Hi Guys. Removing & Reinstalling the Midfairing above the JT8 Engine on B737-200 for Structural inspection of Lwr Wing Skin Pylon Area comes to mind as one of the worst jobs I have ever done, with all those hiddenfastners at the front end that you can barely see with a mirror/torch etc. Also replacing Pneumatic Duct Ovht/Leak Det Firewires on A300B4's in the wing root through the Eng Pylon can be next to impossible.
Cheers & Happy Christmas to All!
Flying Mech