Tiedown and Securing
Anytime the glider is left unattended, it should be tied down with the canopy closed and latched. When selecting a tiedown location, choose a spot that faces into the wind if possible. Permanent tiedowns are often equipped with straps, ropes, or chains for the wings and tail. Having the proper tie down kit is recommended for a cross-country trip. Check tiedown conditions before using to ensure the safety of the glider. When tying down on airports shared by powered aircraft, propeller wash can cause damage to an improperly secured glider.
If strong winds are expected, tie the spoilers open with seat belts, or place a padded stand under the tail to reduce the angle of attack of the wings. This reduces the pull of the glider against the tiedowns. When securing the glider outside for an extended period of time, install gust locks on the control surfaces to prevent them from banging against their stops in the wind. Cover the pitot tube and the total energy probe to prevent spiders, wasps, and other insects or debris from getting inside. [Figure 6-4]
Always use a cover to protect the glider canopy. It can be damaged by blowing dust and sand or scratched by apparel, such as watches or belt buckles. A cover protects the canopy from damage while shielding the interior of the cockpit from ultraviolet (UV) rays. [Figure 6-5]
When transporting a glider or parking the glider for long periods of time, especially overnight the water ballast should be emptied due to the danger of freezing. This is usually done while in flight before landing. When de-rigging, the water ballast tanks will empty themselves through the wing root connecting pipes. If the glider has to be towed for a long way it is best to empty the water tanks. If that is not an option, ensure that antifreeze is added to prevent freezing when traveling in cold temperatures.
Moving a glider on the ground requires special handling procedures, especially during high winds. Normally, gliders are pushed or pulled by hand or towed with a vehicle. When moving a glider, ensure that all appropriate personnel have been briefed on procedures and signals.
When using a vehicle to tow a glider, use a towline that is more than half the wingspan of the glider. If one wingtip stops moving for any reason, this towline length prevents the glider from pivoting and striking the tow vehicle with the opposite wingtip. Full wingspan length is desirable; however, half the wingspan plus 10 feet provides safe operation. Ensure that the glider canopy is always closed if no one is around the glider. This prevents the wind, or turbulence from a taxiing towplane, to cause the canopy to close abruptly, which could damage the canopy frame or even crack the canopy glass.
When starting, slowly take up slack in the line with the vehicle to prevent sudden jerking of the glider. The towing speed should be no faster than a brisk walk. When towing a glider, always use at least one wing walker. The wing walker and the driver of the tow vehicle function as a team, alert for obstacles, wind, and any other factor that may affect the safety of the glider. The driver should always stay alert for any signals from the wing walkers. [Figure 6-6]
If it is necessary to move the glider during high winds, use two or more crewmembers placed at the wingtips and tail. Also, have a pilot in the cockpit, with the spoilers deployed, holding the controls appropriately to reduce lift on the glider. Strong winds and gusts can cause damage to the glider during ground handling, so exercise care during these conditions.
Another method of towing uses specially designed towing gear similar to a trailer tow bar that attaches directly to a vehicle towing a trailer. The tow bar makes guiding the glider much easier and allows the wing walkers to concentrate on ensuring wingtip clearances. [Figure 6-7]
Launch Equipment Inspection
Prior to making a flight, it is important to inspect the condition of the towline/towrope. The glider pilot is primarily responsible for inspection and selection of the proper towrope. However, the tow pilot has a responsibility to ensure that the towrope selection meets the criteria stated in 14 CFR part 91 and is acceptable for use. This inspection is the responsibility of the tow pilot. The towline should be free from excess wear; all strands should be intact, and the line should be free from knots. Towropes should be inspected prior to every flight. Consideration should be given in replacing the towrope after a period of time due to usage and ultraviolet (UV) exposure from being in the sun and exposed to the elements. [Figure 6-8] 14 CFR part 91, section 91.309, requires that the strength of the towline be within a range of 80 to 200 percent of the maximum certificated weight of the glider. If the towrope is more than twice the maximum strength, a safety link is required between the tow rope and glider rated at not less than 80 percent of the maximum certified operating weight of the glider but not greater than twice the operating weight. Also, a safety link must be installed between the towing aircraft and towrope with breaking strength greater than the glider safety link, but no more than 25 percent greater, and not greater than twice the maximum certificated weight of the glider. Figure 6-9 shows the strength of some ropes typically used.
A knot in the towline reduces its strength by up to 50 percent, and causes a high spot in the rope that is more susceptible to wear. Pay particular attention to the ring area to which the glider attaches because this is also a high-wear area.
The safety link is constructed of towline with a towring on one end and the other end spliced into a loop. The weak link at the glider attach end of the towline must be 80 to 200 percent of the maximum certificated operating weight of the glider. The safety link at the towplane attach end must be of greater strength than the safety link at the glider attach end of the towline, but not more than 25 percent greater, nor greater than 200 percent of the maximum certificated weight of the glider. Towlines and weak links are assembled using a towring that is appropriate for the operation. Lightweight balls are attached to the towline to help protect the towline, prevent line rash, and prevents the line from whipping. [Figure 6-10]
The tow hooks on both the glider and the towplane need to be inspected. The two most common types of tow hook are an over-the-top design, such as a Schweizer hook, or a grasping style, such as a Tost hook. Any tow hook must be freely operating, and free from damage. [Figures 6-11 and 6-12]
Glider Preflight Inspection
A thorough inspection of the glider should be accomplished before launch. A preflight checklist for a glider should be in the GFM/POH. If not, develop a checklist using the guidelines contained in Figure 6-13.
Adjustments to the pilot or passenger seats, as well as adjustable controls, such as rudder pedals, should be made prior to buckling the seat belt and shoulder harness. Caution should be exercised to avoid crimping or clamping the oxygen supply. At this point, especially if the glider has just been assembled, it is appropriate to do a positive control check with the help of one crewmember. While the pilot moves the control stick, the crewmember alternately holds each aileron and the elevator to provide resistance. This also applies to the spoilers and flaps, and ensures the control connections are correct and secure. If the stick moves freely while the control surfaces are being restricted, the connections are not secure, and the glider is not airworthy. [Figure 6-14]
If the GFM/POH does not provide a specific prelaunch checklist, then some good generic checklists are CB SWIFT CBE and ABCCCDD, which are explained in Figure 6-15. Regardless of which checklist you elect to use, have a plan. Stay with that checklist and ensure that each step is being carefully followed.