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Parachute and Harness Care by Rob Kells |
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Attend a Parachute Seminar!
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Contents
- Attend A Parachute Seminar!
- Parachute Deployment Sequence
- Equipment Selection and Care
- Harnesses
- Carabiners
- Ultraviolet Deterioration
- Bridles
- Canopy Design
- Deployment Bags
- Pin Locks
- Ballistic And Manually Deployed Parachutes
- New Harness Initial Inspection / Preflight
- General Harness Care
- Preflight Inspection Before Each Flight
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Attend A Parachute
Seminar!
The following article is taken from an outline we use to do parachute
seminars. It is written with the hope that you will take this information and put it
to use in your flying, to increase your flight safety. This is not about how to repack
your parachute. We suggest that you leave the packing to someone who does it often.
Over the last fifteen years we have done 40 parachute seminars, and repacked more than
fifteen hundred parachutes
Over 50% of the systems in the early seminars were improperly maintained and 10% of these
parachutes would not have deployed under any circumstance! These statistics have improved
dramatically over the years as pilots come back to service their equipment year after
year.
If you have not attended a formal parachute seminar we suggest that you do so immediately.
Aviation has made the world much smaller but it is still
hard to miss it if you fall! |
When To Throw Your Reserve
You only want to use your reserve when you are in an emergency situation.
After a mid-air collision, or in flight medical emergency are two good examples. A number
of good pilots have waited too long trying to fix the problem and ran out of altitude to get
a successful deployment. NASA test pilot Mark Stucky puts an imaginary 200 foot bubble around
himself when paragliding. If anything happens to his paraglider within that bubble he will
deploy immediately. He has practiced visualizing every possible emergency he can think of,
and has contingencies thought out ahead of time for each one. Good advice. |
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Parachute Deployment Sequence, Parachute System Care
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Parachute Deployment Sequence
LOOK-GRASP-PULL-LOOK-THROW-PULL
LOOK for the handle, GRASP
the handle, PULL the deployment bag from the container (with most
systems a down-and-out at about 45 degrees works best), LOOK for
clear air, THROW towards clear air and with the direction of the
spin, PULL the bridle (reach back to your main support strap to
locate it) to clear the 'chute from the deployment bag and accelerate the deployment sequence.
If the parachute does not open, pull it back and repeat the throw. After you are under canopy,
stand in the control bar (if you can find it), or climb to the highest point in the glider.
Let the structure of the glider take as much of the landing impact as possible. Sometimes,
it is possible to direct the descent with weight shift. Try to steer away from ground obstacles
and land into the wind. In a paraglider after the deployment you want to try to fly the glider
up to meet the reserve, or if you are unable to do that, do a B-line stall to avoid downplaning.
If your glider is falling at 60 miles per hour, (88 feet per second),
three seconds is 264 feet; if you take ten seconds the distance will be 880 feet. Also, when
a glider structurally fails, it often spins at such a high rate that the pilot is unable to
maintain any visual reference with either the terrain or the broken structure. The successful
execution of the deployment sequence under adverse conditions will depend on your level of
preparation. Do not practice in air deployments! They can be very dangerous.
There is no substitute for repeatedly practicing this procedure
in a simulator. Further, you should grasp the handle and mentally rehearse the
deployment sequence while flying. During parachute seminars, we time practice deployments
in a simulator. Deployment times range from three to ten seconds.
The deployment times have gotten faster over the years of repeated
seminars through practice.
Equipment Selection and Care
This information should not be used as a guide for repacking
parachutes. Regular repacking should be performed by someone who is both experienced and professionally
trained and qualified.
Your parachute is only one part of your safety system. As with any
system, reliability is only as good as the weakest link.
Harnesses
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If you are interested in a technical reference
on conventional skydiving equipment and parachutes, we recommend
The Parachute Manual
by Dan Poynter,
available from
Parachuting Publications
P.O. Box 4232
Santa Barbara, CA 93103 |
All properly built harnesses are strong enough to withstand the opening shock
of a normal parachute deployment if they are properly maintained. Most harnesses are not designed
to withstand the opening shock of a hang glider reserve from terminal free fall velocity.
