pagirard Posted May 16, 2023 Report Share Posted May 16, 2023 Hi all, our '74 Mooney just went thru a major panel overhaul and we disposed of vacuum pump, all steam gauges, the original Mooney positive control system. I was hoping we would reduce the basic empty weight but unfortunately we went the other way around: Jun-15 Apr-23 Delta Basic Empty Weight 1651.15 1733 81.85 CG 45.9 44.8 -1.1 Moment 75788.91 77631.75 1842.84 Granted the last W&B was done back in 2015 but I wasn't expecting such a delta and also an unfavorable shift in the CG. Have you ever experienced a similar issue ? Should we consider re-doing the W&B ? Help much appreciated Quote Link to comment Share on other sites More sharing options...
AIREMATT Posted May 16, 2023 Report Share Posted May 16, 2023 Are posted results due to re-weighing or recomputing removals vs. additions? 1 Quote Link to comment Share on other sites More sharing options...
pagirard Posted May 16, 2023 Author Report Share Posted May 16, 2023 19 minutes ago, AIREMATT said: Are posted results due to re-weighing or recomputing removals vs. additions? Actually weighting with 3 wireless cells Quote Link to comment Share on other sites More sharing options...
KSMooniac Posted May 16, 2023 Report Share Posted May 16, 2023 I would have expected an improvement as well. Were the scales calibrated recently? Had you fully audited the old W&B trail over the last 49 years? The original number from the factory is an estimate/average, so it could (likely) had some error or tolerance, and any math errors over the years could have compounded it. Did your installers remove all of the old wiring, coax, PC tubing, etc. or just abandon in place? Do you have a fancy modern interior with denser foam, leather coverings everywhere, sound-deadening insulation, or thicker windows? There are lots of ways to add weight, and perhaps they weren't captured in old W&B updates... Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted May 16, 2023 Report Share Posted May 16, 2023 Was the fuel and oil properly accounted for? Quote Link to comment Share on other sites More sharing options...
PT20J Posted May 16, 2023 Report Share Posted May 16, 2023 Even if the weights are right, you have to be careful and follow the procedure in the service manual to get the CG right because the axel positions are not fixed due to the gear geometry. 1 Quote Link to comment Share on other sites More sharing options...
1980Mooney Posted May 16, 2023 Report Share Posted May 16, 2023 38 minutes ago, pagirard said: Actually weighting with 3 wireless cells Was the June 2015 W&B also done by reweighing with cells or was it done by recomputing additions and removals? Quote Link to comment Share on other sites More sharing options...
pagirard Posted May 16, 2023 Author Report Share Posted May 16, 2023 Trying to answer all *very good* questions: * Yes the scales were in calibration and certified * The W&B stated that the aircraft was weighted per Mooney IAW TCDS 2A3 Rev:58 and Mooney M20 Series Service and Maintenance Manual rev:July 1980 * The 2015 W&B was done by calculation and I'm digging thru the logbooks to find the last *measured* W&B - if any * The repair station what prepare the plane for the W&B did empty the tanks (main and aux) down to unusable level and kept the oil. * The repair station went thru every wires and tubes and removed all the unnecessary wires and tubes from the old systems * We did remove the old seats fabric and re-upholster the seats and the interior with leather - I didn't this to weight the seats&panels before/after (facepalm) Thanks all for your suggestions I'm going to dig into these logs & records to find the last *real* W&B Quote Link to comment Share on other sites More sharing options...
takair Posted May 16, 2023 Report Share Posted May 16, 2023 I think this is due to Global Gravity increase that has occurred over the last 50 years, likely due to man pumping oil from the ground. This increases the pull of gravity. I have noticed this in my personal weight and balance as well as that of my airplane. It is rare to find something unaffected by todays increased gravity. A Time Machine could help. Go back in time and have your avionics shop do a manual weight and balance and the aircraft will magically weigh less. Very satisfying. :-) 11 Quote Link to comment Share on other sites More sharing options...
Greg Ellis Posted May 16, 2023 Report Share Posted May 16, 2023 @pagirard I feel your pain. When I overhauled my panel, removed the vacuum system, including a mountain of wiring that had collected behind my panel over the years that lead to nowhere, etc...etc...etc... I also had a decrease in my useful load. The scales were calibrated and certified, etc... I have not poured through the books to see if there were any errors on previous W&B sheets that would make this any less drastic. However, a glance at the AFM for my airplane shows a W&B sheet done by the factory that was full of errors. I guess the slide ruler or the ENIAC that they used back then were not calibrated. 1 Quote Link to comment Share on other sites More sharing options...
Hank Posted May 16, 2023 Report Share Posted May 16, 2023 How clean was your plane when weighed? Dirt inside the wheelwells? Junk in the baggage area? Stuff in the hatrack? Were the seat pockets empty, headsets removed, manuals taken out? This stuff adds up, too. Some people carry spare parts; I keep a few tools and a quart of oil in the back. The plane should be empty and clean when weighed . . . . 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted May 16, 2023 Report Share Posted May 16, 2023 I went through every W&B change made to my plane, put them all in a spreadsheet and found about 20 errors out of 100 entries. In my case they mostly balanced out, there was about 1lb difference when all said and done.Every AP wants to weigh it (and charge me of course) instead of doing the math when a change is made, I firmly refuse. No one has ever had the plane weighed and come out less than book.I and others have loss close to 70lbs on a full upgrade with loss of vacuum and heavy avionics. 1 Quote Link to comment Share on other sites More sharing options...
