Shawn Coyle mentions a looping Gazelle in the UK some years ago. Let me assure him it was a full blown loop with no AOB on at all. Entry was at 140 knots with 1G pulled throughout. Tq whilst inverted was never greater than 10%, when done well the exit height was greater than the entry height!! Best demo was 5 loops in under 90 seconds, longest was 11 in a row.
Best loop was the flick loop, the Gazelle was pulled to 90 degs nose up and when Airspeed fell to zero, the gazelle was flicked over for a full loop.
All genuine its on video!!
Any chance you could post the video?
Heliport