Mooney m20f 1967 elevator counter weights

[Clipper]

Hi Everyone

Would anyone know the parts #  for the elevator counter weights  and where I could purchase them. My counter weights are pretty badly cracked .(Model M20F  yr 1967 serial #670021)

[carusoam]

Start with pics…

Some people recognize pics better than part numbers…

Then ask @Alan Fox because he has a collection of parts that may include your part numbers… (elevator counterweights for 67F)

Then end with pics showing the cracks…

They may be lead… and lead is soft and not so prone to cracking… 

Then expect to weigh and balance the control when you are done…. Flight controls are tricky…

PP thoughts only, not a mechanic…

Best regards,

-a-

[DCarlton]

Could we please see a pic of the cracks?  I’ll look a lot closer at mine during the upcoming annual.  Thanks.  

[mcrouch]

There are updated counterweights available for the 67F and you can get them with installation for about $500 a pair. I don't have the part numbers off the top of my head but they are shown in the Mooney maintenance binder with the part number. Any Mooney dealer should be able to get them for you if you call and inquire. Of course the original part numbers have changed but a Mooney dealer will have the conversation list for them. The original weights were put on with rivets, I think. The updated ones use bolts instead of rivets, which makes installation a bit easier after  you the get the original rivets drilled out. 

[carusoam]

11 minutes ago, mcrouch said:

There are updated counterweights available for the 67F and you can get them with installation for about $500 a pair. I don't have the part numbers off the top of my head but they are shown in the Mooney maintenance binder with the part number. Any Mooney dealer should be able to get them for you if you call and inquire. Of course the original part numbers have changed but a Mooney dealer will have the conversation list for them. The original weights were put on with rivets, I think. The updated ones use bolts instead of rivets, which makes installation a bit easier after  you the get the original rivets drilled out. 

Great input…

Lets combine that with an invite to @M20Doc who knows most of the MSCs in Canada… and a lot of part numbers it seems…

Best regards,

-a-

[Guest]

From the IPC.  

And there are only two MSC in Canada, me and one out in Alberta.

[Clipper]

15 hours ago, DCarlton said:

Could we please see a pic of the cracks?  I’ll look a lot closer at mine during the upcoming annual.  Thanks.  

These are my counterweight 

[Clipper]

15 hours ago, mcrouch said:

There are updated counterweights available for the 67F and you can get them with installation for about $500 a pair. I don't have the part numbers off the top of my head but they are shown in the Mooney maintenance binder with the part number. Any Mooney dealer should be able to get them for you if you call and inquire. Of course the original part numbers have changed but a Mooney dealer will have the conversation list for them. The original weights were put on with rivets, I think. The updated ones use bolts instead of rivets, which makes installation a bit easier after  you the get the original rivets drilled out. 

Thank you for the info much appreciated 

[Clipper]

8 hours ago, M20Doc said:

From the IPC.  

And there are only two MSC in Canada, me and one out in Alberta.

Thank you very much very helpful

[Clipper]

15 hours ago, carusoam said:

Great input…

Lets combine that with an invite to @M20Doc who knows most of the MSCs in Canada… and a lot of part numbers it seems…

Best regards,

-a-

Thank very much for the info

[EricJ]

3 hours ago, Clipper said:

These are my counterweight 

Hard to tell from the pic whether that's cracked paint or cracked weight material.  

Since it's already out, you'll have to rebalance the elevator when the new weight is installed.

[A64Pilot]

On my J they appear to be lead, soft metal that you can stick a pick into, and a magnet has no attraction. Lead is very malleable and unless the casting if full of trash I wouldn’t expect cracking of the lead.

The rivets I think are Iron, strong magnet attraction and it appears could be replaced with screws and blind nuts. I wouldn’t want bolt heads and nuts in the airflow myself.

When you rebalance, do so nose heavy as much as allowed, nose heavy increases the speed that flutter can occur and if the surface is ever repaired or repainted they tend to gain wait on the trailing edge side as that’s the greatest surface area.

[PT20J]

Note that Mooney control surfaces are underbalanced.

[A64Pilot]

10 minutes ago, PT20J said:

Note that Mooney control surfaces are underbalanced.

Didn’t know that, but still making the nose less light is the way to go? I’ve never seen an in service airplane flight control that had to be rebalanced because the trailing edge was too light, always had to increase the nose weight. Often it’s paint that causes it.

On edit let me understand what your saying, when you hang the flight control from its hinge line and level, you weigh the trailing edge and it will have between x and x weight to be good, right?

If so then that’s what I’m used to, but if it has negative weight meaning that hung level the nose drops, then that’s a new one to me.

