Flap Issue/Not working

[TJSuper21]

20 hours ago, 47U said:

Have you checked the fluid level in the reservoir?  

Hi, Yes, double checked it yesterday and all is fine there.

[TJSuper21]

7 hours ago, Shadrach said:

Reads like there is a blockage in the system. Ordering the rebuild kit is good idea since he system will need to be opened up any way. 

Hi and thanks for the advice. I am going to drop the belly panel this morning and inspect. I printed Ross' 12 step program and will bleed the system today with my A&P. 

[Keith20EH]

I just rebuilt my leaky flap pump with the Lasar kit, not that difficult, even bleeding from the actuator fwd to reservoir went well, but what I spent the most time on was the rigging of the pump valve cable.  This has to be disconnected for pump removal.  There is not much throw in the flap selector lever, so getting the valve set just right took some effort, too much movement and valve would not fully close, and flaps would bleed up, or not come down at all.  Best to have a helper, because going from under wing to the flap controls and back under the wing is annoying.

[47U]

12 hours ago, Shadrach said:

Negative. A leak in the brake system may  drain the shared reservoir but it will not affect the operation of the flaps as long as the flap system is fluid tight.

Thank you for making me think about this... if I understand, the theory is that there is enough fluid in the supply line to the flap pump, in excess of the volume required to fully extend the actuator.  The upward-turned 45 degree fitting on the reservoir port to the flap system increases the amount of hydraulic fluid available to the flap pump.  The supply line acts as its own reservoir to the flap system.  

Do I (finally) understand?

(Picture credit to PilotCoyote...)

   

[Shadrach]

14 minutes ago, 47U said:

Thank you for making me think about this... if I understand, the theory is that there is enough fluid in the supply line to the flap pump, in excess of the volume required to fully extend the actuator.  The upward-turned 45 degree fitting on the reservoir port to the flap system increases the amount of hydraulic fluid available to the flap pump.  The supply line acts as its own reservoir to the flap system.  

Do I (finally) understand?

(Picture credit to PilotCoyote...)

   

You’ve got it. A simple way of saying it is that neither brake nor the flap system use fluid from the reservoir for operation unless there is a leak. The reservoir is there to ensure no air is ever pumped in to either system and to ensure continued operation in the event of a non catastrophic leak. The brake system will not steal fluid from the flap system and flap system will not steal fluid from the brake system. One or the other or both could consume all of the fluid in the reservoir if leaking but can’t steal from each other.

[TJSuper21]

19 hours ago, Shadrach said:

You’ve got it. A simple way of saying it is that neither brake nor the flap system use fluid from the reservoir for operation unless there is a leak. The reservoir is there to ensure no air is ever pumped in to either system and to ensure continued operation in the event of a non catastrophic leak. The brake system will not steal fluid from the flap system and flap system will not steal fluid from the brake system. One or the other or both could consume all of the fluid in the reservoir if leaking but can’t steal from each other.

I lowered the belly panels and it is dry as a bone. No evidence of a drip.  The pump does not show any sign of leakage. Unfortunately was not able to bleed the system but will do today. I tried to order the rebuild kit from LASAR but they were out. I found one at Knots2U HE625/HE1506 Mooney M20 Series Hydraulic flap actuator 65-67 M20C, M20D, M20E, M20F - Knots 2U, Ltd. if anyone is looking for one.

[0TreeLemur]

On 4/12/2021 at 7:01 AM, TJSuper21 said:

Hi and thanks for the advice. I am going to drop the belly panel this morning and inspect. I printed Ross' 12 step program and will bleed the system today with my A&P. 

Wow, there's a 12 step program for brake bleeding?   Why is that not in a FAQ section?  Somebody share a link!  @Shadrach?

[Shadrach]

18 minutes ago, 0TreeLemur said:

Wow, there's a 12 step program for brake bleeding?   Why is that not in a FAQ section?  Somebody share a link!  @Shadrach?

1) Loosen the bleed screw (as I've already stated above).

2) Ensure that the small lever in the "flaps up" position (this is to say needle valve off the cam lobe that opens the check valve).

3) Remove the plastic blocking plate from the T shaped AN fitting on the ACTUATOR (lowest point in the system) and attach a pressure pot filled with the specified hydraulic fluid.

4) Attach an AN fitting with a 2' hose to the reservoir to act as an overflow. position the hose over a catch can (bucket).

5) Actuate the pressure pot and watch for fluid at the overflow hose at the front of the aircraft.

6) When you detect fluid coming through the overflow, cut the pressure from the the pressure pot.

7) Plug overflow hose and reservoir vent.

8) This is where it gets messy... remove pressure pot fitting and replace the blocking plate.

9) Remove whatever you used to block the reservoir vent plug (I've used chewing gum). Leave the overflow plug in place.

