there are two guys working on fixing that engine while it's running, on either side of the engine, sitting on an interesting rope swing each.... must be an ignition timing problem

A Catalina (A24-65) of 43 Squadron RAAF (Black Cats) undergoes engine tests whilst taxiing near Darwin Harbor in 1945.

https://dailytimewaster.blogspot.com/2024/02/looks-like-hes-working-on-it-as-its.html

https://www.facebook.com/story.php/?story_fbid=413355411205307&id=100075925548307&paipv=0