Design and Construction
Chapter 2
Introduction
It is important for the aspiring rigger to understand basic
design parameters and construction techniques of modern
parachute systems. The master rigger must have a thorough
understanding of these areas to perform any desired or
necessary alterations. An understanding of how the systems
or components were originally designed, and why they were
constructed as they were, is essential. Any proposed alteration
may degrade the function and/or structural integrity of the
assembly or component thereby causing it to fail.
Canopy
Suspension lines
Slider
Steering lines
Figure 2-1. Component parts of a ram-air parachute.
Parachute Design and Construction
The design parameters for certificated parachutes are set
forth in Federal Aviation Administration (FAA) documents,
specifically within the Technical Standard Order (TSO)
system. Parachute certification standards fall within the
TSO C23 series. Currently, there are three TSO documents
under which parachutes are manufactured: C23b, C23c,
and C23d. Appendix A of this handbook explains these
standards in detail. Military parachutes are manufactured
and certified under a military drawing system; however,
some manufacturers have certified them under the TSO
system as well.
Advisory Circular (AC) 105-2D, Sport Parachuting explains
that a parachute assembly normally, but not exclusively,
consists of the following major components: a canopy, a
deployment device, a pilot chute and/or drogue, risers, a
stowage container, a harness, and an actuation device (ripcord).
Component Parts
Parachute assemblies and component parts are identified in
the following discussion. The appropriate nomenclatures, as
well as the commonly accepted names, are defined below.
Main Parachute Canopy
The main parachute canopy is used in conjunction with a
reserve parachute assembly as the primary parachute canopy
for a premeditated jump. The main canopy consists of
everything from the main riser connector links to the bridle
attachment point (excluding the steering toggles). The major
parts are the suspension lines and the canopy. [Figure 2-1]
Reserve Parachute Canopy
The reserve parachute canopy is worn in conjunction with
a main parachute used for premeditated jumps. The reserve
parachute consists of everything from the reserve riser
connector links to the bridle attachment point (excluding the
steering toggles). The major parts are the canopy, suspension
lines, and any type of deployment device that is sewn to the
canopy or lines.
Emergency Parachute Canopy
The emergency parachute canopy is worn for emergency,
unpremeditated use only. The canopy may be identical to
the reserve parachute canopy.
Harness/Container
The harness and container assembly includes all the
remaining parts necessary to complete an airworthy
parachute system except for the canopies. The basic harness/
container assembly is what remains when all items that can
be removed without unstitching have been removed. Most
sport parachute assemblies have the harness and containers
integrated into one assembly, but many military assemblies
may be disassembled into separate harness and container
subassemblies. The following items are subcomponents of
the harness/container assembly and are shown in Figure 2-2.
Pilot Chutes and Bridles for the Main and Reserve
Parachutes
The pilot chute is a small parachute or similar device that
enters the airstream when released to act as a drag device and
withdraw the canopy from the container. As such, it maintains
tension on the canopy and lines during the deployment
process, except for reserve “Free Bags.” Pilot chutes are
either spring-loaded or manually thrown into the airstream as
a “hand deployed” pilot chute. Some military or emergency
pilot chutes are ballistically deployed. A bridle is a piece
of line or webbing that connects the canopy or deployment
device to the pilot chute.
Chest strap
Horizontal back strap Upper leg strap
Hip ring
Lower main lift web
Upper main lift web
Harness 3-ring
Reserve parachute
Container
Main parachute
Reserve deployment bag
Main risers and toggles
Reserve pilot
chute
Main deployment bag Main pilot chute
and bridle
RSL lanyard
3-ring release
handle
Reserve ripcord
Figure 2-2. Subcomponents of the harness/container assembly.
Figure 2-3. Lolon cable is yellow. Teflon cable is red or orange.
Ripcords or Equivalent Devices for the Main and
Reserve Parachutes
The ripcord is a device for securing the container closed
prior to use. It usually consists of a handle, a flexible cable,
one or more pins, and a device for securing the cable to the
handle. Some ripcords use a stiffened cable instead of a pin.
Similar to the ripcord is the main riser retain/release cable/
handle assembly if the parachute is equipped with a main
riser release system, such as the 3-ring release.
Deployment Devices for the Main and Reserve
Parachutes
Deployment devices are designed to provide an orderly
and controlled deployment of the parachute during use.
Typical devices include bags, sleeves, pockets, straps,
diapers, and sliders.
Main Parachute Release Mechanism and
Associated Handles or Static Lines
The main parachute release mechanism has two parts. One
part is attached to the harness and the other to the risers.
