You're not
expected to do any repairs - it just goes over well with the engineers if, when it comes time to take off the cowling at inspection time, you are ready with a screwdriver to help take the fasteners off, and do some of the grunt work. Over the years I've learned more about how my aeroplanes work by hanging out in the hangar when maintenance is happening..
Another handy thing in your backpack, if you are on floats is a tube of aluminum putty...if you manage, through, bad luck, negligence or ignorance (or a combination of all three!

) to put a hole in a float, the putty will patch it up so's you can get home. A leatherman would help, in that case, to get the float hatches off so that you could inspect the damage from the inside. [Not that that actually happened to me - I was told about it by a "friend"

]
Leatherman? Any decent outdoors shop should have a good selection. Try here:
http://www.mec.ca/shop/?q=Leatherman or
http://www.cabelas.com/
I wouldn't buy one mail-order, though..try it out first - I think that they've changed the designs now, but some of the early Leatherman designs had sharpish edges on the plier handles, so when you squeezed hard on them, they dug into your hands quite painfully..