Mooney Elevator AD

[PT20J]

2 hours ago, Sabremech said:

You’re talking something that could define damage history if it wasn’t repaired correctly. If it was repaired with new or serviceable parts just like original and doesn’t require a 337, then it’s maintenance. 

I went through this when I bought my airplane because the previous owner had dinged a wingtip on a hangar door and it was repaired by Maxwell with factory parts (wingtip, skin and a rib as I recall) and an appropriate logbook entry but no 337. My IA (been an IA for 40 years) insisted this was a major repair and needed a 337. Don insisted it was just a replacement of damaged parts with factory new parts and did not. He was nice enough to file one just to keep my guy happy since, as he said, "It's only a piece of paper." 

Later I asked the Director of Maintenance at the 135 operation where I worked summers and he said it was one of those areas that is open to interpretation, but in my case he agreed with Maxwell.

In the end I don't think it matters much. Damage is damage and the repair will be recorded in the logbooks whether a 337 is filed or not.

Skip

[takair]

FAA breaks out damage as none, minor, and major.  I don’t think they hold advertisers to these definitions.  As you all know, a good pre-buy lets an individual determine their tolerance to the damage that likely exists on most vintage aircraft.  In other words, I think a significant percentage of the fleet has at least minor damage history.   Most folks would not claim that as “damage history”.  Damage history advertising seems to depend on how a repair is made.  A sheet metal patch on a major skin might be considered damage history in advertising, but a reskin with factory skins might not be.  From an FAA context, they are both damaged and repaired. Sellers and buyers will view it differently..depending on their motivations.

[RobertGary1]

On 2/4/2023 at 1:44 AM, M20Doc said:

We got an email from Mooney yesterday saying they are now taking orders for new weights.

Does the elevator have to come off to inspect the balance?

[EricJ]

29 minutes ago, nosky2high said:

FWIW, Here’s what mine look like on our original NDH 67’ M20F. My IA says they passed. 

Are those hybrid weights?   The steel slug is not apparent in your weights.

[MikeOH]

On 2/4/2023 at 5:28 PM, PT20J said:

…the previous owner had dinged a wingtip on a hangar door and it was repaired by Maxwell with factory parts (wingtip, skin and a rib…)

Skip

Hmm, wingtip, skin, and RIB!?

That’s quite a “ding”!

[PT20J]

12 minutes ago, MikeOH said:

Hmm, wingtip, skin, and RIB!?

That’s quite a “ding”!

Well, I didn't see it. But, Don's got a good sheet metal guy and it looks like new!

[EricJ]

1 hour ago, RobertGary1 said:

Does the elevator have to come off to inspect the balance?

The service bulletin says it has to come off just for the inspection, and also if the weights are replaced.

[Guest]

10 hours ago, RobertGary1 said:

Does the elevator have to come off to inspect the balance?

I would say yes, as they are traditionally balanced on a pair of knife edges.

[Fly Boomer]

11 hours ago, PT20J said:

Well, I didn't see it. But, Don's got a good sheet metal guy and it looks like new!

How did you deal with paint?  Repaint the whole airplane, or just the wingtip?

[PT20J]

1 hour ago, Fly Boomer said:

How did you deal with paint?  Repaint the whole airplane, or just the wingtip?

They scuff sanded the tops of the wings and painted them both (except for the ailerons snd elevators) so that the paint matches.

[EricJ]

I can't tell from the SB or the MM whether the elevator is supposed to be balanced with the control horn attached or not.   I suspect it should be attached, but the figure in the SB shows an exploded diagram, Detail A of  Figure 345-3, with it separated.

[Gary0747]

4 hours ago, EricJ said:

I can't tell from the SB or the MM whether the elevator is supposed to be balanced with the control horn attached or not.   I suspect it should be attached, but the figure in the SB shows an exploded diagram, Detail A of  Figure 345-3, with it separated.

Yes I was a bit confused by that too since the SB shows taking them apart and the M20F service manual did not seem to explain but the M20J and M20M service manuals do a better job.  Step 3 says:

Elevators and rudders are balanced with the control horn facing upwards.