10) Select "down" position on flap lever and have someone simultaneously pump the the handle (slowly) while you back off the plastic plate on the aforementioned actuator "T fitting" just enough to allow it to leak. You should get fluid only, but possibly a small amount of air and then fluid. Have your pump person maintain gentle pressure. Make sure to only have the bottom of the system open under positive pressure from the pump person. Close it under pressure. If the person pulls up on the flap pump and the system is open it will draw air into the system...

11) With T fitting secure, pump the flaps down. Remove overflow hose, retract flaps and be ready with a rag to catch any overflow. If fluid level is too high in the reservoir , siphon a bit off with a drinking straw (use your thumb not your mouth).

12) close up the system, adjust flap retraction speed set screw so that the flaps take apprx 10 secs to retract, ops check, buttoneverything up and go fly...

[Shadrach]

1 hour ago, TJSuper21 said:

I lowered the belly panels and it is dry as a bone. No evidence of a drip.  The pump does not show any sign of leakage. Unfortunately was not able to bleed the system but will do today. I tried to order the rebuild kit from LASAR but they were out. I found one at Knots2U HE625/HE1506 Mooney M20 Series Hydraulic flap actuator 65-67 M20C, M20D, M20E, M20F - Knots 2U, Ltd. if anyone is looking for one.

Also dry at the actuator? If so, it seems something has broken.

[N201MKTurbo]

On 4/11/2021 at 4:46 AM, TJSuper21 said:

Hi All,

Great information. I now have a flap issue which would seem to point to the actuator. Yesterday I was on approach and pumped twice and the flaps extended. I went to put the 3rd pump in and the flap handle went limp. I pumped with no resistance. I did a go around and the flaps that were down retracted and I headed back to my home airport. This time on approach, flap handle had no pressure and I was unable to lower flaps. After landing and getting to my hangar, the symptom changed. I feel pressure when I try to lower the flaps , on the first pump the flaps go down but, the handle immediately bounces back and the flap retracts.

I have ordered a rebuilt kit for the actuator also, I do not detect any leaks. Can anyone provide any advice on what to check?

I would bleed them before you started taking things apart. A bunch of air in your system could cause all your symptoms.

[TJSuper21]

On 4/13/2021 at 8:54 AM, Shadrach said:

Also dry at the actuator? If so, it seems something has broken.

Hi Ross, thanks for all the advice. My A&P bled the system but no luck. It still continues to do the same thing. I pump the flap handle and the flaps go down but the handle springs back and the flaps retract. It seems I can only pump it once and the flaps don't stay down. Could that be the check valve? I really hate to take anything apart but obviously something is not right. 

[Lionudakis]

That is the symptoms of air in the system, and the valve isn't adjusted. 

[Shadrach]

8 hours ago, TJSuper21 said:

Hi Ross, thanks for all the advice. My A&P bled the system but no luck. It still continues to do the same thing. I pump the flap handle and the flaps go down but the handle springs back and the flaps retract. It seems I can only pump it once and the flaps don't stay down. Could that be the check valve? I really hate to take anything apart but obviously something is not right. 

It reads to me like the inlet valve is either stuck or something is blocking fluid from entering.  The spring back is caused by a vacuum in the pump cylinder. As if you've blocked the outlet of a depressed syringe and pulled the plunger up, it's going to return to the depressed position.  Fluid is not entering the pump cylinder on the second pump. Why is anyone's guess.  I suspect the mystery will be solved when the system is opened.  What's genuinely odd is that 1) your mechanic was able to bleed the system with no trouble and 2) you are able to draw enough fluid for the first pump of flaps.  Are you sure the system was working correctly prior to this symptom?

Edited April 15, 2021 by Shadrach

[TJSuper21]

4 hours ago, Shadrach said:

It reads to me like the inlet valve is either stuck or something is blocking fluid from entering.  The spring back is caused by a vacuum in the pump cylinder. As if you've blocked the outlet of a depressed syringe and pulled the plunger up, it's going to return to the depressed position.  Fluid is not entering the pump cylinder on the second pump. Why is anyone's guess.  I suspect the mystery will be solved when the system is opened.  What's genuinely odd is that 1) your mechanic was able to bleed the system with no trouble and 2) you are able to draw enough fluid for the first pump of flaps.  Are you sure the system was working correctly prior to this symptom?

Yes it was. 4 pumps to full flaps, but the retract was almost immediate. I actually thought that was normal until reading through all of the threads and now understand that the flow should be restricted so on the ground it should take 8-10 seconds. I checked the set screw and found it to be loose. I was hoping that once  I tightened it and adjusted the retract speed, it would fix it but it did not (I pumped it down once, then held the flap handle,  raised the flap switch to retract and the flap retracted smoothly! I pulled the pump out today and now have my kit so tomorrow I will open it up. If I find something interesting, I will take photos.

