Multi Engine Rating transitioning to twins

Multi Engine Rating Transitioning to Twins

In 2011, I bought myself a big fat expensive christmas present.  I’ve been a private pilot since I was 16 and I felt like it was time to add a couple of additional ratings to by green plastic card, including a multi engine rating, so I signed up for a week of flight training at Sheble Aviation at the Alpha 20 / Sun Valley Airport in Arizona.

Currently I’m a private pilot with an instrument rating in airplanes and I also have a private helicopter rating.  I’ve got about 750 hours, most of it taildragger time from when I used to live in Alaska, but I’ve been busy doing other things for the last 10 years or so and I really haven’t been flying that much.

I recently bought a share in a Cessna 182 and I’m getting used to the added work load of flying in congested airspace in California — which is pretty different from the uncontrolled gravel strip that I used to fly from in Alaska.

Most of the places that do multi engine rating training are set up for airline pilot career training and I’ve been in and out of those places over the years.  There’s an FBO and aviation academy near where I live and the students in the aviation school all run around in make believe airline pilot uniforms, which seems kind of silly when you are flying around the pattern in a 152.   However, if you are in the market for an airline job, this is also a really good place to start because I personally know a lot of corporate and commerical pilots who have gotten more than just their multi engine rating from Sheble over the years.

I picked Sheble Aviation because for my multi engine rating because a lot of pilots that I know in my part of California have been down there to get their multi engine rating, and to be honest, I sort of liked the look of the place online.  Their advertising and marketing materials makes it look like a multi-generational family with a bunch of cool airplanes teaching people how to fly in the desert.  Their most charismatic airplane is their twin beach on floats, but I’m going to save that for another time.

I’m going to take you through what I did to prepare for my multi engine rating training in the desert and what happened on a day by day basis as we go through the process of getting a multi engine rating from Sheble Aviation.

Before I left for Arizona I studied for this course using 4 resources:

  • The good ole’ WWW
  • Sporty’s Video So You Want to Fly Twins
  • The ASA softcover book called Transitioning to Twins
  • And the stuff published online by Sheble Aviation

These days, if you’ve got a question, type it into the google search bar and you’ll be amazed at what you come up with.  Want to know how to do a Chandelle, there’s a YouTube video for that.  Not clear on Accelerate and Go versus Accelerate and Stop Distances?  There’s plenty of information out there.  On this site, I’ve published my take on Sheble’s training information, but remember, YOUR flight instructor always has the last word.  Well….maybe not the last word…that’s for the FAA.

Since we are on the subject of the FAA, one of the things that you can get free on the internet is a copy of the FAA’s practical test standards for your multi engine rating checkride.  I’ve got a copy in a PDF format that you can download by clicking on the following link and this will give you a good idea of what to expect from your multi engine rating training.  These days, expect your examiner to use this as a multi engine rating checklist when you go for your check ride so make sure that you are more than familiar which the description of each of the tasks that you will need to complete.

FAA PTS PRIVATE

FAA PTS COMMERCIAL

Home study materials

Here’s my review on Sporty’s video So You Want to Fly Twins.  Buy It!  It is 70 bucks which seems a little steep in a era of Napster, BitTorrent, and iTunes, but compared to the cost of twin engine flight instruction, its worth it.  Its about an hour and a half long and it does a really good job of going over all of basics of what is going to be expected of you during your transition training.

This video is available as a download from the Sporty’s Pilot Shop site with this link http://www.sportys.com/pilotshop/product/13657 and it comes as a MPEG that you can view on your computer or iPad.  I watched it twice before I left for Arizona and I give it a thumbs up.

Multi Engine Rating

Transition to Twins by ASA publications.  ASA must be making a mint off flight training because if there is a subject that needs to be covered during the process of becoming an airline pilot, ASA has a publication for it.  This book is written by an Australian named David Robson who is an ex military fighter pilot and a former head of the Australian Aviation College.  His entire career after the military was devoted towards training future airline pilots so if you are heading for a job with the major carriers, this is for you.  The book is well written, concise, and the pictures are clear.  It has a good explanation of asymmetrical thrust forces and Vmc and between this and the Sporty’s video, I figured I was prepared.

transition to twins

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What do you need to bring to Sheble Aviation?