Fly Boomer Posted May 16, 2023 Report Share Posted May 16, 2023 8 hours ago, pagirard said: Actually weighting with 3 wireless cells Has it been painted since 2015? 1 Quote Link to comment Share on other sites More sharing options...
Fly Boomer Posted May 16, 2023 Report Share Posted May 16, 2023 2 minutes ago, ArtVandelay said: I went through every W&B change made to my plane, put them all in a spreadsheet and found about 20 errors out of 100 entries. In my case they mostly balanced out, there was about 1lb difference when all said and done. Every AP wants to weigh it (and charge me of course) instead of doing the math when a change is made, I firmly refuse. No one has ever had the plane weighed and come out less than book. I and others have loss close to 70lbs on a full upgrade with loss of vacuum and heavy avionics. Amen, brother. I have heard over and over "if you weigh it, you're going to be disappointed". 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted May 16, 2023 Report Share Posted May 16, 2023 Has it been painted since 2015?Why would that matter?Did paint get heavier in 2015? Quote Link to comment Share on other sites More sharing options...
PT20J Posted May 16, 2023 Report Share Posted May 16, 2023 If you have all the previous W&B calculations, you can review them all and check the math. Quote Link to comment Share on other sites More sharing options...
Nico1 Posted May 16, 2023 Report Share Posted May 16, 2023 Make sure they used the right data. A shop re-did WB for mine and gained a ridiculous amount of weight.. turns out they completely miss-read the TC data sheet and used many wrong numbers. Quote Link to comment Share on other sites More sharing options...
EricJ Posted May 16, 2023 Report Share Posted May 16, 2023 It's not unusual to gain some weight during a weight-and-balance check with scales, but eighty-two pounds is a lot! Especially after significant removal/installations that could be expected to lose weight, it's definitely unexpected imho. That's a lot more than accumulated dirt or repair patches, etc., would explain. That's evidence a mistake was made somewhere along the way. Whether the mistake was in deducting too much during a recalculation after a repair or mod at some time in the past, or the weighing wasn't done properly (e.g., scales weren't zeroed or something), it may be difficult to figure out. One way to sort it out is to take it someplace else and get it weighed again, but that's kind of a hassle, too. Quote Link to comment Share on other sites More sharing options...
Jim Peace Posted May 16, 2023 Report Share Posted May 16, 2023 Redid my whole panel. Took out standby and normal vacuum system and a bunch of old heavy stuff. Had it reweighed and it went up. All I can think of is that it was weighed wrong years ago or weighed wrong with the new W&B. 1 Quote Link to comment Share on other sites More sharing options...
Skates97 Posted May 16, 2023 Report Share Posted May 16, 2023 3 hours ago, ArtVandelay said: Why would that matter? Did paint get heavier in 2015? Probably not a lot of difference in the paint, but if there was body work to take out dents and dimples in the plane that can add some weight. Quote Link to comment Share on other sites More sharing options...
Rick Junkin Posted May 16, 2023 Report Share Posted May 16, 2023 I'm looking forward to an accurate W&B when my panel work is done this summer. I routinely fly at or near maximum gross per the current recorded numbers and if they were wrong I want to know that. I think they're correct according my review of all the historical W&B data, otherwise I wouldn't load up to max gross, but the scale-verified W&B will give me the valid data I need to operate safely within the W&B limits with my new configuration. By my calculations just based the equipment that is to be removed and added I should gain a little over 40# of useful load. We'll see. Cheers, Rick Quote Link to comment Share on other sites More sharing options...
kris_adams Posted May 16, 2023 Report Share Posted May 16, 2023 I did a similar upgrade and ended up gaining 7 pounds in spite of everything removed. I will weigh again after paint and make sure everything is completely out of the plane. I suspect I may get 15-20 pounds back. Quote Link to comment Share on other sites More sharing options...
carusoam Posted May 17, 2023 Report Share Posted May 17, 2023 Sooo much opportunity to lose some weight when going digital…. A few pounds at a time… So much opportunity to gain some weight when adding comfort…. Digital avionics weigh far less than the old analog ones… extra vac systems come with a lot of weight… Comfy interior items… fancy leather, and lots of thick foam…. Hidden behind the walls… more foam insulation…. Many upgrades over time… add a bunch of dead wires running everywhere… a few more pounds…. When Re-weighing… following the guidance is important… You don’t want to catch extra fuel and oil pounds when they don’t belong… it is a bit of a challenge to empty every pocket, and remove each tool… but, it’s part of the weighing job. As is leveling…. Good luck… there isn’t much room for getting lighter…. Be careful… there is always room for calculation mistakes…. Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Jim Peace Posted May 17, 2023 Report Share Posted May 17, 2023 1 hour ago, carusoam said: there is always room for calculation mistakes…. especially at a certain MSC..... just found out today that one of my CEIS fuel senders was installed incorrectly by said MSC.... well actually I found out years ago they installed both wrong by using a goop on the install screws....and today I found out they did not follow the instructions to keep a float away from some dome nuts....this was verified by CEIS... 1 1 2 Quote Link to comment Share on other sites More sharing options...
DXB Posted May 17, 2023 Report Share Posted May 17, 2023 14 hours ago, Jim Peace said: especially at a certain MSC..... just found out today that one of my CEIS fuel senders was installed incorrectly by said MSC.... well actually I found out years ago they installed both wrong by using a goop on the install screws....and today I found out they did not follow the instructions to keep a float away from some dome nuts....this was verified by CEIS... I distinctly recall your prior abhorrent experience with that particular MSC, which led me to stop using them. Quote Link to comment Share on other sites More sharing options...
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