Multi Engine Rating
"Million Dolla Question". Are multi-engine airplanes really safer? Why require an additional rating to fly multi-engine airplanes?
Muti Engine Safety Math
Muti Engine Safety Math
Per flying hour a Twin Engine Airplane compared to a Single is:
2 times more likely to develop problems in ANY of its engines;
4 times less likely to develop problems in TWO of its engines.
Surprisingly safety doesn't improve significantly with 3 or 4 engines. A dual failure in the 3 engine types usually creates an unacceptable loss of performance.
In the 4 engine types a dual failure on the same side creates a directional control dilemma.
2 times more likely to develop problems in ANY of its engines;
4 times less likely to develop problems in TWO of its engines.
Surprisingly safety doesn't improve significantly with 3 or 4 engines. A dual failure in the 3 engine types usually creates an unacceptable loss of performance.
In the 4 engine types a dual failure on the same side creates a directional control dilemma.
The Pilot Makes All The Difference
Two engines are better than one, but ...
Proficiency
Incompletely trained or rusty pilots can fly multi engine airplanes, but not safely. In normal operations they would be at least twice safer flying a single engine airplane. This is due to the higher probability of any of the engines failing in a multi and the consequences of not being prepared to handle those cases.
Oceans
Long over water flights are safer in multi-engine airplanes, but only with proper preflight planning. The pilot needs to make computations which prove that, in case of an engine failure, enough range is available to reach the destination, the departure, or the alternate airport. The computations should assume the worst possible moment for engine failure - the equal time point - and take into consideration existing winds and temperatures.
Mountains
Multi engine airplanes have a significant safety advantage over singles in mountain over flights. Again, this only holds true if care is taken to ensure that a takeoff and flight at safe altitudes above peak levels is possible after an engine failure.
Myths
Given the above no wonder there is a popular saying "If an engine fails in a twin the remaining engine will only carry you to the scene of the accident." Obviously this is not true for airline operations as well as for private pilots who take the time and effort to stay proficient in engine out operations.
Proficiency
Incompletely trained or rusty pilots can fly multi engine airplanes, but not safely. In normal operations they would be at least twice safer flying a single engine airplane. This is due to the higher probability of any of the engines failing in a multi and the consequences of not being prepared to handle those cases.
Oceans
Long over water flights are safer in multi-engine airplanes, but only with proper preflight planning. The pilot needs to make computations which prove that, in case of an engine failure, enough range is available to reach the destination, the departure, or the alternate airport. The computations should assume the worst possible moment for engine failure - the equal time point - and take into consideration existing winds and temperatures.
Mountains
Multi engine airplanes have a significant safety advantage over singles in mountain over flights. Again, this only holds true if care is taken to ensure that a takeoff and flight at safe altitudes above peak levels is possible after an engine failure.
Myths
Given the above no wonder there is a popular saying "If an engine fails in a twin the remaining engine will only carry you to the scene of the accident." Obviously this is not true for airline operations as well as for private pilots who take the time and effort to stay proficient in engine out operations.
So One of My Engines Failed
Engine out operations frustrate flight in two basic ways :
significant performance degradation
directional control difficulties
significant performance degradation
directional control difficulties
Performance - Will She Climb?
Performance degradation affects our climb rate, service ceiling, range and airspeed. In a twin we lose much more than 50% from any of these when we lose 50% of our thrust power. Why? Climb depends on excess power. A significant amount of power is used just to overcome drag in level flight. Therefore if we lose half of our power we lose much more than half of our climbing ability, which in turn lowers our service ceiling. Multi engine pilots are taught to combat performance problems by maintaining proper flight speed and bank, minimizing drag, and by preflight verification that performance will be adequate after an engine loss.
Directional Control - Will She Fly?
Directional control problems after an engine failure are insignificant at normal flight speeds, but become severe as speed decreases. There is a speed (Vmc), usually higher than stall speed, below which control is impossible to maintain. Pilots can regain directional control by increasing airspeed, banking into the working engine(s) (the more the better), feathering the dead engine. If altitude is not an issue - when we're very high or still on the ground - we can cure all directional problems by simply closing all the throttles we have.
