GE has released SB 72-0347-R00, which relates to a one-time compressor inner diameter inspection for corrosion and variable geometry system functional check.

The release of service bulletin SB 72-0347-R00 addresses shop findings that revealed corrosion in the High-Pressure Compressor (HPC) case boreholes, impacting Stage 4 and Stage 5 of the variable geometry (VG) system on engines that have been operated and parked in saline environments for long periods of time.

This SB is intended to identify possible interface corrosion/obstruction between the compressor case, compressor case bushings, vane spindles, and compressor stator variable vanes. Progressive corrosion in the VG system may lead to a reduced range of motion due to higher friction, resulting in sub-idle stall margin reduction that could lead to hung starts, with higher probability in the second or subsequent starts of the day.

This SB is effective for all CF34-1A/-3A/-3A2 and CF34-3A1/-3B models that entered service prior to July 2024. The SB inspection target is based on engine utilization. GE recommends compliance within 12 months for engines with utilization lower than or equal to 250 hours/year. For engines with utilization higher than 250 hours/year, GE recommends compliance within 24 months. Engines that are not in-service or will be changed or swapped from aircraft should be inspected before further flight.

West Star Aviation can assist with this SB at any of our four full-service facilities (ALN, GJT, CHA, and PCD). This inspection can be performed in-house at our facilities using a borescope and can be easily performed during any scheduled maintenance event.