Protective Sleeve for a Pyrotechnic Reefing Line

Lyndon B. Johnson Space Center, Houston, Texas

A metallic sleeve provides protection and guidance for the actuating lanyard pull of a parachute system reefing line cutter. This device ensures that the reefing line cutter is not damaged during packing or deployment. In addition, the device ensures that the actuating lanyard that initiates the cutter is pulled within the device’s specification cone angle. Combined, these features increase the durability of the reefing line cutter used in parachute reefing systems, and significantly increases the reliability of the underlying reefing cutter. Protecting such a critical element of the controlled deployment of parachutes significantly improves the operation of the parachute reefing system.

The sleeve is designed as an “add on” component to provide lanyard pull guidance and cutter bending resistance. The end user can procure off-the-shelf hardware with no changes, and then choose to add the cutter sleeve at a later time based on usage and environment. This metallic sleeve is reusable and allows for a decrease in unit cost of the reefing line cutter.

The cutter sleeve provides containment of gases or shrapnel in the event of an unexpected cutter failure/rupture. It also provides a more positive retention location, in the form of a groove around its diameter, for attachment to a parachute through stitching/sewing. Testing of reefing line cutters without the protective sleeve resulted in failures that included broken pull loops and bent cutters. Testing with the protective sleeve resulted in all cutters functioning correctly.

This work was done by James H. McMichael, Hai D. Nguyen, Mark Landeck, and Richard Hagen of Johnson Space Center. MSC-25523-1

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