by Alan Sanderson
There are some balloons that do not get a proper inspection between trips to a repair station for the FAA mandated annual or 100 hour inspection. In many cases, no damage occurs during the flying season, but sometimes the annual inspection finds some serious and expensive problems.
Normal balloon operations result in fabric wear, and sometimes accidental damage caused by passengers, crew, or spectators stepping on the fabric. Sometimes the crew can cause other accidental damage. One common instance of crew damage is a 3-corner fabric tear caused by pulling on the parachute valve while the bridle cords are tangled in the envelope fabric. The fabric becomes caught in the "V" formed by the cords, and opens an 18 inch triangle in one of the panels.
The bridle cord tear is very easy to preventbrief the crew at the top of the envelope on proper valve handling procedures.
1. Do not force anythingif it does not come easily, you will probably damage something.
2. If the valve is not free, just hold the vent opening closed until the envelope spreads enough to free the valve lines.
3. You can usually free the valve line by walking under the envelope during the cold inflation. This allows the envelope to spread out more evenly.
Some of the other accidental damage occurs during hot inflation. Inattention during inflation can cause damage to cables. Most commonly, a cable droops into the path of the flame, and the pilot does not notice until it is too late. Contact with flames can damage all types of suspension cables. The steel cables can lose their temper and become weak and brittle. If you have burned a steel cable, check to see if you can wrap the burned area around a soda can. If it retains the curve around the can, it is no longer airworthy and must be replaced before the next flight. If it remains flexible, you were lucky that time.
Kevlar cables are made of a non-conductive and extremely strong aramid fiber that is also used in tire cords. The Kevlar fibers are normally pale yellow. Excessive heat, moisture, or exposure to ultraviolet light can damage Kevlar. A woven polyester covering protects the Kevlar braid. If the covering is melted enough that it has hardened, or the Kevlar is exposed, the cable probably needs to be replaced. Contact your repair station for confirmation. Some cables with mild damage can be repaired by a repair station in accordance with the manufacturer's maintenance procedures. Do not fly with damaged cables that have not been inspected and approved for return to service.
Major burn damage can be caused by windy inflations, the pilot's carelessness or inattention, or improper design or use of the inflator fan. Frequently, as Murphy's Law (whatever can go wrong, will go wrong at the wrong time) would have it, just as you start to burn, the wind comes up and dishes in the top of the envelope near the throat. In the best case, you bake a little bit of moisture out of the fabric. In the worst case, a few panels of fabric disappear.
You cannot predict the random wind gusts, but you can prevent a lot of the problems. The combination of a solid cold pack and proper tension on the crown line can reduce the amount of deformation the wind can cause around the throat. Position the fan so its air stream completely seals the throat of the balloon. I have measured a 65 mile per hour wind velocity in front of some better designed propellers. That high pressure, along with proper positioning, will prevent a lot of problems.
A reasonable amount of tension on the crown line will pull the upper suspension cables taut, keep the cables out of the flame, and keep the throat open. If suspension cables droop toward the burner, you need a heavier pull on the crown line, more cold pack in the envelope, or both.
Some pilots were taught to turn the fan off before starting to burn. As soon as they turn it off, the cold air they worked so hard to put into the envelope comes rushing back toward them. Add a little wind across the top of the balloon, and the flame can blow back in their face. Balloons that are inflated this way eventually have crisp skirts or scoops, throats, and load tapes. Leave the fan running until the balloon stands up and the air is no longer blowing into the throat.
After the envelope starts to stand up, or as it gets above a 45 degree angle from the ground, stop burning for a while. This will prevent one more type of damage, and assist the crown line person. When a balloon is inflated on cut grass or hay, the inflator fan blows small pieces of debris into the envelope. When the balloon stands up, the debris flutters down past the burner. If you burn while these particles are falling, the flame ignites them and the heat circulates the burning embers to the top of the envelope. The falling embers cause small burn holes in the fabric.
Danger Signs
In addition to the cable damage, rips, and large burns, there are other types of damage that you should look for. Any of the following call for a trip to a repair station for inspection:
1. Melted or glazed load tapes, especially around the throat. This can indicate structural burn damage that could allow the suspension cables to separate from the envelope.
2. Pilot light problems. If your pilot light blows out in any but abnormal conditions, have it checked. It could be a matter of cleaning or adjustment, or a failed pressure regulator. Most of these problems can be fixed inexpensively. Make sure you can still light the main burner with a striker. Try it on the ground first.
3. Hard landing damage. In a hard landing, you may have inflicted some structural damage on some part of the system. A rebound or a sudden stop caused by hitting a solid object can cause enough damage to warrant a complete inspection. If it was hard enough to cause bumps or bruises, it possibly damaged some part of the system. If you tell your repair station what you did, they should know what needs to be checked.
Your life and those of your passengers are on the line. If you see anything you have any reason to question, ask your repair station or the balloon manufacturer about it. Preventing a problem is the best insurance you can get.