Figure 6-10 shows the strength of some ropes typically used. The rope manufacturer can provide exact specifications.
14 CFR part 91, section 91.309(a)(3), requires tow line strength within a range of 80 to 200 percent of the maximum
certificated weight of the glider. However, the tow line may have a breaking strength more than twice the maximum
certificated operating weight of the glider if using safety links as specified in 14 CFR part 91, section 91.309(a)(3). Note
that a specific model of glider may have a more stringent limitation on the maximum tow line strength. The POH would
list this limitation.
Diameter
3/16"
1/4"
5/16"
Polyethylene
Hollow braid
1,200
1,750
Polypropylene
Monofilament
1,300
1,900
Polypropylene
Multifilament
1,200
2,050
Nylon
1,500
2,400
Dacron
1,150
1,750
Figure 6-10. Typical rope strengths.
If using a tow line with a breaking strength more than twice the maximum certificated operating weight of the glider,
14 CFR part 91, section 91.309(a)(3) requires installation of two safety/weak links, either of which can break before
excess tension on the tow line causes structural damage to either the glider or the tow plane. The weak link near the
glider attachment point [Figure 6-11] requires the same breaking strength range as the tow rope, 80 to 200 percent of the
maximum certificated operating weight of the glider. The weak link installed near the tow plane attachment point must
have a breaking strength greater, but not more than 25 percent greater, than that of the weak link at the glider end of the
tow line and not more than twice the maximum certificated operating weight of the glider. See figure 6-12 for a sample
weak link strength analysis.
Weak link
Figure 6-11. A safety link. The foam added to the tow line prevents tow line abrasion.
Greater, but not more than 25 percent greater than
that of the safety link at the glider end, and not greater
than twice the glider max gross weight (MGW).
RULE
1000 lbs. x 25% = 250 lbs.
1000 lbs. + 250 lbs. = 1250 lbs.
700 lbs. x 2 = 1400 lbs.
700 lbs. MGW
Glider safety link
breaking strength
1,000 lbs.
To meet the rule below, the tow plane safety
link strength requirement must be greater than
1,000 lbs. and not more than 1,250 lbs.
The 1,400 lb. strength requirement is
not relevant since 1,250 lbs. is the maximum
allowed by rule.
Figure 6-12. Safety link strength requirements assuming a 1,000 lb. safety link installed near the glider.
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. Pilots should inspect and verify that any tow hook is free from damage and operates freely. [ Figure 6-13
and Figure 6-14]
Figure 6-13. Schweizer-type tow hook.
Figure 6-14. Tost hook.
Glider Preflight Inspection
Pilots should conduct a thorough inspection of the glider before launch. If the glider GFM/POH does not contain a preflight
checklist, the pilot should develop a checklist using the guidelines contained in Figure 6-15.
Begin by assessing the overall condition of the fiberglass
or fabric.
Be alert for signs of damage or excessive wear.
Ensure that the canopy is clean and free from damage.
Verify the interior wing and control connections are safe and
secure.
If a battery is used, ensure that it is charged and safely
fastened in the proper spot.
Ensure that seat harnesses are free from excessive wear.
Buckle and tighten any harness that will not be used to
prevent it from inadvertently interfering with controls.
Test the tow hook to ensure it is operating correctly.
Inspect top, bottom, and leading edge of wings, ensuring
they are free from excess dirt, bugs, and damage.
Inspect spoilers/dive brakes for mechanical damage. They
should be clear of obstructions. Perform control continuity
check.
Inspect the wingtip and wingtip skid or wheel for general
condition.
Inspect ailerons for freedom of movement, the condition
of hinges and connections, and the condition of the gap
seal. Perform control continuity
check.
Check the condition of flaps for freedom from damage and
for appropriate range of motion. Perform control continuity
check.
Inspect the general condition of the empennage.
Check static ports, pitot tube, and total energy probe to
ensure they are free from obstruction.
Check top, bottom, and leading edge of tailplane for
bugs, dirt, and damage.
Check the landing gear for signs of damage or excessive
wear. The brake pads should be checked if they are visible;
otherwise, the brakes can be checked by pulling the glider
forward and applying the brakes. Note that the landing gear
is frequently a problem area for gliders used in training.
