Did I witness an engine test for a 757 at MAN?
See this avherald report: https://avherald.com/h?article=4db1ccdb&amp;opt=1

A Jet2.com Boeing 757-200, registration G-LSAN performing a test flight from Manchester,EN to Manchester,EN (UK), was in the initial climb out of Manchester's runway 05L when the right hand engine (RB211) emitted a loud bang and streaks of flame. The aircraft levelled off at 5000 feet and returned to Manchester for a safe landing on runway 05R about 25 minutes after departure.

So yes, it was a test flight, but it obviously did not go according to plan, resulting in an engine failure.