Years ago we had an Army Air Corps Squadron based at Farnborough, initially 664 Sqdn but re-numbered to 656 Sqdn. They were equipped with Scouts and Siouxs, changing the Siouxs to Gazelles in the late '70s.
Scenario is a Sioux calls for departure on air test. I watch him start to air taxy to the takeoff point, then another aircraft calls and my attention is diverted. I look back at the AAC hangar and the Sioux had taxied back and shut down.
5 min later a phone call from a very apologetic Sioux pilot.
'Sorry I didn't call you shutting down' (SOP at Farnborough in those days) he says, 'I was a bit annoyed because the stupid RXXX engineers had fitted the rotor blades upside down'!