Wasn't David Morgan credited with a kill over an Argentine Puma which lost control and crashed after he made a high speed run at it in 1982?
Falklands: The Air War
Puma AE503: 23/5/82.
3 x Puma and 1 x A-109 engaged in vicinity of Shag Cove House.
........"Rather than be exposed over water for a lengthy time they had crossed Falkland Sound at its narrowest point opposite Shag Cove House and were just turning north-eastwards towards Port Howard when Dave Morgan saw the lead helicopter........ Morgan's first pass caused the pilot of AE503 to take violent avoiding action and head for the relative safety of the nearest shore. Unfortunately, the pilot's desperate manoeuvres (possibly made worse by turbulent wake from the Sea Harrier) caused him to lose control of the helicopter, which then crash landed on a hillside. Fortunately, the crew had just enough time to scramble clear before it caught fire and exploded."
The A-109 and a second Puma were destroyed y cannon fire on the ground, the last escaped.
So, 3 out of 4 in one engagement. Maybe not as impossible as described.....