What is a potential hazard of improper structural modifications in an aircraft?

Improper structural modifications in an aircraft can create unexpected stress concentrations, which may significantly compromise the integrity of the aircraft. When structural changes are made without thorough analysis and understanding of how they alter load distribution and structural behavior, localized areas of increased stress can develop. These stress concentrations are hotspots where materials may fatigue more quickly, leading to cracks or complete structural failure over time.

For instance, if additional weight is added or if there are alterations to the reinforcement of certain components, the overall load-bearing capacity may be adversely affected. Such failures can occur in critical areas, potentially leading to catastrophic incidents during flight. Therefore, ensuring that modifications are designed, implemented, and validated by qualified personnel is essential for maintaining the safety and reliability of the aircraft.

The other choices present outcomes that imply enhancements or improvements, which are generally contrary to the results of improper modifications. Structural changes can indeed lead to reduced performance and unacceptable safety risks if not approached with the right engineering principles in mind.