Final answer:
Under FAR Part 135, single-pilot operations are limited to 8 hours of flight time in any 24-hour period, while pilots in a crew may fly up to 10 hours with proper rest periods. An approved Fatigue Risk Management System can extend these limits, but the default rules generally apply.
Step-by-step explanation:
When operating under FAR Part 135, which governs commuter and on-demand operations, pilots are subject to specific duty regulations designed to ensure safety. These regulations include limits on the number of hours a pilot can fly within a 24-hour period. For single-pilot operations, the maximum flight time during any 24 consecutive hours is 8 hours. However, if there are multiple pilots (a crew), then the operation may be able to extend the flight time up to 10 hours provided appropriate rest periods are given.
The flight duty period may be extended if the operator has an approved Fatigue Risk Management System, but these are specialized allowances, and the default rules must be adhered to in most situations. Hence, without such an approval, one should compute flight time either as if it is only on for 12 hours or operating at half-power for 24 hours. Though this hint might have been relevant in an engineering context, for calculating available flight time under FAR Part 135, strictly adhering to FAA regulations is required.
In addition to flight time, rest periods are equally regulated. The FAA mandates a rest period of at least 10 consecutive hours of rest following any duty period before beginning the next duty period. The design of such regulations is to mitigate fatigue and maintain a high level of safety in air operations. Any service that involves flying for money under FAR Part 135 must follow these regulations to stay compliant with the Federal Aviation Administration's safety guidelines.