Multi-Engine Oral Exam Guide: Systems, Vmc And Engine-Out

The multi-engine add-on has no knowledge test, so the oral portion of the practical test carries the entire weight of the knowledge requirement. Expect two to three hours of questions concentrated on four subjects: the airplane's systems, V_MC, the critical engine, and what a light twin will and will not do with one engine out.

This page sets out those subjects in the order examiners tend to work through them, with the answers an examiner is listening for. The regulatory framework around the rating itself is on our multi-engine rating requirements page, and the airplane's published figures are on our Piper Seminole PA-44-180 page. Always check every number against the airplane flight manual for the specific airframe you are flying; the manual is the authority, not a website. Our multi-engine rating in Los Angeles is a seven-day course in the Seminole for $5,100, starting on a Monday with the checkride the same weekend.

Why This Oral Is Longer Than The One You Remember

Under 14 CFR 61.63(c) an added class rating requires no additional knowledge test if you already hold an airplane rating at that certificate level. Examiners are acutely aware that the oral is therefore the only point at which anyone verifies what you understand about twin-engine aerodynamics, and they compensate. A private pilot adding multi-engine typically sits a longer oral than they did for the private certificate itself.

The good news is that the subject matter is narrow. There is no weather theory dragnet, no airspace quiz, no regulations marathon. Almost everything asked falls into the sections below.

How The Day Is Structured

Knowing the shape of the day removes a surprising amount of anxiety, so here it is.

The examiner starts with paperwork: your certificate, medical, photo identification, logbook endorsements, the IACRA application, and the airplane's airworthiness and maintenance status. Nothing about flying happens until that is complete, and a missing maintenance record ends the day before it starts.

Then the oral, usually at a table with the flight manual open, running two to three hours. Expect it to begin with a real-world scenario rather than a quiz: you are taking two passengers and bags to Bakersfield this afternoon, show me the weight and balance, tell me whether we can go, and what happens if an engine quits at four hundred feet. Good examiners hang every technical question off that scenario, which is why a candidate who has actually worked the numbers for the day's flight is immediately ahead of one who has memorized a list.

After the oral there is a break, then the preflight inspection, in which you will be asked to explain systems while pointing at them, and then the flight. The flight is typically an hour to an hour and a half, and it ends with a single-engine approach to a full stop. Plan on being at the airport for the better part of a day.

The V-Speeds That Only Exist In Twins

Learn the blue line and the red line as reflexes. Blue line is what you pitch for when an engine quits; red line is the number you must not go below. The published V_MC figure for our Seminole is 56 KIAS, and you should confirm it against the flight manual for N311EF before your ride.

What Determines V_MC

This is the single most reliable question in a multi-engine oral. V_MC is not a fixed property of the airplane; it is a number established during certification under a specific and deliberately unfavorable set of conditions. Being able to list those conditions, and then say which way V_MC moves when each one changes, is the answer examiners want.

The published V_MC is determined with:

• the critical engine inoperative and its propeller windmilling, not feathered;
• the operating engine at maximum available takeoff power;
• the most unfavorable center of gravity, which is the aft limit;
• maximum certificated takeoff weight;
• flaps in the takeoff position;
• landing gear retracted;
• the airplane out of ground effect;
• trimmed for takeoff;
• up to 5 degrees of bank toward the operating engine.

Which Way Does V_MC Move?

The density-altitude answer is the one that separates candidates. At Van Nuys on a hot summer afternoon the density altitude can be several thousand feet, V_MC falls, and the stall speed does not. That matters because if V_MC falls below the stall speed, the airplane will stall before it loses directional control, and a stall with asymmetric thrust is how twins end up inverted. This is the reason the V_MC demonstration is recovered at the first indication of either loss of directional control or a stall warning, whichever comes first.

The Critical Engine, And Why The Seminole Has None

The critical engine is the engine whose failure most adversely affects the performance and handling of the airplane. On a conventional twin where both propellers turn clockwise seen from behind, it is the left engine, for four reasons that are worth memorizing as a group:

• P-factor. At a high angle of attack the descending propeller blade produces more thrust. On both clockwise-turning engines the descending blade is on the right-hand side of each engine, so the right engine's thrust line is further from the centerline. Losing the left engine leaves the longer moment arm working, which is worse.
• Accelerated slipstream. The right engine's thrust line being further out also means its slipstream acts over a longer arm, adding to the same asymmetry.
• Spiraling slipstream. The left engine's slipstream wraps around the fuselage and strikes the vertical stabilizer in a direction that helps counteract yaw. Lose the left engine and you lose that help.
• Torque. With the left engine failed, the torque reaction from the operating right engine rolls the airplane in the same direction as the yaw, compounding it.

