Huey had flown some seventy hours with crews commenting on a high freq, chap walking down the flight line one day commented "some thing wrong with that aircraft, don't know what", following some contemplation and comparison with other aircraft on the line realised the tail rotor blades reversed.
Looking up the mast of a Huey seeing the split cones had slipped out of place when the head had been dropped on.
Always had a night standby aircraft all prepped for immediate take off in the event of emergencies, a 76 in this case, if called out you arrived at work, pulled the plugs and went. Chap called out, flew the trip, medical emergency, commented on return the thing needed tracking, pilot taking over the aircraft found powder on all four elastomerics, investigation found all four blades were missing the retention/support bearings in the head. One wonders about the track and balance following the head rebuild.
212 high freq following take off, pilot landed, screw driver left in tail rotor drive tunnel, had cut half way through the drive shaft in five minutes
205 on fixed floats with a load of pax for a quick circuit joyride, engineer standing on float doing an engine leak check after start, pilot took off and flew the circuit with engineer hanging on. Shades of the lass who got a ride around the circuit sitting on the tail of a Spitfire.
Fed inspector castigating engineering because the single engine Cessna parked on the flight line minus engine and cowling didn't have an unservicable tag.