Many moons ago I was the co-pilot of a Mk. 3 Shackleton when we had a translation unit failure. We were very heavy, could not fully feather the prop, and could not maintain height without the Vipers.The Vipers were then limited to only a few minutes at full power.
There was no option but to jettison fuel (Avgas, of course) with the Vipers running, which had not been tried. The jettison pipes were only about 6 feet outboard of the Viper jet pipes. We half expected "reheat", but it was all a non-event.