Sheble Aviation

sheble aviationSheble aviation is a by the book operation so its worth taking a bit time to get everything organized before you head to alpha 20.  Here’s a minimum list of what you will need to show up with:

ALL of your logbooks
Current medical certificate – Class 2 if you are taking a commercial checkride
Pilot’s license
Driver’s License or some form of government issued photo ID
Passport or Birth Certificate to prove that you are a US citizen.
Cash!  Each checkride that you are planning to take is going to cost you 500 US dollars in cash which is not included in your course fee.  There are banks in the area, but you are going to be busy and the last thing you want to do is drive around looking for ATMs in the middle of the night so go to the bank before you leave.  Put your 500 dollars cash in an envelope.  Designated pilot examiners take their jobs very seriously and I think that its a sign of respect to give them their payment in cash in an envelope.

Here are a few things that I think you should do before you go to Sheble aviation as well:

Take your knowledge tests before you go.  If you are going to make the most of your time at Sheble aviation in Arizona, you’ll want to be flying, not sitting in a classroom taking tests.  Get the knowledge tests out of the way before you go, so that you can maximize the use of your time in Arizona.  Plus, I find that flight instructors take you more seriously when you show up ready to fly.
Create an IACRA account with the FAA.  follow this link https://iacra.faa.gov/iacra/ to the FAA website for computerized processing of new certificates and applications.  Create a username and a password and write them down somewhere where you won’t lose them — like the inside of your logbook.
Get really familiar with the FAA form 8710 — especially the flight hours section of the form.  You can click on the link below to get a PDF copy of 8710 that you can print out before your check ride.

FAA 8710

If you are serious about flight training, one of the best things that you can do to keep track of your time accurately is to buy a copy of Log 10 Pro and transfer all of your flight hours.  Log 10 pro is an electronic log book that runs on macs and ipads and can be downloaded from the app store.  For more information, visit www.coradine.com.

Making an electronic copy of your log books is a major pain if you’ve got a lot of time, but at least you’ll have a complete copy in case you ever loose your log books.  Log 10 Pro will then spit out a completed 8710 flight hours form which saves a lot of hassle in terms of adding up a bunch of .6 and .8 hours.  Here’s a screenshot of Log 10 Pro’s menu for all the different forms you can export your time in, and a screenshot of my completed FAA 8710 that I printed out before I left for Arizona.

I love Log 10 pro.  It makes it really easy to correct any mistakes that you have made in the way that you categorized your time and if you put the correct airport identifiers in the program it will automatically calculate the straight line distance for cross country flights for you.

Log 10 Pro flight tracking  Log 10 FAA 8710  LOG-10-PRO-FAA-8710

If you go through your logbooks really carefully before you leave for Sheble aviation, you’ll save yourself a lot of time and you’ll be sure that you meet all of the aeronautical experience requirements before you show up.  This isn’t that critical for the multi-engine check ride, but it is REALLY IMPORTANT if you are taking a commercial check ride at the same time.

For example, the commercial airplane single engine land checkride specifies that you must have one cross-country flight of not less than 300 nautical miles total distance, with landings at a minimum of three points, one of which is a straight-line distance of at least 250 nautical miles from the original departure point.

The best way to demonstrate that you have this requirement met, is to go to skyvector.com and put in the flight with the correct take off and landing points and print out a copy of the screen shot.  For example, here is a screen shot of a flight that I used to meet my long cross country flight experience.  I printed this out and gave it to my instructor at the beginning of the check in process to show that I had the required flight experience.  (click on the image to enlarge it).

flight training cross country

Finally, get a REALLY good headset.  It is a proven medical fact that exposure to noise increases your sense of fatigue and slows your reaction times.  Check my references, this data is real!  I personally use a Lightspeed Zulu headset with active noise reduction.  This headset is comfortable, the noise reduction works really well, and while it is an expensive headset at 900 bucks, in my opinion it is really worth it.

Lightspeed ZULU headset

 

References
__________________________________________

Fatigue after work in noise – an epidemiological survey study

Published in Noise and Health, 1988.

