TRANSITION TO A TWIN

By Mark Frankum

Are light multi engine aircraft gaining renewed appeal?  As fuel prices climbed during the post-2009 economic recovery, many aircraft owners and operators traded their light multi engine aircraft for more fuel efficient, high-performance singles. Many of these sophisticated singles deliver the speed the owners are looking for while sacrificing a certain amount of useful load, roominess, and perceived safety advantages. One obvious result of this paradigm shift is a very depressed market for light twins. Many light twins that might have fetched more than $250k before the market crash now sell for perhaps 60% of that former value.
Now, with Avgas prices tumbling nationwide, many are giving light twins a second look partly because the gap between the operating costs associated with a light twin versus the costs of operating a high-performance single is narrowing.  Sure, it’s still more expensive to operate a light twin, but with cheaper fuel many are reconsidering the advantages a light twin offers such as increased payload, range, climb performance, cabin space and the added margin of safety they might afford. The cost of admission is still cheap and the cost to play thegame just went down. Indeed, some flight schools are noting an uptick in multi engine training.
What about the safety advantage? Are light twins safer than light singles? Seems the answer is not so cut-and-dry. Some might say, “I like the added safety of two engines” while others insist “the only thing the second engine does is take you to the scene of the crash.”  Let’s consider the ubiquitous Beechcraft Bonanza versus the Beechcraft Baron. These airplanes share many of the same systems and the fuselages are nearly identical. The Model 58 Baron shares the A36 Bonanza’s fuselage. The Baron comes with an extra engine, two vacuum pumps, two alternators, and often flies off with a nicer avionics suite than the typical Bonanza.  Intuitively, we associate “extra” with “safer”. For many years insurance companies must have thought so too, and charged lower premiums for the twin. This seems to have changed, perhaps after they examined the loss rates a bit more closely. The result is now a general reluctance among insurance underwriters to insure light twins without increasing the training and pilot experience requirements In certain situations the extra engine may come with extra liabilities. These liabilities are most evident when we examine “loss of directional control following an engine failure” accidents, particularly on takeoff when light twins are most vulnerable. If, after an engine failure, the airspeed is allowed to fall below the single engine minimum controllable airspeed (Vmc), only prompt action can prevent the dreaded Vmc roll. Without question, the Bonanza fairs better than the Baron when it comes to fatal takeoff accidents simply because loss of directional control following and engine loss is far less common with the Bonanza. The inherent controllability issues when a twin experiences an engine failure on takeoff, and how well or badly the pilot handles the emergency, often determine the outcome. Sadly, statistics suggest over 80% of these “loss of control following and engine loss” accidents, in Barons specifically, involved some degree of pilot error or aircraft mismanagement rather than purely mechanical failures. The data seem to suggest errors such as selecting the wrong fuel tank or fuel pump mismanagement accounted for many of the engine failures in the first place. But all too often it was what happened after the engine failure that separated the quick from the dead. Turns out many of the aircraft that met a tragic end may have continued to fly had the pilot performed everything right, and performed it right then. The airplane should have been capable of continued flight – but the pilot was not.
One of the most important steps following an engine failure during a critical phase of flight (such as on takeoff) is getting the propeller of the inoperative engine feathered to reduce drag. Feathering stops the prop and twists the blades so the leading edges of the blades are faced into the relative wind as it comes to a stop. This greatly reduces the very substantial drag created by windmilling prop blades. With many light twin aircraft, a windmilling propeller will reduce the rate of climb by some 200-350 feet per minute, which may be beyond the aircraft’s performance capability on just one engine. When a twin engine aircraft loses an engine, it will lose about 80% of its rate of climb. This is because rate of climb is a function of excess horsepower, specifically horsepower in excess of the power needed to sustain level flight. An airplane with two, 200 horsepower engines has a total of 400 available horsepower. Perhaps 160 horsepower (about 40%) is required for level flight leaving 240 hp (60%) available for climb. If we lose an engine we are down to 200 hp leaving only 40 hp (20% of two-engine total power) available for climb. Thus we lose about 80% of our climb rate. Keep in mind it will be much more than an 80% loss of performance if the pilot fails to feather the prop on the inoperative engine. This 80% reduction in climb performance is best case and assumes we did everything right – and we did it right then.
A good friend of mine and fellow DPE with the Little Rock FSDO region, Rick De Angelo, may have summed it up with a simple corollary: “A multi engine aircraft on takeoff is like a team of horses pulling a wagon up a hill. If one of the horses suddenly drops dead, the remaining horse will have a tough time pulling the wagon up the hill while dragging a dead horse along. But if the teamster climbs down and cuts the harness away from the dead horse, the remaining horse stands a much better chance of pulling the wagon to the top of the hill.” What a simple and elegant analogy! A windmilling prop is like dragging a dead horse. We can cut away that dead horse by feathering.
