If you ever traveled by plane, you probably recognize the excitement you feel while awaiting take-off. In those moments, did you ever wonder how aircraft engines are started? It is a complex process involving four aircraft systems (APU, starter, AGB, PTO). Did you know that BMT Aerospace is present in all these crucial parts that are needed to start an aircraft engine?

In short, it’s impossible to start an engine without BMT Aerospace! Curious how this process takes place? Learn more about it below.

How does an aircraft start?

The following parts are crucial in the activation process of an aircraft.

1. Auxiliary Power Unit (APU)

The Auxiliary Power Unit is an independent small turbine generating electrical and pneumatic power for a variety of aircraft systems. It is typically located in the tail section of the aircraft and provides power for air conditioning, cabin pressurization, and other auxiliary systems.

BMT Aerospace manufactures ring gears for the APU in the tail of the plane.

2. Starter

The starter is connected to the Accessory Gearbox (AGB) of the main engines. When activated, it provides the necessary torque to spin the engine up to operating speed.

BMT Aerospace manufactures spur gears for the starter for aircraft starters.

3. Accessory gearbox (AGB)

The AGB is an engine module that allows all subsystems of the aircraft (electrical, pressured air, pressured oil system, etc..) to operate thanks to the power extracted from the main engine (unique power plant on board). The AGB will empower all accessories via a complex drivetrain of spurs, bevels and gears. The AGB is connected to the Main engine shaft via the PTO.

BMT Aerospace manufactures high-end components of accessory gearboxes (housings and gears).

4. Power take-off shaft (PTO)

The PTO is a shaft put in motion from the main engine shaft via the internal gearbox (IGB) and driving the motion up to the AGB.

BMT Aerospace can manufacture internal gearbox components, as well as shafts of the PTO’s shafts.

The process

These parts of the aircraft are in co-relation with each other and are crucial to start the aircraft engines. The process goes as follows:

The APU is an autonomous source of power and will generate compressed air and electricity to the starter. On its turn, the starter will set the AGB in motion. The accessory gearbox will then drive the PTO and this will activate the main engine shaft. This will eventually activate the compressor. When the compressor has heated the air enough, fuel is injected and the engine can start.

BMT Aerospace is a world-class leader in manufacturing complex parts for aircrafts. We manufacture more than gears that play a role in the start-up of the engines. Discover all our products here.