Through-transmission ultrasonic inspection system and testing methods

Methods and systems are provided for protecting an acoustic liner having a perforated facesheet from water leakage during a through-transmission ultrasonic (TTU) inspection using an ultrasonic squirter system. The testing method utilizes a repositionable mask that covers the openings in the perforated facesheet. The repositionable mask utilizes a pressure sensitive adhesive that adheres to the surface of the perforated facesheet. The repositionable mask can be removed after completing a TTU inspection and can be reused for subsequent TTU tests with minimal adverse effects on the mask or on the facesheet. For ease in handling, the repositionable mask may be configured with a semi-rigid backing carrier.