The fuel supply tube fitting pulling out of the left engine’s operability bleed valve (OBV) during the landing rollout, allowing fuel to leak and contact hot engine cases, which ignited a fire that caused thermal damage to the engine pylon. Contributing to the fitting pullout from the OBV was an undetected progressive environmental control system (ECS) support link wear condition that allowed excessive OBV movement relative to the engine, and the lack of alignment instructions in the base engine assembly drawing and the lack of maintenance tasks to assess the operational condition of the ECS links.