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Flying Twins

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					Seeing Double
 Transition from Single to
   Twin-Engine Aircraft

      Peter Del Vecchio
        CFI, CFII, MEI


         Seeing Double         May 19, 2004
         Transition to Twins         Slide 1
Outline
  Single vs. Multi-Engine

  Multi-Engine Terminology

  Obtaining a Multi-Engine Rating

  Multi-Engine Safety Tips

  Staying Current and Competent

  Summary




                      Seeing Double         May 19, 2004
                      Transition to Twins         Slide 2
Single vs. Multi-Engine - Safety
  Main benefit of twin: Redundancy
       Still have power if one engine quits
       Dual vacuums pumps
       Dual alternators

  Main detriment of twins: If managed incorrectly,
   that one engine will try to flip the plane over
       The large yawing moment caused by the operative engine can
        cause the plane to enter a spin




                             Seeing Double                 May 19, 2004
                              Transition to Twins                Slide 3
Single-Engine vs. Multiengine


  Single-Engine                             Multiengine
      lower sex appeal                                 higher sex appeal
      lower useful load                                higher useful load
      lower climb rate                                 higher climb rate
      slower cruise                                    faster cruise
      lower service ceiling                            higher service ceiling




                               Seeing Double                                  May 19, 2004
                               Transition to Twins                                  Slide 4
Single-Engine vs. Multiengine
  Single-Engine                             Multiengine
      longer range                                     shorter range
      greater endurance                                less endurance
      lower stall speed                                higher stall speed
      lower fatal accident rate                        higher fatal accident rate
      lower cost                                       higher cost
           operating/maint cost                             operating/maint cost
           acquisition cost                                 acquisition cost




                               Seeing Double                                  May 19, 2004
                               Transition to Twins                                  Slide 5
Piper Saratoga II TC vs. Seneca V


                                      Saratoga          Seneca
  # of Engines/Seats                             1/6       2/6
  Max. Gross Weight                   3600 lbs         4750 lbs
  Useful Load                          1135 lbs        1337 lbs
  Payload w/full fuel                    523 lbs        605 lbs
  Cruise Speed (10,000’)                 175 kts        182 kts
  Service Ceiling                       20,000’         25,000




                        Seeing Double                        May 19, 2004
                           Transition to Twins                     Slide 6
Piper Saratoga II TC vs. Seneca V


                                    Saratoga       Seneca
  Range w/reserve                     950 nm       828 nm
  Endurance                            7.8 hrs      5.6 hrs
  Fuel Burn                         18.5 gph      24.0 gph
  Stall Speed (gear/flaps dn)            63 kts     61 kts
  S.E. Rate of Climb @ S.L.        1175 fpm       250 fpm
  Cost New                         $456,100       $564,200




                         Seeing Double                   May 19, 2004
                         Transition to Twins                   Slide 7
 takeoff

 decision making

 need to keep up with emergency skills

 more complex - multiple fuel tanks, crossfeed,
  multiple electrical systems - must determine what
  to do if one fails
      increases workload

 higher speeds further increase workload




                            Seeing Double         May 19, 2004
                            Transition to Twins         Slide 8
Arguments Against Twins
  More complex

  Twice as many engines to fail

  Twice as many engines to maintain

  Higher fuel consumption

  May not be able to maintain altitude
     “The second engine will fly you to the scene of the crash”
     Example: SE ceiling for Duchess 6200 @ max gross
             However, increases to 10000 at 400lbs less
        What percentage of your flight time is spent over Absolute Ceiling?

  Less efficient
     two engines - less efficient, which means more horsepower, which
      implies more fuel consumption, which means more hp, which implies
      more weight/etc


                                   Seeing Double                     May 19, 2004
                                    Transition to Twins                    Slide 9
Arguments For Twins
  Higher Performance

  Increased Safety
       Backup engine!
       If emergency procedures practiced

  Increased Useful Load

  Required For Most Commercial Operations

  Bragging Rights

  Slipstream produces lift



                            Seeing Double         May 19, 2004
                            Transition to Twins        Slide 10
Outline
  Single vs. Multi-Engine

  Multi-Engine Terminology

  Obtaining a Multi-Engine Rating

  Multi-Engine Safety Tips

  Staying Current and Competent

  Summary




                      Seeing Double         May 19, 2004
                      Transition to Twins        Slide 11
Multi-Engine Cockpit




              Beechcraft
               Duchess

                 Seeing Double         May 19, 2004
                 Transition to Twins        Slide 12
ME Aerodynamics
 Why low performance for SE operation?
     Thrust not in centerline (for conventional twin) -> to maintain
      directional control, must use rudder

