Tip Rubbing as a Rare Metallurgical Root Cause of Gas Turbine Compressor Blade Failure

A heavy-duty gas turbine engine at the heart of a seawater desalination plant on the Arabian Peninsula exhibited multiple impact damages on their compressor airfoils that were detected during an inspection. Many blades showed heavily damaged airfoils and some even lost fractured-off parts. One moving blade in row 8 lost 50 % of its airfoil. Most compressor blade tips from stages 4 to 15 were damaged and bent. It was reported from the site that turning gear operation had been omitted once after engine shut-down in the recent past, i. e., the still hot rotor had not been turned until cool-down, resulting in rotor bend. This is believed to have caused the tip rubbing and airfoil break-off during the next engine start.