EDIT--fixed!! mooney flap question pt 3. need part #

[rbridges]

The nylon inserts aren't included with the lasar kit, and I suspect they were dinged up when they separated the pump.  I heard the A&P mention that he removed them when they inspected it.  I watched him use a pick to pry them out and thought nothing of it.  Now you can see small gaps between the inserts and the ball bearings.

We've bled and reassembled the pump several times.  No external leaks, and we can get the flaps to go down when pumping quickly, and they would hold position.   No hydrolock, and it takes 30 really fast pumps to get the flaps down.  

We had another IA who owns a mooney work with us today.  I mentioned the dings in the nylon inserts, and I asked if this could cause fluid to get pushed where it's not supposed to go since the ball bearings seat on these inserts to close off flow.

I'll call Lasar on monday, but does anyone know if these can be purchased anywhere?  Does anyone know if this could be the source of my problems?  FYI, the flaps worked perfectly prior to the repair, it just had a small leak around the pump.

[rbridges]

here's another pic.  you can see the deformed areas around the edges.

 

[carusoam]

RB, great pics...

1) Check to see if the steel balls are seating properly...  if they are supposed to seal against those plastic pieces, they are too marred to make a seal... (call Dan at Lasar)

2) Check to see if the control cable is shutting the valve properly...  sounds like the flap valve is nearly in the up position...  pump as fast as you can... If the valve is allowing the fluid back, you are in a race against the flap return speed....

Either way, it Sounds like hydraulic fluid is being allowed to escape back to the reservoir...

10year old PP memory of my M20C, not a mechanic...

Best regards,

-a-

[Shadrach]

Remove the inserts and stake them with the ball. If you can get new ones great.

[N201MKTurbo]

I think you can turn them over.

[RLCarter]

16 hours ago, N201MKTurbo said:

I think you can turn them over.

If memory serves, the hole is beveled on the ball side

Edited December 2, 2018 by RLCarter

[rbridges]

It looks like gaps are around the balls. My guess it's the tool marks from being removed. This is what it looked like when the AI separated it.

[rbridges]

8 hours ago, Shadrach said:

Remove the inserts and stake them with the ball. If you can get new ones great.

That's what I'm going to recommend.  Thanks. I'll call Dan on Monday to see if they know where to replacements. 

[Shadrach]

23 hours ago, rbridges said:

That's what I'm going to recommend.  Thanks. I'll call Dan on Monday to see if they know where to replacements. 

The only thing that matters is that the ball is sealed against the nylon insert.  Remove the insert and place it on a hard surface (the anvil part of a bench vice is ideal) either side of the insert will do. Stake the ball against the insert with a hammer and drift. It doesn’t take a lot of force. The inserts you have will likely seal just fine. 

Edited December 3, 2018 by Shadrach

[Shadrach]

15 hours ago, RLCarter said:

If memory serves, the hole is beveled on they ball side

Well yes...and no. I do not believe they were manufactured with a bevel. You likely had what appeared to be a bevel from being well seated for the last 50 years. Manufacturing the curved seat into the insert would be more expensive and complicated than simply seating the balls at the time of assembly.

Edited December 2, 2018 by Shadrach

[N201MKTurbo]

1 hour ago, Shadrach said:

The only thing that matters is that the ball is sealed against the nylon insert.  Remove the insert and place it on a hard surface (the anvil part of a bench vice is ideal) either side of the insert will do. Stake the ball against the insert with a hammer and drift. It won’t take a lot of force. The inserts you have will likely seal just fine. 

While that works with the aluminum seat on the release ball, It doesn't seem like it would work well with the nylon (Teflon maybe). Have you had success doing this? It seems like heating the ball up (400F or so) and setting it in place with slight pressure might be more effective.

 

Update: Nylon will start to deform at 180 F, 400 F is near its melting point. That would be to hot. to reseat the ball use about 200F

Nylon has almost no cold flow, so they probably would not form to the ball. I think the seals are Teflon. Teflon will cold flow and take the shape of the ball in time. Nylon is extremely resistant to cuts and scratches and is unlikely to get scratched by a pick. Teflon is much easier to damage.

Edited December 2, 2018 by N201MKTurbo

[rbridges]

2 hours ago, Shadrach said:

The only thing that matters is that the ball is sealed against the nylon insert.  Remove the insert and place it on a hard surface (the anvil part of a bench vice is ideal) either side of the insert will do. Stake the ball against the insert with a hammer and drift. It won’t take a lot of force. The inserts you have will likely seal just fine. 

you are correct!  I took a teflon hammer I use for sinus lifts  and used it to force the ball into the teflon ring.  I also brought my dental loupes for a better view.  The hammering deformed it enough to close the gaps.  I had to reverse one teflon seal b/c the tool mark gauges were too deep on one side.  Anyway, you can hear a slight suction sound when you put your finger over the hole without a ball and push the internal ball.  I knew we had it when we heard it.

so, that would explain the inability to hydrolock; you're basically pushing the fluid back into the reservoir through the gap. It also explains why pumping super fast got the flaps to go down and why they held in place.  I compare it to a heart valve that doesn't close properly and allows blood flow to reverse when it pumps.

Anyway, a huge thanks to everyone that chipped in with advice.  Thanks to Shadrach for answering a ton a questions via private messages and on the threads!

