We've all seen the images from last week's Sun 'n Fun Fly-In. Broken wings, crunched elevators and rudders, and crushed windshields resulted from an EF-1 tornado that hit the Lakeland Linder Airport on Thursday, March 31. Nothing can prevent an airplane from being damaged from the force of a tornado, but there are ways to improve the chances of getting through a nasty storm unscathed. If there is no time to fly away from the threatening weather and no option to park the airplane in a hangar, a solid tie down is the last resort. And if it's done properly, chances are the airplane will weather the storm just fine.
Most small airplanes are ready to fly at about 50 to 60 knots, speeds well exceeded by many severe storms. And since an airplane's wings don't know the difference between wind created by the force of its engine or the winds from a storm, it will literally take off unless it's somehow secured.
First, turn the airplane into the wind. This streamlines the airplane's fuselage, which will otherwise want to weathervane, so the strain on the airframe is minimized.
If there are no solid, permanent attachment points on the tarmac, several great products are available that provide strong anchor points in the dirt. The Claw is probably the most well known product available for this purpose, but Storm Force Tie Downs and FlyTies are also worth exploring. And while the anchor points are critical, the ropes, chains or straps that attach them to the airplane are just as important. They need to be able to withstand at least 3,000 pounds of force. The kits mentioned previously include ropes, but make sure you inspect them after each use to make sure they're still in good condition. I saw many ropes ripped to shreds in Lakeland.
While the products mentioned above only include three anchors — one for each wing and one for the tail — it is a good idea to add a fourth anchor for the nose. This will prevent the airplane from lifting off or tilting as the wings start to produce lift from the strong winds.
No matter how well tied down your airplane was during the storm, make sure you do a very thorough preflight inspection prior to taking it back up into the skies. There may be cracks or stress points that can seriously affect the airworthiness of the airplane.
Advisory Circular 20-35C released by the FAA in 1983 includes many other good ideas for how to best secure an airplane.