ENGINE START
Different aircraft with different engines have different startup procedures. Once preflight procedures have been completed, we get back in the cockpit. We complete any relevant checklists, including the ‘Before Engine Start Checklist’. We are then ready for engine start.
Beware of what’s around you. There may be people on the ramp. Your tail may be pointed toward an open hangar door, parked cars, or a group of bystanders. This is not only discourteous but may result in personal injury and damage the property of others. Propeller blast can be surprisingly powerful.
A good pilot will look in all directions making sure that nothing is or will be in the vicinity of the propeller, i.e. nearby persons or aircraft that could be struck by the propeller blast or any debris it may pick up from the ground.
Ensure anti-collision lights are on prior to the engine start, even during daytime operations. At night, position (navigation) lights should also be on.
The pilot should call “CLEAR!” out of the side window and wait briefly for response from anyone who may be nearby before activating the starter.
When activating the starter, keep one hand on the throttle. This allows a prompt response if the engine falters during startup and allows you to rapidly retard the throttle if RPM are excessive after starting the engine.
Low RPM is recommended immediately following engine startup. Check the Oil Pressure! If it does not rise to manufacturer’s specified value the engine may not be receiving proper lubrication and should be shut down immediately to prevent serious damage.
Although quite rare, the starter motor may remain on and engaged after the engine starts. This can be detected by a continuous very high current draw on the ammeter. If this occurs, shutdown the engine immediately.
Starters are small electric motors designed to draw large amount of current for short periods of cranking. If the engine fails to start readily, avoid continuous starter operation for periods longer than 30 seconds without a cool down period of at least 30 seconds to one minute. Their service life is drastically shortened from high heat through overuse.
Beware of the potential for HOT & HUNG starts during engine start procedure.
A hot start is one in which the engine ignites and reaches self sustaining rpms, but the combustion is unstable and the exhaust gas temperature (EGT) rises rapidly past its maximum limit.
Causes of a hot start include;
- Overfueling (throttle open)
- Air intake/exhaust blocked
- Tailwind, causing the compressor to run backward
- Seized engine, e.g., ice blockage
Indication of a hot start is an EGT rising rapidly toward its maximum limit.
Actions required for a hot start are;
- Close fuel lever/stop fuel delivery before the EGT limit has been reached.
2. When the engine rpms have slowed to the reengagement speed, motor over the engine to blow out the fuel (approximately 60 seconds).
A hung start occurs when the engine ignites but does not reach its self sustaining rpms.
Self sustaining speed is an rpm engine speed at and above which the engine can accelerate on its own without the aid of the starter motor.
The cause of a hung start is insufficient airflow to support combustion due to the compressor not supplying enough air because of one or a combination of the following, but not restricted to:
- High altitude, low-density air
- Hot conditions, low-density air
- Inefficient compression
- Low starter rpms
Indications of a hung start include:
- High exhaust gas temperature (EGT), above normal
- Engine rpm below normal self-sustaining speed
Actions required for a hung start are:
- Close fuel lever/stop fuel delivery.
- Motor over the engine to blow out the fuel (for approximately 60 seconds)
Pro tip: To gain a successful start in hot and high conditions, you have to introduce more air into the engine. Adjusting the fuel supply does not help.
- Increasing fuel = rpm decreases & EGT increases
- Decreasing fuel = rpm increases & EGT decreases
Furthermore, an engine wet start is otherwise known as a failure to start after the fuel has been delivered to the engine.
The cause of a wet start normally is an ignition problem.
Indications of a wet start are:
- EGT does not rise
- Rpms stabilize at starter maximum
Actions required for a wet start are:
- Close the fuel lever/supply as soon as a wet start is diagnosed (usually at the end of the starter cycle).
- Motor over the engine to blow out the fuel (approximately 60 seconds).
