Aircraft Landing Gear
With a maximum takeoff weight of over 560 imperial tonnes and anywhere between 550 and 800 valuable lives on board (e.g. Airbus A380), landing gear, used for takeoff and landing, is designed to be extremely strong and robust. It cannot fail.
Aircraft landing gear is comprised of wheels, shock absorbers or oleo struts. It is usually retractable and kept stowed away in order to reduce drag during flight time. Therefore, some parts need to carry extremely high weight and others need to endure repeated folding and jolting movement.
Precipitation hardening grades like 13-8 and 17-4 combine high strength with corrosion resistance, low carbon steel 300M/S155 have exceptional strength (both longitudinally and transverse) and fatigue resistance, whilst Aermet 100 combines high strength with exceptional toughness. These different combinations of properties give aircraft designers a large degree of freedom to select materials matching their requirements.
Lastly, due to high weight-to-strength ratio, titanium grade 5 (Ti 6Al-4V) is also a popular choice for landing gear parts as it offers a weight saving option without compromising on strength and robustness.