Aircraft landing gear high-strength steel and inspection

Landing gear are designed first because they take the highest stresses, and they are steel at 250–280 ksi because no composite can match the critical-flaw-size / strength combination. Triple vacuum arc melted, magnetic particle inspected.

In very high strength steels like landing gear at 250 ksi, the critical flaw size is four tenths of an inch, a centimeter. If you go to 300 ksi, it's a tenth of an inch, about three millimeters. When we get into something like this, the smallest flaw you can reliably detect by non-destructive testing is about three millimeters. So we don't use steels in this region unless we're going to have a really tight inspection program. Landing gears on aircraft are in the 250, maybe 280 ksi range, and they have a really tough inspection criteria. Triple vacuum arc melted steel, get rid of all the inclusions, go in there and do magnetic particle inspection.