The contribution of noise exposure to fatigue at work was studied in a survey study and three field studies. The survey study was based on a questionnaire covering symptoms and work place exposure answered by 50 000 state employees. Noise exposure was also estimated from their type of job and self-rated noise exposure. Fatigue and headache were found to be more common among the noise exposed groups even after control for the effects of other critical variables. Study 2 compared reaction times before and after a week’s work in high noise exposure and one in low exposure exposure in a group of aeroplane mechanics. Reaction times were prolonged after work in the noise week, whereas an opposite trend was seen in the control week. Study 3 showed a gradual increase of reaction times during a week of noise exposure in a group of aeroplane technicians. Study 4 compared reaction times and subjective fatigue among naval crews on a day with low and a day with high noise exposure. In one of the studied boat types the development of fatigue during the work day was accentuated on the day with high exposure.

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Beechcraft Travelair

The Beechcraft Travelair

On Sheble’s website, they have a pdf document that helps you prepare for flying the Beechcraft Travelair BE-95 Light Twin.  For the sake of this website, I’ve taken that document, cleaned it up, and added to it, so I can use it during my training.

Here are the basics….The Beechcraft Travelair is a light twin-engine airplane that has the same basic fuselage as the Beechcraft Bonanza.  It fills the gap between the Model 35 Bonanza and the much bigger Model 50 Twin-Bonanza.  Beechcraft airplanes are well built, and in their review of twin engine accidents, aviation consumer found that Barons (as compared to Cessna 310s and 421 and Aztec Apache/Navajo airplanes) had the fewest maintenance-related crashes — indicating that the airplanes are well-built and don’t break much.

Beechcraft Travelairmulti engine ratingtwin engine instruction

The Beechcraft Travelair is one of those airplanes that sort of illustrates the adage about light twins: Two engines double the changes that something will fail, and when it does, the remaining engine only has enough horsepower to carry you to the site of the accident.  In a recent review of 545 accidents in light twins, aviation consumer (http://www.avweb.com/news/safety/185267-1.html) concluded the following:

  • Having reviewed the accident database, we conclude what most rational owners already know: A well-maintained twin with a current, well-trained pilot is probably safer than a single, provided it isn’t flown over gross weight. The safety accrues, of course, from an additional engine with dual vacuum pumps and dual alternators.
  • If one engine fails, a competent pilot has real, not illusory, options by having meaningful backup systems to fill in until the airplane can be landed safely on one engine. The accident record seems to suggest that a pilot who’s overtaxed by a system or engine failure is less likely to survive in a twin than in a single.
  • For that reason, in our view, on safety issues alone, an owner contemplating upgrading to a twin shouldn’t consider the proposition unless there’s enough money in the kitty to maintain the airplane to the highest reasonable standards and to both fly often and train often. To do less probably results in an overall reduction in safety.

Sheble is a bit more brief.  Their multi-engine preparatory information states that in general,

  • Light twin are typically more complex, but not excessively.
  • They require more cockpit management tasks and memorized procedures, especially engine out procedures.

However, in the hands of an appropriately trained and competent pilot, the increased performance and the ability to maintain level flight and climb under certain conditions does increase the margin of safety.  Their opening line is as follows: Those multi-engine pilots who do not know the engine out procedure off hand or have a lackadaisical attitutude toward the procedure are not competent multiengine pilots.  KNOW THE PROCEDURE.

Since we are in fact preparing for a checkride in this process, I read over the Sheble’s information and added to it by researching some of the specifics on the Travelair on line.

The Fuel System

There are 4 tanks in the Beechcraft Travelair, with a total capacity of 112 gallons.  Fuel burn for rough calculations is 20 gallons per hours total, 10 per side.  There are 4 fuel pumps, 2 that are engine driven and 2 electrical boost pumps and 8 fuel drains.  The 8 drains are for the following components of the fuel system:

  • 4 tanks (2 main and 2 aux) with a drain each =’s 4 drains
  • 2 crossfeed drains
  • 2 low point drains

The fuel system on twin engine aircraft does require particular attention during the transition period.  There are a surprisingly large number of twin engine aircraft crashes related to a basic misunderstanding of the fuel system.  To quote, “some pilots kill themselves by simply not understanding the aircraft systems, chiefly the fuel plumbing. Mismanaging fuel crossfeed during single-engine drills can turn a ho-hum proficiency exercise into a genuine no-engines survival struggle. It seems obvious that if a pilot loses one good engine due to fuel mismanagement, he stands a good chance of losing the other when trying to right the situation.”

