The most amusing spurious fire warning I had was a double fire warning on a Puma in Northern Ireland.
Early Pumas had ventilated engine cowlings with ribbed ventilators along the top to keep the engine bay temperature down. Some noddy had decreed that this would reduce the efficiency of the fire extinquishers so they were blanked off. The result off this was that the engine bay temperatures increased and in certain conditions, hovering or ground running downwind, the fire lights would come on.
This day I was operating in South Armagh with an aircraft that was very prone to this and I also had a VERY senior officer in the jump seat who was coming along to see how the chaps were getting on. I swung into the LZ at Crossmaglen and as usual it was a downwind approach and landing and as I landed both fire lights came on.
There then followed five minutes during the troop changeover when this senior officer was shouting at me because the fire lights were on and I was shouting at him to shut up because I already knew about it.
As soon as we got airborne and took off into wind both lights went out.
He didn't even say thank you when we got back to Aldergrove.