M20J Gross Weight Increase

[Jack46]

Who and how can I get info on M20J 2900 lb. gross weight increase?

[carusoam]

Find the key serial number in the M20J history...

Everything after that serial number is available for the higher MGTW...

One of the change enacted in that serial number was a few heavier tubes in the frame...

PP thoughts only, not a mechanic...

Best regards,

-a-

[PT20J]

Go to Mooney.com and download Special Letter 92-1. 

[PeytonM]

My serial number is within range and I am thinking about doing the GW Increase, per Special Letter 92-1. The Letter lists various "kits" for certain serial numbers.  1) pdf file for the POH changes; 2) remarked ASI; 3) rudder balance check.  $1750 net to Mooney for "kit." I do not know what is in the kit.

I received the pdf file for the POH revisions; I can send out the ASI for remarking, and rudder balance can be done by a MSC or someone skilled in the art for 2-5 hours.  What am I missing? Is it a logbook entry and POH revision all that is needed once everything has been done? I'd like some insight on who, where and how much, please? Has anyone bought the kit?  

Who out there in MooneySpace has actually accomplished this for their M20J?

 

 

[toto]

1 minute ago, PeytonM said:

My serial number is within range and I am thinking about doing the GW Increase, per Special Letter 92-1. The Letter lists various "kits" for certain serial numbers.  1) pdf file for the POH changes; 2) remarked ASI; 3) rudder balance check.  $1750 net to Mooney for "kit." I do not know what is in the kit.

I received the pdf file for the POH revisions; I can send out the ASI for remarking, and rudder balance can be done by a MSC or someone skilled in the art for 2-5 hours.  What am I missing? Is it a logbook entry and POH revision all that is needed once everything has been done? I'd like some insight on who, where and how much, please? Has anyone bought the kit?  

Who out there in MooneySpace has actually accomplished this for their M20J?

 

 

I don't think there is any need to buy the kit, which iirc includes a new ASI.  If you do the SB and have your ASI remarked, a logbook entry is all that's required.  It's not an STC, so there is no other paperwork aside from the AFMS.

I was very eager to get this done years ago, and it was a primary consideration when purchasing the a/c, but I haven't done it yet -

[A64Pilot]

A manufacturer can issue an STC, but as they are the TC holder it’s not required.

‘I believe they actually may amend the TC, but there should be POH changes and placards if there is one in the aircraft that specifies weight, as well as recorded by the manufacturer so they amend the TC.

This is one that was done where used to work that increases gross from 6,000 lbs to 10,500 lbs, it’s not particularly well written for instance in one place it says it’s a field approval, and it’s not.  It’s a “Custom Kit”

https://www.thrushaircraft.com/getmedia/c64a571e-d4f4-45d8-90d6-fe647b0eeb09/CK-AG-45-Rev-B-7-6-18.pdf

 

So nothing stops you from reading the Custom kit and changing any parts necessary, but at least in this instance, the gross weight increase isn’t completed until you fill out the card and send it to QC, and if you didn’t buy the “kit” your not getting the gross weight increase, if you could do it without buying the kit, I can assure you that no crop duster would ever buy the kit.

‘They used to play fast and loose with the turbine conversions, making a logbook write up that they had complied with the kit, but they never bought a kit, they scrounged parts from wherever.

Edited May 20, 2021 by A64Pilot

[EricJ]

1 hour ago, PeytonM said:

My serial number is within range and I am thinking about doing the GW Increase, per Special Letter 92-1. The Letter lists various "kits" for certain serial numbers.  1) pdf file for the POH changes; 2) remarked ASI; 3) rudder balance check.  $1750 net to Mooney for "kit." I do not know what is in the kit.

I received the pdf file for the POH revisions; I can send out the ASI for remarking, and rudder balance can be done by a MSC or someone skilled in the art for 2-5 hours.  What am I missing? Is it a logbook entry and POH revision all that is needed once everything has been done? I'd like some insight on who, where and how much, please? Has anyone bought the kit?  

Who out there in MooneySpace has actually accomplished this for their M20J?

One piece of the puzzle that may be missing is Mooney drawing 940071 referenced in the SL.   Supposedly it has the "instructions".   I've not been able to find it.

 

[A64Pilot]

I don’t think you will legally get the gross weight increase without paying Mooney.

‘But honestly who really cares? Gross weight really doesn’t worry me as long as I have enough power to make the trees at the end of the runway, CG on the other hand will hurt you if you don’t respect it, or can hurt you anyway.

Speaking of an 200HP Mooney now, I think we are power limited, not structure, the big motor guys may be different

Edited May 20, 2021 by A64Pilot

[jaylw314]

36 minutes ago, A64Pilot said:

I don’t think you will legally get the gross weight increase without paying Mooney.

