One Piece Belly Mod W&B Change?

[Yooper Rocketman]

I purchased my Mooney Rocket back this spring, removed the engine for tear down and inspection of the engine due to an unfortunate prop strike by the previous owner (4 years ago).  We completed the engine installation and are getting the logbook entries completed and reviewing the past log entries since I sold the plane 4 years ago.  I found the shop completing the one piece belly mod did NOT make a W&B logbook entry!  Anyone have a copy of a W&B for completing the one piece belly mod?  That would save my A&P a bit of work to see the removed weights, installed weights  and the "arm".

Tom

[N201MKTurbo]

The weight and arm are easy enough, but the removed weight is going to be hard to come by. 

I have a LASAR one piece belly, I can look to see what I have. You can contact LASAR and ask them.

[David Lloyd]

W&B on my C showed "No Change" on the weight and arm.  In the STC, it did state "Weight Change-None." You might want to contact Lasar for your mid-body answer.

[ArtVandelay]

Mine was done by Mod Works, I have a log entry referencing STC, but there was no W&B entries. Don’t know if STC would have this information, but since the other work they did was listed I can only assume it was negligible.

[N201MKTurbo]

My one piece belly probably weighs 5-10 Lbs. A bit more then the aluminum panels it replaced. The difference isn't much but more than a pound.

[ArtVandelay]

My one piece belly probably weighs 5-10 Lbs. A bit more then the aluminum panels it replaced. The difference isn't much but more than a pound.

Don’t forget the bazillion screws it replaces with 20-25 camlocs.

[Hank]

34 minutes ago, ArtVandelay said:

Don’t forget the bazillion screws it replaces with 20-25 camlocs.

It depends on which one piece belly you have. Mine is held on by 48 #8 screws and five little #6 screws behind the nose wheel. 

[KSMooniac]

Tom, I can't help in the near future, but I plan to be doing the same mod with a factory belly on my J later in the winter.  I will be weighing the panels and fasteners as part of my work, but I don't have those values now.

[carusoam]

Rumor has it…

it was a simplification when it used camlocs…

Lasar is the contact…

Bill ‘Mr. Terrible’ Wheat, i believe is the STC holder…

There is a mod works one piece with skids showing…  visually different…

my search results are here…

https://mooneyspace.com/search/?q="One piece belly"&quick=1&updated_after=any&sortby=relevancy

time flys at Mooney Speeds…

Best regards,

-a-

[Guest]

11 hours ago, Yooper Rocketman said:

I purchased my Mooney Rocket back this spring, removed the engine for tear down and inspection of the engine due to an unfortunate prop strike by the previous owner (4 years ago).  We completed the engine installation and are getting the logbook entries completed and reviewing the past log entries since I sold the plane 4 years ago.  I found the shop completing the one piece belly mod did NOT make a W&B logbook entry!  Anyone have a copy of a W&B for completing the one piece belly mod?  That would save my A&P a bit of work to see the removed weights, installed weights  and the "arm".

Tom

If it’s the factory kit, Mooney should be able to provide you the data, if it’s an aftermarket STC you could contact the STC holder for the data. My guess is that it weighs more than the metal belly it replaced.

[1980Mooney]

I had the one piece belly installed on my J at the Mooney Factory in 2005.  They did not make a W&B entry because there was no material change.  And there are only ~10 camlocks holding it on.

Edited September 17, 2022 by 1980Mooney

[carusoam]

Great detail shared!

Go 1980!

Best regards,

-a-

[Yooper Rocketman]

Thanks everyone.  It was a Mooney supplied one piece belly.  It's actually pretty light but I guess the aluminum panels are too.  Based on what @1980Mooney says, it's pretty clear no W&B change.

Tom

[Guest]

While the weight change may be minimal, if the instructions contain a weight change it should be recorded, otherwise the kit isn't installed in accordance with the approved instructions.

[Yooper Rocketman]

It’s says “negligible” on the paperwork from Mooney

[M20F]

I never understand why folks are reluctant to just reweigh the plane.  We post and cry safety as pilots except when it comes potentially at the expense of facts and useful load.  