[Shadrach]

2 hours ago, N201MKTurbo said:

While that works with the aluminum seat on the release ball, It doesn't seem like it would work well with the nylon (Teflon maybe). Have you had success doing this? It seems like heating the ball up (400F or so) and setting it in place with slight pressure might be more effective.

 

Update: Nylon will start to deform at 180 F, 400 F is near its melting point. That would be to hot. to reseat the ball use about 200F

Nylon has almost no cold flow, so they probably would not form to the ball. I think the seals are Teflon. Teflon will cold flow and take the shape of the ball in time. Nylon is extremely resistant to cuts and scratches and is unlikely to get scratched by a pick. Teflon is much easier to damage.

Yes, I've had success with it many times both in person and over the phone.  All of these situations have been with the involvement of owners and credentialed mechanics trying to learn the idiosyncrasies of a system with which they have limited experience.   I would say that next to improper assembly, this is the number one issue people have after overhauling the pump.  Staking the balls to the seats (both nylon and the brass bleed valve) should be SOP during reassembly.  It's sucks to install the system and have to remove it for this reason (ask me how I know)...

Also, to be clear the release ball seat is brass not aluminum.

Edited December 2, 2018 by Shadrach

[Shadrach]

43 minutes ago, rbridges said:

you are correct!  I took a teflon hammer I use for sinus lifts  and used it to force the ball into the teflon ring.  I also brought my dental loupes for a better view.  The hammering deformed it enough to close the gaps.  I had to reverse one teflon seal b/c the tool mark gauges were too deep on one side.  Anyway, you can hear a slight suction sound when you put your finger over the hole without a ball and push the internal ball.  I knew we had it when we heard it.

so, that would explain the inability to hydrolock; you're basically pushing the fluid back into the reservoir through the gap. It also explains why pumping super fast got the flaps to go down and why they held in place.  I compare it to a heart valve that doesn't close properly and allows blood flow to reverse when it pumps.

Anyway, a huge thanks to everyone that chipped in with advice.  Thanks to Shadrach for answering a ton a questions via private messages and on the threads!

Glad you got it sorted! well done!

[rbridges]

14 minutes ago, Shadrach said:

Glad you got it sorted! well done!

Me too. Just waiting for the next headache to surface.  

[carusoam]

Usually you get one head-ache each year...

At year 10, you are seeing the same headache a second time...

You get really good at this after awhile...

Until your memory fades...?

 

You know the seals are Teflon(PTFE) when.... you clean them with any solvent that works and they shine very white...

They are so soft that any tool pressed into them will leave a scar...

It will burn before ever melting...

Its strength isn’t very strong at all... it is made through a process of sintering powder while under temperature and pressure...

Final form is created using tools like a lathe...

Teflon tape is the result of lathing (skiving) and collecting what comes off the cylindrical bar....

Best regards,

-a-

[Andy95W]

Ross and rbridges- thanks for the information.  I had a pretty good understanding of the hydraulic flaps before, but it's even better now.

[rbridges]

Just a follow up about the teflon seats.  I spoke with Dan at LASAR, and he informed me that the company that made the teflon rings went out of business in the 70s.  He said there are no places that offer a replacement.  

Does anyone know if these can be replicated to the original dimensions?  I wouldn't think it would be that hard if you knew who to ask.

[M20F-1968]

If you can get me a sketch of the teflon parts, and some information about the material, I can probably make then given that I have  metal lathe.

John Breda

[Open4cycle]

If you provide the drawings and material type / grade I can fabricate these seats for you. I'm thinking for this to be legal they have to be fabricated from the original design drawing.

[rbridges]

My flaps are working pretty decent. I was just wondering if anyone had thought about this. If I ever take it apart again, I can take some measurements. 

 

[carusoam]

Welcome aboard O4C...

There are rules and there are legal work arounds when the parts become unattainable...

There are a few ways of generating official technical details for an owner produced part...

If not familiar, search on owner produced parts... there should be some good info that details the requirements... and some good examples...

Best regards,

-a-

[Shadrach]

On 2/4/2019 at 8:39 PM, rbridges said:

My flaps are working pretty decent. I was just wondering if anyone had thought about this. If I ever take it apart again, I can take some measurements. 

 

Decent? Too ambiguios a description for a mechanical system. They’re either working properly or they are not. Still have air in the system? Bleeding up too fast? Decent implies tolerable but not much more...What’s up?

Edited February 17, 2019 by Shadrach

[Shadrach]

19 hours ago, Open4cycle said:

If you provide the drawings and material type / grade I can fabricate these seats for you. I'm thinking for this to be legal they have to be fabricated from the original design drawing.

Outlined and clarified in AC 20-62E
n. Owner/Operator Produced Part. Parts that were produced by an owner/operator for installation on their own aircraft (i.e., by a certificated air carrier). An owner/operator is considered a producer of a part, if the owner participated in controlling the design, manufacture, or quality of the part. Participating in the design of the part can include supervising the manufacture of the part or providing the manufacturer with the following: the design data, the materials with which to make the part, the fabrication processes, assembly methods, or the quality control (QC) procedures.

[rbridges]

55 minutes ago, Shadrach said:

Decent? To ambiguios a description for a mechanical system. They’re either working properly or they are not. Still have air in the system? Bleeding up too fast? Decent implies tolerable but not much more...What’s up?

They work and hold, but it's almost like the first pump doesn't count. I don't know if there is still air or if it's related to the balls not seating 100%, but I was going to see if it improves over time. It's minor at this point, so I don't want to disassemble everything just in case it's air and will improve.