Before you get this all wrong I would like to comment.
The inspection being done was to inspect the pylon attachment pins.It saved several hundred man hours to leave the engine attached.
On the number 2 engine a forklift was used to lift a work platform that included the engine,a crew of mechanics and all of their tools. The engine was actually rolled into position on rails and was then lifted with come alongs with dynamometers attached to measure the force.
The reason the airplane crashed is because the slats retracted on the left wing and because these airplanes only had one AOA sensor and a single channel stall warning system that was powered by the number 1 generator which was on the engine that was lost.