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104 Cards in this Set
- Front
- Back
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Because no two engines
and no two compressors N1 and N2 operate at the same speed, ... is used to simplify the flight deck indications. |
percent revolutions per minute
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Turbine Engine Speed Measurement:
2 systems in common use : |
* T acho-generator
* Phonic wheel and pulse probe |
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@ Turbine Engine Speed Measurement:
* Tachometer 1. an ... , 2. consisting of ... . 3. tacho-generator is connected to ..., > which is driven by ... . |
* independent electrical system
> an engine driven 3 phase AC gen. > and a synchronous motor driven indicator. * the main gearbox > the HP spool |
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Tachometer is most commonly used to indicate ... .
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the HP spool speed
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@ Tacho-generator
The ..... is dependent upon the speed of the engine. |
frequency of the generated AC current
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Phonic Wheel and Pulse Probe
Often called a ... system. |
"Variable Reluctance"
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Phonic wheel
is .... mounted on the ... . |
* a toothed wheel
* engine shaft |
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Phonic Wheel and Pulse Probe
It consists of ... in ... , and a ... situated in ... . |
* one or two permanent magnets
* close proximity to the phonic wheel * pickup coil * the magnetic field |
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Phonic Wheel and Pulse Probe
Princ. of op: > The magnetic field, which is greatest when ...... , > The resulting ... has a ... proportional to the speed of the engine shaft. |
* the teeth of the wheel
> are in-line with the pole pieces * fluctuating induced current in the coil * frequency |
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Propeller RPM indicator is
> graduated in ... increments > from ... to ... RPM typically. |
* 50-RPM
* 0 - 2700 |
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The normal governed operating range of the propeller RPM is ... RPM with a maximum allowable of ... RPM typically.
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1800-2200
2200 |
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RPM indicator @ older AC
use ... . |
* mechanical cable driven tachometer
* flyweights |
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Drag-cup RPM indicator
Construction : ... . |
* mechanical cable driven magnet
* rotating inside an aluminium cup > fixed to spring & pointer |
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@ Propeller RPM indication
Drag-cup RPM indicator Principle of operation |
> Rotating magnet
> gen eddy currents @ cup > creating a mag. field > coinciding with that of the magnet > cup cannot rotate > dragged up by the field |
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@ Propeller RPM indication
* DC Electrical tacho's > Relate RPM to ... > problem : ... * AC Electrical tacho's > Relate RPM to ... > Adv : ... |
* a generated voltage
* V drops with cable length * Freq * immune to cable length / Resistance |
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@ Propeller RPM indication
latest modern engines incorporate a ... and ... . |
* electric pickup
* a digital counter |
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@ Propeller RPM indication
Mechanical Tachometers basic components : ... |
* a flex drive from a drive outlet @ engine
* an indicator @ cockpit |
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@ Propeller RPM indication
Mechanical Tachometers main drawback : ... |
* the flexible drive
> limited wear life > no more than 25-feet > limited to 9" radius bend |
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@ Propeller RPM indication
Mechanical Tachometers The flex drive consists of .... . |
* an outer flexible casing
> supporting the inner drive |
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@ Propeller RPM indication
Mechanical Tachometers Casing of the flex drive Formed by .... Made from ... . Is packed with ... . |
* spirally wound interlocking metal strips
* either brass or steel. * asbestos stringing |
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@ Propeller RPM indication
Mechanical Tachometers The inner drive is made up of ... on which ... are wound left then right alternatively, with a ... @ each end. |
* a central steel core
* layers of steel wire * square drive |
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@ Propeller RPM indication
Mechanical Indicators Consists of ...* on a ... which rotates at ending speed, causing the ... forces to act on the ...* ; it tries to assume a ... position but is opposed by ... . |
* a pivoted weight > spindle