[ArtVandelay]

I never understand why folks are reluctant to just reweigh the plane.  We post and cry safety as pilots except when it comes potentially at the expense of facts and useful load.  

Because it’s never done correctly.

Planes don’t fall out of the sky because they’re 10 lbs overweight, every time weight is an issue it’s because it’s grossly overweight.

[EricJ]

1 hour ago, M20F said:

I never understand why folks are reluctant to just reweigh the plane.  We post and cry safety as pilots except when it comes potentially at the expense of facts and useful load.  

It's kind of a pain to do, not something one elects to do frequently, and certainly not, imho, anyway, for something like a belly replacement.   I'd put the old metal panels on a scale with all its fasteners and the new fiberglass hotness on a scale with its fasteners and maybe verify that the difference is "negligible", if I was really curious.

 

[Shadrach]

23 hours ago, M20F said:

I never understand why folks are reluctant to just reweigh the plane.  We post and cry safety as pilots except when it comes potentially at the expense of facts and useful load.  

If weighing the plane significantly added to safety, people would be more enthusiastic about doing so. The W&B numbers on most legacy aircraft were “fuzzy” the day they left the factory. 
 

CG is more important than weight from a safety standpoint. Mooneys are not particularly sensitive to either. 
The reason most don’t want to weigh a plane is because there is some chance that a reweigh will narrow the legal operating window of the aircraft by some degree with almost no upside with regard to operational safety. 
Safety with regard to aircraft performance is primarily a function of margin. The less a pilot knows the plane, the more conservative their decision making should be. Losing 10lbs 30lbs or 50lbs of useful isn’t likely to keep anyone out of the weeds if things go pear shaped, but it might give the investigator some additional rope for the hanging.

[GeeBee]

I have always been able to gain a few pounds of useful on a re-weigh. Not hard. Just weigh it with full fuel, but be careful how you service to the full mark.

 

[Guest]

I’ve never seen a maintenance manual that said to fill the tanks for a weight and balance calculation and then remove the fuel by arithmetic.  In my experience they end up wrong.  They all show de fuelling the plane, then adding back the unusable fuel, then take the scale readings for the calculation.

[David Lloyd]

3 hours ago, M20Doc said:

I’ve never seen a maintenance manual that said to fill the tanks for a weight and balance calculation and then remove the fuel by arithmetic.  In my experience they end up wrong.  They all show de fueling the plane, then adding back the unusable fuel, then take the scale readings for the calculation.

Yes, although the factory did just that in 1975 with my C.  There was a calculation for deducting useable fuel based on the 80*F temperature (a nice winter day in K'ville). Guess no one outside the factory is trusted to correct the 52 gallon fuel weight for temperature.

[EricJ]

4 hours ago, M20Doc said:

I’ve never seen a maintenance manual that said to fill the tanks for a weight and balance calculation and then remove the fuel by arithmetic.  In my experience they end up wrong.  They all show de fuelling the plane, then adding back the unusable fuel, then take the scale readings for the calculation.

That's the preferrable method, but it isn't always practical.   Many people don't have a means to defuel or store the offboarded fuel, and many airports (like mine), don't allow it to be done in the hangars and the logistics get impractical.   Since it isn't a precision operation, anyway, the error due to variance in the fuel weights may be acceptable.

[ArtVandelay]

Since it isn't a precision operation, anyway, the error due to variance in the fuel weights may be acceptable.

So unless you’ve lost your W&B history makes it useless exercise.

[GeeBee]

Well actually there are more reasons. Especially on larger aircraft, as often times dirt and other accumulations add up, which is why the FAA requires 135, 125 and 121 to be reweighed every 36 months. Also those "negligible items" add up. At the carrier I worked at the airplane was washed, ( a belly of grease weighs a lot), heavily steam cleaned, interior vacuumed and wiped before reweigh. 

I've seen some big changes. On one King Air we could not believe it. A difference of more than 50 pounds. So much so, we brought in a new set of load cells and a different processor only to get the same readings. A serious error at the factory we thought until we called the factory and had the build file pulled. It was then they discovered the numbers in our AFM were in fact for the S/N before our airplane. Which is why if you use it for hire, the FAA wants to see new numbers every 36 months.