Which of the following are common causes of aircraft fires?

Fuel leaks and electrical malfunctions are indeed common causes of aircraft fires. Aircraft systems are designed for safety, but vulnerabilities exist. Fuel leaks can happen due to a variety of reasons, including damaged fuel lines or connections, and when combined with sources of ignition, they pose a significant fire risk. Electrical malfunctions can lead to overheating or spark generation, which can also ignite combustible materials onboard the aircraft.

The other choices highlight scenarios that, while they can contribute to emergencies, are not typically recognized as direct causes of aircraft fires. Structural failures and weather conditions may impact the overall safety of a flight but do not intrinsically lead to fires without a secondary triggering event. Bird strikes may damage aircraft but don't directly cause fires, while pilot error, though critical to flight safety, tends to have broader implications rather than being a direct ignition source. Reckless landings and overloading are operational risks, but they do not directly lead to fires in the same manner as fuel and electrical issues.