Helicopter blade crack indicator
First Claim
1. A system for indicating cracks in a hollow aircraft blade, wherein a pressure differential is maintained within the blade with respect to the ambient atmosphere, including in combination:
- a pressure sensor adapted for mounting on the blade in communication with the interior of the blade,said sensor including a member movable between a first position for a higher pressure differential and a second position for a lower pressure differential;
a radiation source mounted on said member;
a radiation shield positioned adjacent said member and having a radiation window, with said source disposed for radiation transmission through said window when said member is in said second position;
a radiation detector adapted for mounting on a non-rotating portion of the aircraft for receiving radiation from said source through said window; and
circuit means having the output of said detector as an input and providing an output varying as a function of the position of said member.
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Accused Products
Abstract
Method and apparatus for continuously detecting cracks in aircraft blades while in flight. A hollow blade is sealed with a pressure differential, either above or below atmospheric. A reduction in the pressure differential such as results from cracks, is detected by a pressure sensor having a member which moves between a high pressure differential position and a low pressure differential position. A radiation source, typically a beta source, is carried on the member and moves from a shielded position to an unshielded position when the pressure differential drops. A radiation detector is mounted on a fixed portion of the aircraft and detects radiation from the source when the member moves to the unshielded position. The detector output may be used to operate a go-no go indicator providing a warning signal when the pressure differential falls below a predetermined value, or to operate an analog indicator providing an output varying as a function of the pressure differential.
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Citations
16 Claims
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1. A system for indicating cracks in a hollow aircraft blade, wherein a pressure differential is maintained within the blade with respect to the ambient atmosphere, including in combination:
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a pressure sensor adapted for mounting on the blade in communication with the interior of the blade, said sensor including a member movable between a first position for a higher pressure differential and a second position for a lower pressure differential; a radiation source mounted on said member; a radiation shield positioned adjacent said member and having a radiation window, with said source disposed for radiation transmission through said window when said member is in said second position; a radiation detector adapted for mounting on a non-rotating portion of the aircraft for receiving radiation from said source through said window; and circuit means having the output of said detector as an input and providing an output varying as a function of the position of said member. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of continuously indicating the condition of a hollow aircraft blade while in flight, including the steps of:
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sealing the blade with a pressure differential therein with respect to the ambient atmosphere; detecting a reduction in the pressure differential; moving a radiation source on the blade between a shielded position for a higher pressure differential and an unshielded position for a lower pressure differential; detecting radiation from the blade at a fixed location on the aircraft; and providing a warning signal when the detected radiation increases. - View Dependent Claims (13, 14, 15, 16)
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Specification