It's not many years (mid 1990s) since pilots were out there changing the gear downlock inspection lights on Airtours' MD83s. Pre-9/11 most of us carried a Leatherman or similar, so it wasn't difficult. The lights were a no-go item, so if one failed in the middle of a night Heraklion you had to fix it. In my current airline, getting any bulb changed on a 30 minute turnround at base is no problem at all.
The rules are of course a little stricter now. In those days we wouldn't think twice about opening up a RB211 downroute, adding oil and and buttoning it up again. If the cowling had closed when it shouldn't have done, the pilot would have been chopped in half. And if it had opened when it shouldn't..........