Ross Taylor Posted March 14, 2019 Report Share Posted March 14, 2019 Hi all... let me say that I've been reading a ton here and thank you all for the great information. This is my first post, as I'm the new owner of an M20E. I have a question about Center of Gravity, as I'm preparing for a cross-country flight in this new-to-me bird. I entered all the W&B info into Garmin Pilot and was surprised to see that the CG is very far aft with me and my wife in the front (combined weight about 280) and 100 pounds in the back. In digging into the last equipment list and W&B revision (after a prop change), I think I'm seeing an error in their calculation. The prior CG/ARM was 46.84, which seems pretty standard for the Es. After a 3-pound weight increase on the nose, with the new prop/hub, they indicate a new CG farther aft... of 48.78. To me, that doesn't make sense. And, with this 48.78 CG, we're barely within the envelope. I think it's actually supposed to be 46.78 but I'd love the hive eyes on this. Once we're back at home base with this plane, I'll have it weighed to figure this out. And, even with the 48+ CG, we're still within the envelope and I don't see a problem with our ferry plans. Until we can get it weighed, though, does it indeed seem like this revision sheet calculation is erroneous? Or am I missing something? Thanks much! Ross Taylor, Flagstaff AZ 26812 Quote Link to comment Share on other sites More sharing options...
RLCarter Posted March 14, 2019 Report Share Posted March 14, 2019 At 380# up front I'm in the forward part of the envelope. Numbers get transposed along with errors in the math, get it weighed and start fresh Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted March 14, 2019 Report Share Posted March 14, 2019 I went through all my W&B changes and found many errors, none that big, and most of mine cancelled out, so I am within. ~2lbs. And I would not reweigh the plane unless you have to, and make sure they do it correctly and the scales have been calibrated. Tom Quote Link to comment Share on other sites More sharing options...
Hank Posted March 14, 2019 Report Share Posted March 14, 2019 You can always doublecheck their math. My C is often near the front limit, especially with two guys and no baggage Quote Link to comment Share on other sites More sharing options...
BDPetersen Posted March 14, 2019 Report Share Posted March 14, 2019 It’s amazing in the course of giving checkouts and flight reviews how many significant w&b errors get uncovered. Quote Link to comment Share on other sites More sharing options...
David Lloyd Posted March 14, 2019 Report Share Posted March 14, 2019 I was looking at the W&B for a Bonanza I owned and noticed an error. Started checking and found about 10 errors. Some were addition, subtraction and multiplication errors, a couple cases of adding a moment rather than subtracting. Guess it is easy to make those errors taking things out, putting others in. Some of that stuff was done back in the day before cheap calculators. In the end, you are the party responsible for your paperwork. Quote Link to comment Share on other sites More sharing options...
Bob_Belville Posted March 14, 2019 Report Share Posted March 14, 2019 I would not weigh the plane. Recalculate the W&B sheet and I suppose you'll find the error that you suspect is in there. I would enter the weights and arms into an excel spreadsheet to minimize the chance of making my own errors. (an A&P should verify and sign your new W&B). My ('66) M20E empty weight is 1680.7 and moment is 79833 for a CG of 47.5. But I have a several heavy mods including avionics in the tail cone with a high moment. I suppose a more typical E would have an empty CG forward of mine and your 46.84 is much more likely than the 48.78. Of course the 3 pounds added to the nose should have moved the CG forward, not back, so I'd start with that calculation if you have both W&B sheets. 1 Quote Link to comment Share on other sites More sharing options...
Andy95W Posted March 14, 2019 Report Share Posted March 14, 2019 2 hours ago, Bob_Belville said: I would not weigh the plane. Recalculate the W&B sheet and I suppose you'll find the error that you suspect is in there. I would enter the weights and arms into an excel spreadsheet to minimize the chance of making my own errors. (an A&P should verify and sign your new W&B). ^^^^^^^^^^^^^^^^ Do this exactly. ^^^^^^^^^^^^^^^^^ Bob knows what he's talking about. Quote Link to comment Share on other sites More sharing options...
steingar Posted March 14, 2019 Report Share Posted March 14, 2019 The w&b in my Mooney POH is exactly this: “don’t put the larger passengers in the back”. I suspect our aircraft are not that easily misloaded. Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted March 14, 2019 Report Share Posted March 14, 2019 I have 120 W&B line items, 15 errors...so 12.5% error rate.Tom 1 Quote Link to comment Share on other sites More sharing options...
Ross Taylor Posted March 14, 2019 Author Report Share Posted March 14, 2019 Okay, thanks all! Three takeaways here, for me... First, my impression that adding 3-ish pounds to the nose couldn't move the CG aft is correct. Yay, I'm not a *complete* idiot! Haha! Second, I'll scuttle my plans to have the plane weighed and will dig through the equipment history and recalculate the W&B from scratch. Third, the correct ARM is under 47 and we're good to fly. I was getting a little worried when I saw where we were landing in the envelope with the 48.78 value. Okay, there's a fourth takeaway for me (which I'd already seen from my prior reading). There are lots of folks here willing to help others - thank you for that! 3 Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted March 14, 2019 Report Share Posted March 14, 2019 You can always weight the plane for a sanity check. Nobody says you have to update your aircraft records. 3 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 16, 2019 Report Share Posted March 16, 2019 Suspect the arms that an errant mechanic may use... some people may accidently use an incorrect reference... Sice the Cg moved back, when weight was added forward of the reference plane... suspect all of the calculations performed by the errant mechanic... The 0.0 arm is a bolt on the nose gear...? Not the firewall... or something really obvious.... (check this detail for accuracy) PP thoughts only, not a mechanic... Welcome aboard, Ross, -a- 1 Quote Link to comment Share on other sites More sharing options...