* centrifugal * horizontal * the springs |
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@ Propeller RPM indication
The Tx and the indicator @ Electrical Tachometers are electrically connected together by ... . While the generator, which is driven by the engine, has a ... . |
* a three cored cable
* 3 phase alternating current output |
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@ Propeller RPM indication
Each tacho generator consists of a ... and a ... , |
stator
rotor |
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@ Propeller RPM indication
Stator @ tacho generator is a ... of ... which has a ... . |
* hollow cylinder
* laminated iron * three phase star connected winding |
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@ Propeller RPM indication
Stator @ tacho generator The conductors of the stator are arranged in ... cut around the ... of the cylinder. |
* slots
* inner surface |
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@ Propeller RPM indication
Rotor @ tacho generator is either a ... or ... |
* 2-pole or a 4-pole
> permanent magnet |
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@ Propeller RPM indication
Rotor @ tacho generator * The 4-pole version has skewed poles to : > produces ... . > prevents the ... . * The 2-pole version achieves the same effect > by ... and ... which make up a phase. |
* a better waveform
* cogging effect * skewing the stator teeth * the individual coils |
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@ Propeller RPM indication
Rotor @ tacho generator > Induces ... in the stator windings. > is mounted on a ... > and runs in ... or ... bearing. |
* alternating electromotive forces
* spindle * ball / Oilite |
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Oilite bearings advantage : .....
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* retain oil
* allow for long periods for use > without maintenance |
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Drive coupling used on tacho generators are : ...
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• Flexible
• Splined > most common • Two pin |
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@ Propeller RPM indication
Tacho gen: To reduce the mechanical load @ generator : ..... .. |
* the operating speed is reduced
> by gears @ engine drive system |
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@ Propeller RPM indication
Tacho indicators are a ... type |
synchronous motor
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@ synchronous motor type tacho indicators:
When the ... equals the ... , the two fields lock and they both rotate synchronized with each other. |
* speed of the rotor field
* rotating field of the generator |
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@ synchronous motor type tacho indicators:
a ... magnet rotates inside a ... . |
4-pole
copper drag cup |
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Maintenance Practices
@ Propeller RPM indication Flexible Drives drive should be fitted with the ... @ engine end |
union vent holes
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Maintenance Practices
@ Propeller RPM indication Flexible Drives No part of the drive should come within ... of a magnetic compass |
11 inches
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Maintenance Practices
@ Propeller RPM indication Flexible Drives Before connecting the engine drive end, adjust the inner drive so that it does not bend or stand up more than ... . |
a quarter of an inch
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Tachometer indicators need no servicing other than ... .
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cleaning
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Vane Type Fuel Flowmeter
Fitted @ ... . |
* LP fuel system
* D.steam of LP fuel pump |
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@ Vane Type Fuel Flowmeter
* Position is determined by ... . * Transmitted to the flight deck > by either ... > or ... position indicator. |
*the speed of flow
* a Desynn * an Autosyn |
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Vane Type Fuel Flowmeter
External power : (y/n) |
Yes
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@ Vane Type Fuel Flowmeter
Bypass valve operates when ... increases above ..., due to the vane seizing. |
* the differential Px across the valve
* a set value |
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Vane Type Fuel Flowmeter
indicates in ... . |
lbs/hr or kg/hr
.,.~ |
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Synchronous Fuel Flowmeter
Also known as ... . |
an Autosyn Fuel Flowmeter
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Synchronous Fuel Flowmeter
greater accuracy in that ... , compensating for ... . |
* it measures mass flow
> rather than volume * fuel temperature |
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Synchronous Fuel Flowmeter
measures in ... . |
kilograms or pounds per hour
