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

CC268

CC268

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CC268
If I want to remove the rear seats in my Cherokee can I do the W&B adjustment myself and have the A&P sign off or does the A&P need to be the one re-calculating?
 
CC268 said:
If I want to remove the rear seats in my Cherokee can I do the W&B adjustment myself and have the A&P sign off or does the A&P need to be the one re-calculating?
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If your A&P is willing to sign off your work, you can do it.

Best to ask him.
 
He will double check your work which means doing the calculations himself anyway so there is no harm in you doing it but don't expect him to just sign it without performing the calculations. You won't be saving any time or money.
 
I asked our A&P if he would do it himself and he claimed he was short on time. He would sign off on it though. I’ve got a checkride in 3 weeks and my dad already took one of the seats out and he is making a big deal out of me putting the seat back in for now. Hence why I asked if I could just do it myself and have our A&P sign off.
 
Just get your AP to make up a couple W&Bs for different configurations.
 
James331 said:
Just get your AP to make up a couple W&Bs for different configurations.
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That's what I was thinking...but our A&P seems hesitant to do it right now...claims he is too busy at the moment. I've been saying we need a new A&P for a while, but my dad just keeps going back to this guy. *Sigh*
 
Walboy said:
Best to keep the old man happy...if I recall, it's his plane, right? Let him make a big deal. My kids think a lot of what I do is irrational too.
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Yea but I’d rather be legal lol. Don’t want the examiner to fail me on the checkride because I didn’t have an updated weight and balance to reflect the current configuration of the aircraft. That would be what the FAA likes to call, “Anti-authority”. (PHAK Page 46). I like to fly on the straight and narrow and follow the rules of the FAA :)
 
Walboy said:
So put the seat back in like the old man wants. Make life easy.
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No I was saying he took the seat out in the first place. I want to put it back in at least for the checkride. But he doesn’t want to do that so he wants me to redo the weight and balance and get it signed off. It’s like holy cow let’s just put the seat back in takes 5 mins so I don’t have to deal with this for the checkride
 
Why not go fly the plane to another AP just to get the W&Bs done
 
CC268 said:
No I was saying he took the seat out in the first place. I want to put it back in at least for the checkride. But he doesn’t want to do that so he wants me to redo the weight and balance and get it signed off. It’s like holy cow let’s just put the seat back in takes 5 mins so I don’t have to deal with this for the checkride
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How does the CG work out for you and an examiner with no back seat? I recall Cherokees being a little forward to start with.
 
MauleSkinner said:
How does the CG work out for you and an examiner with no back seat? I recall Cherokees being a little forward to start with.
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Good question...hence why I need to recalculate W&B if we’re gonna have the back seats out.
 
Checkout_my_Six said:
Do the work for him.....and if done correctly alls he needs to do is sign it.
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My W&B is set up in an Excel spreadsheet. It empty weigh scenario, max gross weight takeoff and min weight landing scenario and several other likely configurations loaded. When my IA looked at it and looked at me, he scratched his head and said, "I've never seen on with so many calculations." He signed the full size for my logs and a smaller size which I had laminated and keep in the airplane. He did the same for my other plane. I also have Aero W&B on my phone with planes. It is nice to be able to have both available in any configuration at the touch of a keypad.
 
SkyDog58 said:
He will double check your work which means doing the calculations himself anyway so there is no harm in you doing it but don't expect him to just sign it without performing the calculations. You won't be saving any time or money.
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CC268 said:
I asked our A&P if he would do it himself and he claimed he was short on time. He would sign off on it though. I’ve got a checkride in 3 weeks and my dad already took one of the seats out and he is making a big deal out of me putting the seat back in for now. Hence why I asked if I could just do it myself and have our A&P sign off.
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I then will assume that what he means is that he doesn't have time to prepare a presentable sheet for you to put in your manual. I will also assume that he will still verify the calculations before signing it off. If he doesn't he is wrong. Preparing the paperwork can take more time to do than the actual calculations unless you have a good template handy. Either way, it doesn't take that long. I'd go ahead and prepare it and take it to him. If he just signs it without breaking out a calculator, I would definitely get another Mechanic.
 
SkyDog58 said:
I then will assume that what he means is that he doesn't have time to prepare a presentable sheet for you to put in your manual. I will also assume that he will still verify the calculations before signing it off. If he doesn't he is wrong. Preparing the paperwork can take more time to do than the actual calculations unless you have a good template handy. Either way, it doesn't take that long. I'd go ahead and prepare it and take it to him. If he just signs it without breaking out a calculator, I would definitely get another Mechanic.
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I feel ya Mr. Skydog...we will see what happens. I will do the weight and balance myself. See what the A&P does. Whole situation has been frustrating. My dad is a bit irritating sometimes.
 
Why did Pop take the seat out?
 
paflyer said:
Why did Pop take the seat out?
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We both agree they are pointless to have back there because we don’t use those back seats and it opens space for easy access to baggage,etc. I just want to make sure an updated W&B is done to reflect it. He kept one in cause he thought we might use it some day but I think we ought to just take both out of we’re gonna take one out.
 
So he didn’t think to do a new wb taking one seat out? Is it just the cushion or the seat back as well?
 