So, If you are in need of a more complete description of the Beechcraft Travelair fuel system, here is what I learned online….

The Beechcraft Travelair fuel system consists of a separate identical fuel supply system for each engine. Each wing contains one Main tank and one Auxiliary tank (Aux.)  The fuel tanks are lined with a rubberized fuel cell. These cells are quite sturdy under normal service conditions but care must be taken to avoid puncturing the cell. Do not use a dipstick to check fuel quantity; instead perform a visual check and crosscheck with the fuel gauges and fueling records to determine the amount of fuel onboard. The Main tanks are particularly easy to check visually.

The auxiliary tanks slope, due to the wings dihedral, so that no fuel is visible at the filler neck when the tank’s quantity drops below ¾ full.  Each fuel tank is filled through its own filler neck. The fuel caps have O-rings to prevent water from entering the tanks. All fillers must be checked to confirm they are securely closed before flight.  The Main fuel tanks hold 25 US-gallons with 22 gallons useable. The Main tanks must be used for all takeoffs and landings. Main tanks should normally also be selected when performing special flight maneuvers such as stalls.

The Auxiliary tanks hold 31 US-gallons with all 31 useable. The auxiliary tanks may be used in normal climbs, cruise and descents. Auxiliary tanks should not be used when performing steep turn, slips, stalls, or other unusual maneuvers unless they are at least ¾ full.

Fuel quantity is measured by a float type transmitter unit in each tank that sends a signal to fuel gauges on the Power gauge panel (see below.) There are two fuel gauges, controlled by a two-position switch on the Pilot sub-panel.  The switch can be set to Main or Aux and displays the quantity of the two main tanks or the two auxiliary tanks respectively.

Each engine has an engine-driven fuel pump driven by the engine accessory box. The engine-driven fuel pump supplies sufficient fuel to the engine for full power operation.

An electric boost pump for each engine supplies fuel pressure for starting and provides for near maximum engine performance should the engine driven pump fail. The electric boost pumps are used to prime the engine for starting and in emergencies, and should be used for takeoff and landing. In extremely hot weather they should be employed for all ground operations, takeoff, climb, and landing.

The electric boost pumps are located in the fuel lines between the fuel cells and theand the engine such that fuel may be drawn from any tank using the boost pumps.  — and here’s a picture..(click to enlarge)

multi-engine-fuel-system

The Electrical System

The Beechcraft Travelair has a 28 vol system with 2 12 volt batteries in series to create a 24 volt system.   The battery is recharged by two belt driven 55 amp alternators.  The two electrical system supplies two separate bus bars (and in case you want a full definition, a bus bar is a strip of copper or aluminium that conducts electricity within a switchboard, distribution board, substation or other electrical apparatus), one that distributes 12 volts for the avionics and the other that sends 24 volts to the other electrical equipment including the flaps, gear, and lights.

The Landing Gear

The landing gear on the Beechcraft Travelair is all electric.  It is an electrically operated tricycle landing gear operated through push-pull tubes by a reversible electric motor and actuator gearbox under the front seat. A two-position landing gear switch located on the right hand side of the center console controls the motor. Limit switches and a dynamic braking system automatically stop the retract mechanism when the gear reaches its full up or full down position.

Aviation consumer notes that in their analysis of twin engine accidents the Beech Baron series has a dramatically higher number of gear-up and inadvertent gear retractions than do the other models. This is due in part, in our view, to the fact that in the early models, Beech put the gear switch to the far right and the flaps on the left, the reverse of the industry standard.

We also noted that the more complex twins — the Cessna 421 and Cessna 310 — seem to have a larger percentage of maintenance-related accidents than do other models. The Apache/Aztec series shared this dubious distinction, perhaps more due to aging airframes than complexity.

Propellers

The Beechcraft Travelair has full feathering hartzell propellers.  High oil pressure drives the props to a flat pitch / high RPM position, whereas complete loss of oil pressure will drive the props to the feather position.  When the engine RPM drops below 800, locking pins prevent the props from feathering when the oil pressure drops at engine shut down.  This is so that the next time the engine starts it doesn’t have to push a feathered blade around in a circle, adding to the resistance of getting the engine going and creating a lot of vibration.

