Aircraft Fitting Factor Test 1

[autothesis]

I have a galley being attached to Aircraft Seat Track using a fitting. I need to analyse this fitting, for fitting factor test. I am testing the fitting along with the laminate panel attached to it and the laminate panel is failing before the required load is reached.
Should I consider this fitting to laminate interface also while testing for fitting factor test.?
or if i test just the fitting separately will that be considered a pass.

Any Idea...

 

[SWComposites]

FAR 25.625:
For each fitting (a part or terminal used to join one structural member to another), the following apply:
(a) For each fitting whose strength is not proven by limit and ultimate load tests in which actual stress conditions are simulated in the fitting and surrounding structures, a fitting factor of at least 1.15 must be applied to each part of--
(1) The fitting;
(2) The means of attachment; and
(3) The bearing on the joined members.

Its pretty clear that item (3) means if the laminate panel is failing at the joint then it must be part of the test.

 

[autothesis]

Thank you SWC.
Appreciate your reply. This makes it more clear.
After reading 25.625 and Boeing D655441, it is clear that we need laminate panel also for FF test.

 

[Sparweb]

One thing I would like to clarify, is that a test is different from an analysis, when using this factor. It sounds like you are only analysing your laminated panel, despite saying "analyse" and "test" in your posts.

Going back to FAR 25.625(a), you can see that the fitting factor applies to a fitting that has NOT been substantiated by limit and ultimate load TESTS. This means that when substantiating by analysis alone, the fitting factor is mandatory. If testing the fitting, then the fitting factor can be omitted.


STF

 

[autothesis]

This is interesting Sparweb. I didn't read properly the analyze and test differences in 625(a).

But to make it clear here, I am Testing the unit anyways. But I am testing it to 1.33 per 785(f)(3). Even though it says for SEAT, I have to apply this for my Galley fitting also which is attached to the Aircraft Track.

 

[Sparweb]

Double-check that factor. You may only need 1.15, but I don't have the book handy to refer to right now.
Compare the exact wording between 785 and 625, and just to be sure go to .561 and also track down the regulation about items of mass in galley compartments - somewhere in the 700's or 800's I think, which may also have something to say on the matter.


STF

 

[rb1957]

there's a thought ... combine fitting factor on top of crash loads ?

I suspect that this "monument" should be critical for 561 crash loads (9g fwd), no?

Quando Omni Flunkus Moritati

 

[Sparweb]

Somehow I forgot to add this:
When fully testing a unit and expect it to survive the load test, then it is possible to eliminate the fitting factor entirely from the load applied to the unit. A careful reading of 25.625 gives you some hint. There may also be Advisory Circular guidance on its use. If your galley unit is "just" failing the test, but you're applying an extra 33% load, then it is actually passing with flying colours AND a 33% safety margin. Be careful with the assumptions and conditions that apply here, and check with the regulator that they agree with this interpretation.

STF

 

[autothesis]

Thank you Sparweb and Rb1957..

I am testing the unit only for 100% load. Then applying 1.33 only to fitting to qualify that.
I don't think I can eliminate testing fitting for 1.33 here.