Gross Weight Increase 2,740 to 2,900

[toto]

1 minute ago, redbaron1982 said:

What's different in the newer J models vs the older ones that are not allowed to get the GW increase? I have a 1985 which is not included and I'm curious from a structural point of view what is the difference. 

This has been much speculated on MS, but the running theory is that there was some minor beef-up of the landing gear to support the extra weight, and that beef-up happened from a specific serial number forward.

[redbaron1982]

5 minutes ago, toto said:

This has been much speculated on MS, but the running theory is that there was some minor beef-up of the landing gear to support the extra weight, and that beef-up happened from a specific serial number forward.

So technically (although not legally) an older J model could have a 2900 MTOW and a 2700 landing weight?

[DC_Brasil]

5 minutes ago, toto said:

This has been much speculated on MS, but the running theory is that there was some minor beef-up of the landing gear to support the extra weight, and that beef-up happened from a specific serial number forward.

It is actually the diameter of the steel tubular structure that is bigger, increasing the structural strength of the aircraft. Some S/N rolled out with that modification but were still certified for 2740lbs GW. Those are the planes that can get the GW increase.

[toto]

8 minutes ago, redbaron1982 said:

So technically (although not legally) an older J model could have a 2900 MTOW and a 2700 landing weight?

I think that's exactly what they did with the Missile

MooneyMissileConversion.pdf

[DC_Brasil]

6 minutes ago, redbaron1982 said:

So technically (although not legally) an older J model could have a 2900 MTOW and a 2700 landing weight?

No. You are either certified for a 2740 GW (MTOW/MLW) or 2900GW.

See the M20J Type Certificate Data Sheet screen shot below.

 

https://drs.faa.gov/browse/excelExternalWindow/6EA0F05ECCA8304486258305006833CF.0001

[PT20J]

34 minutes ago, redbaron1982 said:

What's different in the newer J models vs the older ones that are not allowed to get the GW increase? I have a 1985 which is not included and I'm curious from a structural point of view what is the difference. 

Mooney increased the wall thickness of a tube in the lower tubular structure.

[Shadrach]

30 minutes ago, redbaron1982 said:

So technically (although not legally) an older J model could have a 2900 MTOW and a 2700 landing weight?

I mean technically rather than legally it could have any take off weight with which it will ascend out of ground effect.  Does not mean it's a good idea.

I am not sure of the specifics but I believe that in Alaska it's possible you could get a waiver to operate a J model commercially at 10% over gross...so 3,014lbs or 3190 without any modifications.

2900lbs is a lot to ask of a 200hp airplane under certain scenarios.  A 2740lb J model requires a considerate pilot on hot, high DA days.  I imagine a 2900lb J model is pretty sluggish under those conditions. that's 13.7lbs per HP vs 14.5lbs per HP.  14.5lbs per HP is the lowest power to weight ratio of an Mooney ever certified. No doubt it can handle it just fine, but the margins are thinner.  The little 65hp Mooney Mite is pulling 12lbs per HP at MGW.   Under normal operating weight, my F model is at around 11.5lbs per HP.  When I flew supplies to NC for Helen, I had 573lbs of cargo on board which meant the plane was within 20lbs gross with 50 gals of fuel on board.  It was near a standard day, but the difference in take off performance was considerable. Once airborne the difference was trivial. Landing in a windy valley at a 3000' strip with surrounding 1800' to 2000' peaks the differences became clear again.  

[redbaron1982]

25 minutes ago, Shadrach said:

I mean technically rather than legally it could have any take off weight with which it will ascend out of ground effect.  Does not mean it's a good idea.

I am not sure of the specifics but I believe that in Alaska it's possible you could get a waiver to operate a J model commercially at 10% over gross...so 3,014lbs or 3190 without any modifications.

2900lbs is a lot to ask of a 200hp airplane under certain scenarios.  A 2740lb J model requires a considerate pilot on hot, high DA days.  I imagine a 2900lb J model is pretty sluggish under those conditions. that's 13.7lbs per HP vs 14.5lbs per HP.  14.5lbs per HP is the lowest power to weight ratio of an Mooney ever certified. No doubt it can handle it just fine, but the margins are thinner.  The little 65hp Mooney Mite is pulling 12lbs per HP at MGW.   Under normal operating weight, my F model is at around 11.5lbs per HP.  When I flew supplies to NC for Helen, I had 573lbs of cargo on board which meant the plane was within 20lbs gross with 50 gals of fuel on board.  It was near a standard day, but the difference in take off performance was considerable. Once airborne the difference was trivial. Landing in a windy valley at a 3000' strip with surrounding 1800' to 2000' peaks the differences became clear again.  

Yeah, I see that. But all J models, even the ones certified up to 2900lb, have 200 HP.

So, the slow climb rate and longer TO distances will apply anyway.

BTW: I usually fly solo, full tanks, and it is amazing how fast it accelerates and gets airborne. In 2200ft, I'm already at 50AGL, and it takes 900ft to get airborne. 

[PT20J]

[Shadrach]

48 minutes ago, redbaron1982 said:

Yeah, I see that. But all J models, even the ones certified up to 2900lb, have 200 HP.

So, the slow climb rate and longer TO distances will apply anyway.

BTW: I usually fly solo, full tanks, and it is amazing how fast it accelerates and gets airborne. In 2200ft, I'm already at 50AGL, and it takes 900ft to get airborne. 

Yeah, that was my point. Regardless of whether it’s certified or not, 2900lbs is a lot to ask of 200 hp Lycoming under certain conditions.   
 