To withstand higher loads and adverse loading conditionslike head downthe shoulder
straps, leg loops and back strap should be joined by a primary structural reinforcement to
the main support straps.
Carabiners
Several years ago a pilot's aluminum carabiner failed while he was
hooking in for flight! Aluminum Carabiners are typically rated at 1800 to 2800 kilos (4,000
to 6,000 pounds) ultimate strength when new, but are susceptible to fatigue from nicks and
scratches. Most steel Carabiners are rated at about 5000 kilos (11,000 lbs.) and are much
more durable. We do not know of any failures of high quality alloy steel Carabiners, but we
suggest that you replace even a steel carabiner after 3 to 5 years of regular service.
As an extra safety measure, use a quick link to connect your parachute
bridle to your harness main supports straps. If your carabiner failed, you would retain a
secondary link to your parachute. Also, verify that the locking gate of the carabiner faces
forward when hooking into the glider and that the parachute bridle is on the back side of
the carabiner. This procedure will prevent the parachute bridle from opening the carabiner
gate and disconnecting from the harness during deployment. |
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Parachute System Care (cont.)
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Ultraviolet Deterioration
Hang glider harnesses, sails, and parachutes are constructed primarily of
nylon, polyester, Kevlar and/or Spectra. All of these materials deteriorate with exposure
to sunlight. Sunlight is by far the greatest factor in the decay and depreciation of your
equipment. The rate of deterioration depends on many factors: the type of material, the finish
or coating applied to the yarn fibers, the thickness of the material and of course, the intensity
of the radiation. A lightweight parachute canopy material will typically lose 50% of its strength
after one week of continuous exposure to sunlight. Fluorescent pigments fade as much as ten
times faster than more stable colors such as dark blue or black. UV deteriorated stitching
in webbing support straps and hang loops may fail long before webbing becomes unserviceable.
You can minimize the adverse effects of exposure by not setting up until you are prepared
to fly and stowing your glider and equipment in their protective cover bags promptly after
landing. If you fly regularly, and your equipment sees a lot of UV, have any suspect items
inspected by your dealer or the manufacturer. Hang Glider sails typically have a useful life
of between 250 and 750 hours or more of air time, depending on materials and construction,
if they are properly cared for and maintained. Paragliders, depending on the fabric are good
for roughly half that long.
Bridles
Most older parachutes were constructed with 1 inch tubular nylon bridles.
If properly sewn, these bridles have an ultimate strength of approximately 4,000 lbs., however
there are four documented incidents of successful parachute deployments which subsequently
had a tubular bridle severed by hardware or cables on the glider. Today's standard bridle
is 1 inch flat webbing, usually Type 18 or Type 24 with an ultimate strength of approximately
2800 kilos (6,000 lbs.). This webbing style is much less likely to be cut by hardware. The
minimum bridle length for hang gliders should be 25 feet to reduce the likelihood parachute
entanglement with the glider. Paraglider bridles are typically five feet in length and require
a structural attachment to the harness that will bring the pilot down feet first. Finally,
a protective sheath on the exposed portion of your bridle will reduce wear and tear and UV
deterioration. A sheath is particularly important on Kevlar bridles which are thinner and
lose strength at a much faster rate.
Canopy Design
Standard conical parachutes were the most common configuration used
for hang glider reserves in past years. A variation of the conical configuration is the "Pulled
Down Apex". These designs have a short center
line attached to the apex of the canopy to increase the inflated diameter. PDAs
can be made smaller in weight and bulk without sacrificing decent rate. Since deployment time
is a function of size, PDAs usually open faster. Unfortunately, opening shock
is a function of opening time, so faster opening chutes open harder. When Wills Wing first
tested a PDA design in 1981, the opening load from a deployment at 120 mph with
a 300 lb. dummy failed the skydiving test harness. At lower speeds typical of most hang glider
and paraglider deployments, this shock would be significantly lower, but we recommend that
you do not combine the PDA design with an inelastic Kevlar bridle. A further
concern with PDAs is sensitivity to design and tuning parameters. A rigorous
drop test program is essential for development of a stable, low sink rate, structurally reliable
design. If for example the apex is pulled down too far the canopy will become unstable and
oscillate.
