'topping off' flap / brake hydraulics

[goalstop]

Hi Mooneyspace,

My M20E's flaps are taking about 8 pumps to get down instead of 4.  My mechanic said fixing it would probably require replacing a seal on the flap actuator which would necessitate a full flush of the hydraulic system.  I called a MSC and they said "I should just leave it because it's an expensive fix and more prone to breaking something else if I mess with it", but suggested that topping it off with hydraulic fluid might fix the issue

Is it simple to just put fluid in the hydraulic fluid reservoir in front of the pilot side firewall, or is there a highly nuanced procedure needed to flush the system and ensure no air bubbles get in?

Thanks!! 

[RLCarter]

It’s less than 100 bucks for both the pump & actuator kits. Do them both, took about a day total.

[goalstop]

24 minutes ago, RLCarter said:

It’s less than 100 bucks for both the pump & actuator kits. Do them both, took about a day total.

Do you have a link? Mechanic said it would also be a 7hr job to flush the whole system.

[markgrue]

I would top it off first.   If that doesn't fix it then all you have lost is a little hud fluid.   Do the easy thing first.   To answer your question,  just put the fluid in and work the flaps up and down a few times.   That will work any air bubbles out. 

 

Mark 

[RLCarter]

54 minutes ago, goalstop said:

Do you have a link? Mechanic said it would also be a 7hr job to flush the whole system.

LASAR has the kits, as others have said top it off with 5606 and see if it helps, the reservoir is for both the flaps and the brakes so as the fluid gets low the flaps suck air first…

[47U]

9 hours ago, goalstop said:

Is it simple to just put fluid in the hydraulic fluid reservoir in front of the pilot side firewall, or is there a highly nuanced procedure needed to flush the system and ensure no air bubbles get in?

Adding hydraulic fluid (5606) shouldn’t be difficult and won’t by itself introduce air in the system, although servicing may be more challenging if you have a 201 windshield and the avionics access panels are closed up.

Does the flap handle ‘feel any different’ than ‘normal’ when pumping down the flaps?  If the hydraulic fluid is so low that the flap pump is sucking air, then I’d be looking for a hydraulic leak.  If the parking brake valve (below the reservoir) is leaking, you might not be aware.      

[carusoam]

1) Leaks come from aging hoses…

2) Lots of fluid can leak and dry up on the belly panel…

3) Getting air in the pump causes it to need to be pumped a lot…

4) OHing the pump is a good step in the middle of OHing the rest of the system…

5) The guy with the best flap pump knowledge around here…. Find Ross… he has done some extensive good writing on the subject…

6) The flaps and brakes share the same reservoir… the flaps run out of fluid before the brakes do….  

 

PP thoughts only, not a mechanic…

Best regards,

-a-

[Hank]

7 minutes ago, carusoam said:

5) The guy with the best flap pump knowledge around here…. Find Ross… he has done some extensive good writing on the subject…

Paging @Shadrach for hydraulic flaps!

Come in, Meshack! Are you there, Abednigo?

[Ragsf15e]

Likely a leak in the valve will show up dripping onto your left foot while your flying.  It’s not terribly difficult to access it by Mooney standards.  The actual reservoir is above that and much less accessible.  I have the 201 windshield mod and they were nice enough to put a filler port through the firewall so it’s easy to fill with just the top cowling off.

[cliffy]

1) Adding fluid is easy and the owner can do it. Just make sure you know how to do a legal signoff in the airframe log book. 

2) Its a closed Hyd System. It shouldn't change from 4+ strokes to over 8 unless for a leak.

3) Chronic leaks- parking brake valve, flap actuator, flap pump and then the rubber hose connected to the flap actuator (one of the least looked at hoses in a Mooney).

4) Resealing both the pump and flap actuator is an easy A&P job.. Couple of hours each tops. Out and in.

5) Fluid replacement in the entire flap system is easy and quick- fill the reservoir and pump with the line loose at the actuator until clean fluid comes out.  Now bleeding and making sure there are no bubbles in the flap system after this may take a while but not extreme  amounts of time. 

7  hours to just flush the flap system?  Hmmmm?????

[DXB]

There’s air in the system- you can bleed it which is a tricky chore - or just  top off reservoir - then pump the handle about a million times quickly without the flap tab in the down position. Most of the air will come out of the system  and it will take just 4 pumps.   If you have significant leaks, deal with them after doing this.   

[DCarlton]

On 10/22/2021 at 8:18 PM, Ragsf15e said:

Likely a leak in the valve will show up dripping onto your left foot while your flying.  It’s not terribly difficult to access it by Mooney standards.  The actual reservoir is above that and much less accessible.  I have the 201 windshield mod and they were nice enough to put a filler port through the firewall so it’s easy to fill with just the top cowling off.

Would are interested in seeing your filler port if you ever have a chance to take a pic.  Is it a hose with a bulkhead fitting off some sort?  

