Not an officer's mess piano burning but the NAAFI at Changi had a piano on the top (third) floor and a long staircase that went all the way down from there to the ground with a short flat bit halfway.
The piano was doused in Avgas and ignited by a celebrating maritime reconnaissance squadron ground crew and sent on its way, where the rest of us formed an honour guard on the middle floor and saluted as it rolled past on its way to the second flight of steps.
The piano was replaced with a new one but encased in a steel cage - with two arm holes for the player to reach the keyboard.