AMT 287

Electromatic Induction

-Lines of force or flux are a property of magnets,producing magnetic fields.They always seek the path of least resistance.

Turbochargers advantages

1. Above the turbulence, icing and high terrain. 2. Utilize beneficial winds aloft at higher altitudes 3. Less traffic generally above 18,000 4. Better Speed for same power setting. Air is thinner and TAS is higher for the same power setting. 5. Better fuel consumption.

Types of turbo charging for engines

1. Boosted - engines receives air that is pushed into the cylinder under pressure, resulting in higher volumetric efficiencies and the ability to produce power at higher altitudes. Sea level performance 31-45 inches MP 2. Normalized- sea level performance continued up to higher altitudes 18-20M ft. This is the typical general aviation turbo charging system.

Water vapor in the air will cause a significant reduction of power output from reciprocating engines. If the humidity is high, more water molecules displace oxygen molecules in a cylinder of air,producing two reducing effects.

1. less oxygen to burn the fuel and 2 the fuel/air mixture is richened become even more richer and causes a further decrease in power.

Manual Waster gate-

>Often used for retrofit installations.- ones made now don't make manual, you must add it in > Usually accomplished with a vernier control in the cockpit connected by cable to eh wastegate. >Engine are not usually designed for MAP's above 30 inches, takeoff and climb to abut 5000feet is accomplished with the waste gate in open position so no boost of MAP.

GENERATORS

A generator is a machine that converts mechanical energy into electrical energy by the process of electromagnetic induction They are driven by the engine(s), and sometimes by APU. A generator must be rated at adequate amperage to drive all the operating components on its circuit(s). The current required to operate each electrical component is known as its load.

Parallel Circuit

A portion of the electrons flow through each filament. The amount of voltage drop is equal to the total voltage produced by the source.

Switches

A switch is used to start, to stop, or to change the direction of the current flow in the circuit.

Series Circuit

All electrons must flow through all active components. The amount of voltage dropped across the filament is always less than the total. Voltage drop depends on the amount of resistance of the individual load.

Example: altimeter 30.12 Hg Field elevation: 800 feet Pressure altitude: 580 feet :PA= 800feet- (30.14 - 29.92) x1000

Ambient pressure= Altimeter setting- 1in Hg x field elev/1000 feet = 30.14-.80 in = 29.34 The gauge should read 29.3 Hg before engine start.

During climb( normally aspirated engines) one inch of Hg = 1000 feet..

As the pilot climbs up if RPM is constant (with a constant speed prop) MAP will decrease 1 in Hg for every thousand feet.

FYI the airline model requires anti-icing equipment on at 10 degrees C or 50 degrees F.

Avoid flight in visible moisture at Temps O degrees C (32F) and below.

Capacitor

Capacitors do a lot for us in airplanes, Capacitors can store electricity for quick use - strobes,Commonly found in most electronic circuits.

Pressure-

Crystalline materials when bent or deformed by a mechanical force an excess of electrons will accumulate on one surface. Microphones and phono pickups

Relays

Electromagnetic switching devices which are used to remotely control electric circuits carrying large amount of current.

Deep cycle

Every 100 hours because they develop a memory. If bat is discharged numerous times to 65% eventually the bat will not discharge much below 65%. Also if one or more cells is out of balance with others. Remedy- Deep cycling In shop the battery is allowed to discharge totally.Then the bat is allowed to remain like this for a period of time. Next it is charge to 140% of its capacity with a constant current. And then discharge again. After rest it is charge up to 140% again. Cost 1000Dollars.

Antenna Icing

Ice accumulations may cause it to begin to vibrate (describe it as a howl)or cause radio signals to become distorted. If a frozen antennae breaks off it can damage other areas of the aircraft in addition to causing a communication or navigation system failure.

Induction Ice

Ice forms in the induction system will block the air filter.

How does a thermocouple work?

In a thermocouple circuit the current continues to flow as long as the two junctions are at different temperatures. The magnitude and direction of the current depends on the temperature difference between the junctions and the properties of the metals used in the circuit.