M20F Posted March 16, 2019 Report Share Posted March 16, 2019 On 3/14/2019 at 3:45 PM, N201MKTurbo said: You can always weight the plane for a sanity check. Nobody says you have to update your aircraft records. I always find the airplane W&B discussons bizarre. If you say I fly my plane over gross all the time people think you are reckless. If you fly around with an incorrect W&B (which almost everyone does) you are smart. Everyone should follow your advice. If you are going to overload the plane do it so knowingly, not unknowingly. 1 Quote Link to comment Share on other sites More sharing options...
Ross Taylor Posted March 19, 2019 Author Report Share Posted March 19, 2019 Hi all, and thanks for the feedback. I'm excited to be picking this lady up tomorrow! Quote Link to comment Share on other sites More sharing options...
Immelman Posted March 19, 2019 Report Share Posted March 19, 2019 If you have all the history of W&B revisions, do this: Open up excel or another spreadsheet, start from how the plane left the factory and work forward. Some pieces of equipment will go in, some will come out, and at the end you should have something very close to or matching the most recent W&B, and if not it can help you spot an error. It may consume some time but I think its worthwhile. But as a gut-check, with 2 in the front and 100 lbs in back you will be fine If you put 2 adults in the back seat it will start getting aft fast... 1 1 Quote Link to comment Share on other sites More sharing options...
McMooney Posted March 19, 2019 Report Share Posted March 19, 2019 what is the negative to having the plane weighed ? Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 19, 2019 Report Share Posted March 19, 2019 The cost... To do it properly requires removing all kinds of dirt and extra wires from years gone by... along with the proper weighing... emptying or filling tanks properly will be needed. Not done with all the extra effort required, ends up with a lower UL than expected... If done officially, the new lowered UL ends up in the log books to be figured out later... Either way... it is better to have the real WnB Numbers to do the proper calculations... PP thoughts only, -a- Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted March 19, 2019 Report Share Posted March 19, 2019 along with the proper weighing... emptying or filling tanks properly will be needed. Do not use the fill the fuel tanks method, in my case if I did that it would cost me 18lbs of useful load, because my 64 gallon tanks actually hold 67 gallons. Tom 1 Quote Link to comment Share on other sites More sharing options...
Hank Posted March 19, 2019 Report Share Posted March 19, 2019 59 minutes ago, ArtVandelay said: Do not use the fill the fuel tanks method, in my case if I did that it would cost me 18lbs of useful load, because my 64 gallon tanks actually hold 67 gallons. Unless you know your actual tank capacity. When my tanks were stripped and resealed, it took 52.4 gallons to fill both to the caps (versus standard capacity of 52 gal). Quote Link to comment Share on other sites More sharing options...
Shiny moose Posted March 19, 2019 Report Share Posted March 19, 2019 I cannot open your file, I hope this helps your investigation on the correct entries into your W&B 1 Quote Link to comment Share on other sites More sharing options...
carusoam Posted March 19, 2019 Report Share Posted March 19, 2019 +1 on the un-opened file... Try to make the file share-able in one way or another... better for somebody to see something... Early Mooneys had critical WnB data on a loose piece of graph paper tucked in the logs... You really want to know... Any errors in the history of the WnB of the plane... Any errors in the calculations the new pilot is making with the new 2 U plane.... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
cliffy Posted March 21, 2019 Report Share Posted March 21, 2019 When I reweighed my Mooney I gained 98 pounds of Useful load. The first factory W&B was in error! One can use the TCDS for figuring out the correct arms for equipment by looking at other listed equipment and their arms. The Mooney Datum is the center of the nose gear mount bolts. Go ahead and refigure all your paper work (if you know you have it all) and see where you sit. But to really know what you have- reweigh. It ain't that hard or expensive. Quote Link to comment Share on other sites More sharing options...
Ross Taylor Posted March 21, 2019 Author Report Share Posted March 21, 2019 Thanks all. I picked her up in Virginia on Tuesday and got back to Flagstaff yesterday evening, right at sunset. It was a really nice trip. It looks like I have all the docs and the original W&B sheet was there, too. I'll do some math and see what I find. And at some point I'll get her weighed, out of curiosity. But I'm certainly not concerned. What a nice flying machine! Quote Link to comment Share on other sites More sharing options...
David Lloyd Posted March 21, 2019 Report Share Posted March 21, 2019 Ross, congrats on your new plane. Looked real good in the pictures. Quote Link to comment Share on other sites More sharing options...
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