Complex sentence: When the three engines heard about it, they accused Duck for the incident and refused to let him in the sheds, however, The Fat Controller was aware of Diesel's antics and immediately sends him away in disgrace.
Split into simpler sentences: When the three engines heard about it, they accused Duck for the situation and refused to let him in the sheds. However, The Fat Controller was aware of Diesel's antics and immediately sends him away in disgrace.