Shiny
Posts: 32
Joined: Mon May 28, 2012 11:57 am

"Appreciable Effect On Weight And Balance"

Thu May 23, 2013 1:30 pm

FAA and EASA use the wording "appreciable effect on weight and balance" as one of the criteria to distinguish between minor and major modification (Part 21).
But I fail to find any definition of "appreciable effect"!? I found a definition of "negligible" effect on weight, but "negligible" is on the other end of the scale... What is not "negligible" is not necessarily "appreciable".

So can anyone point to a definition when it comes to "appreciable effect on weight"? I expected to find some percentages as for "negligible"...
 
Raventech
Posts: 147
Joined: Thu Aug 30, 2012 10:25 pm

RE: "Appreciable Effect On Weight And Balance"

Fri May 24, 2013 4:25 am

I don't think there is one because if they set a number and an incident results because it should have been done but FARs indicated it was not necessary then they are partially liable. Instead they used those terms to let the person performing the maintenance/alteration make the determination based on their best judgement (and thus solely on the hook). From what I picked up at A+P school is simply if you can't say beyond a reasonable doubt that is was negligible/not appreciable then recalculate/re-weight it. (If anyone knows different would also like to hear so).

If you haven't come across it yet, a good guide for determining major/minor alteration designation (FAA jurisdiction Aircraft) is FAR 43 Appendix A.
 
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Starlionblue
Posts: 17371
Joined: Fri Feb 27, 2004 9:54 pm

RE: "Appreciable Effect On Weight And Balance"

Fri May 24, 2013 5:54 am

It sounds like one of those catch-all phrases that regulators so love. If they regulated specifically, someone made a change within the limits, and then something went wrong due to the change...
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Shiny
Posts: 32
Joined: Mon May 28, 2012 11:57 am

RE: "Appreciable Effect On Weight And Balance"

Fri May 24, 2013 6:52 am

They can be more specific without any liability as often done - there are ACs, GMs, AMCs, etc., etc.
Just some kind of a direction would have been good as such is certainly known.

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