The B737, which is among the most preferred aircraft by airline companies, does not have main landing gear doors that completely cover the landing gear.
The B737 was originally designed for use in short-range regional transport. Designing the fuselage of the aircraft close to the ground provides a great advantage in order to perform flight operations quickly.
This design made it impossible to use the main landing gear doors. Boeing engineers decided not to use the landing gear doors to solve the problem. In this way, the design problem was solved and the extra weight of the doors was removed from the aircraft.
Hubcaps are used to create an aerodynamically smooth surface after the landing gear is retracted. In addition, the rubber seal prevents water or foreign objects entering the landing gear compartment.