SkyDog58 said:
I then will assume that what he means is that he doesn't have time to prepare a presentable sheet for you to put in your manual. I will also assume that he will still verify the calculations before signing it off. If he doesn't he is wrong. Preparing the paperwork can take more time to do than the actual calculations unless you have a good template handy. Either way, it doesn't take that long. I'd go ahead and prepare it and take it to him. If he just signs it without breaking out a calculator, I would definitely get another Mechanic.
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That's an interesting perspective. So long as you've got a decent relationship with your A&P, and he trusts you, I see no reason the A&P would need to actually re-do all of the calculations. A quick glance should show any obvious errors. I've re-done several weight and balance calculations, for a couple different A&Ps, and none have given them any more than a quick glance to make sure it looks right.
 
bradg33 said:
That's an interesting perspective. So long as you've got a decent relationship with your A&P, and he trusts you, I see no reason the A&P would need to actually re-do all of the calculations. A quick glance should show any obvious errors. I've re-done several weight and balance calculations, for a couple different A&Ps, and none have given them any more than a quick glance to make sure it looks right.
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I'd also say that a lot of A&Ps, like a lot of pilots, struggle with basic weight and balance calculations, and so would be happy to have someone else do the work.
 
bradg33 said:
That's an interesting perspective. So long as you've got a decent relationship with your A&P, and he trusts you, I see no reason the A&P would need to actually re-do all of the calculations. A quick glance should show any obvious errors. I've re-done several weight and balance calculations, for a couple different A&Ps, and none have given them any more than a quick glance to make sure it looks right.
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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.
 
MauleSkinner said:
I'd also say that a lot of A&Ps, like a lot of pilots, struggle with basic weight and balance calculations, and so would be happy to have someone else do the work.
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My experience is that the average A&P does a better job of it than the average pilot. Plus when you say "like a lot of pilots", why should an A&P trust a pilot to do it correctly? If a lot of pilots struggle with W&B, that is all more the reason for me to double check.
 
SkyDog58 said:
I then will assume that what he means is that he doesn't have time to prepare a presentable sheet for you to put in your manual. I will also assume that he will still verify the calculations before signing it off. If he doesn't he is wrong. Preparing the paperwork can take more time to do than the actual calculations unless you have a good template handy. Either way, it doesn't take that long. I'd go ahead and prepare it and take it to him. If he just signs it without breaking out a calculator, I would definitely get another Mechanic.
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I would say the opposite...
I know my a&p well, and he knows me. I’ve stayed with him because on things as simple as a w&b, he trusts me and wouldn’t redo my calculations. I would look for a new a&p if he did redo them.
 
MauleSkinner said:
I'd also say that a lot of A&Ps, like a lot of pilots, struggle with basic weight and balance calculations, and so would be happy to have someone else do the work.
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I think you hit the nail on the head in my case
 
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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And that's totally your prerogative. But with that prerogative, I wouldn't be working with you. Part of the "owner-assisted" maintenance game is that the A&P has to develop a level of trust with the owner. If the A&P can't trust the owner to do simple math on a W&B form, the relationship isn't going to work. I'm not suggesting the A&P blindly sign it, but I'd expect the A&P to be able to eyeball the W&B numbers and ensure it "looks right" without having to re-do the entire thing. Of course, most decent W&B forms show the work anyway (and automatically do the math), so the A&P isn't really checking MY math, he's checking Microsoft's or Google's.
 
SkyDog58 said:
My experience is that the average A&P does a better job of it than the average pilot. Plus when you say "like a lot of pilots", why should an A&P trust a pilot to do it correctly? If a lot of pilots struggle with W&B, that is all more the reason for me to double check.
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"A lot" is a relative term that doesn't indicate equality in numbers.

I've only found a dozen or so bad W&B calculations in AFMs, and all of the A&Ps I've done weight and balances for have trusted me.

YMMV.
 
Do you know the arm for the seat that was removed? If you have the arm and the weight it's trivial (which you probably already know). If you don't know the arm or the datum to get the arm you might have trouble getting a W&B that would stand up to scrutiny. Using the aft passenger arm is probably close, but as far as FAA-acceptable? Dunno.

I'm ignorant in the ways of standard cat W&B requirements - does an A&P have to approve the new W&B when he didn't have to do the seat removal?

Nauga,
and binders full of Form F's
 
MauleSkinner said:
I'd also say that a lot of A&Ps, like a lot of pilots, struggle with basic weight and balance calculations, and so would be happy to have someone else do the work.
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Holy crap, it's 2nd Grade math. How many hundreds of billion$ have we spent on education in this country?
 
On the day of the check ride, take the seat out of the closet and install it(5min). After the check ride take seat out and put it back in the closet...:)
 
nauga said:
Do you know the arm for the seat that was removed? If you have the arm and the weight it's trivial (which you probably already know). If you don't know the arm or the datum to get the arm you might have trouble getting a W&B that would stand up to scrutiny. Using the aft passenger arm is probably close, but as far as FAA-acceptable? Dunno.

I'm ignorant in the ways of standard cat W&B requirements - does an A&P have to approve the new W&B when he didn't have to do the seat removal?

Nauga,
and binders full of Form F's
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Pulled out the Ole binder in the plane and it has the weight of the seats and the arm. Bam problem solved.
 
I don't see no need to do a new airplane weight and moment calculation. Take the seat out. Weigh it. While it's out, when you do your W&B's just use a negative number when you add up the columns of numbers.
 
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