Some very early parachutes were manufactured with only 10 lines compared
to the twenty or more lines on most designs. These early chutes should be either refitted
with 20 lines by a certified parachute shop or replaced with a more air worthy design. Also,
most modern canopies use "vtab" reinforcements at the line / skirt junction and
additional panel reinforcement. Most chutes can be upgraded to this configuration if desired.
Any chute which has been exposed to excessive heat or caustic/acidic liquids should be inspected
by a qualified rigger or the manufacturer. Damaged panels can be repaired or replaced for
a nominal charge.
It is very important to realize that all parachute are not created
equal! Different makes of canopies with the same numbers of gores (panels that make up the
parachute) can vary in sink rate performance by more than fifty percent!
|
Model
|
Area |
Test Weight |
Descent |
| LARA 175 |
283 Sq. Feet |
175 Pounds |
17 F.P.S. |
| LARA 250 |
343 Sq. Feet |
250 Pounds |
17 F.P.S. |
| LARA 400 |
509 Sq. Feet |
400 Pounds |
17 F.P.S. |
| 20 Gore PDA |
238 Sq. Feet |
250 Pounds |
19.5 F.P.S. |
| 22 Gore PDA |
302 Sq. Feet |
350 Pounds |
19.4 F.P.S. |
| 24Gore PDA |
336 Sq. Feet |
450 Pounds |
20.5 F.P.S. |
Free Flight Enterprises has discontinued production of the 18 Gore PDA. We
feel that too many pilots are choosing size based on cost and weight, rather than margin of
safety. Many heavy pilots, flying in adverse conditions, have purchased them for the reasons
cited above. A pilot under 150 pounds body weight is within the recommended weight range of
an 18 gore only at low density altitudes (although there have been many saves with more weight).
Wills Wing and Free Flight have chosen the conservative path and recommend larger reserves.
We have provided a table that will allow you to compare the relative sink rate versus test
weight data. It is usually better to go for a larger rather than smaller parachute. Even though
a smaller one will open slightly faster, you want to have a low enough sink rate to minimize
injury at impact. |
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Parachute System Care (cont.) & General Harness Care
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Deployment Bags
All modern hand deploy systems are packed in a bag or diaper to help clear
the canopy and lines to the perimeter of the glider before the opening sequence initiates.
Most malfunctions that we have observed during practice deployments at parachute seminars
are related to poor deployment bag design and/or lack of maintenance (the rubber bands are
brittle or even broken). If your deployment system relies on rubber bands, they should be
replaced at least once every six months; more often if you live in a hot climate. You must
use the recommended size and type of bands for the bag to function properly. Wills Wing/Free
Flight containers include a separate pocket for protecting and stowing lines, which also reduces
the likelihood of deployment problems normally encountered with poorly maintained deployment
systems.
Pin Locks
An accidental parachute deployment is a very dangerous occurrence. A pin
lock system is the most effective mechanism for preventing an unintentional deployment without
compromising your ability to execute a normal deployment sequence. If you do not have a pin
lock system, have one installed before your next flight. You must use the proper pins, which
are characterized by a curved finger lock and continuous eye assembly. Cotter pins can jam
and effectively make deployment impossible.
Ballistic Deployed Parachutes
Rocket deployed systems offer the best performance and are the only
ballistic systems suitable (and currently marketed) for hang glider pilots. Deployment is
very fast without recoil. Both the rocket and parachute are mounted on the harness. Some configurations
have an optional hand deployment sequence in case of mechanical failure, however this option
may compromise the reliability of the primary deployment system. Rocket systems have many
saves to their credit. Some of these deployments might have been unsuccessful with hand deployments.
Still, there are significant safety concerns beyond those associated with hand deploy systems.
Proper installation and maintenance is more critical to reliable performance. Improperly installed
rocket systems may be impossible to activate, or worse, may injure the pilot or bystanders
within range of the rocket. Many pilots opt for an independent dual parachute systemone
rocket and one hand deploy. A dual system also provides an additional margin of safety in
case of parachute entanglement, at the cost of increased weight and expense.
