shiny From Germany, joined May 2012, 32 posts, RR: 0 Posted (9 months 3 weeks 1 day 10 hours ago) and read 2611 times:
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 From United States of America, joined Aug 2012, 40 posts, RR: 0
Reply 1, posted (9 months 3 weeks 19 hours ago) and read 2428 times:
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.