Check elevator and trim tab for condition of connections,
freedom of movement, and condition of gap seal. Perform
control continuity check.
Check rudder freedom of movement and condition of
connections. Perform control continuity check.
Figure 6-15. A glider preflight inspection checklist.
Prelaunch Checklist
The pilot should conduct a positive control check with the help of an additional crewmember, especially if the glider was
just assembled. The pilot moves the control stick and rudder pedals while the crewmember provides resistance, holding
each aileron, the elevator, spoilers, flaps, and the rudder to ensure correct and secure control connections. [ Figure 6-16]
A stick or pedal that moves freely with the corresponding control surfaces restricted indicates the connections are not
secure, and the glider is not airworthy. Pilots should adjust the pilot or passenger seats, as well as adjustable controls, such
as rudder pedals, prior to buckling the seat belt and shoulder harness. Caution should be exercised to avoid crimping or
clamping any onboard oxygen supply.
Figure 6-16. Positive control check of spoilers.
If the GFM/POH does not provide a specific prelaunch checklist, then some good generic checklists are CB SWIFT CBE
and ABBCCCDDE, which are explained in Figure 6-17. Pilots should follow each step carefully regardless of the checklist
used.
Altimeter set to correct elevation
Ballast
Seat belts and shoulder harnesses fastened and tightened
Controls checked for full and free movement
Canopy closed, locked, and checked
Cable or towline properly connected to the correct hook
Dive brakes closed and locked
Direction of wind checked
Emergency Plan reviewed
Phase I:
• Controls (plural)
• Ballast
Phase II:
• Straps (plural)
• Wind
• Instruments (plural)
• Flaps (singular)
• Trim
Phase III:
• Canopy
• Brakes (singular for most gliders, plural for a Blanik, since the
wheel brake is not at the end of the air brake travel)
• Emergency plan (the three phases plus the return speed that
can and should be prebriefed prior to closing the canopy)
Before Takeoff Checklist
Figure 6-17. Generic prelaunch checklists.
Glider Care
Depending on the type of glider, different cleaning methods should be employed. After all flights, the pilot or ground
personnel can wipe down the glider with a soft cloth or a wet chamois. This removes any debris or bugs. Delaying this
process allows bugs to dry and makes removal difficult.
Gliders made of fabric should be cleaned with spray-on and wash-off products. Anyone cleaning a glider should avoid using
large amounts of water as the water may penetrate cracks and holes, especially on earlier wood or fabric gliders, which
damages and reduces the life of the wood or fabric. Persistent and prolonged moisture exposure can damage any glider
over time. On metal gliders, personnel can use a low-pressure hose and mild detergent for cleaning. High-performance
fiberglass gliders use a special spray or paste for cleaning. Care must be taken when using a powered buffer, as the buffer
may burn the fiberglass if not used in a proper manner. Anyone cleaning a canopy should use only recommended cleaners
for that purpose. The GFH/POH or a glider supply store or organization can suggest appropriate cleaning materials based
on the type of glider.
After cleaning, a coat of wax or a sealer may be applied to fabric, metal, and fiberglass gliders. However, wax containing
silicon adheres to the pores of fiberglass and complicates future fiberglass repair. After applying any wax, personnel may
use a clean, soft cloth to wipe off excess wax and buff the area by hand.
An owner or pilot may perform minor repairs on a fiberglass glider such as fixing a scratch or a chip. Individuals should
consult a fiberglass expert prior to making any minor repair and use approved parts and materials when conducting these
repairs. All gliders, including those certified as standard or experimental, should be repaired in accordance with the
manufacturer’s recommended procedures and 14 CFR part 43.
Preventive Maintenance
Pilots may conduct preventive maintenance on their glider. Preventive maintenance does not involve complex assembly
operations. For the list of permissible pilot-performed maintenance activities and for more information on preventive
maintenance, refer to Appendix A of 14 CFR Part 43, Major Alterations, Major Repairs, and Preventive Maintenance found
at www.ecfr.gov.
Chapter Summary
This chapter introduces recommended safety practices for assembly, storage, tie-down, securing, and ground handling for
a glider. The final authority for any glider is the specific Flight Manual or Pilot’s Operating Handbook (POH) developed
by the aircraft manufacturer and approved by the FAA.