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Synchronous Fuel Flowmeter
Construction & operation * Fuel enters the ... , > which is rotated at ... by ... . * The ... of the fuel > will determine its volume > and the ... to be created by the action of the impeller. * turbine is twisted against its restraining spring > by the ... . |
* transmitter impeller
* a constant 60 RPM * the synchronous impeller motor * temperature * amount of force * mass flow force |
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Motorless Integrated Fuel Flow Transmitter
Construction * a housing containing > ... , ... and ... , which is .... * Two ... , > ... degrees apart, > at the ... . |
> a swirl generator
> a free- spinning rotor > a turbine * restrained by a spring > attached to the housing * permanent magnets are fixed > 180 > fwd and aft end of the rotor |
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Motorless Integrated Fuel Flow Transmitter
* Fwd end magnet > induces an electrical pulse @ ... > known as ... . * Aft end magnet > aligns with ... > induces an electrical pulse @ ... > known as ... . |
* small coil @ outer wall
> ‘start’ pulse * signal blade fixed @ turbine > larger coil @ outer wall > ‘stop’ pulse |
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Motorless Integrated Fuel Flow Transmitter
Princ. of operation Fuel mass flow causes .... creatina .... measured by ... , and converted to ... . |
* turbine deflection
* time difference btw start & stop pulses * the ECU * Fuel Flow |
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Motorless Integrated Fuel Flow Transmitter
Operating range of the fuel flow transmitter output > ... milliseconds, > corresponds to a fuel flow range of ... . |
0 to 170
0 to 27,000 lbs/hr |
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Synchronous Integrated Fuel Flowmeter
Uses the ... method to produce a signal. (dev. btw synch motore type & motorless integ. type) |
pulse difference
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@ Synchronous Integrated Fuel Flowmeter
A ... is essential if total fuel used is to be measured as the Kg/hr figure |
integrator
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Fuel flow transmitters that are not installed within ... must be treated to ... .
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24-hours
prevent corrosion |
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Thrust can only be measured in ... .
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an engine static test cell
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Engines are rated by ... or ... thrust,
always quoted on the engine data plate. |
Static
Gross |
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Pressures sensed for EPR are :
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* compressor inlet Px > P1
* turbine outlet Px > P6) |
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@ EPR measurement
A ratio of the two Px > converted into a ... > by the ... for transmittal to the flight deck indicator. |
electrical signal
pressure ratio transmitter |
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EPR is not a direct indication of the thrust itself
the ratio ... and can be used as a thrust "indicator". |
does vary linearly with thrust
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Pressure Ratio Transmitter
consists of ... sensitive to ... , > processed into a ratio by ... , > converted into ... . |
* a series of bellows
* the air pressure tappings * mechanical means * an electrical signal |
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Fwd speed effect @ EPR
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Due to Ram effect
P1 : inc EPR = P6 / P1 : dec |
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High Bypass Fan engines define EPR as
... or ... . |
* Fan Outlet Pressure (Pf)
> to Fan Inlet Pressure (P1) * Turb Integrated Px + Fan Outlet Px > to Fan Inlet Px (integrated EPR) |
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Engine Turbine Discharge/Jet Pipe Pressure
utilizes a ... > to measure the ... > of the ... . |
* pitot probe
* dynamic pressure * jet stream aft of the turbine |
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Engine Turbine Discharge/Jet Pipe Pressure
Indication could be in the form of ... (3) |
* Lb/in2
* in Hg * % of the max thrust |
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Older engines simply used ... as the indication of thrust.
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compressor RPM
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Oil Pressure Measurement
Oil pressure is ... transmitted to an indicator @ instrument panel. |
electrically
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Oil Pressure indication could be of ... or ... type
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flag / dial
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Oil pressure transmitter may be of either the ... or the ... type.