[Gary0747]

I hope the people who have already done the rebalance using this SB have recognized that the control horn does not come off for rebalancing.  The SB clearly leads one to think that.  Also the weight balance numbers in the SB do not agree with the M20F service manual numbers.  I think the factory owes the owners some clarification.  Perhaps another example why a NPR comment period would have been appropriate. 

[Igor_U]

33 minutes ago, Gary0747 said:

I hope the people who have already done the rebalance using this SB have recognized that the control horn does not come off for rebalancing.  The SB clearly leads one to think that.  Also the weight balance numbers in the SB do not agree with the M20F service manual numbers.  I think the factory owes the owners some clarification.  Perhaps another example why a NPR comment period would have been appropriate. 

Gary,

I asked Frank at Mooney this question today and will report back when I hear from that.

As for different weight balance numbers: They have to be, IMO. Reason is hybrid (-1) and -7 Weights are not the same and have different CG due to steel rod in -1. 

[EricJ]

46 minutes ago, Igor_U said:

Gary,

I asked Frank at Mooney this question today and will report back when I hear from that.

As for different weight balance numbers: They have to be, IMO. Reason is hybrid (-1) and -7 Weights are not the same and have different CG due to steel rod in -1. 

One would think the balance would be dictated by the desired flutter immunity, not the implementation of the weight.

The balance criteria for the inspection differs from the balance criteria for the replacement in the SB.    The replacement numbers in the SB match the numbers in the SMM, which should presumably include the aircraft that were released from the factory with the hybrid weights.

I'm curious as to the reason for the difference as well.

[Igor_U]

16 hours ago, EricJ said:

One would think the balance would be dictated by the desired flutter immunity, not the implementation of the weight.

The balance criteria for the inspection differs from the balance criteria for the replacement in the SB.    The replacement numbers in the SB match the numbers in the SMM, which should presumably include the aircraft that were released from the factory with the hybrid weights.

I'm curious as to the reason for the difference as well.

Eric,

My service manual for 1967 F calls for 1.57 - 1.725 lb unbalance and the same value is in SB M20-345A in step 2 (detail inspection of hybrid weights).

Replacement (Step 3 in SB) calls for different, lower numbers: 1.09 - 1.3 lb unbalance. this is with solid weights, -7.

BTW,

Frank confirmed elevator is balanced with the horn installed ad referred to newer SM as well as SB M20-335.

 

 

[EricJ]

11 minutes ago, Igor_U said:

Eric,

My service manual for 1967 F calls for 1.57 - 1.725 lb unbalance and the same value is in SB M20-345A in step 2 (detail inspection of hybrid weights).

Replacement (Step 3 in SB) calls for different, lower numbers: 1.09 - 1.3 lb unbalance. this is with solid weights, -7.

BTW,

Frank confirmed elevator is balanced with the horn installed ad referred to newer SM as well as SB M20-335.

 

 

Interesting.   The only SMM I have for C-G models is the Rev G of Manual 106, dated October, 1983.   This covers 1968 models from S/N 68001 and up, so nothing on the 1967.    It shows the clip below, where the elevator balance weights for the F and G match the replacement values in Part 4 of the SB, not the inspection weights in Part 2.

Even more confusinger.   

 

[Gary0747]

It is hard for me to understand why there is now this distinction between hybrid and non hybrid weights since the original manuals did not make this distinction.  In fact the hybrid and non hybrid weights appear to have been mixed together randomly in the production of the early M20F airplanes.  It sounds like the reasoning is the CG for the moment arm for the weight is different for hybrid and non hybrid weights.  I can’t see why the elevator itself really cares as long as the elevator itself has the correct force and moment? 
To complicate the issue further those that have already found and reused salvaged solid weights have found that the mounting holes do not match and have had to drill new holes by moving the weight out a bit.  This will  change the CG on the weight just like the hybrid weight does.  I don’t  see why this matters though as long as the correct force moment is being exerted on the elevator itself.  