A nitrogen driven oil accumulator on each engine contains a reserve of pressure that will allows the props to be unfeathered inflight during a restart procedure.  This accumulator is necessary because during unfeathering, there is no oil pressure from the engine to drive the prop to a flat pitch so energy stored in the form of compressed nitrogen gas is used to change the angle of the blades.

Vacuum pumps

  • Each engine has its own vacuum pump for the gyroscopically driven flight instruments.

Hydraulic systems and Flight Controls

  • The brakes and the propellers are hydraulically actuated.
  • Primary and secondary flight controls are all standard pulley and cable connections

And the Beechcraft Travelair has the usual panel layout for an older steam gauge airplane.

The POH for a twin engine has got a couple of new items, and for the sake of a review, I collected a list of all of the V speeds that I’ll need in order to pass this checkride.  The list of appropriate V speeds for twin engine training is as follows, and I’ve got in a pdf document that you can print out and fold in half and slip inside a normal Jepp chart protector

Va     Maneuvering Speed is the maximum speed which you may use abrupt control travel.
Vfe    Maximum Flap Extended Speed is the highest speed permissible with flaps extended.
Vle    Maximum Landing Gear Extended Speed
Vlo    Maximum Landing Gear Operating Speed max speed at which the gear position may be changed.
Vno    Maximum Structural Cruising Speed is the speed that should not be exceeded except in smooth air, then only with caution.
Vne    Never Exceed Speed is the speed limit that may not be exceeded at any time.
Vs   Stalling Speed or the minimum steady flight speed at which the airplane is controllable in cruise configuration.
Vso    Stalling Speed in the landing configuration at the most forward CG
Vx    Best Angle of Climb Speed is the speed that results in the greatest gain of altitude over distance.
Vy    Best Rate of Climb Speed is the speed that results in the greatest gain of altitude in a given time.
Vxse    Best Angle of Climb Speed on Single Engine.  Failed engine is feathered.
Vyse    Best Rate of Climb Speed on Single Engine.  Failed engine is feathered.  (BLUE LINE)
Vmc    Minimum Single Engine Control Speed: see this link Vmc explained
Vsse    Intentional One Engine Inoperative Speed

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Aircraft Procedures and Checklists

Aircraft Procedures and Checklists

I like checklists, so I went through the pre-course study material and collected all of the checklists and emergency procedures and organized them in a Aircraft Procedures and Checklists pdf document.  This document is sized so that you can print it in landscape mode, fold it in half, and slip it inside a standard 7 ring Jeppensen approach plate protector.  All of the airspeeds in this guide were in MPH (presumably because the airspeed indicator in their beech is in MPH as well) but when I get back I’ll probably edit this and add a KIAS version as well.

BE 95 CheckList

The first page is the a/c data sheet, which lists all of the relevant data that you would get asked in a BFR or checkride situation about this airplane.

Aircraft Procedures and Checklists

The second page is a tabulated form of all of the procedures that are scattered through their online version of the POH.

And finally, I have a little program for taking the weight and balance data for an aircraft and putting it into microsoft excel so that you can plug in various different parameters and it will automatically graph where the center of gravity is with respect to the published limits.  This excel spreadsheet can be dowloaded by clicking here: BE 95 Weight and Balance Worksheet

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Twin Engine Airplane – Flying On One Engine

Twin Engine Airplane

It doesn’t take long to realize that most of the challenge of learning to fly a twin engine airplane is learning how to do it on one engine.  Compared to a single engine aircraft, the engines of a twin (with the exception of centerline thrust twins like the Cessna Skymaster) are not on the centerline of the aircraft.  Therefore, when only one engine is operating, the twin engine airplane is in an unbalanced, and potentially unstable state.  Here’s a picture of a skymaster — and if you learn to fly a twin engine airplane in one of these your license will be limited to centerline thrust configurations only, versus a twin engine airplane with conventional displacement of the engines out on the wings.

