Powerplant

1
Lecture 3

• Powerplant
• and
• Other Systems (2)
• Chapter 2, Jeppesen

2
Lecture Overview (1)

• The Engine (Continued)
• Fuel systems
• Lubricating oil systems
• The engine cooling systems
• Exhaust system
• Propellers
• Fixed-pitch propellers
• Constant speed propellers

3
Lecture Overview (2)

• Electrical Systems
• Alternator
• Battery
• Ammeter
• Master switch
• Circuit breakers and fuses

4
Fuel System (1)

• Fuel is stored in fuel tanks in both wings.
• Fuel is delivered from the tank to the carburetor
  through fuel lines either by pumps (in low-wing
  planes wings below engine) or through gravity
  (in high-wing planes wing above engine).
• In a plane with fuel pump, running the tank dry
  may allow air to enter the fuel system. In such
  case the engine might be difficult to start
  again.
• Each fuel tank has a vent to equalize the air
  pressure inside and outside of the tank.
  Otherwise a vacuum can be built inside the tank,
  preventing fuel from going out of the tank to the
  fuel lines.

5
Fuel System (2)

• There is a fuel selector valve in the cockpit
  which allows the pilot to choose fuel from the
  LEFT, RIGHT, or BOTH tanks.
• Using fuel from only one tank is usually
  restricted to trying to balance the amount of
  fuel in each wing tank.
• Also, pilots are required to use BOTH tanks
  during takeoff, landing, and maneuvering due to
  safety reasons.

6
Fuel System (3)

• A fuel strainer is used to remove moisture and
  other sediments in the fuel.
• Never take off unless you are sure that all
  moisture is removed from the fuel.
• Moisture can freeze and block fuel lines in cold
  weathers. In hot weather it can flow into the
  carburetor and stop the engine.
• It is a good practice to fully refill the tanks
  after the last flight of the day since moisture
  can condense in partially filled fuel tanks.

7
Refueling

• Fuel tanks are refilled through a cap on top of
  the wings.
• The major refueling hazard is the possible
  combustion of the fuel by a spark that causes
  fumes to ignite.
• The most possible cause for a spark is from
  static electricity that discharges between the
  refueling equipment and the airplane, due to any
  different electrical potentials.
• Thus it is very important to have a ground wire
  from the fuel truck connected to the airplane
  before the fuel cap is removed from the tank.
• Both the airplane and the fuel truck should be
  grounded to the airport surface during the entire
  refilling process. (Fig 2-41)

8
Both the fuel truck and the plane should be
grounded
9
How much does fuel account for their operation
cost?
10

• Oil Systems
• Cooling Systems
• Exhaust System

11
The Oil Systems (1)

• Engine oil is circulated through all moving parts
  of a reciprocating engine by an oil pump to
• Lubricate engines moving parts
• Help to reduce engine heating by reducing
  friction and by removing some of the heat from
  the cylinders
• Improves engine efficiency by providing a seal
  between cylinder and piston
• Carries away contaminants to the oil filter
• You should
• Check the oil quantity before each flight
• After the engine starts check the oil pressure
  gauge and the oil temperature gauge periodically

12
The Oil Systems (2)

• Oil pressure
• If oil pressure is below normal the oil pump is
  not putting out enough pressure
• If the oil pressure is too high may indicate a
  clogged oil line
• You should
• Follow instructions in the POH
• Most manufacturers recommend shutting down the
  engine if the oil pressure does not begin to rise
  within 30 seconds after the engine start in warm
  weather, or 60 seconds in cold weather

13
The Oil Systems (3)

• Oil temperature
• Abnormally high oil temperature may also mean a
  clogged oil line, or a low quality oil

14
The Cooling Systems (1)

• The combustion in the engine cylinders produces
  enormous amount of heat
• Excessive engine temperatures can result in loss
  of power, high oil consumption, and possible
  engine damage
• The oil system help cool the inside of the engine
• Outside air ventilation over the engine block
  also help cool the engine
• The remaining heat is dissipated in the exhaust
  gases

15
The Cooling Systems (2)

• Air cooling over the outside of the engine is
  less effective during high power, low speed
  operations like take-off or go-arounds
• It is most effective (or even too effective)
  during low power, high air-speed operations like
  fast descends.
• To have better control on air cooling many planes
  are equipped with controllable cowl flaps that
  allows better ventilation when they are opened,
  and can reduce ventilation when they are totally
  or completely closed.
• The cowl flaps are controlled in the cockpit

16
The Cooling Systems (3)

• Besides the standard cooling systems stated
  above, if the pilot needs to further cool the
  engine he can
• Enriching the fuel-air mixture
• Reducing the rate of climb
• Increase airspeed
• Reducing power

17
The Exhaust System

• After the fuel-air mixture is burnt in the
  cylinder the resulting gases (which is very hot)
  is disposed through the exhaust system, which
  consists of a muffler and a tail pipe.
• The muffler is used to reduce the noise produced
  by the high pressure exhaust gases
• Part of the heat in this exhaust gases are used
  to heat up the planes cabin, by circulating air
  over the hot muffler and direct that heated air
  into the cabin.
• The amount of heated air entering the cabin is
  controlled in the cockpit.

