the invention comprises a borescope plug for sealing a borescope inspection port on a turbine engine having a fluid flowpath and multiple casings . the borescope plug comprises a plug body having an interlocking drive interface , a plunger portion positioned for sliding coaxial movement relative to the plug body and spring means engaging both the plug body and the plunger . the spring means presses the plunger towards a fully extended position relative to the plug body . the plunger comprises a fixedly attached tip portion shaped to conform with the fluid flowpath . key means is provided for aligning the tip to conform with the fluid flowpath and the tip is cooled with a cooling airflow .