WRIGHT-PATTERSON AFB, Ohio --- Aircraft engine inspections are an essential part of maintaining a healthy and reliable fleet. However, the inspection process is often labor-intensive and challenging, and parts are often replaced before their serviceable life is over.
The Air Force Research Laboratory Materials and Manufacturing Directorate is working to change this.
In an effort to improve the turbine engine inspection process, AFRL researchers have recently transitioned the Sonic Infrared (SIR) nondestructive evaluation inspection method for turbine engine airfoils. This system, developed for AFRL by Florida Turbine Technologies, Inc., can replace traditional inspection methods for crack detection, such as Fluorescent Penetrant Inspection (FPI), which can be costly and time-consuming.
Through SIR, ultrasonic waves are used to vibrate the part, creating friction between crack faces. This friction creates a tiny amount of heat, which can then be detected using highly-sensitive infrared cameras, thereby pinpointing the defect.
Researchers embarked upon this effort to answer a need from aircraft maintainers for a reliable, cost-effective, and efficient alternative to FPI for whole-field, engine airfoil inspection.
According to AFRL project engineer Siamack Mazdiyasni, the advantages to SIR inspections are many. Most notably, the increased level of reliability of SIR inspections over FPI means aircraft maintainers can often return engine airfoils to service, rather than replacing them.
The initial target application for this technology is turbine engine compressor blades. Mazdiyasni and AFRL project engineers estimate that keeping these engine components in service can result in at least $5 million in annual savings. Additionally, the reduction in the amount of chemicals purchased, used, and disposed annually adds additional cost saving on top of that figure. SIR inspection also takes less time to complete and has the potential to detect smaller cracks than FPI. SIR saves labor hours and is more environmentally-friendly because it does not require that maintainers clean engine parts with chemicals before inspection.
AFRL recently transitioned this inspection method to the Oklahoma City Air Logistics Complex at Tinker Air Force Base, where the technology will be further refined, qualified, and readied for implementation. The Air Force Life Cycle Management Center has expressed plans to merge the technology into their automated airfoil inspection and repair initiative.
Studying SIR inspection for engine airfoils is only the first step. Mazdiyasni says future plans include investigating the technology for other engine components including coated parts and fracture critical parts.