What is apu in aircraft?

What is APU in Aircraft?

The Auxiliary Power Unit (APU) is an essential component of an aircraft’s power system, providing backup power to the aircraft in case of an engine failure or other emergency situations. In this article, we will delve into the world of APU and explore its functions, types, and benefits.

What is the Function of APU in Aircraft?

The primary function of an APU is to provide backup power to the aircraft’s essential systems, such as:

• Electrical systems: Lighting, instruments, and communication equipment
• Hydraulic systems: Landing gear, brakes, and flight control systems
• Pneumatic systems: Air conditioning, pressurization, and oxygen systems

In the event of an engine failure or other emergency, the APU can provide the necessary power to maintain critical systems, ensuring the safety of the aircraft and its occupants.

Types of APU

There are two main types of APU:

• Gas turbine APU: Powered by a small gas turbine engine, these APUs are commonly used in commercial aircraft
• Reciprocating engine APU: Powered by a small piston engine, these APUs are often used in general aviation and business aircraft

Characteristics of APU

Here are some key characteristics of APUs:

• Power output: Typically ranging from 5-90 kW (6.7-120 HP)
• Noise level: APU noise levels are significantly lower than those of main engines
• Fuel consumption: APUs are designed to be fuel-efficient, with some models consuming as little as 0.5 kg/h (1.1 lb/h)
• Weight: APUs are relatively lightweight, with some models weighing as little as 20 kg (44 lbs)

Benefits of APU

The benefits of APU are numerous:

• Improved safety: Provides backup power in case of engine failure or other emergencies
• Increased reliability: Reduces reliance on main engines, reducing the risk of failure
• Reduced maintenance: APUs are designed to be low-maintenance, reducing downtime and costs
• Improved passenger comfort: APUs can provide air conditioning and other amenities during ground operations

APU Installation and Maintenance

APUs are typically installed in the tail section of the aircraft, with the engine and fuel system located in a separate compartment. Maintenance is typically performed by the aircraft’s maintenance crew, with regular checks and overhauls recommended to ensure optimal performance.

APU Operation

Here’s a step-by-step overview of APU operation:

1. Start-up: The APU is started using a dedicated switch or button
2. Warm-up: The APU runs at a reduced power setting to warm up the engine and generator
3. Power generation: The APU generates power to the aircraft’s systems
4. Monitoring: The APU is monitored for performance and any issues are addressed promptly

Conclusion

In conclusion, the APU is a critical component of an aircraft’s power system, providing backup power and improving safety, reliability, and passenger comfort. Whether you’re a pilot, maintenance technician, or aircraft owner, understanding the function, types, and benefits of APU is essential for ensuring the safe and efficient operation of your aircraft.

Table: APU Characteristics

Bullets: APU Benefits

• Improved safety
• Increased reliability
• Reduced maintenance
• Improved passenger comfort