 More options for CG
     Can use nose compartment
     W&B calculation same as for SE




                            Seeing Double                      May 19, 2004
                            Transition to Twins                     Slide 13
Straight-and-Level




                 Seeing Double         May 19, 2004
                 Transition to Twins        Slide 14
Engine Failure




                 Seeing Double         May 19, 2004
                 Transition to Twins        Slide 15
Engine Failure
Relative
Wind



           X




                 Seeing Double         May 19, 2004
                 Transition to Twins        Slide 16
Eliminating the Side Slip



       X




                  Seeing Double         May 19, 2004
                  Transition to Twins        Slide 17
Types of Twins
  Light Twin
       Check FARs for weights, requirements

  Centerline Thrust
       Cessna Sky Master
       Adams A500

  Conventional vs. Counter-rotating

  Turbo-Prop
       King Air

  The P-38 had no critical engine because both
   propellers rotated outwards.

                            Seeing Double         May 19, 2004
                            Transition to Twins        Slide 18
Comparison of Twins




                Seeing Double         May 19, 2004
                Transition to Twins        Slide 19
New V-Speeds
All of the standard v-speeds, plus:

 VMC - Minimum Controllable Airspeed

 VXSE - Best Single-Engine Angle of Climb

 VYSE - Best Single-Engine Rate of Climb

 VSSE - Safe Single-Engine Speed                       AIRSPEED

                                                          MPH       40
                                                  240
                                             220                          60


                                            200                           80

                                             180                         100
                                                160                120
                                                          140




                      Seeing Double                                  May 19, 2004
                      Transition to Twins                                 Slide 20
Other Twin Lingo
  Airspeeds
       Red Line
       Blue Line

  Critical Engine

  Propeller Terms
       Windmilling
       Feathering
       Counter-rotating

  Takeoff Distance
       Accelerate-Stop Distance
       Accelerate-Go Distance

                            Seeing Double         May 19, 2004
                            Transition to Twins        Slide 21
Multiengine Glossary
 Blue Line Airspeed (VYSE)
      Airspeed that gives the best rate of climb with an engine out
       (VYSE), marked by a blue radial line on the airspeed indicator

      If an engine fails in a multiengine airplane, the blue line airspeed
       gives the best rate of climb or the least rate of descent.




                              Seeing Double                       May 19, 2004
                              Transition to Twins                      Slide 22
Multiengine Glossary
 Critical Engine
      The engine on a multiengine airplane that would cause the
       most difficulty in maintaining control of the airplane if it failed
       in a critical condition of flight, such as takeoff.

      To eliminate the critical engine, the right engine on some
       airplanes rotates counterclockwise while the left engine
       rotates clockwise. Thus the moment arm for both propeller
       disks is close to the fuselage.




                              Seeing Double                       May 19, 2004
                              Transition to Twins                      Slide 23
Multiengine Glossary
 Minimum Controllable Airspeed (VMC)
      Lowest speed at which the airplane is controllable with one
       engine developing takeoff power and the other engine’s
       propeller windmilling.

      The minimum controllable airspeed (VMC) is marked by a red
       radial line on the airspeed indicator.




                            Seeing Double                     May 19, 2004
                             Transition to Twins                   Slide 24
Multiengine Glossary

 Minimum Safe Single-Engine Airspeed (VSSE)
      The airspeed recommended by the airplane manufacturer as
       the minimum safe speed at which to perform intentional
       engine cuts.

      Never intentionally cut an engine below the minimum safe
       single-engine airspeed (VSSE). This speed is intended to reduce
       the accident potential from loss of control after engine cuts at
       or near VMC.




                             Seeing Double                      May 19, 2004
                             Transition to Twins                     Slide 25
Multiengine Glossary
 Accelerate-Stop Distance
      The runway distance required for an airplane to accelerate to
       V1 or VYSE, lose an engine at that speed, and then slow the
       airplane to a full stop.

      This definition of accelerate-stop distance applies to commuter
       and air transport category aircraft.




                            Seeing Double                      May 19, 2004
                             Transition to Twins                    Slide 26
Multiengine Glossary


  Accelerate-Stop Distance                                (small
   aircraft, >10 occupants, Part 135 ops.)
       The runway distance required for an airplane to accelerate
        to V1, lose an engine at that speed, and slow the airplane
        to a speed no greater than 35 knots.

