Can a passenger jet fly with one engine?
A twin-engine aircraft can perfectly fly with one engine. In fact, it can even continue takeoff and then land safely with just one engine. Engine failure in flight is usually not a serious problem and pilots receive extensive training to deal with such a situation.
What do the pilots do in the event of an engine failure?
All pilots are taught to follow a basic aviation rule, regardless of the intensity of any in-flight event. This is summarized by the acronym; Navigate, Navigate, Communicate. The key is to ensure that the flight crew prioritize flying the aircraft first. This is to ensure that it is fully controlled before checking or correcting its navigation path and to ensure that it flies where the pilots want it to fly, i.e. that he is not heading for a high mountain. This is followed by the communication of relevant information to all parties involved, starting with air traffic control.
There are several different severities of engine problems that may require slightly different responses from the flight crew, defined by the level of urgency. For example, if an engine fire is indicated, this requires an immediate response after ensuring the aircraft is under control (“Aviating”!). If, for example, there was an indication of an engine fire, there are several “memory actions” that the flight crew must perform. This will involve shutting down the engine and deploying memory shooters, without using a checklist.
Once the engine has stopped…
Once the engine is safely shut down and the fire extinguished, the crew will indicate that the “Engine Fire Memory Actions” have been performed correctly by referring to the appropriate checklist. The checklist will then detail other tasks to be performed by the crew that were not included in the “memory actions”.
On the other hand, if it was a simple engine failure with no damage indicated, there would be no “memory actions”. In this case, pilots would follow a checklist to diagnose and possibly restart the engine. Any engine failure on a twin-engine aircraft will require pilots to land at the nearest suitable airport. Statistically, it is unlikely that this is your destination unfortunately!
“Memory actions” for engine fire or serious damage
Different aircraft types may have different names for the various switches, handles, and procedures, but the basic principle remains the same; to stop safely and secure the engine in a timely manner. These steps are usually as follows:
- Disengage the autothrottle – this stops automatic thrust control.
- Reduce the thrust of the damaged engine to idle – this involves returning the respective thrust lever fully to its idle position.
- Fuel control switch off – this closes the fuel valve, stopping the flow of fuel to the engine.
- Pull the fire handle switch – this usually disengages the electrical, hydraulic, pneumatic and fuel systems of the respective engine.
- If a fire is still indicated in the engine, turn the engine fire handle to discharge the first fire bottle. After waiting about 30 seconds, if indications of fire are still present, turn the fire handle the other way to discharge the second fire bottle.
Each of these actions MUST be verified by both crew members. For example, the pilot moving the checklist will touch the respective control switch, such as the fuel control switch, and the other pilot will confirm that he is about to operate the correct switch before that . It should be done at a reasonable pace (without rushing) to ensure that the wrong engine is not stopped.
Engines are designed to contain any fire within its housing to prevent it from spreading to any other part of the aircraft. However, if an engine fire persists after this procedure has been followed, the flight crew may need to consider an immediate landing. In very serious cases, this may mean a forced landing away from any airport (i.e. in a suitable field or area). However, rest assured, the potential for such an event is incredibly remote.
Reasons an engine may fail or be shut down by pilots:
- Severe damage (e.g. turbine/fan blade separation or bird strike)
- Airplane separation
- To go up
- Stall (an engine stall is different from an airplane wing stall)
- Lack of fuel or contamination
- flame extinguished
- High vibrations
- Limits exceeded (too hot for example)
What are the implications of engine failure?
Asymmetric Thrust / Controllability
The first implication is the asymmetric thrust that will be produced. If one engine fails and is shut down, the other engine’s thrust is increased to arrest a decrease in airspeed. This results in the aircraft wanting to pull away from the running engine and enter a turn. If left unchecked, this will result in loss of control of the aircraft. This usually has to be manually corrected by pilots via the rudder pedals. Whenever there is an adjustment in speed, thrust or altitude, pilots will need to ensure the aircraft remains balanced and in control.
With 50% of the airplane’s power no longer available, it will not be able to maintain its cruising altitude. If the aircraft is in cruise at the time of the failure (which is statistically the most likely), a descent will need to be quickly initiated to an intermediate altitude that can be maintained by the remaining engine (usually between 15,000ft and 25,000ft for most aircraft, depending on weight).
Many of the aircraft’s systems are powered by its engines. These typically include hydraulics, pneumatics (which provides cabin air) and electricity. Although these systems have some level of redundancy (partly through the other engine), some parts of the system may no longer be available, which could affect aircraft handling and performance.
The loss of an engine often requires a different flap configuration for landing, in part due to the performance that must be achieved if the aircraft were to abort the approach/landing and perform a go-around. Landing with a lower flap configuration increases the required landing distance and therefore pilots must carefully consider which airport they choose to land at. Airport weather, runway length, and aircraft weight all play a role in these considerations.
What is the most dangerous phase of flight to have an engine failure?
For a pilot, the most trying place to have an engine failure is during the takeoff phase, that is, the beginning of the ground roll until the plane passes through approximately 1,500 feet. However, extensive training is provided for this scenario and pilots are tested on their reactions to such an event every six months in the simulator. They must deal with such a scenario safely at a high level or they will not be allowed to continue flying until adequate performance is demonstrated.
During takeoff, pilots use a carefully pre-calculated speed called V1 (pronounced “Vee One”) to determine their actions in the event of an engine failure. During the take-off run, if an engine failure occurs before V1 speed, pilots must abort the take-off, which is known in the industry as “rejected take-off” or RTO for short. If they elected to continue, the aircraft would not gain enough airspeed to take off with the remaining engine power available on the remaining runway length.
Continuation of take-off
If a failure occurs after V1, pilots must continue takeoff and take off. If the pilots attempted to abort the takeoff at this speed, there would not be enough runway left to bring the aircraft to a safe stop.
Once the aircraft is in the air, pilots will focus solely on flying and controlling the aircraft up to approximately 400 feet. At this altitude, they will review what happened and perform “memory actions” if necessary.
What happens if you lose an engine on an aircraft with more than two engines?
A four-engine aircraft losing a single engine is even less of a problem. A few years ago, a four-engined Virgin Atlantic The Boeing 747-400 (a jumbo jet) had an engine failure over the United States en route to the United Kingdom. The plane continued all the way over the Atlantic Ocean to the UK without any further problems.
If a four-engined aircraft has lost more than one engine, it can still potentially fly at a lower altitude and will perform better at lower weights.
What is the probability of engine failure?
With the significant technological improvements that have taken place over the past decades, the motors are built to incredibly high standards and are therefore very robust. Over the past few decades, engine failures have become increasingly rare to the point that the majority of pilots will now only see one engine failure in the simulator during their career.
Safety statistics suggest that less than one in a million thefts will experience engine failure or forced engine shutdown in the air or on the ground. This equates to approximately 25 such failures per year in commercial aviation.
In the event of a failure, the engine is designed to contain any problem and prevent its spread to the rest of the aircraft. For example, if one of the fan blades at the front of the plane becomes detached, the crankcase must prevent it from coming out of the engine.