Which three basic conditions influence engine power output?

• A. temperature, pressure, and bleed air extracted
• B. temperature, humidity, and altitude
• C. temperature, humidity, and pressure
• D. pressure, temperature, and bleed air extracted

Answer: (A)

The main idea here is that engine power output is driven by how much air actually gets into and through the engine, which is governed by air density and the available mass flow. Temperature and pressure directly affect air density: hotter air is less dense, and lower ambient pressure also yields less dense air, so the engine receives fewer air molecules per cycle, reducing power. Bleed air extraction adds a further factor: air is taken off from the compressor to feed other systems, which reduces the amount of air that remains to support combustion and thrust. This bleeding effectively lowers the engine’s mass flow and its ability to produce power, making it a direct influence on output alongside temperature and pressure. Humidity and altitude also affect density, but their impact is typically smaller or redundant with pressure effects in this context, so the trio most consistently cited as the factors you can control or encounter that influence engine power are temperature, pressure, and bleed air extracted.