Figure 6. Through transmission vs. same side (pitch-catch) technique for inspection of delamination between Nomex honeycomb and CFRP skin. catch technique has significant advantages if it can be implemented, but there remain challenges for achieving a high signal to noise ratios in production environments. This technique is being further developed and is expected to be deployed in production QC sometime in 2019. Figure 7. U710x Instrument with Honeycomb part sample provided by Exelis Aerostructures. RESULTS Analysis has been conducted upon large aerostructures for several companies, but specific results are protected by NDA as they are under early implementation. However, for the purpose of demonstration, the following data has been conducted upon equivalent materials, such as aerospace honeycomb panels with carbon and aluminum skins. Honeycomb Panel Analysis with Unfocused (Planar) Transducers Analysis conducted with Ultran U710x non-contact ultrasonic analysis system and NCG200-D25 (200 kHz and 25 mm active diameter) non-contact transducers. Transducer excitation of 375V tone burst negative square wave with 3 cycles. Analog receiver was set 63-75 dB of gain (amplification). From Figure 7 it is seen that the honeycomb part is analyzed in through transmission using the X-Y scanning capability of the U710x system. This is conducted in a benchtop configuration for the purpose of simulation; however, the ultimate application includes sophisticated robotics for large part inspection. In Figure 8, a two-sided thrust tube honeycomb panel sample is analyzed and imaged with planar transducers. Embedded defects are easily noticeable on both sides of the sample, however there is a "smoothing" effect noticed due to the use of relatively large active diameter (25 mm) planar transducers. An advantage of planar transducers is the high signal to noise ratio achieved through w w w. s a m p e . o r g Figure 8. Thrust tube NDI sample imaged with planar transducers. J A N UA R Y/ F E B R UA R Y 2 0 2 0 | SAMPE JOURNAL | 39http://www.sampe.org