The Seminole's propellers are counter-rotating: one turns clockwise, the other counter-clockwise, and each engine's descending blade is on the outboard side. The asymmetry disappears, and the Seminole has no critical engine. Say so, then explain the four factors anyway, because the examiner is testing whether you understand the mechanism or have simply memorized a fact about one airplane.

Identify, Verify, Feather

Every examiner has a preferred phrasing of the engine-out flow and they are all the same sequence. What they are checking is that you can do it without touching the wrong lever.

1. Control. Maintain directional control with rudder. Pitch for blue line, V_YSE. Bank roughly five degrees toward the operating engine.
2. Configure. Mixtures, propellers, throttles forward. Flaps up. Gear up. Establish the airplane as a clean, climbing machine before doing anything else.
3. Identify. Dead foot, dead engine. The foot that is doing nothing is on the side of the failed engine.
4. Verify. Slowly close the throttle on the engine you believe has failed. If nothing changes, you identified correctly. If the airplane's behavior changes, you did not, and you have just confirmed it safely.
5. Feather. Pull the propeller control on the failed engine to feather. Then secure the engine: mixture, fuel, magnetos, alternator, cowl flap, as the checklist directs.

Below a briefed safe altitude the drill stops at identify and verify, and the answer is to land straight ahead. Nobody feathers an engine at 200 feet on a training flight, and no examiner expects you to.

The Drag Demonstration

The drag demonstration exists to make one point physically rather than verbally: the things that produce drag cost you more, one engine out, than most pilots expect. Flown at a safe altitude, with one engine set to zero thrust, you show what happens to the airplane's ability to maintain altitude at V_YSE as you add, one at a time, a windmilling propeller, the landing gear, and full flaps.

The answer to the examiner's follow-up is that a light twin on one engine has very little excess power, and each of those items consumes a meaningful fraction of it. Drop the gear early on a single-engine approach and you may not be able to go around. That is not a theoretical point; it is the reason single-engine approaches are flown with the gear held until landing is assured.

Single-Engine Performance: The Real Answer

The question examiners use to find out whether you actually understand light twins is some version of: with one engine out, how much of your climb performance have you lost? The wrong answer is half. The right answer is roughly eighty percent or more of your excess power, because climb comes from the power available above what is needed for level flight, and losing one engine removes half the total power while the drag of the dead engine and the asymmetric control inputs add to what is required.

Then be ready for the follow-ups:

• Single-engine service ceiling. The altitude at which the airplane can still manage 50 feet per minute of climb on one engine, at maximum weight. On a hot day, this can be below the terrain.
• Where you find it. In the performance section of the airplane flight manual, and it is weight- and temperature-dependent.
• What it means departing Van Nuys. The San Gabriel and Santa Susana ranges are close and high. On a summer afternoon, a fully loaded light twin that loses an engine after takeoff is a drift-down problem, not a climb problem. Your departure briefing should say which way you will turn and where you will land.
• Accelerate-stop and accelerate-go distance. The runway needed to accelerate to a decision speed and then either stop, or continue on one engine. Know where both charts live and be able to work one.

Systems Questions To Expect

• Fuel. Tank arrangement, usable fuel, crossfeed: when you would use it, when you would not, and what the flight manual says about crossfeed in a climb or on takeoff.
• Electrical. Two alternators, one battery, what happens when one alternator fails, load shedding, and what the annunciators tell you.
• Propellers. How a constant-speed propeller works, how feathering works, what unfeathering accumulators do, and why there is a minimum speed below which a propeller will not unfeather in flight.
• Landing gear. Retraction and extension, the emergency extension procedure, the squat switch, and the warning horn logic.
• Deicing or anti-icing equipment if fitted, and what it does not do.
• Weight and balance. Work an actual loading for the flight you are about to make, including the aft CG case, because aft CG raises V_MC.

Answers That Cost Marks

Examiners rarely fail a candidate for not knowing one fact. They fail candidates for patterns, and these are the ones that show up in multi-engine orals.

