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No ballast on my M20K 252, maybe required...


turbotrk

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On 10/22/2015 at 9:15 AM, turbotrk said:

I just did a bit of research and found out that my plane afer repainting and avionics installation went for weighting and the CG went from 43.5in at 2091lb to 42.5 at 2200lb. Looking at the maintenance manual it states clearly that for the a/c to be released you need to keep the CG within a certain limit by installing fixed ballasts (charlie weights). They give 4 options: 

no ballast

6lbs

13lbs

20 lbs

On my plane 20lbs was required but the GENIUS maintenance guy released it without doing anything. That's why unless someone is sitting at the back I am always out of envelope so at least 60-80lbs are required to balance it.

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Where can we buy these weights 

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  • 4 months later...
On 7/2/2020 at 12:42 PM, jetdriven said:

Where can we buy these weights 

I ordered a set this week. Here was the process for me...

I called Kerrville. They still have some weights in stock (depending on the plate - there are two different 6lb's and a 7lb, they had between 3-5 of each available). The y don't sell it directly to you or me. You call any MSC and they will have it drop-shipped to you. Also, you don't order it as a kit, you have to order as each individual part. The price hasn't changed much since the $500 post in 2015 above. Parts price for me buying the 19lb set was $548.57 which included everything but the anchor nuts (which are on backorder) plus shipping. Two day shipping was $125. Snail mail quote was $35.

I'll grab my parts manual and snap a pic of the parts list to attach to this post for your reference. 

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On 10/22/2015 at 8:15 AM, turbotrk said:

I just did a bit of research and found out that my plane after repainting and avionics installation went for weighting and the CG went from 43.5in at 2091lb to 42.5 at 2200lb.

 

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I am curious - what did you install that added 112.4 lbs?  You said you repainted and added (upgraded ?) avionics above.  Repainting should not add much if any weight since it is stripped first.  Over the first 32 years of its life, your K-model had 2 avionics modifications that added 6.6 lbs. to the original weight from the Mooney factory.  Most avionics modifications/retrofits/replacements today are lighter than the avionics they replace, even 20 year old equipment, and owners generally gain Useful Load. 

You have lost 112.4 lbs. of Useful Load leaving your plane with only 690 lbs.  To add insult to injury you have now added another 19 lbs. of lead in the tail dropping your Useful Load to 671 lbs.  With full 75 gallon tanks this is basically a single person plane with luggage.  Maybe a 3 hour IFR flight with 2 adults (depending on size).

If I did the W&B right the these numbers logged above mean that the average arm or location of this 112 lb. of installation(s) is at 25.2 in. arm.  I think the datum line is the firewall just below the windshield so this "average" weight is centered roughly about in your lap.

You mention in one response that you have a 3 blade prop and dual alternators.  Were they just installed also?  The prop would be a 15-20 lb penalty and the alternator about 25 lbs.  That still leaves about 65-70 lbs of avionics net of what was ripped out.  That seems like a lot.

Is it possible that your A&P measured your weight wrong or has defective equipment?  Did you really add 65-112 lbs. of new avionics net of the old equipment that was removed?  If so did your avionics shop anticipate this issue and suggest remotely mounting some of the equipment in the tail next to the autopilot?  

Edited by 1980Mooney
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  • 3 months later...

I’m reviving this thread since I seem to have a similar problem with my CG being too far forward when I have full fuel, and I am hesitant to pay $550 for 19lbs of lead.

I have checked with a few of the people around that salvage Mooney parts and I’ve had no luck finding any charlie weights. If anyone has removed the weights and would like to get rid of them, will you let me know?

The other thought is, this seems like a prime candidate for an owner produced part. What would be the main criteria to verify?  I assume if I could get the dimensions of the bars and mounting holes I would have most of the engineering data. Am I missing anything here?  I do have lead and a small smelter.  Any thoughts?

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On 11/7/2020 at 9:55 PM, 1980Mooney said:

I am curious - what did you install that added 112.4 lbs?  You said you repainted and added (upgraded ?) avionics above.  Repainting should not add much if any weight since it is stripped first.  Over the first 32 years of its life, your K-model had 2 avionics modifications that added 6.6 lbs. to the original weight from the Mooney factory.  Most avionics modifications/retrofits/replacements today are lighter than the avionics they replace, even 20 year old equipment, and owners generally gain Useful Load. 

You have lost 112.4 lbs. of Useful Load leaving your plane with only 690 lbs.  To add insult to injury you have now added another 19 lbs. of lead in the tail dropping your Useful Load to 671 lbs.  With full 75 gallon tanks this is basically a single person plane with luggage.  Maybe a 3 hour IFR flight with 2 adults (depending on size).

If I did the W&B right the these numbers logged above mean that the average arm or location of this 112 lb. of installation(s) is at 25.2 in. arm.  I think the datum line is the firewall just below the windshield so this "average" weight is centered roughly about in your lap.

You mention in one response that you have a 3 blade prop and dual alternators.  Were they just installed also?  The prop would be a 15-20 lb penalty and the alternator about 25 lbs.  That still leaves about 65-70 lbs of avionics net of what was ripped out.  That seems like a lot.

Is it possible that your A&P measured your weight wrong or has defective equipment?  Did you really add 65-112 lbs. of new avionics net of the old equipment that was removed?  If so did your avionics shop anticipate this issue and suggest remotely mounting some of the equipment in the tail next to the autopilot?  

Fascinating topic for me as my plane also has the mysterious weight gain of 108lbs only a few off from yours. After talking to several A&P’s they agree i should go reweigh the plane as they cannot think what would cause that bump since it still has factory paint scheme. And mine was reweighed just 2 years after coming off the factory assembly line not some 3 decades later like the original poster. I just wonder why no previous owner questioned the weight bump. I want to know what I got for that extra weight.

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Edited by Will.iam
Added comment that my reweigh was only 2 years after she was built.
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  • 10 months later...

There are three different plates. You add the number of plates you need. Sounds like at 13, you just need to add another plate. Once the extra plate is installed, you'll also need new bolts to hold out down (different length since the stack is taller).

I just uninstalled all three plates and all of the bolts out of my plane (New 4-bladed prop and all new avionics changed my plane to where I no longer need them). I'll be ready to sell them this week if anyone is interested. 

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8 hours ago, SkepticalJohn said:

There are three different plates. You add the number of plates you need. Sounds like at 13, you just need to add another plate. Once the extra plate is installed, you'll also need new bolts to hold out down (different length since the stack is taller).

I just uninstalled all three plates and all of the bolts out of my plane (New 4-bladed prop and all new avionics changed my plane to where I no longer need them). I'll be ready to sell them this week if anyone is interested. 

John,

Let Mike take #3 and the bolts, and I'll take #1 & #2 please.  supercub180@gmail.com

Aerodon

 

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