Patent ID: H0002127

Claim:
A method of detecting corrosion presence intermediate an aircraft workpiece metal substrate and an overlying layer of organic material, said method comprising the steps of: applying a continuing periodic sequence of radiant thermal energy pulses of repetition frequency below ten Hertz to said aircraft workpiece metal substrate and overlying layer of organic material; said radiant thermal energy pulses communicating from an external surface portion of said layer of organic material through said layer of organic material to said aircraft workpiece metal substrate; sensing instantaneous temperature response undulations of said surface portion of said aircraft workpiece overlying layer of organic material in response to said continuing periodic sequence of radiant thermal energy pulses; determining a phase angle of lag between said applied continuing periodic sequence of radiant thermal energy pulses and said instantaneous temperature response undulations of said surface portion of said workpiece overlying layer of organic material; and examining a workpiece map of said determined phase angles of lag for a corrosion presence-related pattern of instantaneous temperature response undulation phase angle variations.