I figured I should chime in here. I've been an aircraft mechanic full-time for the past 11 years until recently. I still do contract work here and there when I have time. I've worked on everything from Super King Airs to 757's, and have used many different lights in the process. Unfortunately the really nice LED lights have only come out in the last few years.. I always cringe when I think about all that wasted time with Mini-Mags and other assorted lights (and what I may have missed when performing inspections..lol).
Ok, so on to my recommendations. I absolutely agree 100% with the Zebralight headlamp suggestion mentioned earlier. I always hated headlamps.. thought they were corny, bulky, cumbersome, etc. Then one day I was struggling in the belly of a King Air trying to support myself with one hand, hold a light with the other, and still manage to use my tools. I then remembered that I had the Zebralight that I brought in to try. After literally the first 10 seconds I said "WHY DIDN'T I TRY THIS SOONER!!" I was totally hooked, and used it all the time since. You really have to have one in your box.
For the other tasks, many lights will do, but I stay away from Li-Ion powered lights. The main reason is that you shouldn't charge Li-Ion batteries unattended. Not too much of a problem, but the last thing you want to worry about when you're at home at night or on the weekend is the Li-Ion batteries you
left on the charger. You'll wonder if the charger really terminated the charge when the batteries were full, or did it malfunction and start a fire? And I'm sure you know, you WILL forget them on the charger at some point.
I really like the 2 x AA format. Perfect size for grip, and you can throw it in your pocket with just a bit of it hanging out. This is important, makes it very easy to retrieve. Smaller lights tend to turn sideways in your pocket, and it can be a pain digging them out. Of course a holster would work great too, but I really don't like anything hanging off of my belt. Another thing is a momentary (forward style) switch... absolute necessity. You want to be able to partially press the switch for quick blips of light, without having to click it fully on and then click it back off every time... that's annoying.
My personal choice is the EagleTac P10A2 and the P100A2. Each has a general mode that works for pretty much anything, and a turbo mode for when you really want some light. I absolutely love the P10A2.. beautiful smooth beam, and tons of output. The beam is perfect in my opinion for mechanic work. You don't want a beam that has too small of a hotspot.. a beam with a good mix of spot and flood is ideal. The only thing I don't like about the light is that it's not as grippy as the P100A2, which has great knurling. The P100A2 has a protruding tail switch, which makes actuation a little easier. The bad thing about the P100A2 is that it's round, and will roll off of just about anything.. it's hard to keep it in one spot on the slightest non-level surface. The P10A2 is great in this regard.. the tailcap and bezel have flat spots, plus the pocket clip keeps it from rolling. My final choice is the P10A2, it's awesome! I think it'll have enough punch for you when you're shining on the aircraft from 75 feet away, unless there's a lot of ambient light.
Yes, I sell both of these lights, so many will think I'm biased. But, I can use just about any light I want and the Zebralight and the EagleTac P10A2 are the ones I use.. the others stay home.