hydraulic fluid under the plane.  Open the belly to confirm it came from the pump area and found the connection to the input line needed a 1/4 turn to tighten.  The I also realized a few days previous I flew with a CFI that allegedly had a lot of vintage Mooney time, but apparently not recently because he did not seem real familiar with the hydraulic flaps.  He advised me when putting the plane away to lower the flaps and leave them down so no one steps on them.  I'm thinking this charged the system and left it for a period of time and something let loose.  I since have refilled the reservoir (didn't need much fluid, maybe cap full) and with the exception of needed 7 -8 pumps it has been fine.  No leaks, no flaps coming up uncommanded even at 100 mph.  Tomorrow we may try to bleed the system per the Service Manual.  The IA was not impressed with the lack of information there and what the process was.    Someone else in here mentioned leave the flap lever in up position and pump the handle a million times to expel air.   Maybe I'll try that.  :-)    Thank you EVERYONE for your insights and sharing your expertise.  It is very learning experience for those of us new to these wonderful "mature" airplanes.

[Shadrach]

10 minutes ago, Tcraft938 said:

The timing for this thread is selfishly perfect for me.  In annual so today the IA and I examined the system.  It is taking 8 pumps to get the flaps all the way down, 10 seconds to retract them.  After many times of cycling and doing so while under the plane checking the actuator, pump and lines (not a drop of leak noted) it got to 6 pumps if pumped fairly fast.  The IA observed that not the full stroke of the handle feels like it is translating into pumping.  Only about 1/2 of the throw of the handle moves the flaps, which makes sense, 1/2 of 8 is 4, about the same as POH.  He is assuming this is due to air in the system, but how did air get in?  The only anomaly I can think of was about two months ago I went to the hangar and found a plate size puddle of hydraulic fluid under the plane.  Open the belly to confirm it came from the pump area and found the connection to the input line needed a 1/4 turn to tighten.  The I also realized a few days previous I flew with a CFI that allegedly had a lot of vintage Mooney time, but apparently not recently because he did not seem real familiar with the hydraulic flaps.  He advised me when putting the plane away to lower the flaps and leave them down so no one steps on them.  I'm thinking this charged the system and left it for a period of time and something let loose.  I since have refilled the reservoir (didn't need much fluid, maybe cap full) and with the exception of needed 7 -8 pumps it has been fine.  No leaks, no flaps coming up uncommanded even at 100 mph.  Tomorrow we may try to bleed the system per the Service Manual.  The IA was not impressed with the lack of information there and what the process was.    Someone else in here mentioned leave the flap lever in up position and pump the handle a million times to expel air.   Maybe I'll try that.  :-)    Thank you EVERYONE for your insights and sharing your expertise.  It is very learning experience for those of us new to these wonderful "mature" airplanes.

Leaving flaps down has no real benefit in my opinion.  Thermal expansion can cause real problems. 

This is a thread from back in 2013 but it goes into detail about bleeding the system.

 

[Tcraft938]

17 minutes ago, Shadrach said:

Leaving flaps down has no real benefit in my opinion.  Thermal expansion can cause real problems. 

This is a thread from back in 2013 but it goes into detail about bleeding the system.

 

Thank you very much.  This is exactly what I was going through the search looking for.  Hopefully we get this sorted out.

[Shadrach]

Just now, Tcraft938 said:

Thank you very much.  This is exactly what I was going through the search looking for.  Hopefully we get this sorted out.

I do better searching Mooneyspace with google.

[Nukemzzz]

If the inlet hose is loose the system can suck air during the up stroke of the lever (you are sucking fluid into the cylinder on the up stroke).
 

Sounds like it just needs bled. 

Edited April 16, 2020 by Nukemzzz

[tmo]

10 hours ago, Shadrach said:

I do better searching Mooneyspace with google.

Easiest, and most precise, way to do it is to append "site:mooneyspace.com" to your search terms.  So you would be searching for "flap system bleed Shadrach site:mooneyspace.com".  This will limit the results to just the named site/domain.  Works with Google and DuckDuckGo, not sure about the other search engines.

I don't think there is a way to limit the search to those by a master of a given domain, nor if Google, et.al. know who that would be. ;-)

[Shadrach]

17 hours ago, Nukemzzz said:

My 66’ E was 5.5 pumps before taking the pump off. 

I’m rebuilding the pump and putting back together Friday. My IA wants to bench test it before install, does anyone know what pressure the  retraction circuit ball should hold?  My 1982 MM has no detail on pump performance specs. 

I can't speak to the retraction circuit but the actuator held 1200psi no problem.  Consider lightly staking the ball to the seat on reassembly. More than a few have reinstalled the pump only to find that one or more of the balls is not completely seating.

[Tcraft938]

2 hours ago, Nukemzzz said:

If the inlet hose is loose the system can suck air during the up stroke of the lever (you are sucking fluid into the cylinder on the up stroke).
 

Sounds like it just needs bled. 