‘But honestly who really cares? Gross weight really doesn’t worry me as long as I have enough power to make the trees at the end of the runway, CG on the other hand will hurt you if you don’t respect it, or can hurt you anyway.

Speaking of an 200HP Mooney now, I think we are power limited, not structure, the big motor guys may be different

AFAIK all aircraft max gross weights are structural limits, dictated by aircraft category (standard, in our case), although I'm assuming there's some engineering voodoo magic that occurs to determine the actual failure point.

[MIm20c]

@Jack46here is a  Link for some of the information you’re looking for. 

[toto]

1 hour ago, A64Pilot said:

I don’t think you will legally get the gross weight increase without paying Mooney.

I'm sure that someone here on MS knows aircraft certification well enough to give us the definitive answer, but it's a curious thing.  I've talked to several shops about doing the service bulletin, and no one seems to think that the Mooney kit is important - everyone seems to send the ASI out for a silkscreen and checks the rudder balance.

Since the gross weight is already specified in the type certificate, I'm not sure what regulatory impact a Special Letter has on Part 91 operations.  The service bulletin itself isn't required by regulation for Part 91, but the letter clearly says that you need to comply with the SB and add the AFMS to use the 2900 GW.

My a/c came with the AFMS already in it, but I've never found any evidence that anyone complied with the SB, so I always treat it as a 2740 craft.  I'll do the SB one of these days, but for the moment I'm happy knowing that I have a 160lb GW buffer that I'm not using for anything

[carusoam]

Somewhere along the way...

Mooney changed the structure...

Then the testing and documents came out to match the structural change...

So....  there were a few Mooneys that had the structure, but needed the kit and documents...

 

Then Rocket engineering skipped all that... and got weight increases for their STC... for all their conversions with or without the added structure...

PP thoughts only, not an airplane designer...

Best regards,

-a-

[A64Pilot]

1 hour ago, jaylw314 said:

AFAIK all aircraft max gross weights are structural limits, dictated by aircraft category (standard, in our case), although I'm assuming there's some engineering voodoo magic that occurs to determine the actual failure point.

No, there are aircraft that if loaded to the structural limit won’t get off of the ground, they don’t have the power available, so Gross weight in their case is an engine performance limit, because there are climb requirements you have to meet too.

‘Some aircraft it’s a function of 61 kts stall, the airplane has the structure and the HP. but any more weight raises the stall above limits, even CG, we manufactured an airplane that the fwd CG limit was when it stalled at 61 kts, due to a lack of elevator authority, so it wasn’t really a stall, just couldn’t hold the nose up and that’s not uncommon

‘However it’s a lot more complex than just that because speed plays into it, it’s easier to load G up on a fast airplane than a slow one, when we went for 10,500 lbs on the S2R-H80 we had to raise flap speed and some other speeds, had to do with turbulence and I think stall, to be honest I never really understood exactly why, just did it.

Then as was noted in the post above, the Rocket has a big ole motor and goes like stink, is much heavier even empty and has a gross weight increase, with apparently no additional structure.

‘I’m not abdicating go fly it like it was light, no if you think your heavy, fly it like you would drive an overloaded truck, no hold my beer watch this stuff

Your allowed to determine strength by analysis, but the scatter factor is much higher, meaning you don’t get nearly as much credit as if you actually pulled the item, if memory serves ultimate load is 150% of design limit, a part is allowed to deform at ultimate, but not break, in fact you ideally want it to deform, that gives a warning.

‘That’s one reason why I don’t like composites, especially carbon fiber, oh it’s strong, but it has a tendency to completely fail when it does and does so without warning, no bending, no loosening of rivets etc. just ”pop”

 

But bottom line is don’t load up an airplane with a history of structural failures, but don’t worry so much on one that has no history, assuming of course it’s a model that has history and not a new design.

 

Now I’m going to ramble a bit, the Huey has no G meter and has no G limits, it’s rotor system simply can’t develop enough lift to break the thing.

The AH-64 has a G meter and has G limits, but I went looking for the over G inspections, there aren’t any, the G limits on that aircraft are aerodynamic, exceed the limits at the specified gross weight and something bad may happen like a blade stall etc. But your not going to break it.

 

Edited May 20, 2021 by A64Pilot

[jaylw314]

28 minutes ago, A64Pilot said:

No, there are aircraft that if loaded to the structural limit won’t get off of the ground, they don’t have the power available, so Gross weight in their case is an engine performance limit, because there are climb requirements you have to meet too.

