Why is it important to lock control surfaces when an aircraft is parked?

Locking control surfaces when an aircraft is parked is crucial primarily to prevent damage from wind. When an aircraft is parked, control surfaces such as ailerons, elevators, and rudders can be vulnerable to wind gusts. If these surfaces are not secured, wind can cause them to move erratically, which might lead to mechanical damage to the surfaces or the attached control mechanisms. Additionally, uncontrolled movement can also put stress on the aircraft's structure or interfere with its ability to operate safely when it is next flown.

Ensuring that control surfaces are locked helps maintain the integrity of the aircraft’s systems and protects against potential harm that could arise from environmental factors. This practice is a fundamental part of pre-flight and post-flight procedures that enhances the overall safety and longevity of the aircraft.