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The Next Step for AAD Cutters

Published by PLI on

The Next Step

 It seems to me that any cutter, which has the potential to close a door and trap, the all-important retaining loop would fail to meet the requirement of “Must not interfere with the normal operation of”.

 When CYPRES first was being introduced Helmut Cloth came to me and requested I redesign the reserve closing loop to his specification, which was to allow it to float in a channel over the pilot chute. I refused because of a near tragic occurrence on a misrigged system. His reasoning was because of a known failure rate of the cutter. I felt that was his problem and was not going to compromise my design not realizing that the failure mode to which he was referring might “interfere with the normal operation of”. I changed the loop material to his requested specification because he told me the Kevlar I was using would shred and not cut cleanly. He assured me that his material would always cut cleanly. Well now it allegedly has not and I wonder if we (the industry), haven’t made a mistake in approving any guillotine cutter which does not fully open again after firing. This would be a simple matter to accomplish with of a small reactive charge in the end cap to drive the cutter piston back into the cylinder, when struck, at the end of the cut cycle, leaving an open hole and never trapping the loop.

 Failing the deployment into the field of a “Fail-Safe” cutter I don’t see how any of us can continue to believe that the current AAD cutter design does not potentially “interfere with the normal operation of”.

 My recommended course of action is to require all the AAD manufacturers to design and develop a “Fail-Safe” cutter, which would be open at the completion of the cycle. This could be coordinated through The PIA Technical Committee. The Committee should poll the AAD manufacturers (whether they are members or not, local or foreign) for estimates of development and delivery time. In consultation with the AAD and Harness & Container manufacturers, establish a date for the beginning of transition, and the completion of transition, after which the old cutters may not be used. The “beginning of transition” means all new sales would be so equipped and field replacement begins. This course would continue to allow the use of the current design, as the potential for failure is statistically low, and less injurious than the grounding of all AAD’s.

 I understand that the cutter industry, which supplies all of the AAD makers, already has designs for “Returnable Pistons”. Somebody is going to make a lot of money selling replacements.

 John

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