This month’s Ask a Tech topic comes from a reader who is doing everything right when it comes to buying an early-gen Cirrus SR22. Aside from the normal engine, airframe and avionics evaluations that should be conducted during the prebuy process, an important system to consider from an upkeep standpoint is the CAPS, or Cirrus Airframe Parachute System.
White it’s widely known that the CAPS has a 10-year repack requirement—which includes replacement of the ballistic rocket—there’s also the mandatory replacement of the pyrotechnic line cutters. To see what’s involved, we flew an early-gen SR22 to U.S. Flight Aircraft Maintenance in Danbury, Connecticut—a busy and respected Cirrus service center.
Limited disassembly
Compared to the 10-year repack on a G1 Cirrus—requiring huge amounts of labor because it requires drilling a hole in the fiberglass cover and using a slide hammer to break the bond between the fuselage and the cover—replacing the cutters is easy. You gain access through the rear bulkhead.
The dual-stage line cutters (there are two, which are essentially fuses) sever a snub line that allows the folded aft section of harness to extend to its full length at just the right time after CAPS deployment. The back section of the parachute harness must remain short during the initial stage of deployment to support the airframe’s rotation. Once the initial tension is achieved, the second set of cutters severs the remaining lines and releases the full parachute canopy.
The cutters are pictured below and there are two types—red and gold—depending on the generation (and weight) of the aircraft and the CAPS deployment time.
Hands on
The line cutters replacement took roughly an hour of shop labor, and of course there is paperwork involved. For our first-gen Cirrus, the process is to remove the CAPS handle access cover and install the safety pin. Then remove the rear bulkhead trim panel and carpeting. Once the access panel is removed, there’s easy access to the cutters as shown in the right image at the bottom of the page.
Pulling open the Velcro flaps gains direct access to the two cutters. You then remove the line cutter lanyard from the D-ring and unthread the lanyard that’s routed through the line cutter’s ignition loops. Then cut and remove the nylon cord that secures the line cutters to the link assembly and remove the cutters. To install the new cutters, thread the new nylon cord through the mini-rings and follow the removal steps in reverse.
An important step is tying the CAPS knot by crossing the upper cord end over the lower one twice and cinching the nylon cord tightly. Then tie a standard square knot, cinch it tight and trim the nylon cord to 1.0 inches. Route the line cutter lanyard through the line cutter’s ignition loops and secure the lanyard to the D-ring. It’s easy to see why botching the installation could mean a faulty CAPS deployment—and there have been some. With the cutter kit priced around $1200, you should expect to pay around $1400 for this service.
Our thanks to the folks at U.S. Flight for accommodating the report.