Twin Engine Airplane

twin engine rating

 

The Beechcraft travelair that I’ll be flying for this check ride does not have counter-rotating propellers.  Viewed from behind, both props turn to the right.  This is important because in a climb attitude, the descending prop has a larger angle of attack with respect to the relative wind than the ascending blade — taking a bigger bite of air — and therefore displacing more air towards the rear of the airplane.  This results in 4 main factors that become important when only one engine is turning:

  • The engine on the right has a greater lever arm about the Yaw Axis because the center of thrust is further from the centerline of the aircraft (P-Factor)
  • The accelerated slipstream created by engine on the right creates an area of increased lift over the wing that is also further from the centerline of the aircraft
  • The accelerated slipstream created by the engine on the right is further from the rudder so the rudder has less authority
  • The counter torque produced by the engine on the right adds to the rolling moment caused by the increased lift of the right wing

These four factors make the left engine the critical engine: IF THE LEFT ENGINE FAILS, YOU ARE IN A MORE CRITICAL SITUATION THAN IF THE RIGHT ENGINE FAILS, because the airplane is more unstable and difficult to control.

Lets go through each of these points one by one, with a few illustrations.  First a review of p-factor.  The Wikipedia consensus statement on P-factor reads something like this: When an aircraft is in straight and level flight at cruise speed, the propeller disc will be perpendicular to the airflow vector. As airspeed decreases and wing angle of attack increases, the engines will begin to point up and airflow will meet the propeller disc at an increasing angle, such that descending blade will have a greater angle of attack and relative wind velocity and therefore increased thrust, while the ascending blade will have a reduced angle of attack and relative wind velocity and therefore decreased thrust. This asymmetry in thrust displaces the center of thrust of the propeller disc towards the blade with increased thrust, as if the engine had moved in or out along the wing.

You can click on all of these figures to enlarge them to read my notes.

P factor twin engine

Seen from above, the situation looks something like this….on the starboard engine, the descending blade creates an accelerated slipstream outboard of the engine.  The increased velocity of the airflow over the wing creates a localized area of increased lift that wants to lift the right wing.  Also, in a conventional centerline vertical stabilizer and rudder configuration, this accelerated airflow is further from the rudder, decreasing its authority.  Ever wondered why airplanes are designed with multiple vertical stabilizers right behind the engines (like the Lockheed Electra in this illustrations) — Now you Know.

twin engine accelerated slip streamHere is a picture of a typical twin engine airplane with a centerline vertical stabilizer and rudder.  In this example you can see that the accelerated slip stream is 3 to 4 times further from the centerline of the aircraft on the right side than it is on the left side.  This has a significant effect on rudder authority at slow speeds when the relative proportion of airflow over the flight control surfaces produced by the wash from the propeller increases.

centerline rudder adverse yaw

Torque Roll.  If you remember back to your high school physics class on Newtonian motion, you’ll recall that for every action there is an equal and opposite reaction.  When a combustion engine turns a propeller in a right hand direction, the propeller tries to turn the aircraft in a left hand direction.  On the right side of the aircraft the torque effect increases the rolling tendency to the left since it reinforces the rolling tendency created by the asymmetric lift produced by the right wing.  On the left side (when the right side engine is inoperative) the torque also tries to roll the aircraft to the left, but this is counterbalanced by the right rolling tendency created by the accelerated slip stream over the left wing.

multi engine trainingSo here is an illustration of our one engine out scenario.  The Critical left engine has failed and the aircraft is yawing to the left and rolling to the left.  The accelerated slip stream is far from the centerline of the aircraft so the vertical stabilizer and rudder have less authority.

twin engine adverse yaw

Seen from behind the situation looks like this.  The left engine is out, the aircraft is banked to the left and yawing to the left as well.

Corrective maneuvers

The moves that we make to correct this situation do two things:

1.  They set the aircraft up for optimal performance.

2. They help identify the dead engine.

The flight attitude that we are trying to achieve is a “zero-side slip” attitude.  If the engine out attitude is corrected only with rudder inputs, the aircraft will slip towards the inoperative engine, decreasing climb performance.  This will occur even if the ball is centered on the turn coordinator.  The result of wings level flight with an inoperative engine is described as a moderate sideslip towards the inoperative engine. Climb performance will be reduced and Vmc will be significantly higher than published as there is no horizontal component of lift available to help the rudder combat asymmetrical thrust.

