Sikorsky S-22 Ilya Muromets had toilet fitted in 1913
WW II (just) ........Ladies & Gentlemen........I give you.......The Supermarine Stranraer
Operational history
(wiki)In service, only 17 Stranraers were operated by the RAF 1937–1941 primarily by No. 228, No, 209 and No. 240 Squadrons along with limited numbers at the No. 4 OTU. Generally, the aircraft was not well-received as its performance was considered marginal.[1]
Due to its less than favourable reception by flight and ground crews, the Stranraer gained a large number of derisive nicknames. It was sometimes referred to as a "whistling shithouse" because the toilet opened out directly to the air and when the seat was lifted, the airflow caused the toilet to whistle
Cheers
Alfie