[Igor_U]

14 minutes ago, Gary0747 said:

It is hard for me to understand why there is now this distinction between hybrid and non hybrid weights since the original manuals did not make this distinction.  In fact the hybrid and non hybrid weights appear to have been mixed together randomly in the production of the early M20F airplanes. 

Well ,

According to Mooney:

"The Service Bulletin has been written that both elevator weights must be installed in pairs. There is no aircraft produced, nor tested by Mooney that has a combination of Lead and Hybrid weights. Now with that said, someone in the field may have installed a fully lead weight on one side somewhere down the road (log books should show the install). If this did happen, what did the they balance the elevator to, there was no criteria in the 1965 thru 1967 S&M for that? ..."

 

Through the MS posts, I have noticed there are number of planes with one hybrid and one solid weight and factory claims it's done in field. I don't know about that but it seems IPC confirms that, stating all '67Fs and first 180 (or so) '68Fs should have hybrid weights from the factory. 

 

As for different elevator unbalance values for 1967F and 1968F (with hybrid weights), there are different Trim assist settings for S/n before 680001 and after so that can be a factor.

following is snipping from M20 FAA TC:

 

 

Airplanes are fun! 

[Gary0747]

I think they have all been installed in matching pairs by the factory. That is not the issue I was talking about. My point is some aircraft came off the assembly line with hybrid weights and some came off with solid weights. They were mixed by airplane serial number.  All in the early serial numbers. The factory at the time made no indication of them having different elevator balance numbers.   I think they were correct in doing this since there is no logical reason why a weight having a minor difference in CG location would matter. The moment required by the elevator to prevent flutter should be the same and should be equal but opposite to the same moment provided by the elevator weight. Granted the moment arm may be slightly different but the total moment provided by the  weights should be the same and driven by the design requirements of the elevator.   Nothing I have seen explains why 1967 design balance numbers should be changed by any shape or form of the balance weights utilized today. 

[Gary0747]

8 hours ago, EricJ said:

This covers 1968 models from S/N 68001 and up, so nothing on the 1967. 

Here is the earlier data for the 1966 and 1967 M20F production.  It includes the smooth elevator design which may require different balance movement from the later non smooth design.  I forget at which serial number the change was made. These early serial number M20F were the ones which got the hybrid weights.   It sure looks like the SB 345A  in step 4 did not use these moments for the smooth elevator but may have used the moments for the later non smooth elevator?  

 

[cliffy]

I'm no flutter engineer but I'll offer a hypotheses-

Each elevator can independently be induced into flutter therefore each one must be 
"balanced"  to known parameters after flight tests.

We have to look at dynamic loads along with static "balance"

By "balance" we are referring to not "total" balance on both sides of the balance point but a "balance"

at a specific under balance with the trailing edge being heavy from true level "balance" at the hinge point

With the issue of 2 different weight balance weights - if one is lighter than the other then it leads one to

assume that the lighter weight would have different inertia and acceleration parameters going into flutter than the heavier one-

there by causing the need for a different "balance" weight trailing edge heavy. 

As to what changed to require a different balance weight at the tip I have no idea at this point. 

The "WHY" is a big question

Just like the change to elevator deflection angles about the same time for which I have never been able to find the answer including talking to Bill Wheat!

I have a suspicion but no one at the factory would approach the subject with me.

[Jim Peace]

confusing the way the AD reads and what I have seen on here.

Can I fly my plane through the 13th of FEB and it becomes a pumpkin on the 14th at 0000 eastern?

 

[SoccerCA]

2 minutes ago, Jim Peace said:

confusing the way the AD reads and what I have seen on here.

Can I fly my plane through the 13th of FEB and it becomes a pumpkin on the 14th at 0000 eastern?

 

Provided you take off on the 12th at 2359 you can keep flying indefinitely as long as you don't land.

[Jim Peace]

14 minutes ago, SoccerCA said:

Provided you take off on the 12th at 2359 you can keep flying indefinitely as long as you don't land.

so I have until the 12th at 2359.....got it...thanks...