fig1 illustrates a general perspective view of a diagnostic system 10 which determines the type of defect present in a core composite sandwich structure . the system 10 includes a hand - held diagnostic tool 12 which includes a housing 14 and a handle 16 . the tool 12 is powered by a vacuum source 18 ( illustrated schematically ) which communicates with the tool 12 through a flow control manifold 20 ( illustrated schematically ) which is operated by a controller 22 . preferably , the vacuum source 18 is available from common sources such as a typical shop vacuum or the like . the controller 22 is preferably a conventional laptop or desktop computer running software to collect and record data for instantaneous and later analysis . it should be understood that the components may alternatively or additionally be integrated into a single device . referring to fig2 , the tool 12 includes a seal assembly 24 and an attachment 26 . the seal assembly 24 includes an inner seal 28 and an outer seal 30 . the attachment 26 is located within the inner seal 28 and is preferably attached through a vacuum - assist . the attachment 26 is movable along axis a in response to a vacuum cylinder 32 which drives the vacuum assisted attachment 26 relative to the seal assembly 24 . it should be understood that attachment devices other than vacuum - assist will also benefit from the present invention . referring to fig3 , the attachment 26 preferably includes a vacuum - assisted suction cup 34 mounted to a hollow shaft 36 . the vacuum cylinder 32 includes a piston 38 which is connected to the shaft 36 to drive the vacuum assisted attachment 26 along the axis a in response to a suction applied to a selected side of the piston 38 within the vacuum cylinder 32 . the vacuum source 18 communicates through the flow control manifold 20 with the tool 12 through a tension vacuum port 40 in communication with the vacuum cylinder 32 on a first side of the piston 38 and a compression vacuum port 42 in communication with the vacuum cylinder 32 on a second side of the piston 38 , an attachment vacuum port 44 in communication with the suction cup 34 through the hollow shaft 36 , and a seal assembly vacuum port 46 ( also illustrated in fig2 ) in communication with a volume v between the inner seal 28 and the outer seal 30 . sensor 48 such as a linear variable differential transformer ( lvdt ) is preferably located adjacent the shaft 36 to measure linear displacement thereof . the sensor 48 communicates displacement to the controller 22 for recordation and analysis . it should be understood that other sensors and / or positions will also benefit from the present invention . a method for utilizing the system 10 to detect a defect in a honeycomb core composite structure c such as a rotor blade will now be described . however , it should be realized that the use of a honeycomb core structure is for illustrative purposes only , and that the methodology of the present invention may be applied to other core composite structures . referring to fig4 a , a core composite structure c includes a honeycomb core h and a skin s applied thereto . here , the core h is damaged at location d . although the general location of the defect d is known through conventional inspection methods , the type of defect would heretofore be unknown without cutting through the skin s . referring to fig4 b , the tool 12 is secured to the structure c through application of a vacuum in the volume v between the seals 28 , 30 of the seal assembly 24 through the seal assembly vacuum port 46 which affixes the tool 12 thereto . the suction cup 34 is also secured to the structure c by application of a vacuum to the attachment vacuum port 44 . the area of the suction cup 34 is preferably 1 sq . in ., which will allow a tension load of 14 . 7 lbs to be applied to the structure . loads greater than this may be damaging to a non - discrepant core structure . the larger area between the two seals 28 , 30 will allow compressive loads of higher value to be applied to the structure , without the tool 12 breaking free of the surface . the core h is typically capable of carrying higher loads in the compressive direction . once the tool 12 is secured to the structure c , a vacuum is applied to the compression vacuum port 42 , such that the suction cup 34 is driven toward the core h ( schematically illustrated by arrow x ). it should be understood that the displacement is exaggerated for disclosure purposes . the sensor 48 measures the displacement and the controller 22 relates the displacement to the load ( fig5 ). a reduced stiffness in the compression direction implies that the core h is crushed . that is , the reduction is as compared to an undamaged section of the structure c . data from undamaged sections are preferably previously sampled and stored as a baseline ( fig5 ) for later comparison . referring to fig4 c , vacuum is applied to the tension vacuum port 40 , such that the suction cup 34 and attached skin s is retracted away from the core h , such that the skin s is pulled . the sensor 48 measures the displacement and the controller 22 relates the displacement to the load ( fig5 ). reduced stiffness in the tension direction , followed by non - discrepant linear stiffness behavior confirms core crushing and no skin - to - core disbond . that is , the suction cup 34 essentially pulls the crush d out of the core h such that the honeycomb in the damaged area is straightened and then the tension is resisted by the core h as the skin s is properly bonded thereto . referring to fig4 d , the sensor 48 continues to measures displacement and the controller 22 relates the displacement to the load ( fig5 ) such that a reduced stiffness in the tension direction ( without “ step - wise ” behavior of fig4 c ) implies that a skin - to - core bond failure . that is , the suction cup 34 pulls the skin away from the core h as the skin is not properly bonded thereto . this behavior is generally linear ( with reduced stiffness ) without the step - wise behavior . although particular step sequences are shown , described , and claimed , it should be understood that steps may be performed in any order , separated or combined unless otherwise indicated and will still benefit from the present invention . the foregoing description is exemplary rather than defined by the limitations within . many modifications and variations of the present invention are possible in light of the above teachings . the preferred embodiments of this invention have been disclosed , however , one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention . it is , therefore , to be understood that within the scope of the appended claims , the invention may be practiced otherwise than as specifically described . for that reason the following claims should be studied to determine the true scope and content of this invention .