Reports of Hydromechanical Unit (HMU) failures caused by corrosion and seizure of the delta P valve when operating on TS-1 fuel. Action: Cleaning, inspection, and repair of affected HMUs.
Here is a report summary based on key CFM56-7B operational data and service bulletins: 1.
Specialized borescope inspections for High-Pressure Compressor (HPC) variable stator vanes to prevent rotor-to-stator contact.
Service bulletins under chapter 73 typically cover Engine Fuel and Control.