At what bulk fuel temperature is takeoff prohibited?

The correct choice reflects the operational limits regarding bulk fuel temperature during takeoff. In aviation, the temperature of the fuel is critical because it can affect the fuel's density and ultimately the performance of the aircraft. Higher temperatures can lead to fuel vaporization issues and can potentially cause engine performance degradation or even failure at critical phases of flight such as takeoff.

Specifically, a bulk fuel temperature of 50°C is generally considered the maximum threshold where takeoff is prohibited. At this temperature, the risk of fuel system malfunctions, such as vapor lock, increases significantly. This can lead to poor engine performance or complications during the takeoff roll, which is why any bulk fuel temperature above this value poses serious safety concerns for flight operations.

Maintaining awareness of fuel temperatures ensures that pilots and flight crews comply with safety regulations designed to prevent hazardous situations that could arise from improper fuel conditions. Thus, the 50°C limit is an industry standard that prioritizes both aircraft performance and overall safety during operations.