Landing gear on aircraft can have some problems, and early Cessna 170 landing gear have a real doozy! On certain models with spring steel landing gear, the landing gear is EXTREMELY INTOLERANT of side loads.
INSIDE THE SCENES: In engineering terms, the Cessna 170 landing gear assumed the pilots would land level on both gear legs. With the arrangement of bolts and fasteners, this would put the load in the downward direction, and would not pull up on the small bolt that was used to secure the landing gear.
WHAT IS A SIDE LOAD? If you are landing in a strong crosswind and you touch down with one wing low, the plane skids towards the wheel that is down. You have just introduced a side load on the landing gear. In an extreme case, you may or may not have ripped the retaining bolt right out of the structure of the plane. If you didn’t, you can fly on with confidence. If you did…
A REALLY BAD DAY
One day at an Alaskan airport, our pilot (who had executed a crosswind landing earlier in the month) pushed his plane back into the hangar and noticed something different — he had to lift the right wing over the refrigerator on the side of his hangar. Instead of stopping to think about why he would have to do that — when he’d never had to do it before — he went home.
A few days later, our pilot returned to the airport to take his plane on another run into the bush. Again, he carefully lifted his wing over the refrigerator, and performed an otherwise good preflight. Then, he started the engine and taxied out to the active runway for departure.
As the plane rotated, the pilot heard a loud thump. Looking out of his windows, he couldn’t see anything wrong. The control tower on the other hand, had noticed something. They called the pilot and asked him if he still had both of his main gear legs. Looking to the left, the landing gear was in place. Looking to the right, our pilot was astounded to see that the right gear leg was missing!
The control tower, of course, knew where the right main was — it was sitting on the runway … right where it fell off. Our pilot made a good approach back to the airport and, with emergency equipment standing by, made a nice one-wheel landing. Regardless, when the wing settled, the plane ground-looped and suffered extensive damage.
MISSING THE BAD DAYS
What did our pilot miss? First off, if one wing suddenly gets lower, it’s time to take a hard look at the airplane. As a general rule, planes are designed to sit level — not on an angle — so any abnormal slants are indicative of a problem.
There is a company with a mod to beef up the weak link in the Cessna 170 landing gear. Our pilot thought he didn’t need the mod, after all, he’d never had problems in the past. Of course, he’d never touched down in such a stiff crosswind before either. That landing pulled the gear leg clean out of the structure, allowing it to fall off when the aircraft left the ground.
• KNOW THE WEAK LINKS IN YOUR AIRCRAFT
As a rule, most aircraft landing gear hate side loads. They were not designed for it and, whether fixed or retractable, they may fail or fold if exposed to a side load of sufficient force.
• WHEN IN DOUBT, INSPECT If you landed hard, and the plane doesn’t look the same, or even if you just landed in a strong crosswind and feel that the plane is handling differently on the ground (despite the wind), get it inspected.
• THINK! Who else knows your plane as well as you do? If you feel something is not right, chances are that it isn’t. Listen to the voice inside your head and have the plane inspected.
BOTTOM LINE: What was a little damage from your overloaded landing gear can become a totaling event if the landing gear falls off. By staying vigilant and using your head, you can fix the plane before the plane fixes you.