If the engine out attitude is corrected only with aileron inputs, there will be a significant bank towards the good engine, resulting in a large sideslip towards the operating engine.  This sideslip will also decrease climb performance and increase Vmc.  The solution is a combination of rudder and ailerons.  2-3 degrees of bank towards the good engine and rudder inputs to center the ball with the reference line on the side of the operative engine.  The exact combination of rudder and aileron input varies from model to model and also with flap and gear settings and with airspeed.  Unfortunately, there is no instrument inside the cockpit to tell when you have achieved a zero side slip configuration, but one can be made by taping a yaw string to the windshield (before the flight!) for training purposes.

zero side slipzero side slip

Zero side slip configuration.  2-3 degrees of bank towards the operative engine, rudder inputs to center the ball with the reference line on the operative side.  If you’ve got any time in gliders you are probably familiar with a yaw string.  It is basically the only way to tell directly if the airflow is flowing along the longitudinal axis of the airplane and therefore minimizing drag.  Here’s a picture of a centered yaw string, and surprisingly enough, a picture of a yaw string on the nose of an F14 that I found on the web.  Who would have thought that the pro’s would need a piece of yarn to help them with out?

yaw string glider  yaw string F14

I said earlier that our corrective maneuvers would also help us identify the dead engine.  The mantra goes something like: “Dead Foot, Dead Engine”, or “Idle Foot, Idle Engine”.  Because we are concentrating on flying the aircraft, our rudder input to stop the yaw will occur on the same side as the operative engine.  Left engine out requires right rudder, right engine out requires left rudder.  You get the idea.  Once we’ve figured out, and called out, “Left Foot Idle, Left Engine Out”, we can go through our checklist for dealing with an engine failure.

Sheble has their checklist organized into a 3 step process: POWER UP, CLEAN UP, and FEATHER.

First POWERUP.

If this engine is going to fail, it is probably going to do it when we’ve just rotated on a short field and are slow and heavy.  We’re going to go to Mixtures RICH, FULL PITCH on both props, and FULL POWER on both engines.  Now that we are at a maximum performance power setting, we’ll clean the airplane up for minimal drag and best climb performance.

Next CLEANUP

BOOST PUMPS ON, FLAPS UP, GEAR UP.  Okay, so far so good.  Airplane is clean and flying.  We’ll pitch for the blue line in order to achieve best climb single engine operative.

Finally, FEATHER

The last thing that we can do is minimize the drag caused by the windmilling propeller.  Remember that a windmilling propeller has the flat portion of the blade perpendicular to the airflow which creates a lot of drag.  We want to rotate the prop blades such that they are parallel to the airflow, minimizing drag.  The most important thing about this maneuver is to do it on the INOPERATIVE ENGINE.  It is super embarrasing to have an engine failure and then shut down the good engine by mistake.  The three step process for feathering is to Identify, Verify, and Feather.  Once again, we’ll want to call out, “left foot dead, left engine out”, but we’ll verify that by pulling back on the left throttle control.  If performance suddenly tanks, we’ve probably pulled back on the wrong throttle control.  But if there is no change to the way the airplane feels and flys, we’ll pull the prop control back to the feather position on the dead engine.

The checklist goes something like this (and can be downloaded in pdf format by clicking here) — CHECKLISTS

POWERUP — FLY the airplane
MIXTURES RICH
PROP CONTROLS FULL
THROTTLES FULL

CLEANUP — FLY the airplane
BOOST PUMPS ON
FLAPS UP
GEAR UP

FEATHER — FLY the airplane at the blue line
IDENTIFY (dead foot — dead engine)
VERIFY (pull back on dead throttle)
FEATHER (pull back on dead prop control)

Twin Engine Airplane – Flying On One Engine Questions?

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The Vmc Demo

Vmc Demo

During your transition to twin training, you’ll be asked to perform a “Vmc Demo“.  This is a training maneuver that is very similar to a power on stall demonstration where you will set the aircraft up in a particular configuration in order to demonstrate your ability to recognize the point at which a loss of control is imminent.  Vmc is defined the minimum airspeed at which a twin engine aircraft is controllable with only one engine running — think V SPEED with MINIMAL CONTROL.  This is an important V speed in flying twins because it it represents the slowest you can fly the aircraft while still maintaining directional control which is important when you are trying to land with only one engine operative.   Vmc, like stall speed, is not constant, it changes with changes in the location of the CG and altitude so recognized and dealing appropriately with what happens just before and after the aircraft slows through this speed is very important.