The most important decisions a multi engine pilot must make must be made before the brakes are released for takeoff. This is usually incorporated into an abort plan briefing conducted just prior to takeoff. The pilot must have a clear, orderly flow of actions to accomplish in the event an engine fails at any point during the takeoff, whether still on the runway, at rotation, or during the initial climb. It is well to note that single engine climb performance must be calculated for each and every takeoff. As Kenny Rogers put it “you have to know when to hold them and know when to fold them”. To attempt continued flight when the performance charts clearly say it’s not possible is just foolish. Unfortunately, after liftoff we have precious little time to pull the performance charts out. Indecision can be deadly – we don’t have time to wait and see if it’s going to climb while we are trying to hold blue line airspeed. And we certainly won’t have time to get the checklist out. We must be well versed and current on the basic engine failure procedures. I doubt there a multi engine pilot alive who does not know the multi mantra: “5 ups” (mixture, props, throttle, flaps, and gear all up), identify, verify, feather, and secure. These are nine little words committed to memory that must be translated into actions we can do in our sleep in the event of an engine failure during a critical phase of flight such as take off. Assume it will happen on your next takeoff.  What are the chances this could happen on your very first solo flight in a twin? Read on.
I received an email yesterday from a gentleman that passed his multi engine check ride with me less than two weeks ago. He had just completed an accelerated multi engine course prior to the check ride and had recently completed type-specific training in his new Cessna 421. On his first solo flight in his Cessna 421 he experienced an engine failure due to a fuel system mechanical failure. Thanks to the skills he mastered during his training, the story has a happy ending. He managed the emergency well and landed uneventfully. I didn’t ask, but I suspect he might agree the outcome may not have been as pleasant had he been in his turbine single that night. I’m pretty sure the rate of climb his 421 can muster on a single engine is a lot better than the rate of climb his Jet Prop could maintain after an engine failure. Don’t even need to do the math to calculate those percentages. Multi engine airplanes, in certain situations, can be safer than singles.  Training, both initial and recurrent training can make the difference.
Transition (back) to Multi Engine Aircraft
Are light multi engine aircraft gaining renewed appeal?  As fuel prices climbed during the post-2009 economic recovery, many aircraft owners and operators traded their light multi engine aircraft for more fuel efficient, high-performance singles. Many of these sophisticated singles deliver the speed the owners are looking for while sacrificing a certain amount of useful load, roominess, and perceived safety advantages. One obvious result of this paradigm shift is a very depressed market for light twins. Many light twins that might have fetched more than $250k before the market crash now sell for perhaps 60% of that former value.
Now, with Avgas prices tumbling nationwide, many are giving light twins a second look partly because the gap between the operating costs associated with a light twin versus the costs of operating a high-performance single is narrowing.  Sure, it’s still more expensive to operate a light twin, but with cheaper fuel many are reconsidering the advantages a light twin offers such as increased payload, range, climb performance, cabin space and the added margin of safety they might afford. The cost of admission is still cheap and the cost to play the game just went down. Indeed, some flight schools are noting an uptick in multi engine training.
What about the safety advantage? Are light twins safer than light singles? Seems the answer is not so cut-and-dry. Some might say, “I like the added safety of two engines” while others insist “the only thing the second engine does is take you to the scene of the crash.”  Let’s consider the ubiquitous Beechcraft Bonanza versus the Beechcraft Baron. These airplanes share many of the same systems and the fuselages are nearly identical. The Model 58 Baron shares the A36 Bonanza’s fuselage. The Baron comes with an extra engine, two vacuum pumps, two alternators, and often flies off with a nicer avionics suite than the typical Bonanza.  Intuitively, we associate “extra” with “safer”. For many years insurance companies must have thought so too, and charged lower premiums for the twin. This seems to have changed, perhaps after they examined the loss rates a bit more closely. The result is now a general reluctance among insurance underwriters to insure light twins without increasing the training and pilot experience requirements.
