Greg-ABQ

M20J Max Gross Weight

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Does anyone know why and when the J model max gross weight changed from 2740 up to 2900 lbs?  I noticed on a 1978 POH the max GWT was 2740 and models produced in the '90s were certified up to 2900 lbs.  Same engine, right?  Same wing?  Or does the wingtip design in the mid-80's allow the increased weight?  Just curious.  Thank you.

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The MSE got the 2900# max gross weight, and a few of the serial numbers prior to the MSE branding can go to 2900 with a service bulletin (which amounts to nothing more than verifying rudder balance) and a remarked airspeed indicator.

 

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Here's the Mooney service letter and SB outlining the applicable aircraft:

http://www.mooney201.de/files/SL92-1_SN24_1686-2999.pdf

Essentially, it's just a change to the airspeed indicator labelling, mucking around with the rudder balance, and a whole bunch of addenda to the POH.

Aircraft built after 1991 are eligible, SN 24-1686 thru 24-3200, 24-3202 thru 24-3217.  I don't know when or if it ever became sold as standard.  AFAIK it's not based on any structural change.  The motor never changed, although max gross weight is based on structural strength, not engine power.

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Just now, toto said:

The MSE got the 2900# max gross weight, and a few of the serial numbers prior to the MSE branding can go to 2900 with a service bulletin (which amounts to nothing more than verifying rudder balance) and a remarked airspeed indicator.

 

With a pre-requisite of having the proper heavier tubes in the steel frame to support the added weight...

There is a serial number that starts off the heavier tubes....

As you can see above... if you don’t have the proper serial number, the STC doesn’t apply...

 

Writing a new STC, and swapping out a few tubes may not cost all that much...

:)

Best regards,

-a-

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12 minutes ago, Captain Warbucks said:

I'm not too sure on it but the J i'm in the process of buying is a 89 and has the "gross weight increase STC". I'm interested in more info on this as well! 

It's definitely *not* an STC.  It's part of the original type certificate.

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What’s the MGW of the Missle? It was a modified J, back before the frame was beefed up, so unless they modified the frame I’m going to say the original frames are strong enough to support 2900lbs.

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48 minutes ago, jaylw314 said:

Here's the Mooney service letter and SB outlining the applicable aircraft:

http://www.mooney201.de/files/SL92-1_SN24_1686-2999.pdf

Essentially, it's just a change to the airspeed indicator labelling, mucking around with the rudder balance, and a whole bunch of addenda to the POH.

Aircraft built after 1991 are eligible, SN 24-1686 thru 24-3200, 24-3202 thru 24-3217.  I don't know when or if it ever became sold as standard.  AFAIK it's not based on any structural change.  The motor never changed, although max gross weight is based on structural strength, not engine power.

There's a structural change related to the steel cage, including an additional bar and reportedly thicker tubing.

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Not an additional bar just increased wall thickness (or so as has been reported) on the two of the longerons. 
 

The missile STC is not SN dependent so the early Js can be upgraded with the same original structure.  They just jumped through a different set of hoops to do it and accommodate the larger engine. 
 

Someone with a DER please do the structural analysis and make an STC for the early Js and late Fs.  :-)

 

Did they issue performance charts for the 2900lb GW as well?

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3 hours ago, bradp said:

 


 

 

Did they issue performance charts for the 2900lb GW as well?


Expect the POH would have adjusted performance charts to cover the variations in performance... with the higher MGToW...

  • T/O distances 
  • climb rates
  • stall speeds
  • All would need to be defined for the new user....

If it is an STC... for updating an older airframe... get a few new tubes, and 20 pages of STC including new performance charts...

Rocket engineering seems to be really good at this...
 

A brave and wild idea.... inspect the existing tubes... identify that they are the same as the Missile’s tubes.... Complete a few flight tests.... call it the more efficient Missile....  with 2900 MGToW.... :) issue the STC with all the appropriate charts...
 

PP imagination, not a mechanic...

Best regards,

-a-

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I looked into this for my J, its eligible.  Cost from MSC/Mooney is terrible, quoted $3k

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34 minutes ago, gacoon said:

I looked into this for my J, its eligible.  Cost from MSC/Mooney is terrible, quoted $3k

Well, the original price in the 1992 SB is listed at $1750, so it has less than doubled in 28 years.