• Reciting the V_MC conditions without understanding them. The list is easy to memorize and the follow-up question is always which way does it move and why. A candidate who can list nine conditions and cannot explain why an aft CG raises V_MC has told the examiner exactly how they studied.
• Saying half. Answering that losing one engine costs half your climb performance is the classic wrong answer, and examiners ask it precisely because it sorts the room.
• Treating the Seminole's lack of a critical engine as the end of the subject. You will fly conventional twins. Explain the mechanism.
• Quoting numbers from memory when the flight manual is on the table. Knowing a figure is good. Knowing where it lives, and opening the book to check it in front of the examiner, is better. That is the habit you want in the airplane.
• Guessing. The correct answer to a question you cannot answer is that you do not know, here is where you would look, and here is what I would do in the meantime. Guessing in an oral is a preview of guessing in flight, and examiners treat it that way.
• Having no plan for an engine failure on departure. If you cannot say, before you start the engines, what you will do if an engine quits at 300 feet off runway 16R, you have not briefed the flight.

How To Prepare In The Week Before

• Read the airplane flight manual cover to cover once, then re-read the systems and emergency procedures sections twice more.
• Write out the V-speeds from memory each morning until you stop making mistakes.
• Work three weight and balance problems, including one at the aft limit.
• Work an accelerate-stop and an accelerate-go distance for a hot Van Nuys afternoon.
• Say the engine-out flow out loud, touching the correct levers, in the parked airplane. Muscle memory beats recitation.
• Sit a mock oral with an instructor who did not train you. Different questions, different phrasing, no shared assumptions.

Related Reading

• Multi-engine rating requirements — 14 CFR 61.63(c), endorsements and certificate limitations.
• Piper Seminole PA-44-180 — published V-speeds, systems and performance figures.
• Accelerated multi-engine rating — the seven-day course and what to study before day one.
• FAA checkride: what to expect — how the practical test runs, start to finish.
• Multi-engine instructor (MEI) rating — teaching this material from the right seat.
• Multi-engine rating cost — the $5,100 breakdown and the examiner fee.

Multi-Engine Oral Exam FAQ

How Long Is The Multi-Engine Oral Exam?

Typically two to three hours. Because 14 CFR 61.63(c) requires no knowledge test for an added class rating, the oral is the only knowledge check in the process and examiners run it thoroughly.

What Is A V_MC Demonstration?

A required task flown at a safe altitude in which power is reduced on one engine and the airplane is slowed until either directional control begins to be lost or the stall warning activates. Recovery is at the first indication of either, by reducing power on the operating engine and lowering the nose to regain speed.

Why Does V_MC Decrease With Altitude?

Because the operating engine produces less power at higher density altitude, which reduces the asymmetric thrust the rudder has to counteract. The stall speed does not fall in the same way, which is why a V_MC demonstration at high density altitude may produce a stall first.

Does The Piper Seminole Have A Critical Engine?

No. The Seminole has counter-rotating propellers, so the descending blade of each engine is outboard and there is no asymmetry between them. You are still expected to explain P-factor, accelerated slipstream, spiraling slipstream and torque.

What Does Dead Foot, Dead Engine Mean?

With an engine failed the airplane yaws toward it, so you press the rudder on the side of the good engine to stay straight. The foot doing nothing is on the side of the failed engine. You then verify by slowly closing that throttle before touching the propeller control.

How Much Climb Performance Do You Lose With One Engine Out?

Roughly eighty percent or more of your excess power, not half. Climb depends on power available above the power required for level flight, and the dead engine adds drag while the asymmetric control inputs add more.

What Is The Drag Demonstration For?

To show physically how little excess performance a light twin has on one engine. Adding a windmilling propeller, the gear and full flaps in turn demonstrates how quickly the ability to hold altitude at V_YSE disappears.

What Should I Bring To The Oral?

Certificate, medical, logbook with the required endorsements, the airplane flight manual, the maintenance records or a maintenance status sheet, your completed application, and a weight and balance worked for the day's flight.

Prepare With An Instructor

We run mock orals with a second instructor as a standard part of the multi-engine course, and pilots training elsewhere are welcome to book one. Ground instruction is $110 an hour. To arrange one, or to talk about the seven-day accelerated multi-engine course, call (818) 330-1318 any day from 9 AM to 9 PM or book a free consultation. If you are not a pilot yet, a discovery flight is $229 for 60 minutes and is logged as dual instruction. We are at 7900 Balboa Blvd, Main Terminal Unit 108, Van Nuys, CA 91406.