In certain situations the extra engine may come with extra liabilities. These liabilities are most evident when we examine “loss of directional control following an engine failure” accidents, particularly on takeoff when light twins are most vulnerable. If, after an engine failure, the airspeed is allowed to fall below the single engine minimum controllable airspeed (Vmc), only prompt action can prevent the dreaded Vmc roll. Without question, the Bonanza fairs better than the Baron when it comes to fatal takeoff accidents simply because loss of directional control following and engine loss is far less common with the Bonanza. The inherent controllability issues when a twin experiences an engine failure on takeoff, and how well or badly the pilot handles the emergency, often determine the outcome. Sadly, statistics suggest over 80% of these “loss of control following and engine loss” accidents, in Barons specifically, involved some degree of pilot error or aircraft mismanagement rather than purely mechanical failures. The data seem to suggest errors such as selecting the wrong fuel tank or fuel pump mismanagement accounted for many of the engine failures in the first place. But all too often it was what happened after the engine failure that separated the quick from the dead. Turns out many of the aircraft that met a tragic end may have continued to fly had the pilot performed everything right, and performed it right then. The airplane should have been capable of continued flight – but the pilot was not.
One of the most important steps following an engine failure during a critical phase of flight (such as on takeoff) is getting the propeller of the inoperative engine feathered to reduce drag. Feathering stops the prop and twists the blades so the leading edges of the blades are faced into the relative wind as it comes to a stop. This greatly reduces the very substantial drag created by windmilling prop blades. With many light twin aircraft, a windmilling propeller will reduce the rate of climb by some 200-350 feet per minute, which may be beyond the aircraft’s performance capability on just one engine. When a twin engine aircraft loses an engine, it will lose about 80% of its rate of climb. This is because rate of climb is a function of excess horsepower, specifically horsepower in excess of the power needed to sustain level flight. An airplane with two, 200 horsepower engines has a total of 400 available horsepower. Perhaps 160 horsepower (about 40%) is required for level flight leaving 240 hp (60%) available for climb. If we lose an engine we are down to 200 hp leaving only 40 hp (20% of two-engine total power) available for climb. Thus we lose about 80% of our climb rate. Keep in mind it will be much more than an 80% loss of performance if the pilot fails to feather the prop on the inoperative engine. This 80% reduction in climb performance is best case and assumes we did everything right – and we did it right then.
A good friend of mine and fellow DPE with the Little Rock FSDO region, Rick De Angelo, may have summed it up with a simple corollary: “A multi engine aircraft on takeoff is like a team of horses pulling a wagon up a hill. If one of the horses suddenly drops dead, the remaining horse will have a tough time pulling the wagon up the hill while dragging a dead horse along. But if the teamster climbs down and cuts the harness away from the dead horse, the remaining horse stands a much better chance of pulling the wagon to the top of the hill.” What a simple and elegant analogy! A windmilling prop is like dragging a dead horse. We can cut away that dead horse by feathering.
The most important decisions a multi engine pilot must make must be made before the brakes are released for takeoff. This is usually incorporated into an abort plan briefing conducted just prior to takeoff. The pilot must have a clear, orderly flow of actions to accomplish in the event an engine fails at any point during the takeoff, whether still on the runway, at rotation, or during the initial climb. It is well to note that single engine climb performance must be calculated for each and every takeoff. As Kenny Rogers put it “you have to know when to hold them and know when to fold them”. To attempt continued flight when the performance charts clearly say it’s not possible is just foolish. Unfortunately, after liftoff we have precious little time to pull the performance charts out. Indecision can be deadly – we don’t have time to wait and see if it’s going to climb while we are trying to hold blue line airspeed. And we certainly won’t have time to get the checklist out. We must be well versed and current on the basic engine failure procedures. I doubt there a multi engine pilot alive who does not know the multi mantra: “5 ups” (mixture, props, throttle, flaps, and gear all up), identify, verify, feather, and secure. These are nine little words committed to memory that must be translated into actions we can do in our sleep in the event of an engine failure during a critical phase of flight such as take off. Assume it will happen on your next takeoff.  What are the chances this could happen on your very first solo flight in a twin? Read on.
I received an email yesterday from a gentleman that passed his multi engine check ride with me less than two weeks ago. He had just completed an accelerated multi engine course prior to the check ride and had recently completed type-specific training in his new Cessna 421. On his first solo flight in his Cessna 421 he experienced an engine failure due to a fuel system mechanical failure. Thanks to the skills he mastered during his training, the story has a happy ending. He managed the emergency well and landed uneventfully. I didn’t ask, but I suspect he might agree the outcome may not have been as pleasant had he been in his turbine single that night. I’m pretty sure the rate of climb his 421 can muster on a single engine is a lot better than the rate of climb his Jet Prop could maintain after an engine failure. Don’t even need to do the math to calculate those percentages. Multi engine airplanes, in certain situations, can be safer than singles.  Training, both initial and recurrent training can make the difference.