[47U]

51 minutes ago, DCarlton said:

Would are interested in seeing your filler port if you ever have a chance to take a pic.  Is it a hose with a bulkhead fitting off some sort?  

Here’s a post from 5 years ago installing a 201 windscreen with some pictures of the hydraulic servicing solution.

 

[Ragsf15e]

1 hour ago, DCarlton said:

Would are interested in seeing your filler port if you ever have a chance to take a pic.  Is it a hose with a bulkhead fitting off some sort?  

I’ll look for a picture, but it looks similar, but a bit “rougher” than what @47U just posted.  It’s got a 1/4” metal tube with a small valve on it sticking through a small bulkhead fitting.  I can only imagine how it goes into the hydraulic fluid reservoir because that’s really hard to get at.

[Shadrach]

On 10/22/2021 at 10:22 AM, goalstop said:

Do you have a link? Mechanic said it would also be a 7hr job to flush the whole system.

If it’s taking eight pumps to deploy the flaps fully, there is air in the system. Topping off may help a bit but the system isn’t going to bleed itself.

If there is air in the system,  it either was not bled properly the last time it was serviced or the system leaked to such a degree that air was drawn into the pump cylinder.

7hrs is a reasonable estimate for someone muddling through this job with  the Mx manual and no experience with it. I’ve heard of people taking much longer, but that’s usually due to poor installation or misassembly of the pump during “Overhaul”.

With experience the pump can be removed, overhauled and reinstalled in about two hours (This does not include bleeding and adjustment). I speak from recent experience.  I had a pump that I bought “as is” many years ago. I sent it to a fellow Forum member just a few weeks ago. Before sending it out I opened the pump to verify everything was oriented correctly, gently staked the ball valves to their seats, reassembled and pressure tested.  It took less than 15min do all that. Reinstalling in the airplane would probably take another 15 to 20 minutes. After that the more challenging part begins....bleeding and adjusting. The former should be done before the latter.  Requires a pressure pot to push fluid from the actuator (lowest point in the system) through the system and up to the reservoir. I’ve never attempted to do it alone.

As much as I admire the system’s design, it’s a challenge for some people. Like old British sports cars and motorcycles, everything appears well-made of high quality materials, yet it’s a struggle sometimes to get everything to work as it should. It would definitely be best to find an A&P who has some experience with the system.

I’ve had my hydraulic system apart three times. Once for the pump, once for the actuator and once for brake caliper overhaul. I’ve helped many others both in person and over the phone get the systems up and running. Nevertheless, I won’t pretend that bleeding the system is easy and fast. I have struggled to get all of the air out of the system but I have never failed to do so. However, If I had swear jar in the hangar...

Where are you located? I can make some time to help you figure out what’s going on with it. Either on the phone or in person. 
 

A experienced, hands on, A&P should be able to handle this as a first time job without much trouble.

Edited December 19, 2021 by Shadrach

[goalstop]

On 10/24/2021 at 3:37 PM, Shadrach said:

If it’s taking eight pumps to deploy the flaps fully, there is air in the system. Topping off may help a bit but the system isn’t going to bleed itself.

If there is air in the system,  it either was not bled properly the last time it was serviced or the system leaked to such a degree that air was drawn into the pump cylinder.

7hrs is a reasonable estimate for someone muddling through this job with  the Mx manual and no experience with it. I’ve heard of people taking much longer, but that’s usually due to poor installation or misassembly of the pump during “Overhaul”.

With experience the pump can be removed, overhauled and reinstalled in about two hours (This does not include bleeding and adjustment). I speak from recent experience.  I had a pump that I bought “as is” many years ago. I sent it to a fellow Forum member just a few weeks ago. Before sending it out I opened the pump to verify everything was oriented correctly, gently staked the ball valves to their seats, reassembled and pressure tested.  It took less than 15min do all that. Reinstalling in the airplane would probably take another 15 to 20 minutes. After that the more challenging part begins....bleeding and adjusting. The former should be done before the latter.  Requires a pressure pot to push fluid from the actuator (lowest point in the system) through the system and up to the reservoir. I’ve never attempted to do it alone.

As much as I admire the system’s design, it’s a challenge for some people. Like old British sports cars and motorcycles, everything appears well-made of high quality materials, yet it’s a struggle sometimes to get everything to work as it should. It would definitely be best to find an A&P who has some experience with the system.

I’ve had my hydraulic system apart three times. Once for the pump, once for the actuator and once for brake caliber overhaul. I’ve helped many others both in person and over the phone get the systems up and running. Nevertheless, I won’t pretend that bleeding the system is easy and fast. I have struggled to get all of the air out of the system but I have never failed to do so. However, If I had swear jar in the hangar...

Where are you located? I can make some time to help you figure out what’s going on with it. Either on the phone or in person. 
 

A experienced, hands on, A&P should be able to handle this as a first time job without much going trouble.

Thanks Shadrach! PM sent.  I'm located at KLZU (Atlanta)