Based on the feel of it I don't feel much of anything happen on the upstroke and nothing through about 1/2 the down stroke then some resistance comes into play

[Skates97]

Something I recently noticed, but has possibly been happening as long as I've owned the plane, is that the left side retracts slightly faster than the right side on the ground. It is maybe two seconds faster in retracting. I'm honestly not sure if it also does in the air when there is air pressure pushing against them. Normal? Not?

[Nukemzzz]

21 minutes ago, Skates97 said:

Something I recently noticed, but has possibly been happening as long as I've owned the plane, is that the left side retracts slightly faster than the right side on the ground. It is maybe two seconds faster in retracting. I'm honestly not sure if it also does in the air when there is air pressure pushing against them. Normal? Not?

Whoa...that doesn’t sound right. I think the actuator (singular) acts on a pivot common to both flaps and they can only go at different rates if a joint/pivot is sloppy or loose. 

[Shadrach]

32 minutes ago, Skates97 said:

Something I recently noticed, but has possibly been happening as long as I've owned the plane, is that the left side retracts slightly faster than the right side on the ground. It is maybe two seconds faster in retracting. I'm honestly not sure if it also does in the air when there is air pressure pushing against them. Normal? Not?

This is likely a rigging issue. I doubt they retract at different rates but rather from slightly differing degrees of trail giving the appearance of one lagging behind the other. 

[Skates97]

29 minutes ago, Shadrach said:

This is likely a rigging issue. I doubt they retract at different rates but rather from slightly differing degrees of trail giving the appearance of one lagging behind the other. 

Will have to look into that. That would make sense, they look like they are retracting at the same rate, just the left side gets there first.

[carusoam]

+1 on both flaps being physically attached to one another...  there is probably a way to separate them from each other... so check to be sure they are operating as one!

 

Ways air can get into the flap system is limited...

1) Running low on hydraulic fluid can do it...

2) original hydraulic return lines were week and didn’t resist oil very well... they got hard and cracked...

3) A hint that your lines are open to leaks air/oil... the hydraulic fluid gels on the bottom of your belly panels... making perfect hard to clean, dirt and dust collectors...

4) if it takes extra pumps to get the flaps down... that is mostly signs of the pump/valve system needing some maintenance...

 

5) getting air out of the flap system is a whole lot easier than getting air out of the brake system...

6) It helps to have two people do the work... one inside operating the flap handle and valve, and one outside operating the flaps...

7) hydro lock... a good sign that the pump is working, and the valve works...  

8) if the flaps are down and the pump is still operational... that isn’t hydro locked... some part of the system is leaking pressure...

9) the pump is pretty old tech... smooth chromed walls on the cylinder, and a leather like piston... both can be imperfect over a half century...

10) My C got new low pressure hoses, and the pump removed, cleaned and inspected, before reassembly and installation.... then re-calibrating the up time (twice)...

PP thoughts only, not a mechanic...

best regards,

-a-

[Nukemzzz]

I started the pump rebuild this afternoon with the Lasar Kit. Some things I’ve learned by opening more of the pump:

• The plastic washers actually have large chamfers in the inner diameter of one side making them actually ball on cone seats. It was hard to see that in the other pictures that I saw on the forum. 
• The plunger that lifts the ball retraction ball has a lot of drag because of the O-Ring. It’s surprising that the retraction spring ball has enough force to overcome this friction to run the ball home. 
• The retraction ball spring is shorter than I thought and there is almost no chamfer on this aluminum seat. If you turn the retraction speed screw counterclockwise more than a couple of turns the ball will fall out of the seat.  It’s not captured very well by a chamfer.  Realizing this Possibility solved one of my mysteries. While troubleshooting the pump I loosened the lock nut and the inner screw backed out with it. I think I backed them both out too far, the ball fell out of position, and when I screwed the inner one in to the bottom it landed on the ball which was no longer in the seat. This is why I was unable to slow the retraction speed at all when I screwed the adjustment to the bottom. 
• On the bench I was able to stop flow through the retraction port by running the adjustment screw to the bottom so I don’t appear to need part #23 for the pump to function. I think that’s an error in the parts manual. 
   

With any luck this will all be back together and working tomorrow.  Side note: we might be pulling the prop to install a front crank seal as well...

[carusoam]

The cone shaped plastic washer starts out as a cylinder and gets compressed with the first use of two... (or at least it used to) better if they start out conic in shape...

it’s highly unlikely that extra parts are OK...

was the extra part in the drawing or in the parts kit?

Did you use anything to stick things together during the assembly process?  Ball and spring?

PP thoughts only, just trying to keep from having to do it twice....

Best regards,

-a-

[Nukemzzz]

9 hours ago, carusoam said:

The cone shaped plastic washer starts out as a cylinder and gets compressed with the first use of two... (or at least it used to) better if they start out conic in shape...

it’s highly unlikely that extra parts are OK...

was the extra part in the drawing or in the parts kit?

Did you use anything to stick things together during the assembly process?  Ball and spring?

PP thoughts only, just trying to keep from having to do it twice....

Best regards,

-a-

There is a part shown in the PM that isn’t in the pump, isn’t shown in the MM, and others are reporting they didn’t have it either.  I think maybe Mooney changed the design but missed the PM publication. 