I too fly solo…often at weights <2200lbs. It’s quite sporty at those weights, especially in winter.

[DC_Brasil]

Soooo...  anyone has the Mooney drawing number 940071? ahahahahah this seems to be the biggest mystery in all of this.

[PT20J]

1 minute ago, DC_Brasil said:

Soooo...  anyone has the Mooney drawing number 940071? ahahahahah this seems to be the biggest mystery in all of this.

I’d try Dugosh or Maxwell.

[DC_Brasil]

45 minutes ago, PT20J said:

I’d try Dugosh or Maxwell.

Would you please ping them in this post? 
 

[PT20J]

I'd email them directly. All the Mooney service centers are listed here: https://mooney.com/contact-2/

[EricJ]

1 hour ago, DC_Brasil said:

Soooo...  anyone has the Mooney drawing number 940071? ahahahahah this seems to be the biggest mystery in all of this.

You may not need the drawing.    I think everything you need is in Mooney Special Letter SL-92-1 and Sevice Bulletin SBM20-252.    Both should be available online for free, either here or at Mooney's site.   There's a handy pdf that used to turn up all the time that had both in the same file.

Edit:   The only physcial/aerodynamice modification is a slight change to the rudder balance weight.   My airplane is not in the eligible serial numbers, so I always just took it to mean that I probably have a reasonable 160 lb margin buffer on my gross weight.    There's also an AI and AFM change, I suspect reflecting an increased stall speed.

[DC_Brasil]

1 hour ago, EricJ said:

You may not need the drawing.    I think everything you need is in Mooney Special Letter SL-92-1 and Sevice Bulletin SBM20-252.    Both should be available online for free, either here or at Mooney's site.   There's a handy pdf that used to turn up all the time that had both in the same file.

I have found that PDF. I am worried (maybe unjustified, though) because I suspect Brazilian aviation authority (ANAC, our FAA) will need to update my CA with the new GW. My A&P said that they need to file a request and add supporting documents. 

My worry is that when someone sees that both the Service Letter and the M20J Type Certificate Data Sheet tell that the GW increase is approved when in compliance with Mooney drawing number 940071.

I am concerned they'll look at it and ask:, Ok, where's this drawing in your request? We don't see it, so we can't verify the procedure has been followed. 

[EricJ]

1 hour ago, DC_Brasil said:

I have found that PDF. I am worried (maybe unjustified, though) because I suspect Brazilian aviation authority (ANAC, our FAA) will need to update my CA with the new GW. My A&P said that they need to file a request and add supporting documents. 

My worry is that when someone sees that both the Service Letter and the M20J Type Certificate Data Sheet tell that the GW increase is approved when in compliance with Mooney drawing number 940071.

I am concerned they'll look at it and ask:, Ok, where's this drawing in your request? We don't see it, so we can't verify the procedure has been followed. 

Yeah, I forgot you have some special requirements down there.  At a minimum you can know that many M20Js just like yours take off and fly around with a heavier airplane than yours, so it's nice to know that you have some functional margin.

[Lax291]

11 hours ago, Slick Nick said:

You have a 1990 and it didn't come with the increased GW already? That's strange, I thought all MSE's had it from the factory? For reference, my 1991 is 2900lb max gross.

I've got a 1990 J and it did not come with 2,900# from the factory. Previous owner purched the upgrade kit as the SN was about 20 off from having the increased GW as standard. 

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://mooney.com/wp-content/uploads/2020/12/M20J-Gross-Weight-Increase-SL92-1-1.pdf&ved=2ahUKEwjeqezH9aCJAxUtLFkFHcE7G-0Q5YIJegQIFBAA&usg=AOvVaw0dsYZ3lkSYO2-zMHlgL_8a

 

[EricJ]

22 minutes ago, Lax291 said:

I've got a 1990 J and it did not come with 2,900# from the factory. Previous owner purched the upgrade kit as the SN was about 20 off from having the increased GW as standard. 

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://mooney.com/wp-content/uploads/2020/12/M20J-Gross-Weight-Increase-SL92-1-1.pdf&ved=2ahUKEwjeqezH9aCJAxUtLFkFHcE7G-0Q5YIJegQIFBAA&usg=AOvVaw0dsYZ3lkSYO2-zMHlgL_8a

 

Well there's the AFM pages, so another piece of the puzzle.

Do you know whether there's a 337 in the data file for your airplane that might contain the drawing?

[Slick Nick]

53 minutes ago, Lax291 said:

I've got a 1990 J and it did not come with 2,900# from the factory. Previous owner purched the upgrade kit as the SN was about 20 off from having the increased GW as standard. 

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://mooney.com/wp-content/uploads/2020/12/M20J-Gross-Weight-Increase-SL92-1-1.pdf&ved=2ahUKEwjeqezH9aCJAxUtLFkFHcE7G-0Q5YIJegQIFBAA&usg=AOvVaw0dsYZ3lkSYO2-zMHlgL_8a

 

I just saw above the serial number range listed, which looks like it split in the 1990 model year.  24-3218 and up were the ones factory equipped with the 2900# GW. My bird is serial 24-3222 so about the 4th one with the new higher gross weight. 

[Slick Nick]

As for the reason for the change to the thicker tube, I believe it was required on the 6 cylinder models to add increased support for the heavier engine. To speed up assembly through more parts commonality, Mooney decided to equip all frames with the thicker tubes, even the J model. 

Not sure how true that is, but it would make perfect sense.