Climb performance defines the service ceiling, so yes, if your service ceiling was 0' MSL, you would not have a very useful aircraft   Since (most) people wouldn't buy planes with a 0' service ceiling, almost all planes are structurally limited.

Edit: read the blurb about the heli's wrong, I thought you were saying they were power limited

Edited May 20, 2021 by jaylw314

[EricJ]

53 minutes ago, toto said:

I'm sure that someone here on MS knows aircraft certification well enough to give us the definitive answer, but it's a curious thing.  I've talked to several shops about doing the service bulletin, and no one seems to think that the Mooney kit is important - everyone seems to send the ASI out for a silkscreen and checks the rudder balance.

Since the gross weight is already specified in the type certificate, I'm not sure what regulatory impact a Special Letter has on Part 91 operations.  The service bulletin itself isn't required by regulation for Part 91, but the letter clearly says that you need to comply with the SB and add the AFMS to use the 2900 GW.

My a/c came with the AFMS already in it, but I've never found any evidence that anyone complied with the SB, so I always treat it as a 2740 craft.  I'll do the SB one of these days, but for the moment I'm happy knowing that I have a 160lb GW buffer that I'm not using for anything

Complying with the service bulleting for balancing the rudder may result in no changes, since the SB balance results specified overlap with the original balance specifications.   So if it is checked and no changes are necessary, it may not have resulted in a logbook entry for that reason.

Otherwise I generally agree that many would see no barrier to performing the upgrade without the kit.   If the ASI and AFM are changed and the rudder at least checked to verify it is within the new balance limits, that seems to cover the requirements.   The only possible hole I can see is if the 940071 drawing has some additional instruction that is otherwise missed.

[A64Pilot]

No, it’s not as simple as 100 FPM climb rate, and many especially smaller aircraft hit the engine performance limit before they hit a structural limit.

on edit if memory serves it’s actually a climb gradient an angle, not a rate.

‘I think pretty much all smaller single engine Cessna’s do and I’d assume Champs, J3’s etc are the same.

‘It’s not that they have a 0 MSL service ceiling, it’s that at it’s gross weight it hits its min performance limit, which is not it’s service ceiling.

‘Even service ceilings are not always when you hit 100 FPM climb at gross weight, it often is but sometimes it could be other limits, one may be that’s as high as the manufacturer chose to certify it to.

‘I did engine performance testing at FL250 in one of our model of crop dusters that was the basis of a military variant, but it’s Certified ceiling was 12,000, because why Certify a crop duster above 120,000? But Certified ceiling isn’t a limit anymore than max demonstrated cross wind velocity is, unless of course it’s in the POH as a limit,then it is.

Edited May 20, 2021 by A64Pilot

[PT20J]

According to the TCDS, you have to comply with Mooney dwg 940071. How do you show compliance if you don’t have a copy? I would ask Mooney for a copy. Maybe they’ll give it to you for free or a nominal charge. Another source might be one of the MSCs that’s been around a long time and may have done some and have a copy of the drawing they would share.

Skip

[Hank]

Does no one google their own stuff anymore?

SL92-1_SN24_1686-2999.pdfSL92-1_SN24_1686-2999.pdf

No, I didn't read it, just scrolled through it quickly. Looks like what you want. It's the second result when I searched "mac drawing" whatever the number is.

[EricJ]

2 hours ago, Hank said:

Does no one google their own stuff anymore?

SL92-1_SN24_1686-2999.pdfSL92-1_SN24_1686-2999.pdf

No, I didn't read it, just scrolled through it quickly. Looks like what you want. It's the second result when I searched "mac drawing" whatever the number is.

I think that's the same pdf that most people have.   It doesn't include the missing drawing.

 

[PT20J]

4 hours ago, Hank said:

Does no one google their own stuff anymore?

SL92-1_SN24_1686-2999.pdfSL92-1_SN24_1686-2999.pdf

No, I didn't read it, just scrolled through it quickly. Looks like what you want. It's the second result when I searched "mac drawing" whatever the number is.

Yep, that document is still available on Mooney's website. However, retrofit kit 940071 is not listed in the current list of retrofit kits, so it's probably no longer available which is why I thought Mooney might make the drawing available. Never hurts to ask.

Skip

[Hank]

7 hours ago, EricJ said:

I think that's the same pdf that most people have.   It doesn't include the missing drawing.

 

There's a drawing of some kind way towards the end, along with a bunch of charts, graphs and tables. Look around page 40 and after, although there's some before then, too.

[EricJ]

4 hours ago, Hank said:

There's a drawing of some kind way towards the end, along with a bunch of charts, graphs and tables. Look around page 40 and after, although there's some before then, too.

That's all the stuff for the AFM replacement pages.