Things I Will Not
Do in Multi-Engine Training

As I tell my multi-engine students, instructors cannot safely or accurately simulate an engine failure close to the ground in an airplane. That’s what simulators are for. I highly recommend multi-engine pilots seek out simulator-based training when they first transition to twin-engine types, then alternate between in-airplane and simulator-based training for recurrent and refresher training thereafter.

Instructors can, however, provide a somewhat gentler transition to single-engine operation, either fully feathering the propeller or into the “zero thrust” condition. Once in actual or simulated single-engine flight, we can accurately present single-engine operation, handling and performance, allowing the multi-engine pilot to experience the process from engine securing to single-engine landing. In other words, we can’t give you the full sensation of engine failure, but we can let you experience the process of flying the airplane to a single-engine landing, which NTSB history shows results in at least as many accidents in twin engine airplanes as failing to maintain control through the engine failure itself.

This all brings up the topic of how instructors may safely present the unique skills of flying a multi-engine airplane – the things we do, and in this context, more importantly, the things we will not do in a twin in actual flight. Typical safety protocols have changed over the years to reflect experience and trends in multi-engine instruction. Some of the inherent limitations of safe in-airplane instruction are now offset with the growing availability of Flight Training Devices (FTDs) and other simulators and regulators’ acceptance of these devices toward flight experience requirements.

As a pilot receiving instruction in a twin you discuss training safety protocols with your instructor before you fly. Unless you’re new to twins very often you will act as pilot-in-command and be legally responsible for the conduct and outcome of the flight. More importantly, safety during flight instruction is a team effort; you and the instructor work together to ensure learning occurs while risks are managed.

Obviously, the major difference between training in a single and instruction in a twin is the presentation of engine failures. Whereas in a single-engine airplane the options are naturally quite limited (and obvious), engine failures in a twin require different responses and decisions in different phases of flight. In some of the phases of flight – most notably takeoff – the risk of providing the training in the airplane outweighs the benefit. For that reason, many instructors impose limitations on their operations and instructors. Here’s what I (and many multi-engine instructors) will and will not do:

