How is the APU's fuel system protected against contamination?

The fuel system of the Auxiliary Power Unit (APU) is safeguarded against contamination primarily through the use of filters and water separators. Filters are designed to trap particles, sediments, and debris that may exist in fuel, preventing these contaminants from entering the APUs fuel components and causing damage or inefficient operation. Water separators are crucial as they help manage moisture in the fuel, which can lead to corrosion and other issues if left unchecked. By effectively removing both solid and liquid contaminants from the fuel before it reaches the APU, this dual system ensures cleaner fuel delivery and enhances the reliability and longevity of the APU’s operation.

While a closed-loop fuel system can contribute to enhanced operational efficiency, it does not directly address the contamination aspect as effectively as filters and separators. Periodic fuel testing is a good practice for monitoring fuel quality, but it is not a proactive method of contamination prevention. Keeping fuel tanks always full can help mitigate the risk of condensation, but it does not specifically filter or separate contaminants from the fuel. Thus, the filter and water separator combination is the most direct and effective approach to protecting the APU’s fuel system from contamination.