Complex sentence: The entire Philippine Airlines fleet of Airbus and Boeing jets were formerly maintained in-house at the PAL Technical Center, which consists of two hangars which contain an engine overhaul shop, two engine test cells and test shops.
Split into simpler sentences: The entire Philippine Airlines fleet of Airbus and Boeing jets were formerly maintained in-house at the PAL Technical Center, which consisted of two hangars. The hangars contained an engine overhaul shop, two engine test cells and test shops.