18

• Propellers

19
Propeller Blades (1)

• The propeller provides the thrust to propel the
  plane through the air.
• The propeller consists of a central hub with two
  or more blades attached.
• Each blade is an airfoil that is like a rotating
  wing that produces thrust.
• The cross sections of the blade at different
  lengths of the blade are different (Fig 2-51)

20
The propeller (2-51)
21
Propeller Blades (2)

• The amount of thrust produced by each section of
  the propeller depends on several factors
• 1. The shape of the section
• 2. The rotational speed of the section
• 3. Its position relative to the oncoming air
• The rotational speed of the section increases
  with its length from the center
• The shape of each section is different, with the
  blade angle gradually decreases along its length.
• The speed and shape of the sections allow each
  section to provide nearly equal amount of thrust
  throughout most of the length of the blade.

22
Propeller Blades (3)

• If the angle of each section is averaged
  throughout the whole length we get the overall
  (averaged) blade angle for the particular blade.
• A propeller with low average blade angle is best
  for takeoff and climb, and is called a climb
  propeller.
• A propeller with a high average blade angle is
  best for high speed cruises and high altitude
  flight, and is known as a cruise propeller.

23
Multi-Bladed Propellers (1)

• As engines get more powerful, propeller blades
  has to be bigger to fully utilize the engine
  power, and get more thrust for the plane
• However, blade size cannot be too large for two
  reasons
• Blades too long might touch the ground
• The rotational speed of long blades will be very
  large, and tip speed approaches the speed of
  sound, drag increases and efficiency decreases
• An alternative solution is to increase the number
  of blades for each propeller.

24
Multi-Bladed Propellers (2)

• Multi-bladed propellers can utilize more engine
  power without excessive blade speed.
• Slower propeller speed also help reduce noise
• Another method to increase blade count is to use
  two propellers per engine
• (Fig on p. 2-37)

25
Multi-Bladed Propellers multiple propellers
(p.2-37)
26
Fixed-pitch Propellers

• Propellers can be fix-pitched or constant speed.
• Fix-pitched propellers have their blade angles
  (pitch) fixed and cannot be changed.
• Engine power is controlled only through the
  throttle, and the only power indicator is the
  tachometer which displays the engine r.p.m.

27
Constant Speed Propellers (1)

• Constant speed propellers can have their blade
  angles adjusted by the pilot using the propeller
  control .
• They are therefore also called variable-pitch
  propellers.
• Constant speed propellers are much more efficient
  in the use of engine power because you can adjust
  the blade angle to get the most efficient
  operation under a wide variety of propeller
  r.p.m. and airspeeds.

28
Constant Speed Propellers (2)

• Engine power is controlled by the throttle and is
  indicated by the manifold pressure gauge .
• The propeller control allows you to select a low
  blade angle and high r.p.m. setting for maximum
  thrust on takeoff.
• After you reach uniform cruising flight, you can
  use a higher pitch and a lower r.p.m. setting to
  maintain just adequate thrust.
• This is comparable to use low gear in a car for
  acceleration and a high gear for cruising speed.

29
Propeller Hazards

• Since the spark plugs of the engine cylinders can
  fire by the electricity generated by engine
  movement (through the magetos), the engine can
  keep running once it is started.
• Therefore one can start the engine by moving the
  propellers manually first, and once started, the
  engine will keep running.
• Therefore it is extremely dangerous to manually
  rotate the propellers if you do not know the
  procedure.

30

• Electrical Systems

31
The Planes Electrical System (1)

• The electrical systems of the plane generate,
  store, and deliver controlled amount of
  electricity to different parts of the plane.
• It includes the following components
• Alternator
• Battery
• Two Ammeters
• Master Switch
• Circuit breakers or fuses

32
The Planes Electrical System (1)

• The alternator similar to a generator but
  generates A.C. current instead of D.C. It is
  driven by the power from the engine.
• The battery stores the electricity generated by
  the alternator, mainly used for starting the
  engine (and also as a standby source of
  electricity).
• Two Ammeters monitor the currents from the
  alternator and from the battery.

33
The Planes Electrical System (2)

• A master switch controls the on-off of the
  entire electrical system, including the engine
  starter
• Circuit breakers and fuses to protect various
  electrical components from overloads. With
  circuit breakers, resetting the breaker will
  reactivate the circuit, unless a components was
  already damaged or a short circuit had taken
  place.