Current-

In current electricity the electrons move through a circuit and perform work, either by magnetic field created or by their movement or by heat generated.

Ammeters And Loadmeter In The Circuit

Installed between the master solenoid and the busbar. Senses the amount and direction of current flow in the battery circuit. Installed between A terminal of the alternator and the busbar. Senses current flow (in one direction), or output, of the alternator (loadmeter).

Inverters/Static Inverters

Inverters convert DC to AC. Commonly and inverter is used in some aircraft systems to convert a portion of the aircrafts DC power system into AC to run instruments. Two types: rotary and static. Since static inverters use solid state components, they are considerably smaller, more compact, and much lighter in weight than rotary inverters. Depending on the output power rating required, static inverters that are no larger than a typical airspeed indicator can be used in aircraft systems. Some of the features of static inverters are: 1. High efficiency. 2. Low maintenance, long life. 3. No warmup period required. 4. Capable of starting under load. 5. Extremely quiet operation. 6. Fast response to load changes.

Ammeters

Measures current flow Battery is charging when electrons are flowing from the positive terminal. This would be a positive indication.

Nickel-cadmium battery

Now most popular.They can accept a high charge rate and to discharge at equally high rate without voltage drop associated with Lead acid batteries.Better at lower temperatures, but is more expensive, requires more maintenance and has a memory which must be periodically erased and is subject to thermal run a way.

Permeability

Permeability-The ease with which the lines of fl Flux can travel through iron much easily and has a permeability of 7,000 ad some magnet alloys have rating of 1,000,000.

Piezoelectric effect

Push a crystal and generates electrical current An everyday life application example is your car's airbag sensor. The material detects the intensity of the shock and sends an electrical signal which triggers the airbag. Ice detection Vibration sensors Shock sensors monitoring Knock sensors Rain sensors Microphones Impact sensors

Solenoids

Remote control devices quite similar to relays; but they are designed to move a shaft over a short distance. Thus, solenoids are used as mechanical control devices to operate hydraulic or pneumatic valves, locking pins, etc.

The Busbar

Rigid point that is a convenient place to terminate many wires neatly and safely. Connected to the positive terminal of the battery, when the master switch is on. Same electrical potential as the battery. Circuit breakers are often mounted.

Circuits- What three items are needed to complete the circuit?

Source = pressure = volts Load = resistance = measured in Ohms Current = measured in amps

Static electricity

Static electricity is created by the friction of the air with an aircraft in flight and the electrical charge remains static or still until it accumulates sufficiently to discharge ( when radio frequency interference RFI) can occur. When the atmosphere contains particulates such as rain, snow, dust or volcanic ash more RFI is generated. wick of wire or a conductive element on one end, which provides a continuous low resistance discharge path between the aircraft and the air.

A circuit must have at least three parts.

The source The electron transportation and distribution system The load (Where the work is done)

Chemical-

There can be an imbalance of electrons and protons, then electrons will be forced to the conductor and a chemical reaction will occur. What do we have a battery.

Fuses :

They are designed to protect the cables against the flow of short-circuit and excessive current. They break the circuit and stop the current flow when the current exceeds a predetermined value.

Diodes :

They are the electronic equivalent to the check valves in hydraulic system. They allow electricity to flow in one way only.

Circuit breakers :

They have same function with the fuses.The difference from the fuse is that they are resettable, while a fuse must be replaced.

Eventually the aircraft climbs to an altitude where the wastegate is fully closed, and turbocharger cannot maintain the max MAP.

This is the engines critical altitude.

Resistors

Used in electrical circuits to control current flow by varying voltage. Can drop voltage by converting some of the energy into heat.

Distribution of Electrical Charges-

When a body having smooth uniform surface is charges, the charge will distribute evenly over the whole surface. If irregular the charge will concentrate at the points having the sharpest curvature.

Thermal-

When a certain combinations of wire such as iron and constantan or chromel are joined into a loop with two junctions a thermocouple is formed. Ex: CHT gauge A electrical current will flow through the wires when there is a difference in the temperature of the two junctions.

