Explainer: why the Boeing 737's main landing gear lacks covering doors

The Boeing 737 still flies without doors covering its main landing gear wells, a design choice that sets it apart from rival narrow-body jets, according to an explainer piece on the type's engineering history.

The 737 and the Airbus A320 share a similar wheel layout: two wheels on the nose gear, and two sets of two wheels on the main gear. Their retraction mechanisms are broadly similar too. But the A320 has doors that close over the gear bays once the wheels are stowed, while the 737's wheels stay exposed in the wells throughout flight.

The explainer traces this back to choices made decades ago in the 737's original design, which favoured simplicity and ground clearance over the aerodynamic refinement that fully enclosed gear doors can offer. Exposed gear wells mean fewer moving parts and mechanisms needing maintenance. That has been cited as a benefit for turnaround times and reliability on an aircraft family built around short-haul, high-frequency operations.

There is a tradeoff. Exposed wheels can increase drag compared with a fully enclosed bay, a small aerodynamic penalty. Even so, the 737 remains one of the most widely produced commercial jets, and the design has persisted through multiple generations of the aircraft, including the current Max series.

The piece carries no new technical development or announcement. It is a retrospective look at an established feature of the aircraft's undercarriage design, not a report on a recent event.