Evaporation...
We had an old Cessna 402 that was doing sterling duty as a sunshade for stray dogs. Like attracts like? Anyway some mad Eyeties decided they really needed it so a deal was done and our very best and most dispensible pilot was chosen to ferry it from Lagos to Rome. Me, of course!
It hadn't even had a run-up in years, plus it was sat there kind of tipped to one side. Well, whatever.
They dragged the battery cart over and plugged it in, hopped in and started flipping switches. Hmm... no fuel in one tank. (This was the 402 with the so-called "tuna tanks" with the main fuel out in the tip tanks.) So they filled up the oddly empty tank and went off to do engine runs.
It wasn't running very well, and when they shut it down afterwards they found it was pissing Avgas all over the ramp from under one engine!
Ah yes, no sense wasting all that Avgas in those big tip tanks, was there, so that one of our own engineers decided to become a criminal mastermind back when we never expected that thing to move again. He had undone the main line at the firewall and used the boost pump to empty the tank. Hah! Of course, being a true son of Mother Africa he didn't bother to "tight-up de foo-el line" afterwards, creating a sort of flying bomb.
I was watching all this with a certain amount of interest, as were the poor old stray dogs. One day, after the engineers, now minus our inofficial fuel vendor, had managed to calm its explosive tendencies, they were off to the compass base. Progress! 30 minutes later here they came back, dragging my steed on the end of a rope! I could only think to myself, "It won't even make it from the ramp to the compass base and back under its own steam and I am going to Rome?"
I did set off for Rome. Well, why not?
About 30 minutes later I knew why not. The prop governers were shagged and would not stay synched. Bwaaaahh, vrooom, vroom, waaah-waah-wah-wah-wah... interlude of twiddling prop levers... bwaaaah, vrooom, vroom, etcetera, every TEN MINUTES! Aargh! Sat there watching the landscape crawl past with this racket beating my head in... madness was setting in when I was thinking, well, if I just shut one down then I don't have to synchronise them, do I?
We got as far as Tamanrasset and hit some paperwork problems. The Wops had done the permits but the number they gave me didn't exist according to my new Algerian friends. I spent a couple of nerve-wracking days drinking mint tea and trying not to think about movies about Turkish prisons.
When they finally got bored playing with me one engine didn't want to fire up, just sputtering, coughing and dying, repeatedly. Turned out that the throttle was off about 1.5 inches so that I was trying to start it with the throttle open too far. D'oh!
You know how sometimes you get to the end of a long flight and you just stand there gazing fondly at the trusty old bird that carried you all the way? I got out of that thing at Ciampino Airport, ripped off my sweaty life vest, tossed the keys to the new owners and said, "You wanted it, it's yours. Good luck!"
I imagine they were going to smuggle cigarettes with it and good luck to them. Well, maybe people who were behind on paying money to the Camorra or Mafia or whomever... they dragged them out to the airport and took them for a long flight in the Cessna, bwaaah-wah-wah-wah, after which the money got paid back right away even if that meant selling one or both kidneys.