What is the most likely cause of heavy chemical deposits on the belly of the aircraft?

The presence of heavy chemical deposits on the belly of an aircraft is most likely due to a loose hose fitting. This situation can occur if the hoses that transport the chemicals from the tank to the spray nozzles are not securely attached. When there is a loose fitting, chemicals can leak out during flight or when the aircraft is on the ground, leading to a buildup of residues on the aircraft's belly.

In aerial application, it's crucial for all fittings and hoses to be tightly secured to prevent leaks that could result in not only chemical deposits but also potential hazards during operation. Ensuring a proper seal helps maintain the integrity of the application system, which is essential for effective and safe aerial application practices.

While other factors like overloading the aircraft, poor weather conditions, or an incorrect fuel mixture can influence various aspects of aircraft performance and safety, they are less directly connected to the specific problem of chemical deposits on the aircraft's belly than a loose hose fitting.