Engines

Several types of Engines

A distinction must be made between aeroplanes equipped with turbo-props, sometimes referred to as propeller planes (ATR, Saab2000, Embraer 120) aeroplanes with turbo-jets (Airbus, Boeing, Canadair RJ, Embraer 145). The latter are equipped with two, three or four jet engines.

Reliability of Turbojets and Turboprops

Jets can now run for tens of thousands of flying hours on wing before being removed for a revision. Turboprops can now run for over 10,000 flying hours de flight before being removed for a revision.

How does an engine failure occur?

There are several types of engine failures

1. Failure that requires a precautionary engine shutdown in flight in order not to damage it.

This is the most common cause and is not necessarily noticed by the passengers.

Each of these failures has a corresponding procedure that the pilots know and for which they are trained. These procedures are described in the aeroplane’s onboard documentation and are the subject of a specific check-list. In this category there are:

• Engine surges: the most spectacular event. It is often accompanied by a bang and sometimes flames from the engine. This phenomenon is temporary and has no repercussions on safety.
• Fuel regulation problems: this leads to fluctuations in engine parameters that are only visible to the crew via the indicators.
• Drop in oil pressure leading to overheating: this generally results from an oil leak in the system or the failure of a part.
• Severe engine vibrations: wear or a slight internal deterioration can lead to vibrations. Indicators in the cockpit allow the level of these vibrations to be monitored.
• Ingestion of bird (bird strike) or foreign object (often small objects on the runway): engines are certified to resist the majority of these ingestions.

In the majority of these cases, the BEA does not carry out an investigation. They are known failures, normally with no impact on safety and for which approved procedures exist.

2. Failure causing serious engine damage or an engine fire.

This type of failure is less frequent and can have consequences on safety.

In the first case, engine components can be projected through the engine casing and can cause collateral damage. In the second case, an internal failure can lead to a fire. The extinguishers installed on the engines and controlled from the cockpit should normally put it out.

These events lead to emergency procedures, for which pilots are trained to react immediately and can lead to an emergency landing. Because of the gravity of the technical consequences and the potential risks that they represent for the safety of the flight, they must be notified to the BEA, which then usually conducts an investigation.