What is the primary consequence of exceeding the aircraft's maximum weight limit?

Exceeding the aircraft's maximum weight limit primarily leads to potential structural damage. An aircraft is designed with specific weight tolerances, including the strength of its airframe and components. When these limits are surpassed, it puts excessive stress on the aircraft's structure, which can result in issues such as structural failure during flight or landing. This can manifest as cracks, deformations, or even catastrophic failures in extreme cases.

Aircraft are rigorously tested and certified for certain maximum weight thresholds to ensure safety and integrity. Therefore, operating beyond these limits can jeopardize not only the airframe but also passenger and crew safety, as the aircraft may not perform as intended under those conditions.

Other options related to performance, safety, and fuel efficiency do not apply when weight limits are exceeded; rather, they would likely degrade under such circumstances. Thus, the likelihood of structural damage is a significant and serious consequence of operating an overweight aircraft.