[carusoam]

Use caution pulling the pump apart... the tiny ball bearings have their own guidance system that heads them directly towards floor drains...   

Getting them back in place takes some mechanic skill...

When done, they will work correctly... and be a memorable experience as well...  

Post a pic of the plastic insert where one of the balls seats... it may have a scratch in it, not allowing a good seal...

Slow flap retract speed is good...  quick flap retract speed can be terrible...   the stall speed depends on flap position...

Accidentally retracting flaps into a stall condition would be really bad...

Flap speed on the ground is about 2X(?) what it is in the air...  so using the procedure in the MM is a good idea for setting the time...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

[Shadrach]

@carusoamis correct regarding careful disassembly. The first time I rebuilt a pump it included an extra 20mins to R&R the gooseneck on my utility sink to retrieve one of the steel balls.

[carusoam]

Mine accelerated across the floor seeking a floor drain...

-a-

 

 

[TJSuper21]

Hi All,

Just wanted to thank all of you for the assist. Your right, overhauling the pump was an education. I worked with my A&P and put in all new o-rings. The nylon washers were in great shape. I did find a small sliver of o-ring across the input check valve ball. Reassembled and then took hours to figure out the settings. The flaps are fulling extended at 5 pumps however, I have to pump a few times to get them to stop creeping up. Once I pump a few times, it stops so I still have some air in the system. I will need to do disconnect the bleed screw and pump the flaps to push the air out.

Thanks again!

 

-T-

[carusoam]

Great follow-up -T-!

Seeing if @Shadrachis cruising by...

Best regards,

-a-

[Shadrach]

On 4/21/2021 at 6:54 AM, TJSuper21 said:

Hi All,

Just wanted to thank all of you for the assist. Your right, overhauling the pump was an education. I worked with my A&P and put in all new o-rings. The nylon washers were in great shape. I did find a small sliver of o-ring across the input check valve ball. Reassembled and then took hours to figure out the settings. The flaps are fulling extended at 5 pumps however, I have to pump a few times to get them to stop creeping up. Once I pump a few times, it stops so I still have some air in the system. I will need to do disconnect the bleed screw and pump the flaps to push the air out.

Thanks again!

 

-T-

I think at this point you’re better off trying to work the air out of the system rather than open everything up again.  You could try raising the nose and cycling the system repeatedly (could take 10 cycles or it could take 200).  The other option is to bleed from the bottom at the actuator until you get all of the air out. This is a two-man job that would require a catch can and good communication. If you do this be mindful of the reservoir level. If you draw air in from the top it would be best to start over.

Edited April 22, 2021 by Shadrach

[rbridges]

On 4/12/2021 at 11:39 AM, Shadrach said:

You’ve got it. A simple way of saying it is that neither brake nor the flap system use fluid from the reservoir for operation unless there is a leak. The reservoir is there to ensure no air is ever pumped in to either system and to ensure continued operation in the event of a non catastrophic leak. The brake system will not steal fluid from the flap system and flap system will not steal fluid from the brake system. One or the other or both could consume all of the fluid in the reservoir if leaking but can’t steal from each other.

I didn't realize that.  The way the reservoir was designed, I though the flaps would give out before you lost brakes.  Interesting to know.

[Shadrach]

5 hours ago, rbridges said:

I didn't realize that.  The way the reservoir was designed, I though the flaps would give out before you lost brakes.  Interesting to know.

I’ve seen brakes that functioned beautifully with almost no fluid in the lines above the brake cylinder much less the reservoir. This was a friends plane that was fresh out of annual, not a Mooney. The brake lines on that aircraft were clear and visible from the front seat.

Edited April 22, 2021 by Shadrach

[EricJ]

8 minutes ago, Shadrach said:

I’ve seen breaks that functioned beautifully with almost no fluid in the lines above the brake cylinder much less the reservoir. This was a friends plane that was fresh out of annual, not a Mooney. The brake lines on that aircraft were clear and visible from the front seat.

As long as there's no air between the master cylinder and caliper it should work fine.

A buddy built a cheapie home-brew turbo charger for his Miata.    During one of our track events he was working a corner and asked me to go flog it on the track a bit, so I took it out for a full session.   It's pretty normal to pop the hood when you park after a session to let the heat out, and when I lifted the hood I saw that the turbo was close enough to the master cylinder that it had completely melted the reservoir.   The reservoir and all the fluid in it were completely gone other than some globby plastic on the sides.   It was working on just the little puddle of fluid left in the top of the master cylinder, which was sufficient.   There were no issues on track with it, it braked fine other than needing better pads.

During lunch somebody stopped at a parts store for a new reservoir and Chipotle for a burrito so we could use the aluminum lid as a heat shield between the turbo and the reservoir.   Worked fine for the rest of the weekend.