Can I re-calculate W&B and have my A&P sign off?

Greg Bockelman said:
It’s really pretty simple math.
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Absolutely.
Not to all A&Ps though.
I had to create my own W&B document once since the A&P guy screwed it up 3 times.
Printed it, handed it to him, he reviewed it, signed it and into my airframe logbook it went. :)
My dad always said: "If you want something done right, you gotta do it yourself". He was a smart man.
 
Found this thread while searching this topic.

I want to occasionally remove one or both of the rear seats in my PA-30. I understand I need a new weight and balance completed showing these alternate configurations and they need to be signed by my A&P. He’s good with it, as long as I provide the document. Does anyone have an example or fillable document or can point me to one to use?
 
I noticed a glaring error in one of my past w&bs, so I went back and checked, and found errors in 3 of them by 3 different mechanics over the history of my aircraft. Amazingly, they balanced each other out to less than a 5 pound difference and a tenth of an inch of cg. But no, I wouldn’t trust an A&Ps math abilities.
 
Banjo33 said:
Found this thread while searching this topic.

I want to occasionally remove one or both of the rear seats in my PA-30. I understand I need a new weight and balance completed showing these alternate configurations and they need to be signed by my A&P. He’s good with it, as long as I provide the document. Does anyone have an example or fillable document or can point me to one to use?
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I’ll pm you one later today.
 
Salty said:
I noticed a glaring error in one of my past w&bs, so I went back and checked, and found errors in 3 of them by 3 different mechanics over the history of my aircraft. Amazingly, they balanced each other out to less than a 5 pound difference and a tenth of an inch of cg. But no, I wouldn’t trust an A&Ps math abilities.
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Even though I am an A&P and am very capable of calculating W&B, I realize that others might not be. Heck, a lot of pilots aren’t either. But I do believe that most mechanics are very capable. Still I think it is prudent upon buying a plane to weigh it and have a new baseline W&B done. This is especially true of an older plane that has had several calculated W&Bs done over the years due to mods. The more flying you do at or near gross weight or at high density altitude the more important this is. Plus just like some of us, planes seem to just gain weight as they get older.
 
SkyDog58 said:
Even though I am an A&P and am very capable of calculating W&B, I realize that others might not be. Heck, a lot of pilots aren’t either. But I do believe that most mechanics are very capable. Still I think it is prudent upon buying a plane to weigh it and have a new baseline W&B done. This is especially true of an older plane that has had several calculated W&Bs done over the years due to mods. The more flying you do at or near gross weight or at high density altitude the more important this is. Plus just like some of us, planes seem to just gain weight as they get older.
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Rather than putting the plane on a scale what I do is start with the original weight and balance, subtract all the equipment that has been removed and add all the currently existing equipment equipment. This eliminates the possibility of calculating an updated weight and balance off of one that was previously screwed up.

I would not advocate putting the plane on scales simply because there are more opportunities to screw up the weighing of the airplane than there is calculating a weight and balance.
 
SkyDog58 said:
Even though I am an A&P and am very capable of calculating W&B, I realize that others might not be. Heck, a lot of pilots aren’t either. But I do believe that most mechanics are very capable. Still I think it is prudent upon buying a plane to weigh it and have a new baseline W&B done. This is especially true of an older plane that has had several calculated W&Bs done over the years due to mods. The more flying you do at or near gross weight or at high density altitude the more important this is. Plus just like some of us, planes seem to just gain weight as they get older.
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When I bought my '66 PA28, the current W&B was only weighed in 1974, then just re-calculated several times after that, whenever equipment was added or subtracted. I had the plane re-weighed, and I expected it to be off (most likely heavier) by 10 or 20 lbs....what I DIDN'T expect was for it to be 80 lbs heavier!!! I recommend everyone get their planes re-weighed.
 
I had mine weighed a year or two ago, since it probably hadn't been done since it was new. Turns out it was off (heavier) by almost 100 lbs.
 
mondtster said:
Rather than putting the plane on a scale what I do is start with the original weight and balance, subtract all the equipment that has been removed and add all the currently existing equipment equipment. This eliminates the possibility of calculating an updated weight and balance off of one that was previously screwed up.

I would not advocate putting the plane on scales simply because there are more opportunities to screw up the weighing of the airplane than there is calculating a weight and balance.
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I don't see why there would be more opportunity to screw it up, but as others have noted, weighing is the ONLY way to get an accurate weight & CG...if accuracy is actually what you're after.

Yes, there are DIFFERENT things to screw up...using the wrong arms for the scale locations is one I've seen a couple of times. But I don't think there are MORE things.
 
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SkyDog58 said:
Now that is a very interesting perspective! It isn't about trust, it's about putting one's name and certificate to something that one neither did or verified. I don't care if you are an ATP who has a PhD in math. If you want me to sign your W&B, I am doing the calculations. An A&P who doesn't do this is foolish in my opinion.
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But it is your opinion. Not all A&Ps follow your rules of conduct.
 
Just remember it's like junior high school and you have to show your work. If it makes sense and is presented clearly, the A&P will sign it off.
 
Okay, I'm not an expert here, but can't you just manufacture some fake seats to put back there? Bit of plywood and cushions or whatnot? Make them real enough to satisfy everyone plus they would probably weigh about the same? That way the old man would be happy, and you would win the argument?

Please don't do this....
 
CC268 said:
Let’s hope my engineering degree helps me get it done correctly :(
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That's cool man.... I've always wanted to drive a train. I didn't think math was that big a deal on those locomotions.
 
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