Careful examination of the IPC will show that lower tube part number 340117-119 in earlier models has a .035" wall thickness and was changed to part number 340155-135 with a .049" wall thickness at S/N 24-1686 which is the first S/N eligible for the gross weight increase.

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6 hours ago, EricJ said:

There's a structural change related to the steel cage, including an additional bar and reportedly thicker tubing.

Thanks, I actually meant applying the SB didn't involve modifying any structure when applied.  I assumed there was some kind of structural change across serial numbers, but I had no idea what that was!

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1 hour ago, gacoon said:

I looked into this for my J, its eligible.  Cost from MSC/Mooney is terrible, quoted $3k

I did the Gross Weight Increase in 2017.  I did not need a new altimeter because I had a Garmin G500; we just had the new POH Supplement Speeds programmed in.  The rudder did need additional counterweights installed to comply with the new balance specifications.  

The original kit price included the new altimeter is the $3K cost.  But if all you need is the paperwork like I did, Henry Weber MSC sold it for less than $500 (I don’t want to give the exact price in case their price has changed in the past 3.5 years.)

All I needed was the POH supplement specifically for my s/n range, as well as the retrofit drawing.

My airplane s/n 34-3002 was a 1987 model year which is probably one of the earliest applicable with the SL91-1-2 kit starting at S/N 34-3000. 

Notable changes:

Max Gross Weight increased from 2740 to 2900

  Vso (dirty)    55 kt @ 2740 / 58 kt @ 2,900 lbs
  Vs1 (clean)    63 kt @ 2740 / 65 kt @ 2,900 lbs (clean)
  VA    119 kt @ 2900, 116 kt @ 2740
  Best Glide    94 kt @ 2900, 91 kt @ 2740
  X wind flaps    15° > 12 kt @ 2740
    above 2,740 lbs    15° < 10 kt > 0° + 10 kt for x wind landings
  
 

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Fwiw, the flight manual supplement is included in the service letter document that jaylw provided above. 

Even if you have an analog ASI, it's no big deal to remark it (instead of buying the kit). As rmag mentioned, the key thing is that the ASI must agree with the FMS. 

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2 hours ago, toto said:

Fwiw, the flight manual supplement is included in the service letter document that jaylw provided above. 

Even if you have an analog ASI, it's no big deal to remark it (instead of buying the kit). As rmag mentioned, the key thing is that the ASI must agree with the FMS. 

Yeah that file wasn’t available to me at the time.  With that link, all you would need to do is the rudder work and altimeter work and you have the gross weight increase for free assuming you fall into that serial number range.

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we just did this on my friend's 1987.  Remarked the ASI, the rudder balance was checked, no mods needed.  and printed a whoile new POH with the latest revision, and then printed the POH packet which replaces about 40 pages.

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On 7/31/2020 at 6:29 PM, ArtVandelay said:

What’s the MGW of the Missle? It was a modified J, back before the frame was beefed up, so unless they modified the frame I’m going to say the original frames are strong enough to support 2900lbs.

Missile’s have two different weight categories based on serial # to make determination. SN-24-0764 and up:

MTOW 3200#

SN-24-0763 and down without landing gear modifications:

MTOW 2837#

Edited by Missile=Awesome
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There are ten different items in the landing Gear modifications for Missile’s with lower serial # to have greater MTOW.  There is NO discussion on the cage?

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On 8/1/2020 at 12:01 AM, PT20J said:

Well, the original price in the 1992 SB is listed at $1750, so it has less than doubled in 28 years.

Careful examination of the IPC will show that lower tube part number 340117-119 in earlier models has a .035" wall thickness and was changed to part number 340155-135 with a .049" wall thickness at S/N 24-1686 which is the first S/N eligible for the gross weight increase.

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What does IPC stand for? I heard it was only a paper STC. Would be interested to hear Don Maxwell’s thoughts.

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1 hour ago, Tx_Aggie said:

What does IPC stand for? I heard it was only a paper STC. Would be interested to hear Don Maxwell’s thoughts.

Illustrated Parts Catalog. It’s not an STC. It's a Mooney design change documented in the Type Certificate Data Sheet (TCDS) and retrofittable to certain serial numbers by Service Bulletin. 

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