A loss of airspeed to a point below Vmc sounds like a pilot’s worse nightmare — running on one engine and unable to maintain control, which results in a roll-over close to the ground — and so it is the subject of dedicated training and evaluation when stepping up to a multi-engine rating.  In a recent review of causes of crashes of light twin aircraft, 7 of 545 sequential crashes were due to Vmc rollovers, which turns out to be less than 1%.  This review noted that this rate was “better than imagined, suggesting that Vmc-roll avoidance training may work”.*

The Vmc Demo

Vmc is established during aircraft certification testing in the least favorable circumstances and the way this V speed is determined is covered by Federal Aviation Regulation 23.149, which reads as follows:

Part 23 AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES
Subpart B–Flight
Controllability and Maneuverability
Sec. 23.149

Minimum control speed.

(a) VMC is the calibrated airspeed, at which, when the critical engine is suddenly made inoperative, it is possible to recover control of the airplane with that engine still inoperative, and maintain straight flight either with zero yaw or, at the option of the applicant, with an angle of bank of not more than five degrees. The method used to simulate critical engine failure must represent the most critical mode of powerplant failure with respect to controllability expected in service.
(b) For reciprocating engine-powered airplanes, VMC may not exceed 1.2  Vs1 (where Vs1 is determined at the maximum takeoff weight) with–
(1) Takeoff or maximum available power on the engines;
(2) The most unfavorable center of gravity;
(3) The airplane trimmed for takeoff;
(4) The maximum sea level takeoff weight (or any lesser weight necessary to show VMC);
(5) Flaps in the takeoff position;
(6) Landing gear retracted;
(7) Cowl flaps in the normal takeoff position;
(8) The propeller of the inoperative engine–
(i) Windmilling;
(ii) In the most probable position for the specific design of the propeller control; or
(iii) Feathered, if the airplane has an automatic feathering device: and
(9) The airplane airborne and the ground effect negligible.
(d) At VMC, the rudder pedal force required to maintain control may not exceed 150 pounds, and it may not be necessary to reduce power or thrust of the operative engines. During recovery, the airplane may not assume any dangerous attitude and it must be possible to prevent a heading change of more than 20 degrees.

In most of the study guides for a twin engine rating they suggest that most designated pilot examiners will ask for a list of the 10 factors that are used to determine Vmc.  In plain English, here are the 10 factors:

  1. the critical LEFT engine is not producing power and the propeller is windmilling
  2. the RIGHT engine is producing maximum thrust at sea level
  3. the airplane is at max gross weight
  4. the CG is at the rear limit
  5. the flaps are in the take-off configuration (normally up on a BE-95)
  6. cowl flaps are in the take-off configuration (open on a BE-95)
  7. the aircraft is trimmed for takeoff
  8. we’ve rotated, are airborne and out of ground effect
  9. the gear is up
  10. less than 5 degrees of bank into the good engine is being used to counteract the asymmetrical thrust

Why all the specifics?  Vmc is all about testing the ability of the airplane to stay stable with the most asymmetrical thrust that it is capable of producing, and this occurs in a take-off configuration when the airplane has slow airspeed and the engines are set for maximum power.  This test is designed to simulate the least opportune time for an engine failure and the situation is worse when the aircraft is slow and heavy with minimal rudder authority and maximal adverse yaw and roll created by operating right engine.

That makes sense, but why the gear up?  While having the gear down creates a lot of drag, the gear acts like a vertical stabilizer.  The presence of the gear in the slipstream has a keel like effect and increases the stability of the airplane about the yaw axis.

According to Sheble’s website, the procedure for performing a Vmc demonstration is as follows:

Full Power
Critical Engine to Idle
Slow aircraft and pitch up until nose yaws
Power to Idle on GOOD engine
Pitch for blue line
Add power on GOOD engine to stop descent
Pitch for blue line

Alright….I memorized that procedure and the list of the 10 factors used to establish Vmc,. so we’ll see what happens during training.

References

* http://www.avweb.com/news/safety/185267-1.html

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