General Harness Care
After re-packing your parachute, bounce up and down in the
harness to test that the parachute container Velcro and
safety lock system is secure and properly installed. Larger parachutes may require a custom
container. The parachute bridle should be taped or velcroed to the main support strap to stop
it from fluttering in the wind.
Do Not Leave Your Equipment In The Sun. Ultraviolet
light is very harmful to nylon and polyester materials.
Avoid Exposing Your Harness To Extreme Heat.
The bed of a pick-up truck or the trunk of a car may get excessively
hot due to the routing of the exhaust system. Heat is particularly damaging to parachutes.
Keep Your Harness Clean. Acids,
gasoline and other solvents may degrade the structural material in your harness. Do not use
harsh detergent or cleaning agents on your harness. Wash with plain water, using a sponge
or soft brush and a mild detergent applied locally to spots and stains.
Inspect
Your Carabiner. Replace it if it
is nicked, deeply scratched or if the locking gate does not function properly. Do not clip
your carabiner into any glider tether point that does not provide a completely free unrestricted
pivot. Torsion or bending loads will significantly reduce its strength. |
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Preflight Inspection Before Each Flight
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Preflight Inspection Before Each Flight
Perform a complete pre-flight inspection of your harness. Check for
excessive wear. Inspect all knots. Hang check to make sure the lines are properly routed,
your parachute is secure and that your harness is properly clipped into the glider. Make
sure that your legs are in the leg loops. If for any reason you unclip before flight,
take the time to do another hang check.
An important part of new harness orientation is determining the proper
hang height above the control bar base tube. The lower you hang, the more authority you will
have in weight shift control. If you are accustomed to hanging high above the base tube and
you decide to lower your hang position, you may feel a little uncomfortable at first. For
most pilots, the transition takes about 10 hours. Make sure that your parachute doesn't touch
the base tube. Leave at least one inch of clearance to provide for suspension stretch in accelerated
maneuvers.
Practice entry and exit procedures in a simulator, with storage containers
loaded, before your first flight. Familiarize yourself with the emergency egress system which
is usually located adjacent to the zipper, below the parachute container. On most harnesses
a hard lateral pull on the handle will peel open the Velcro in the event of a zipper jam on
landing approach.
Exercise extreme caution when flying over water or landing in a restricted
beach area. If you land in the water, unhook from the glider and hold the carabiner in your
hand to prevent it from hooking a cable. Do not try to get out of the harness until you are
free from the glider. Most harness bodies are padded with closed cell foam which will provide
some flotation.
Most harnesses have a zippered convenience pouch in the bottom
of the parachute container. Do not load this pocket with anything which might interfere with
the parachute. Do not store any sharp object in the front mounted containers which
might be dangerous on a crash landing. During your hang check, verify that items secured to
the side accessory straps, radio and camera mounts, and ballast containers cannot snag on
the glider flying wires. Install a hook knife on an easily accessible area of your harness.
Connect the bridle to the back of the carabiner and tape or Velcro
it in place against the main support. Place a rubber band over the assembly to keep the bridle
in the proper position. Make sure the band is positioned low enough that it doesn't interfere
with the carabiner gate. It is a good idea to use a fabric sheath between the container and
the carabiner to protect the bridle from UV deterioration , otherwise you should replace it
at the same intervals that your mains are replaced.
It is extremely important to do a hang check with your feet extended
as far as possible in the boot of the harness while bouncing up and down to make sure the
parachute is secure in the container. If the Velcro on the container starts opening, and you
have recently had your chute repacked, there may be too much air left in the canopy. Usually
sitting on your parachute and harness for a few minutes will solve this problem. If you are
still having trouble, take your parachute and harness to your dealeryour chute could
be improperly packed, too big for the harness container or have an incompatible deployment
bag.
REMEMBER THAT IT IS IMPORTANT TO BE PROFICIENT AT USING YOUR EMERGENCY
RESERVE AND TO MAINTAIN YOUR EQUIPMENT.
THE SINGLE MOST IMPORTANT DECISION WE CAN MAKE AS PILOTS IS
WHEN NOT TO FLY SO WE NEVER NEED TO USE OUR RESERVE!
Please Fly Safely,
Wills Wing Inc.
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