[Shadrach]

10 hours ago, carusoam said:

The cone shaped plastic washer starts out as a cylinder and gets compressed with the first use of two... (or at least it used to) better if they start out conic in shape...

it’s highly unlikely that extra parts are OK...

was the extra part in the drawing or in the parts kit?

Did you use anything to stick things together during the assembly process?  Ball and spring?

PP thoughts only, just trying to keep from having to do it twice....

Best regards,

-a-

Anthony I’ve personally disassembled four different pumps and as I recall the part labeled  #23 has not been present in any of them.

Edited April 17, 2020 by Shadrach

[Shadrach]

10 hours ago, Nukemzzz said:

I started the pump rebuild this afternoon with the Lasar Kit. Some things I’ve learned by opening more of the pump:

• The plastic washers actually have large chamfers in the inner diameter of one side making them actually ball on cone seats. It was hard to see that in the other pictures that I saw on the forum. 
• The plunger that lifts the ball retraction ball has a lot of drag because of the O-Ring. It’s surprising that the retraction spring ball has enough force to overcome this friction to run the ball home. 
• The retraction ball spring is shorter than I thought and there is almost no chamfer on this aluminum seat. If you turn the retraction speed screw counterclockwise more than a couple of turns the ball will fall out of the seat.  It’s not captured very well by a chamfer.  Realizing this Possibility solved one of my mysteries. While troubleshooting the pump I loosened the lock nut and the inner screw backed out with it. I think I backed them both out too far, the ball fell out of position, and when I screwed the inner one in to the bottom it landed on the ball which was no longer in the seat. This is why I was unable to slow the retraction speed at all when I screwed the adjustment to the bottom. 
• On the bench I was able to stop flow through the retraction port by running the adjustment screw to the bottom so I don’t appear to need part #23 for the pump to function. I think that’s an error in the parts manual. 
   

With any luck this will all be back together and working tomorrow.  Side note: we might be pulling the prop to install a front crank seal as well...

 

I’m a little concerned that a previous owner may have lost your spring and replaces it with similar but not exact part. If I recall correctly one can feel moderate spring compression before the the retraction adjustment screw grabs the threads in the body. 

Another small point of clarification. I know others have suggested that the retraction ball seat is aluminum. I don’t believe that to be the case. I believe that both halves of the pump our machined from solid brass. 

[Nukemzzz]

2 hours ago, Shadrach said:

I’m a little concerned that a previous owner may have lost your spring and replaces it with similar but not exact part. If I recall correctly one can feel moderate spring compression before the the retraction adjustment screw grabs the threads in the body. 

Another small point of clarification. I know others have suggested that the retraction ball seat is aluminum. I don’t believe that to be the case. I believe that both halves of the pump our machined from solid brass. 

Feels like an anodized aluminum housing to me. Brass colored aluminum. 

None of this matters anymore though. Found my oil leak. 

[Nukemzzz]

Brass color is only skin deep. 

[Shadrach]

Just now, Nukemzzz said:

Brass color is only skin deep. 

Thanks, Indeed looking at yours I have learned something.  Mine is darker but certainly is made from the same material. That does not look like solid brass. I stand corrected.

[Shadrach]

14 minutes ago, Nukemzzz said:

Feels like an anodized aluminum housing to me. Brass colored aluminum. 

None of this matters anymore though. Found my oil leak. 

I'm sorry for  the bad news. Been there and done that in 2010.  880SMOH so I elected to have the case overhauled.  Has not leaked a drop since.

How much time on the engine and where are you located?

[Nukemzzz]

27 minutes ago, Shadrach said:

I'm sorry for  the bad news. Been there and done that in 2010.  880SMOH so I elected to have the case overhauled.  Has not leaked a drop since.

How much time on the engine and where are you located?

300hrs TSMO but the engine sat for 2yrs prior to buying it. The cam is likely questionable. 

About 10hrs total flight training in it and 100hrs working on it. Now it’s engine time. I’ve not had good luck. Lol

[Shadrach]

57 minutes ago, Nukemzzz said:

300hrs TSMO but the engine sat for 2yrs prior to buying it. The cam is likely questionable. 

About 10hrs total flight training in it and 100hrs working on it. Now it’s engine time. I’ve not had good luck. Lol

I was in a similar situation. Airplane sat for several years with little activity. I flew it for two years before a one of the lower bolt bosses cracked on the passenger side of the case.  The crack propagated from the boss and into the parting flange, puking oil everywhere.

If you have an engine shop within reasonable distance I would urge you to go local.  There is a great benefit in being able to work with someone in person rather than just being a voice on the phone.  That case may very well be overhaulable.  I pulled my engine and accessories and dropped my engine at an overhaul shop about 40min drive from me.  They had the case halves crated same day and sent to Tulsa for overhaul.  The engine internals were in excellent shape.  I hung the engine under supervision. The price was quite reasonable and I really got to know my airplane. 10 years on it runs like a top and has been totally oil tight.

 

Mooneyspace is littered with the posts of folks that have been through this. I would not be resigned to a new engine without more info.

Edited April 17, 2020 by Shadrach