Typically such devices are the 3-ring release or Capewell
releases. These types may utilize a separate release handle
to provide release of both sides with one motion. This cable/
handle assembly consists of a cable to each riser and a
velcro-mounted handle. The cables must be kept lubricated
to function properly. There are several types of cable coatings
used by various manufacturers. Nylon coating, which is
hydroscopic, includes the yellow (Lolon) coated cables and
the clear coated cables. This type of cable should be oiled
frequently as climate conditions dictate. When you pull the
cable between your fingers, if it squeaks like clean hair, then it
needs to be lubricated. The Red or (new) orange-coated cable
is pure FEP Teflon coating and requires no maintenance.
Typically when the cable is removed from its housing, it has
black oil in spots along the cable. This black oil is the residue
of the cutting oil used in the manufacture of the housings. It
is not harmful. In fact, if this black oil is distributed evenly
along the cable, it provides limited lubrication. There is no
need to worry about sand or dirt being attracted to the oil on
the cable as it is more important for the cable to be lubricated
than it is to be clean. [Figure 2-3] The reserve may employ
a static line (RSL) that is activated upon cutaway. This is
covered in greater detail later in the chapter.
Risers and Associated Steering Toggles
Risers are part of the suspension system between the lines and
the harness or load. Generally made of webbing, emergency
parachutes usually have the risers integral to the harness. If
they are detachable and not integral and are being used for
an emergency parachute, they require a cross connector, as
they are tested with only one side connected. Main risers used
on sport or military systems used for intentional jumping
have release mechanisms installed. Steering toggles are
usually design specific to the riser for the type of canopy
installed. Ram air canopies use the steering toggle to lock
the deployment brake. Pulling on the toggle after opening
releases the brake. Premature brake release is a major cause
of malfunctions. [Figure 2-4]
TSO Documents
TSO number C23b C23c C23d
Performance standard
Effective dates
Performance specifications
Placard limitations
Number of drop tests
NAS-804
Low speed 3000 lb
Standard category 5000 lb
Low speed 3000 lb
Standard category 5000 lb
AS-8015a
Category A Weight: 300 lb
Speed: 150 knots
Category B Weight: 300 lb
Speed: 175 knots
Category C Weight: 300 lb
Speed: 230 knots
Category A Weight: 198 lb
Speed: 130 knots
Category B Weight: 254 lb
Speed: 150 knots
Category C Weight: 254 lb
Speed: 175 knots
AS-8015b
1994-Present
Variable-
Maximum operating weight x 1.2
Maximum operating weight x 1.2
Placard with average peak force
measured during the strength
drop.
28 68 68
Figure 2-4. Toggle through brake eye and stowed.
Figure 2-5. TSO comparisons.
Aerospace Standard AS-8015. When the TSO was revised
again in 1994, the revised document became AS-8015b with
the original as AS-8015a. Figure 2-5 is a table showing the
pertinent points of each of the TSO certifications. For a more
thorough study of the documents, refer to Appendix B.
The TSO system consists of two parts. The first is the
performance standards listed above. This ensures that the
parachute performs as specified. The second is the production
approval, which ensures that the manufacturer is able to
produce the parachute as designed and tested. While minor
design changes are allowed, any major design change must
be submitted to the FAA for approval before implementation.
A major change is anything that affects the airworthiness of
the system of the parachute.
For the aspiring rigger, the primary purpose of knowing the
TSO system is determining the compatibility of components
when assembling the parachute system. This is necessary
in order to ensure that, besides fitting together properly,
the performance standards are compatible. Under Advisory
Circular (AC) 105-2, Sport Parachute Jumping, “the assembly
or mating of separately approved components may be made
by a certificated and appropriately rated parachute rigger
or parachute loft in accordance with the manufacturer’s
instructions and without further authorization by the
manufacturer or the FAA.” Under these guidelines, there are
certain parameters that must be met. One of them is to ensure
that “the strength of the harness must always be equal to or
greater than the maximum force generated by the canopy
during the certification tests.” Full knowledge of the TSO
documents ensures that the above requirements are met.
Other Harness/Container Assembly Components
Other components designed to function as part of the harness/
container assembly, such as closing loops, also may be used.
Closing loops used with automatic activation devices (AADs)
on reserve or emergency parachutes are usually design
specific to ensure proper operation of the system.
TSO Standards
The original TSO C23b for parachutes came into existence
in 1949. The specifications were revised in 1984 to C23c
and again in 1994 to C23d. The TSO is a simple two-page
document that specifies the requirements for certification.
This document also references a performance standard that
the parachute must meet. C23b parachutes were tested to
standards under National Aircraft Standards Specifications
NAS-804. When the TSO was revised in 1984, the
specification document was drafted under the auspices of the
Society of Automotive Engineers (SAE) S-17 committee as