Take off Decisions - Fast or Fatal
Both control and performance are even more critical during takeoff. In a takeoff engine failure situation a quick decision needs to be made whether to abort or continue the takeoff. This decision entirely depends on the airspeed achieved, the runway length, and surrounding terrain. In typical propeller twins and runway length combinations most of the accident causing errors are MISJUDGED CONTINUED TAKEOFFS. On the other hand the typical Turbojet-runway length combinations more often result in MISJUDGED ABORTED TAKEOFFS.
Performance degradation affects our climb rate, service ceiling, range and airspeed. In a twin we lose much more than 50% from any of these when we lose 50% of our thrust power. Why? Climb depends on excess power. A significant amount of power is used just to overcome drag in level flight. Therefore if we lose half of our power we lose much more than half of our climbing ability, which in turn lowers our service ceiling. Multi engine pilots are taught to combat performance problems by maintaining proper flight speed and bank, minimizing drag, and by preflight verification that performance will be adequate after an engine loss.
Directional Control - Will She Fly?
Directional control problems after an engine failure are insignificant at normal flight speeds, but become severe as speed decreases. There is a speed (Vmc), usually higher than stall speed, below which control is impossible to maintain. Pilots can regain directional control by increasing airspeed, banking into the working engine(s) (the more the better), feathering the dead engine. If altitude is not an issue - when we're very high or still on the ground - we can cure all directional problems by simply closing all the throttles we have.
Take off Decisions - Fast or Fatal
Both control and performance are even more critical during takeoff. In a takeoff engine failure situation a quick decision needs to be made whether to abort or continue the takeoff. This decision entirely depends on the airspeed achieved, the runway length, and surrounding terrain. In typical propeller twins and runway length combinations most of the accident causing errors are MISJUDGED CONTINUED TAKEOFFS. On the other hand the typical Turbojet-runway length combinations more often result in MISJUDGED ABORTED TAKEOFFS.
When learning multi engine flying two additional training factors are :
increased airplane and systems complexity
higher speed leading to increased workloads
The last two present no difficulties to pilots experienced with high performance single engine airplanes. On the other hand newly certified private pilots are likely to require more training addressing the above areas.
increased airplane and systems complexity
higher speed leading to increased workloads
The last two present no difficulties to pilots experienced with high performance single engine airplanes. On the other hand newly certified private pilots are likely to require more training addressing the above areas.
Centerline Thrust - Is It Better?
Pilots of centerline twins will be similarly affected by performance loss as any other twin after an engine failure. There won't be directional control complications. This is a great blessing, but it has some negative consequences. It is now harder to detect an engine failure on takeoff, and much harder to figure out which engine failed. Each airplane has different engine failure indications which make recurrent training very important. It is just as imperative to maintain blue line (Vyse) speed after a failure as in any other multi engine airplane.
Additionally :
A multi-engine rating is required to fly centerline twins
If a centerline twin is used on the practical test a 'centerline thrust only' limitation will be placed on the pilot certificate
Pilots of centerline twins will be similarly affected by performance loss as any other twin after an engine failure. There won't be directional control complications. This is a great blessing, but it has some negative consequences. It is now harder to detect an engine failure on takeoff, and much harder to figure out which engine failed. Each airplane has different engine failure indications which make recurrent training very important. It is just as imperative to maintain blue line (Vyse) speed after a failure as in any other multi engine airplane.
Additionally :
A multi-engine rating is required to fly centerline twins
If a centerline twin is used on the practical test a 'centerline thrust only' limitation will be placed on the pilot certificate
Requirements
|
DCA
Hold a Private Pilot License
3 Light Load Landings 3 Full Load Landings Pass Practical Test ( Skills Test) |
FAA
Test can be done together with Private Pilot Skills Test
(Checkride) 10 Hours in areas listed here Pass Practical Test ( CheckRide) |
EASA
Hold a Private Pilot License
70 Hours PIC 2.5 Hours of Dual - Normal ops 3.5 Hours of Dual - Emergency Ops Pass Knowledge Exam Pass Practical Test ( Skills Test) |
Privileges
May exercise the privileges of Pilot-in-command of a multi-engine aircraft.
If aircraft weighs over 12 500 pounds - a valid type rating is required
If aircraft weighs over 12 500 pounds - a valid type rating is required
Coming soon
Subjects/Topics
Systems By Plane