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Recording monitor for structure faults

  • US 4,106,332 A
  • Filed: 04/04/1977
  • Issued: 08/15/1978
  • Est. Priority Date: 04/04/1977
  • Status: Expired due to Term
First Claim
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1. A crack detection system for aircraft structure having a normally conductive test circuit affixed to said structure and subject to being temporarily rendered noncontinuous under stress and to regaining continuity when stresses are removed which comprises:

  • (a) an oscillator for periodically applying a search pulses to said test circuit and including a visual indicator energized by current flow due to each pulse,(b) latch means connected to said test circuit and responsive to high voltage levels for setting a circuit condition therein, and(c) test means for utilizing said condition for actuating said oscillator to energize said indicator in a first sense responsive to said condition and in a second sense when said condition is nonexistent.

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