       I think the accelerate-stop distance should be called the
        “accelerate-slow distance”, because you don’t have to
        stop. Even better, it could be called the “accelerate-then-
        survive-the-crash” distance.




                           Seeing Double                      May 19, 2004
                           Transition to Twins                     Slide 27
Multiengine Glossary
 Accelerate-Go Distance
      The takeoff roll distance required for an airplane to accelerate
       to V1 or VYSE and then continue the takeoff if an engine fails at
       that speed.

      The accelerate-go distance is not provided for all airplanes.
       This could be an implied admission by the manufacturer that
       the airplane can not accomplish this.




                             Seeing Double                       May 19, 2004
                              Transition to Twins                     Slide 28
Factors of VMC
  Full Power at Sea Level

  Cowl Flaps Open

  Max Gross weight

  Most rearward CG

  Max bank 5 degrees into good engine
       Raise the dead

  Critical engine windmilling (or auto-feathered)




                         Seeing Double           May 19, 2004
                         Transition to Twins          Slide 29
Outline
  Single vs. Multi-Engine

  Multi-Engine Terminology

  Obtaining a Multi-Engine Rating

  Multi-Engine Safety Tips

  Staying Current and Competent

  Summary




                      Seeing Double         May 19, 2004
                      Transition to Twins        Slide 30
Training Overview
  Main goal: How to handle failure of one engine
       Especially on takeoff roll, and just after takeoff

  ME airplanes are not tremendously faster than
   high-performance SE

  ME systems are somewhat more complex
       Crossfeed
       Two engines, vacuum pumps, alternators, fuel pumps, etc.
       Synchronizers, yaw dampers, pressurization, strobe-effect
        indicator, deice, weather radar, oxygen
       most me ac use constant speed, controllable pitch, full-
        feathering propeller
            3/4 plate drag
            similar to se except high/low rpm and feathering capability

                                Seeing Double                         May 19, 2004
                                 Transition to Twins                       Slide 31
Training (cont.)
  one major difference is the function of engine oil in
   the propeller system
       ME oil moves to flat pitch, high rpm

  expect to spend more time learning the systems of
   a me ac
       dual electrical busses, what happens when one fails?

  multiple tanks - mains and aux, left and right, can
   only crossfeed from mains normally - for this
   reason, aux tanks should be used early in flight




                             Seeing Double                     May 19, 2004
                              Transition to Twins                   Slide 32
Additional Aircraft Class
  MEL = Multi-Engine Land

  Requires a checkride
       Oral and flight test, but no written
       As with any checkride, makes you current for the next two years

  Can be added to Private or Commercial

  Can also be done as an initial Private or Commercial rating
       For example, can have Commercial ME privileges and Private SE
        privileges
       Don’t need to do commercial single maneuvers

  If you have an instrument rating, you must perform
   instrument maneuvers
       Two instrument approaches on the practical test: one SE, one ME


                                 Seeing Double                      May 19, 2004
                                 Transition to Twins                     Slide 33
Private Pilot Requirements
  Hours required

  Maneuvers required




                    Seeing Double         May 19, 2004
                    Transition to Twins        Slide 34
Commercial Pilot Requirements
  Hours required

  Maneuvers required




                    Seeing Double         May 19, 2004
                    Transition to Twins        Slide 35
Multiengine Training Syllabus
  FAA Advisory Circular 61-9B

  Practical Test Standards


  Multiengine Training
       Preflight Examination
       Flight Maneuvers and Procedures
       Ground Reference Maneuvers
       Flight at Minimum Controllable & Landing Airspeeds




                            Seeing Double                    May 19, 2004
                                Transition to Twins               Slide 36
Multiengine Training Syllabus
  Multiengine Training (continued)
       Stalls
       Maximum Performance Operations
       Control by Reference to Flight Instruments
       Use of Radio, Autopilot and Special Equipment
       Emergencies
            Emergency Operation of Aircraft Systems
            Engine-Out Emergencies




                               Seeing Double            May 19, 2004
                               Transition to Twins           Slide 37
Multiengine Training Syllabus
  Engine-Out Emergencies
      Propeller Feathering or Engine Shutdown
      Engine-Out Minimum Control Speed (VMC) Demo
      Engine-Out Best Rate-of-Climb Demo
      Effects of Configuration on Engine-Out Performance
      Maneuvering with an Engine-Out
      Approach & Landing with an Engine-Out




                           Seeing Double                    May 19, 2004
                           Transition to Twins                   Slide 38
Outline
  Single vs. Multi-Engine

