Four Winds PPG Glider Shop
Have you recently finished first in the "Who Can Land in the Biggest Tree” competition? Has your wing functioned as a Mouse Motel 6 during the winter and the critters have been treating your wing as if it were an all you can eat buffet? Does your inflated wing look like a lopsided banana? Or perhaps, having glanced at the manual that came with your wing, you have decided to follow the manufacturer's recommendations for a change and get your wing inspected. Wing inspections are a good idea on many levels. The first being that it could prevent a failure and save your life. Secondly, if you weren’t convinced that the first was enough, is that having a successful inspection can make your wing worth more when you go to sell it on those Facebook pages.
My name is Shannon Michaels and I own and operate Four Winds PPG Glider Shop. I trained with Elisabeth Guerin of Paratour for many months, learning the ropes, before she handed over the baton to me. I now do Annual Inspections, Lines and small repairs. My shop has been outfitted with the tools and gear needed to perform inspections and repairs. A wing hanger is suspended from the ceiling allowing a wing's canopy to be pulled-up and hung vertically to facilitate the inspection process. A large grid hangar allows for complete line inspection of every line and attachment points. Around the sides of the shop are sewing machines of different types, set up on their own worktables. Spools of colorful line stock, in every color and size I can get my hands on, are on shelves, in an organized and functional fashion.
The inspection process starts off with a detailed porosity check. It is used to measure the amount of air that can pass directly through the fabric, disrupting the ideal airflow for a paraglider wing. Using a device called a porosimeter, a section of fabric, usually from near the leading edge, is placed over a cylinder and sealed. A weight draws down on a diaphragm and records its ability to pull air through the fabric providing a score of 0 to 1,000. The findings are compared to manufacturer’s specification listed on charts kept on file. If findings are less than optimal, additional tests are performed on other sites along the canopy. Poor results on the porosity test may be indicative of improper storage technique, age/use, or the quality of the fabric used by the manufacturer.
Pilots that notice that their wing is difficult to inflate or has changed in performance may mean poor porosity. Three sections are checked, top and bottom, and an average is taken and compared with new fabric. Canopy fabric is made from a material that is designed to stop rips in order to eliminate the possibility that a small hole can enlarge through a stressed fabric and cause a catastrophic failure. To check this safety feature, the fabric is subjected to a "tear resistance" test in order to determine its strength. A small needle, attached to a meter is inserted into the fabric and pulled to a specific tolerance as determined by the manufacturer. Fabric weakened by overexposure to the sun, humidity, mildew or other causes will tear unacceptably.
Next, the wing is hoisted vertically on the hanger, leading edge down and each cell is cleaned out. I then check the top and bottom of the canopy as well as the interior cell walls for wear, holes, tears, separating seams, and loose or broken stitching. Any defects are marked for later repair. The wing is checked for any holes that may need to be patched.
The wing is then hung on the grid, separating each line and checking all along the length for damage. Care is taken to inspect lines for wear or damage at the quick links, where there is a lot of movement. The lines are inspected for wear along the sheath and more importantly, for inner core damage. Running each line through my fingers, I can feel breaks by sensing a sudden thinning of the line's diameter. The line’s length is also checked against line charts supplied by manufacturers. Stretched lines or ones that have shrunk due to being put away wet, exposed to UV rays, exposed to excessive heat or other damaging environmental conditions are replaced. Stretched lines can cause a glider to change its profile and respond to circumstances differently than designed. Brake lines are especially subject to wear and tear and are carefully inspected, and replaced if needed. Brake lines are changed out automatically after the wing is two years old. In order to check the strength of the lines, one of the "A" lines, an intermediate and a top line are taken off the glider and pulled until they fail. A meter on a special device designed for this purpose provides data on the line's strength. The meter reading is compared to manufacture's specifications to determine if the lines need to be replaced.
The wing inspection replaces cracked or worn "O" rings and applies a thread compound to the threads of the quick link to secure the connection before tightening them down. PPG pilots especially need to check these as the vibrations from our motors will loosen these quick links. Each inspection comes with a written report detailing the findings on each of the tests. The report can be used during resale to articulate the glider’s condition. It is the total of all test results that determines the airworthiness of a glider. Customers will be contacted usually by email or text regarding any needed repairs. Digital images will be taken of the damaged portions of the wing needing attention and sent to you with an explanation of the work required along with an estimate.
UV damage caused by pilots leaving wings out in the sun is the most unforgivable. For every minute the wing sits in the sun, that’s one less minute the wing will be flyable. Your wing will fade quickly and the fabric weakens, just like your old patio furniture on the back porch. Try not to put your wing away wet. This promotes mold growth. If you pack it up after a nice, dewy morning flight, loosen your wing bag when you get home and put it in a nice dry area. If you are a beach flyer or fly in a particularly dirty area, clean your wing out occasionally. Dirt and debris in the cells rub against the fabric causing unnecessary wear. New wings should be inspected every year or after 100 hours of use. With proper care and regular inspections to check on the wing’s condition, it should last 400 hours but individual results vary. 400 hours is a long time if your wing is properly cared for. Manufacturer’s materials used in the wing’s construction and a pilot’s flying style obviously contribute to the life span of a wing.