Photo electric effect

When a surface is exposed to sufficiently energetic electromagnetic energy, light will be absorbed and electrons will be emitted.

Superchargers-

are driven directly from the engine using some of the power produced by the engine-accessory drives.

Turbochargers-

are driven directly from the hot exhaust gasses that are being expelled from the engine.

Diode/Rectifier

are used to change AC current to DC current. Can be combined with transformers to Step down or up voltage and change the current flow. Example: Transformer Rectifier takes AC engine generator output and steps down down the voltage and changes it to DC current.

Thermal Run-away

causes excessive charging of the battery, which generates excessive battery temperature. >> combine this with one bad plate in a cell, provides the beginning of a core melt down. Such a condition has been known to cause a fire in the batter box, melt thru and dropped out the bottom of the aircraft.

Dry Vacuum Pump System

have carbon vanes and rotors and require no external lubrication Drive instruments by producing a vacuum and pulling air through them

Electrostatic Fields-

if the lines of force between charges could be seen, it would appear that the lines leave one charge object and enter the one having a negative charge.

Differential-pressure controller-

if the turocharger is set to less than full power the it regulates the position of the wastegate and also prevents bootstrapping. This unit is set to provide approx. 2-4 inches of Hg pressure drop across the throttle at a specified MAP. If the differential is exceeded, the oil valve will open sufficiently to reduce the turbocharging until the desired differential is restored.

A battery

is a device that converts chemical energy into electrical energy. It is a power reservoir that stores energy in chemical form.It does not produce energy. The capacity of battery is measured in ampere-hours. have three parts, an anode (-), a cathode (+), and the electrolyte.

Bootstrapping

is an undesirable cycle of turbocharging events causing the manifold pressure to drift in an attempt to reach a state of equilibrium. Any change is the exhaust gas flowing to the turbine will cause a change in MAP an thus power output.

Turbo-supercharger-

is most correctly applied to an engine system that has both a turbocharger that boost air pressure before the carburetor and a supercharger that further boosts pressure of the fuel air/mixture. These are rare in general aviation.

Overboost-

is one in which MAP pressure exceeds the limits prescribed for a particular engine and can cause serious damage

Normally aspirated engine-

its cylinders are filled with air due to the force of atmospheric pressure.

Lead Acid-

most commonly used storage battery.In aircraft batteries the cell opening are closed with vented screw in type caps. Sulfuric acid and water.

Overshoot-

often confused with bootstrapping, but this is when rapid movement of throttle can cause a certain amount of MAP drift in turbocharged engine. The automatic controls cannot respond rapidly enough. Slowly make changes in throttle settings and them wait!

Anti-icing

prevents the formation of ice

De-icing

remove ice after it has formed.

voltage regulator

samples the system voltage and increases or decreases the field voltage which limits alternator output.

Density controller

senses pressure and temp in the upper-deck. The density controller is designed to maintain deck pressure and density at levels required for full power operation of the engine. If low it restricts the oil from returning to the crankcase thus closing the wastegate Speeds up turbine and more pressure. If power selected then is less than full power, the deck pressure will be less than that for full power and thus control will pass to the differential pressure controller.

Static-

sometimes serves a useful purpose, and is more often a nuisance rather than a useful form of electrical energy.

Thermocouples

temperature sensor. Its characteristics include good inherent accuracy, suitability over a broad temperature range, fast thermal response, ruggedness, high reliability and low cost.

Thermal Run-away

thermal runaway is a descriptive name for a failure mode that exists in sealed batteries. It is observed by noting that the batteries continue to accept charge after they are fully charged. This excess power is converted to heat within the battery and can in a boiling of the electrolyte. The battery surface gets very hot in a sealed battery

Wet-type Vacuum Pump System

use steel vanes moving in a cast iron housing sealed and lubricated by engine oil metered into the inlet air port. Oil is discharged with the air and is removed by an oil separator before the air is used for boots or is or is pumped overboard.

Light-

when it strikes certain materials electrons will be knocked off and forced to flow in a circuit and do work.