  Multi-Engine Terminology

  Obtaining a Multi-Engine Rating

  Multi-Engine Safety Tips

  Staying Current and Competent

  Summary




                      Seeing Double         May 19, 2004
                      Transition to Twins        Slide 39
Staying Current
  FAA Regulations

  WVFC Regulations




                      Seeing Double         May 19, 2004
                      Transition to Twins        Slide 40
Outline
  Single vs. Multi-Engine

  Multi-Engine Terminology

  Obtaining a Multi-Engine Rating

  Multi-Engine Safety Tips

  Common and New Twins

  Summary




                      Seeing Double         May 19, 2004
                      Transition to Twins        Slide 41
Safety Tips
  Never go below VYSE

  Keep current on emergency procedures
      With a SE airplane, the decision is made for you if the engine
       fails

  Don’t combine emergencies during training




                            Seeing Double                      May 19, 2004
                             Transition to Twins                    Slide 42
Engine-Out Performance
  Title 14 of the Code of Federal Regulations
   (Federal Aviation Regulations) §23.67


    IF        MGW > 6000 lbs
    OR IF     Stall Speed > 61 knots
    THEN      Single Engine Rate of Climb @ 5000’
               .027 × (VS0)2
    WITH      Gear & Flaps Up
              Dead Engine Feathered
              Cowl Flaps on Good Engine Open




                      Seeing Double              May 19, 2004
                      Transition to Twins             Slide 43
Engine-Out Climb Performance


     Aircraft          Required ROC            Actual ROC
     Piper Seneca                    N/A            0 fpm
     Piper Aztec                     N/A           50 fpm
     Beech Baron D55          121 fpm             121 fpm
     RC 500S Shrike      107.16 fpm               129 fpm
     Cessna 310            110.2 fpm              119 fpm


 Source: AOPA

                         Seeing Double                  May 19, 2004
                         Transition to Twins                 Slide 44
Engine-Out Climb Performance
  When one engine is lost in a light twin, the loss in
    climb performance is 80-90%.

                  Airplane                         % Loss

            Beech Baron 58                          80.7

            Cessna 310                              78.1

            Cessna 402B                             86.0

            Piper Aztec                             83.5

            Piper Seneca                            89.8
 Source: AOPA
                             Seeing Double                  May 19, 2004
                             Transition to Twins                 Slide 45
Multiengine Rule #1
 Never allow the airspeed to drop below published
   VMC except during the last few yards of the landing
   flare, and then only if the field is extremely short.




Source: Richard N. Aarons, FAA Accident Prevention Program
        FAA-P-8740-25, AFO-800-1079
                                       Seeing Double          May 19, 2004
                                        Transition to Twins        Slide 46
Multiengine Rule #2
 A best all-engine angle-of-climb speed that is
   lower than VMC is an emergency speed and should
   be used near the ground only if you’re willing to
   bet your life that one engine won’t quit during the
   climb.




Source: Richard N. Aarons, FAA Accident Prevention Program
        FAA-P-8740-25, AFO-800-1079
                                       Seeing Double          May 19, 2004
                                        Transition to Twins        Slide 47
Multiengine Rule #3
 Use the manufacturer’s recommended liftoff speed
   or VMC plus five knots, whichever is greater.




Source: Richard N. Aarons, FAA Accident Prevention Program
        FAA-P-8740-25, AFO-800-1079
                                       Seeing Double          May 19, 2004
                                        Transition to Twins        Slide 48
Multiengine Rule #4
 After leaving the ground above VMC, climb not
   slower than single-engine best rate-of-climb speed
   and not faster than best all-engine rate of climb
   speed. The latter speed is preferable if obstacles
   are not a consideration.




Source: Richard N. Aarons, FAA Accident Prevention Program
        FAA-P-8740-25, AFO-800-1079
                                       Seeing Double          May 19, 2004
                                        Transition to Twins        Slide 49
Multiengine Rule #5
 Be a skeptic when reading the performance tables
   in your aircraft owners manual and be doubly sure
   you read the fine print. Add plenty of fudge
   factors.




Source: Richard N. Aarons, FAA Accident Prevention Program
        FAA-P-8740-25, AFO-800-1079
                                       Seeing Double          May 19, 2004
                                        Transition to Twins        Slide 50
Multiengine Safety Tip #1
  Don’t even think of spinning a multiengine
   airplane.
       Manufacturers are not required to demonstrate spin recovery
        for certification of multiengine airplanes

       Even if spin recovery techniques are published in the owners
        manual, they may not work, especially if not started quickly
        and properly.




