How does an aircraft starter work?
The process of starting an aircraft engine isn’t exactly the same as starting your car in the morning. The average aircraft engine needs a boost to get going, and luckily, a device called a starter provides exactly that.
There are many mechanical components that make up an aircraft starter, and each plays an important role in the process of starting an engine. We’ll explain everything you need to know about the device, what it does, and how it works.
The parts of an aircraft starter
The following are some of the most important parts of an aircraft starter, which help it run properly to complete its job:
Battery — powers the starter
Flywheel — a heavy metal disc on the flange of the engine crankshaft
Magnetos — A magneto is a self-contained generator that powers an engine’s spark plugs for ignition
Spark plugs — used to ignite fuel and air mixture inside the cylinders
Starter adapter — a “clutch-like” device used as part of the starter system on many aircraft engines, which connects the starter motor and engine
How it works
Now that you know all the components involved, let’s get to the important part. Here’s a step-by-step breakdown of how the aircraft starter works:
- A small gear attached to the starter unit is responsible for engaging the flywheel, which kick-starts the whole process.
- The flywheel turns the crankshaft, which forces the pistons to move up and down.
- The magnetos start spinning, which generates a strong current that travels to the spark plugs.
- When the spark plugs ignite a mixture of fuel and air in the cylinders, the engine starts and your aircraft is ready to go.
The role of pre-start inspections
Performing a pre-start inspection ensures the reliable operation of an aircraft starter and prevents unnecessary wear on engine components.
Before engaging the starter, pilots should check key systems, including:
- Verifying the battery charge level
- Confirming proper fuel levels and flow
- Checking that magneto switches are correctly positioned
These pre-flight checks enhance engine performance and contribute to the safety and longevity of the starter.
More about aircraft starters
Modern magneto aircraft starters are more efficient and powerful. They use permanent magnets instead of the heavy field windings found in traditional direct-current (DC) starters. These permanent magnets are lighter and generate a stronger current, making the starter more reliable and reducing the aircraft’s overall weight.
Modern starters also include dual magnetos, high-voltage generators that spin inside a coil to create the magnetic force needed to ignite the spark plugs. The permanent magnetos and magnetos ensure a quick, smooth, and dependable engine start, offering a big improvement over older starter designs.
Traditional starters
- Traditional starters rely on DC motors equipped with heavy field windings to generate the magnetic force needed to initiate the engine start sequence.
- These designs are bulkier, less energy-efficient, and add unnecessary weight to the aircraft. They impact overall performance and fuel efficiency.
Modern magneto starters
- Modern starters replace heavy field windings with lightweight, permanent magnets. This design enhances the starter’s performance while significantly reducing its weight.
- Permanent magnetos produce a stronger magnetic field with less energy consumption, resulting in faster and more reliable starts.
What is an aircraft starter adapter?
Many Continental engines use aircraft starter adapters to provide that extra “push” needed to get the engine fired. The starter motor is mounted to the adapter at a 90-degree angle. When the motor starts spinning, it turns a shaft inside the starter adapter, and a larger brass gear starts to spin as a result.
As the rotational speed increases, a coil spring attached to that gear tightens and turns the drive shaft and starts the engine. When the speed of the engine exceeds that of the starter, the spring tension is released and the starter turns off.
Troubleshooting common aircraft starter issues
Despite regular maintenance, aircraft starters can occasionally encounter problems. Here are some common issues and their potential fixes:
If the starter won’t engage, it often indicates a faulty solenoid or a low battery. Test the solenoid for proper function and ensure the battery is fully charged.
- A grinding sound typically indicates a worn flywheel or a misaligned starter gear. Inspect both components for damage and correct any misalignment.
- Slow cranking may result from insufficient battery power or internal friction within the starter motor. Check the battery’s charge and inspect the starter for any signs of mechanical resistance.
- Addressing these issues can help prevent further damage and keep your aircraft starter operating smoothly.
The problem of overheating aircraft starters
It’s not always easy to get an aircraft engine started, and this can be the source of much frustration. However, in the process, it’s important to keep in mind the risk of your starter overheating.
Tip: if your first attempt at starting the engine fails, you may want to consult your Pilot Operating Handbook (POH) to determine how long to wait between attempts. This allows your starter to cool before trying again.
How to extend the life of your aircraft starter
Extending the lifespan of your aircraft starter involves proper care and regular maintenance. By following these tips, you can reduce the likelihood of repairs or replacements:
- Conduct regular inspections. Check gears, flywheels, and starter adapters for wear or damage to catch issues early.
- Lubricate all moving parts to minimize friction and prevent unnecessary strain on the starter.
- To maintain the battery, keep it fully charged to avoid overworking the starter and ensure consistent performance.
- Avoid excessive cranking and follow the manufacturer’s recommended crank time limits to prevent overheating and wear.
Implementing these practices will extend the life of your aircraft starter and enhance its reliability and overall performance.
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