1. Minimum runway length: 4,000 feet. For accelerate/stop distance and in the event of a planned engine failure simulation on the runway, a minimum 4,000-foot runway works in most piston twins. The required runway may be longer at higher density altitudes.
2. Minimum runway width for simulating engine failure on the ground: 100 feet. Directional control is the skill to teach and learn if an engine fails during the takeoff roll. To provide a margin for under- or over-correcting, I require a runway at least 100 feet wide for a simulated engine failure on the runway.
3. Maximum speed for simulating engine failure on the ground: 40 knots. FAA guidance for instructors and examiners is that simulated engine failure on the ground should not be initiated at speeds more than 50 percent of the published VMCA speed for that aircraft. Apparently, the reduced inertia and therefore stopping distance at lower speeds offsets the lessened control authority at those speeds. Most piston twin VMCAs are around 80 knots, making 40 knots a good all-types limitation. Further, most original (analog) airspeed indicators become effective at 40 knots. This made an easy crosscheck for instructors: If there is any indicated airspeed at all, you’re too fast to simulate an engine failure.
   Note that VMCA (red radial) speed is a worst-case scenario for engine failure in the air (the subscript “A”). There is also a VMCG (for “ground”) that takes into account nosewheel steering and the nose tire’s resistance to turning. However, in the absence of a published VMCG in most piston twins, VMCA is usually the only guidance we have.
4. Minimum altitude for simulated engine failure after takeoff: 500 AGL/above field elevation. The rate of departure from desired flight path on all three axes (pitch, roll and yaw) is very great in a twin at low altitude. The operating engine is generating more thrust, so the effects of asymmetric thrust are greater. Even in turbocharged airplanes, there is less thrust at higher altitudes because of reduced propeller efficiency. What you see practicing engine failures at the FAA-suggested 5,000 feet AGL minimum altitude is much less dynamic than what you’d experience in a real-world engine failure on takeoff because at altitude the “good” engine is putting out much less power.
   Meanwhile, there is more drag on the “dead” side’s windmilling propeller in thicker, low-altitude air. If the gear is down the loss of airspeed is so great that you don’t even have time to retract the gear before it becomes critical – hence push the nose down, chop both throttles to idle to remove thrust asymmetry, and hold heading with rudder while you land straight ahead. If the gear is up you may be able to push and hold to remain at VYSE (“blue line”) while you address the engine failure and, if appropriate, feather the correct propeller. But you may climb very little or even lose some altitude while you do so.
   That’s why I do not initiate a simulated engine failure within 500 feet of the ground – to give you room for a possible loss of altitude during your response.
5. Single-engine go around minimum altitude: 500 AGL/above field elevation. Experience shows that it takes roughly 400 feet to turn a single-engine final approach descent into a single-engine go-around climb in many piston twins. As you apply full power on the operating engine and adjust controls for the change in asymmetric thrust, re-trim the airplane and retract the landing gear and flaps. The airplane will continue to descend before it slowly begins to climb at the very low rate of a piston twin on one engine. This is an exception to the rule “positive rate, gear up.” Most pistons and even some turboprops will rarely be able to climb at all on one engine with the gear extended. You need to retract the gear before seeing a positive rate of climb because you’ll never see it if you don’t retract the gear.
   This brings up another decision point: When landing on one engine (in a real-world engine failure), you are committed to land when either (1) you select full flaps (because of the substantially added drag and long retraction time) or (2) you descend below 500 AGL. If either (1) or (2) occurs, you may have to side-step and land on a taxiway or in the grass if something blocks the runway. But you have a very low chance of success if you attempt a single-engine go around.
   Personally, I use 800 AGL as a minimum single-engine go around altitude to provide a little margin. Unless the go around is done specifically for training (i.e., we’re simulating a single-engine landing and someone taxis onto the runway ahead of us, or we’ll land long or short, or we aren’t holding centerline without sideways drift), I’ll follow a prebriefed procedure with the student where we restore climb power to both engines and control the airplane into a two-engine climb.
6. No landing with a propeller feathered except in an actual emergency. There was a time when many multi-engine instructors would have the student feather a prop and then land. It’s a great confidence builder and many members enjoyed the experience. But there are no margins for error. And restarting a feathered propeller on the ground is difficult and stressful on the engine (that’s why the props have anti-feather lock pins for normal shutdown). So most multi-engine instructors limit themselves against actual one-engine landings – a personal minimum I fully support.
   I do, however, have the student land with an engine in zero thrust. This allows the pilot to experience the “rudder reversal” when reducing the operating engine to idle for landing. The rudder trim, set to counter the effects of asymmetric thrust, now yaws the airplane in the opposite direction. It also demonstrates the “float” and substantially longer landing distance on one engine, so much so I’ve always personally required at least 5,000 feet of pavement for a zero-thrust landing. This maneuver requires good pre-briefing and coordination between the instructor and student because to be effective the pilot must leave the “dead” engine in zero thrust and not reduce its throttle before touchdown (simulating the reduction in drag from a feathered prop). To be safe, the two must work as a crew to advance power on both engines in the event of that previously described real-world go around.

The reduction in drag from a feathered prop). To be safe, the two must work as a crew to advance power on both engines in the event of that previously described real-world go around.
I follow these personal minimums on presenting engine failures to protect you and your airplane. Multi-engine instruction is a very risky business, and I for one have a well-developed sense of self-preservation in addition to my concern for you and your airplane. As a pilot receiving instruction in your twin, I suggest you speak with your instructor to set similar boundaries before you fly.

If you want to practice more realistic engine failures during the takeoff roll and immediately after takeoff, that’s what simulators are for. In fact, if you have a favorite Flight Training Device-based or simulator-based training facility, let me know its name, location and contact information at mastery.flight.training@cox.net.