                            Seeing Double                     May 19, 2004
                             Transition to Twins                   Slide 51
Multiengine Safety Tip #2

  Don’t even think of stalling a multiengine airplane
   while operating on one engine.
       A single-engine stall in a multiengine airplane can turn in to a
        spin very quickly. (See Tip #1).




                              Seeing Double                      May 19, 2004
                              Transition to Twins                     Slide 52
Multiengine Safety Tip #3
  Avoid VMC demonstrations when the stall speed is
   higher then VMC.
       VMC decreases with altitude while the stall speed remains
        constant. Climbing to a high altitude for a VMC demonstration
        may cause the airplane to stall before VMC is reached. This is
        not good. (See Tip #2).
       Rather than doing VMC demonstrations at a low altitude, block
        the rudder pedal, which will cause VMC to increase.




                             Seeing Double                     May 19, 2004
                              Transition to Twins                   Slide 53
Multiengine Safety Tip #4

  Don’t use the extra engine to justify taking extra
   risks, especially with the weather.
       A thunderstorm can trash a multiengine airplane just as easily
        as a single-engine airplane.

       Weather related issues are a more significant factor in
        multiengine accidents than in single engine accidents.




                             Seeing Double                        May 19, 2004
                              Transition to Twins                      Slide 54
Multiengine Safety Tip #5

  Don’t fly IFR in any airplane unless you are IFR
   proficient in that specific airplane.
       If you have both an IFR rating and a multiengine rating, you
        may still not be proficient flying IFR in a multiengine airplane,
        especially if an engine fails in instrument conditions or during
        a missed approach.




                              Seeing Double                      May 19, 2004
                              Transition to Twins                     Slide 55
Multiengine Safety Tip #6
  If you must takeoff with a high gross weight, use a
   longer runway.
       Gross weight is the single most important factor affecting
        climb performance. Single-engine climb performance will be
        greatly increased with a lower gross weight.

       Longer runways allow for safer aborts after T/O emergencies.
        Avoid intersection departures!




                            Seeing Double                    May 19, 2004
                             Transition to Twins                  Slide 56
Multiengine Safety Tip #7

  If you must takeoff on a short runway, reduce
   takeoff weight as much as possible.
       Reducing takeoff weight will reduce ground roll and increase
        climb performance.




                             Seeing Double                    May 19, 2004
                             Transition to Twins                   Slide 57
Multiengine Safety Tip #8

  Perform a pre-takeoff briefing - decide on an
   altitude, below which the takeoff will be aborted in
   the event of an engine failure.
       It is always better to go through the fence at 50 kts than hit the
        trees at 120 kts.

       The pre-takeoff briefing puts the pilot in the proper frame of
        mind, removing distractions and preparing to react if problems
        occur during takeoff.




                              Seeing Double                       May 19, 2004
                               Transition to Twins                     Slide 58
Multiengine Safety Tip #9

  Maintain currency on multiengine emergency
   procedures.
      A one hour flight review every two years is not enough.

      Consider training to “professional” standards, with flight
       checks every six months.




                            Seeing Double                      May 19, 2004
                             Transition to Twins                    Slide 59
Adams A500
 Six Seats

 Speeds
    Max Cruise (75% Power) 230 KTAS (22,000 ft)
    Stall Speed (VS0) 70 KTAS


 Climb Performance
    Sea Level, Both Engines 1,800 fpm
    Sea Level, Single Engine 400 fpm
    15,000 ft, Single Engine 230 fpm


 Weights
   Max Gross Weight: 6,300 lb
   Useful Load:      2,100 lb

 Engines: TCM TSIO-550 350HP
    41.4 GPH Rich of Peak
    35.0 GPH Lean of Peak

                            Seeing Double          May 19, 2004
                             Transition to Twins        Slide 60
Diamond DA42 Twin Star
  Four Seats

  Speeds
     Max Cruise (80% Power) 181 KTAS (12,500 ft)
     Stall Speed (VS0) 56 KTAS


  Climb Performance
     Sea Level, Both Engines 1730 fpm
     12,000 ft, Single Engine 400 fpm


  Weights
    Max Gross Weight: 3,637 lb
    Useful Load:      1,237 lb

  Engines: Thielert Centurion 135hp turbo diesel
     10.7 GPH Total Fuel Consumption
     FADEC, auto-feather
     Runs on Diesel or Jet A

                             Seeing Double          May 19, 2004
                              Transition to Twins        Slide 61
Backup Slides




   Seeing Double          May 19, 2004
    Transition to Twins        Slide 62

				
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