Flying Twins

1
Seeing Double Transition from Single
to Twin-Engine Aircraft Peter Del Vecchio CFI,
CFII, MEI
2
Outline

• Single vs. Multi-Engine
• Multi-Engine Terminology
• Obtaining a Multi-Engine Rating
• Multi-Engine Safety Tips
• Staying Current and Competent
• Summary

3
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

4
Single-Engine vs. Multiengine

• Single-Engine
• lower sex appeal
• lower useful load
• lower climb rate
• slower cruise
• lower service ceiling

• Multiengine
• higher sex appeal
• higher useful load
• higher climb rate
• faster cruise
• higher service ceiling

5
Single-Engine vs. Multiengine

• Single-Engine
• longer range
• greater endurance
• lower stall speed
• lower fatal accident rate
• lower cost
• operating/maint cost
• acquisition cost

• Multiengine
• shorter range
• less endurance
• higher stall speed
• higher fatal accident rate
• higher cost
• operating/maint cost
• acquisition cost

6
Piper Saratoga II TC vs. Seneca V
Saratoga 1/6 3600 lbs 1135 lbs 523 lbs 175
kts 20,000
Seneca 2/6 4750 lbs 1337 lbs 605 lbs 182
kts 25,000
of Engines/Seats Max. Gross Weight Useful
Load Payload w/full fuel Cruise Speed
(10,000) Service Ceiling
7
Piper Saratoga II TC vs. Seneca V
Saratoga 950 nm 7.8 hrs 18.5 gph 63 kts 1175
fpm 456,100
Seneca 828 nm 5.6 hrs 24.0 gph 61 kts 250
fpm 564,200
Range w/reserve Endurance Fuel Burn Stall Speed
(gear/flaps dn) S.E. Rate of Climb _at_ S.L. Cost New
8

• 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

9
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 _at_ 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

10
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

11
Outline

• Single vs. Multi-Engine
• Multi-Engine Terminology
• Obtaining a Multi-Engine Rating
• Multi-Engine Safety Tips
• Staying Current and Competent
• Summary

12
Multi-Engine Cockpit
Beechcraft Duchess
13
ME Aerodynamics

• Why low performance for SE operation?
• Thrust not in centerline (for conventional twin)
  -gt to maintain directional control, must use
  rudder
• More options for CG
• Can use nose compartment
• WB calculation same as for SE

14
Straight-and-Level
15
Engine Failure
16
Engine Failure
Relative Wind
X
17
Eliminating the Side Slip
X
18
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.

19
Comparison of Twins
20
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

21
Other Twin Lingo

• Airspeeds
• Red Line
• Blue Line
• Critical Engine
• Propeller Terms
• Windmilling
• Feathering
• Counter-rotating
• Takeoff Distance
• Accelerate-Stop Distance
• Accelerate-Go Distance

22
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.

23
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.

24
Multiengine Glossary

• Minimum Controllable Airspeed (VMC)
• Lowest speed at which the airplane is
  controllable with one engine developing takeoff
  power and the other engines propeller
  windmilling.
• The minimum controllable airspeed (VMC) is marked
  by a red radial line on the airspeed indicator.

25
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.

26
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.

27
Multiengine Glossary

• Accelerate-Stop Distance
  (small aircraft, gt10 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 dont have to stop. Even better, it could be
  called the accelerate-then-survive-the-crash
  distance.

28
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.

29
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)

30
Outline

• Single vs. Multi-Engine
• Multi-Engine Terminology
• Obtaining a Multi-Engine Rating
• Multi-Engine Safety Tips
• Staying Current and Competent
• Summary

31
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

32
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

33
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
• Dont 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

34
Private Pilot Requirements

• Hours required
• Maneuvers required

35
Commercial Pilot Requirements

• Hours required
• Maneuvers required

36
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

37
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

38
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

39
Outline

• Single vs. Multi-Engine
• Multi-Engine Terminology
• Obtaining a Multi-Engine Rating
• Multi-Engine Safety Tips
• Staying Current and Competent
• Summary

40
Staying Current

• FAA Regulations
• WVFC Regulations

41
Outline

• Single vs. Multi-Engine
• Multi-Engine Terminology
• Obtaining a Multi-Engine Rating
• Multi-Engine Safety Tips
• Common and New Twins
• Summary

42
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
• Dont combine emergencies during training

43
Engine-Out Performance

• Title 14 of the Code of Federal Regulations
  (Federal Aviation Regulations) 23.67

IF MGW gt 6000 lbs OR IF Stall Speed gt 61
knots THEN Single Engine Rate of Climb _at_ 5000
? .027 (VS0)2 WITH Gear Flaps Up Dead
Engine Feathered Cowl Flaps on Good Engine
Open
44
Engine-Out Climb Performance
Aircraft Piper Seneca Piper Aztec Beech Baron
D55 RC 500S Shrike Cessna 310
Required ROC N/A N/A 121 fpm 107.16 fpm 110.2 fpm
Actual ROC 0 fpm 50 fpm 121 fpm 129 fpm 119 fpm
Source AOPA
45
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
46
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
47
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 youre willing to
  bet your life that one engine wont quit during
  the climb.

Source Richard N. Aarons, FAA Accident
Prevention Program FAA-P-8740-25,
AFO-800-1079
48
Multiengine Rule 3

• Use the manufacturers 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
49
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
50
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
51
Multiengine Safety Tip 1

• Dont 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.

52
Multiengine Safety Tip 2

• Dont 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).

53
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.

54
Multiengine Safety Tip 4

• Dont 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.

55
Multiengine Safety Tip 5

• Dont 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.

56
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!

57
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.

58
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.

59
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.

60
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

61
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

62

• Backup Slides