Abstract -- Screw Compressor is one type of air compressor in the main utility at the DSLNG LNG Plant. This Screw Compressor is used as instrument water (clean, oil-free, and dry air) produced by the Air Compressor Package (Tag No. 065-C-1001 A / B / C), which is dried by the Air Dryer Package (065-V-1001A / B) until it reaches a dew point of -40 degrees Celsius before being accommodated in the Instrument Air Receiver (065-D-1002). Water instruments are needed to operate instrumentation equipment such as actuated valves, control valves, and others.This research was conducted to analyze the failure of rotary screw compressors and their modifications. The failure occurred in the lube oil (lubricating oil), which was contaminated by water from the surrounding wet air. This failure analysis is done with a fishbone diagram and plans to overcome the problem by modifying the breather system. Analysis of this failure by looking for the water content into the lubricating oil. Know the results of the analysis of the increase in the vibration value of the bearing screw elements and check the effect of corrosion in the lubrication system using a borescope. In addition, taking corrective action (repair) so that there are no recurring problems by making modifications to the Breather System on the gear casing