Some years ago now had a Sqn Ldr turn up on an Airborne Forward Air Controllers course at RAF Brawdy who asked for a "cabbie" (he was an ABFAC instructor who usually sat in the back of the Gazelle). Following a refuelling turn around, I rather rashly let him in the front with me, somewhat swayed by his leather flying jacket, nomex growbag, and silk scarf (I kid you not). He said he had some experience on Rotary and was comfortable in the hover.
Looking back on it, the thing that saved me from the subsequent Board of Inquiry was my decision to start in a fairly high hover, rather than the usual couple of feet. After I said, 'follow me through, you have control' my self declared 'student' grabbed the controls in a vice like grip, accelerated us backwards towards Vne, while at the same time trying to push the left pedal out through the front of the perspex (that would be the bad pedal) and getting us up to a very impressive anti-torque spin rate. I finally managed to overcome his grip on the controls, stopped us spinning, and checked the rearwards movement (that's the one where you end up stationary at about 50' with the nose 60 degrees down hoping you only need 49' to recover). I descended, landed and shut down.
He was modest enough to realise he had just nearly killed us both (or at least killed what laughingly passed for a career in my case) and was very apologetic about the whole thing. That was the point where he took off his leather flying jacket and revealed to me on his flying suit the single wing brevet of an Air Electronics Operator! Apparently he was an Ex-Kipper fleet AEO who was dabbling in ABFAC, and he had about as many formal flying qualifications as a retarded frog.
Learned some good lessons from that one:
1. Never check - Always assume!
2. A Leather Jacket is not an adequate substitute for a formal flying course.
3. Flying Helicopters is not intuitive - recovering from unusual positions is even less intuitive.
4. Never trust anyone wearing a slik scarf.