Metal Wing Strut Attachment Fitting Inspections

J

JoeSF

New member
Are new American Champion Aircraft subject to the Wing Strut Attachment Fitting Inspections every 1000 hours?
 
The Upper Front Strut Attach Fittings have a 1000 Hour Dye-Penitrant Inspection interval on all metal spar wings.

Its called Damage Tolerance Method for Continued Airworthiness. With an inspection that is more frequent than nessecary, you can safely use a part forever (or until its got a crack). As opposed to just tossing the part out at 3000 hours. Its how modern structural attachments are certified. Since, its an older airplane...you got this ONE part that was brought up to date. Looks a little strange.

Intersting Fact about that fitting. Here is how you come to the 1000 hours....

1) Take the part and use Finite Element Analysis to find the worst posible place to put a crack.
2) Assume we put a 0.050" crack before its ever installed right at that spot. (if you think that is conservative....next...)
3) Take the absolute worst loading case senario posible...okay...umm....4 Intermediate Acrobaic Routines (flown sloppy at g limits) in an 8KCAB PER HOUR.
4) Repeat those routines until part fails = 3100 hours
5) Divide by three = about 1000 hours

How it THAT for margin of safety? :lol:
 
It's really conservative. When you consider the airplanes the civilian top gun dogfighters were tearing up I suppose it makes sense though.
 
Jerry, I just purchased a spare set of fittings for my 7KCAB. When the time comes I can swap them out and have the old fittings checked at my leisure. How close is the 8KCAB fitting to mine? Just curious. Thanks, David Johnson
 
Dave, That takes all the guess work out of the inspection. I'll do the same when it is time.
 
Yes, thats a good idea.

The 8KCAB fittings have one extra attachment hole on the end.
Basically, its even more conservative for the other models.

Overbuilt is usually a Champ's middle name....why ya think useful load is not so great?
 
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