[Fly Boomer]

34 minutes ago, PT20J said:

Note that Mooney control surfaces are underbalanced.

I don’t know what that means (or anything about balancing for that matter).  Can you elaborate?  Thanks!

[ArtVandelay]

…if the surface is repainted they tend to gain wait on the trailing edge side…

That’s why I had the control surfaces painted just 1 color, no stripes.

[Fly Boomer]

1 hour ago, ArtVandelay said:

I had the control surfaces painted just 1 color, no stripes.

What does the painter do to rebalance the control surface if the paint adds too much on the trailing edge?

[PT20J]

28 minutes ago, Fly Boomer said:

What does the painter do to rebalance the control surface if the paint adds too much on the trailing edge?

You can purchase heavier weights from Mooney.

 

[PT20J]

Most control surfaces are overbalanced (i.e., leading edge heavy) to control flutter. With the control surface CG ahead of the hinge line, a deflection of the control surface causes a correcting hinge moment that tends to dampen out motions caused by aerodynamic forces.

Evidently the Mooney control system is stiff enough that flutter is not an issue and so the control surfaces are underbalanced (i.e., trailing edge heavy) most likely for improving handling qualities. The Mooney ailerons have fairly heavy control forces due to their short span, wide chord design and the elevator forces are a bit high due to the springs and bobweights. Underbalancing would tend to reduce the initial hinge moment when a surface is deflected. But, that's just a guess; to know for certain the designer's intent you'd have to ask Al. 

Skip

[Guest]

2 hours ago, Fly Boomer said:

What does the painter do to rebalance the control surface if the paint adds too much on the trailing edge?

Strip the paint off and start again if it falls out of limits.

[M20F]

JB Weld

[N201MKTurbo]

It seems to me that if you got a piece of steel tubing that the counterbalance would fit in, cut a piece a bit longer than the weights, drill mounting holes in the side of the tube and faster the weights inside of the tubes. Pack around the weights with casting sand, make a cap for the bottom out of some of the steel tube and clamp it on with lock wire. Then heat the whole thing with a torch until the lead melts. Let it cool and take the reflowed weight out of the mold.

I would strip the paint off first.

https://www.amazon.com/Teton-Bond-Petrobond-Fine-Mesh-Foundry-Casting/dp/B07J19XZYD?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=A2F0NR23SCAQGR&th=1

[Clipper]

On 9/2/2022 at 12:13 AM, mcrouch said:

There are updated counterweights available for the 67F and you can get them with installation for about $500 a pair. I don't have the part numbers off the top of my head but they are shown in the Mooney maintenance binder with the part number. Any Mooney dealer should be able to get them for you if you call and inquire. Of course the original part numbers have changed but a Mooney dealer will have the conversation list for them. The original weights were put on with rivets, I think. The updated ones use bolts instead of rivets, which makes installation a bit easier after  you the get the original rivets drilled out. 

Than you for the info very helpful

 

[Clipper]

On 9/3/2022 at 4:00 PM, PT20J said:

Most control surfaces are overbalanced (i.e., leading edge heavy) to control flutter. With the control surface CG ahead of the hinge line, a deflection of the control surface causes a correcting hinge moment that tends to dampen out motions caused by aerodynamic forces.

Evidently the Mooney control system is stiff enough that flutter is not an issue and so the control surfaces are underbalanced (i.e., trailing edge heavy) most likely for improving handling qualities. The Mooney ailerons have fairly heavy control forces due to their short span, wide chord design and the elevator forces are a bit high due to the springs and bobweights. Underbalancing would tend to reduce the initial hinge moment when a surface is deflected. But, that's just a guess; to know for certain the designer's intent you'd have to ask Al. 

Skip

Thank you so much for your info

[Sheriff23]

On 9/2/2022 at 12:13 AM, mcrouch said:

There are updated counterweights available for the 67F and you can get them with installation for about $500 a pair. I don't have the part numbers off the top of my head but they are shown in the Mooney maintenance binder with the part number. Any Mooney dealer should be able to get them for you if you call and inquire. Of course the original part numbers have changed but a Mooney dealer will have the conversation list for them. The original weights were put on with rivets, I think. The updated ones use bolts instead of rivets, which makes installation a bit easier after  you the get the original rivets drilled out. 

Do you have any info/link for the upgraded weights from Mooney?  My 67F, serial number 67-0093, also has the bad hybrid weights and is affected.  I’ve spoken with Mooney and they stated they don’t have the weights or the iron rivets, in case I spruced salvage solid weights.  I’m still searching but now looking at replacing the entire elevators since replacing weights seems  impossible due to parts.