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direct
differential pressure |
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The differential Px type
Oil Px transmitter senses the difference between ... and ... Px. |
engine feed
return oil |
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The differential Px type
Oil Px transmitter takes into account ... . |
changes of altitude
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In addition to the pressure gauge
operated by a transmitter, an oil pressure switch may be provided to indicate ... . |
absolute minimum
allowable oil pressure |
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Direct Reading Pressure Gauges
could of ... , ... or ... type |
* Bourdon Tube Principle
* Pressure Capsule * Pressure Bellows |
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Strain Gauges
are ... devices which are used to detect ... . |
electric passive
forces |
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Strain Gauges
Principle of operation * metallic wire consists of a ... alloy. * The ... and the ... of the conductor > is function of the force. * Expanding force increases, shortening force decreases the ... . |
* chrome-nickel
* length / diameter * resistance |
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Piezo- resistive Sensors
have ... which are diffused into ... . |
* P- or N- conducting elements
* a pure silicon substrate |
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Piezo- resistive effect changes the ...
with a much ... sensitivity than what a metallic strain gauge does. |
resistance
higher |
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@ an accurate pressure transducer
based on Variable Frequency Signals: * An oscillator coil assembly oscillates the ... . * Its ... increases with the applied Px > against the ... reference inside the transducer. * A ... , proportional to the pressure will be produced. * a ... compensates for the amb temp. |
* diaphragm
* resonant frequency * vacuum * output freq * temp sensing resistor |
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Oil pressure Warning Light
puts light on when ... . color is ... . |
* oil Px reaches a low level
* Red |
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Oil pressure Warning Light
2 switches on later ACFT A ... will decide which switch to monitor. |
speed comparator
(based on engine speed) |
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Oil Quantity Measurement
utilise a ... around a series of ... . |
sliding magnet
reed switches |
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Oil Quantity Measurement
Current to the indicator varies as a function of ... . |
the resistances in the probe circuit
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Reason for boost gauge
to indicate ... of ... in ... of a supercharged engine in relation to ... . |
pressure
fuel/air mixture induction system STD atmospheric Px |
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The boost gauge dial is calibrated to show both ... and ... .
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positive
negative pressures |
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The pointer @ boost gauge
only registers zero when ... . |
the induction pressure is 14.7 PSI
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Boost gauge principle
A ... is subjected to ... which operates a ... . |
* evacuated aneroid capsule
* induction pressure * quadrant |
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The bezels of boost gauges are coloured ... to indicate that they are associated with the ... system.
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red
fuel |
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Adjustable lubber mark
@ bezels of boost gauges to indicate ... . |
the maximum permissible boost
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Adjustable lubber mark
@ bezels of boost gauges locked by ... . |
a grub screw in the bezel
(or bazel itself) |
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Boost gauge construction (type1)
Px fed to ... via ... , which houses 1. a ... to [prps] ... 2. and ... to ... . |
* an airtight case
* a union * small gauge filter > prev. FO * a choke > surge protection |
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Boost gauge construction (type2)
formed by two ... one is ... the other is ... through ... . they are connected by a ... in the middle. |
* flexible metal bellows
* vacuum * fed by induction Px * a union * a distance piece |
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In the boost gauge pipeline
is a ... which prevents fuel entering the gauge. |
fuel trap
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Fuel Trap is fitted to the ... type of boost gauge.
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airtight
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A typical fuel trap
is cylindrical with two ... on top and a ... at the bottom. |
unions
captive drain plug |
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Fuel Trap must be mounted ... (V/H)
with the ... end (marked top) uppermost. |
vertically
union |
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@ Fuel Trap
Pipe to boost gauge > connected to the ... , > the other : connected to pipeline from ... . |
* central union
* the engine induction system |
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Zero error test @ boost gauge
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Check PSI equivalent of Met Px
to gauge's reading |
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Leak test @ boost gauge
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+ve Px to union
monitor the pointer |
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... is primary performance instrument in the flight deck
for Turbo prop/shaft engines. |
torque indicating system
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Torque @ engines
may be presented as ... (4) |
* torque oil pressure (PSI)
* direct torque (ft-lb) * torque percent * direct horsepower |
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Torque indicating system
Principe (type 1) |
angle of twist
of output shaft |
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Torque indicating system
Principe (type 2) ... @ ... produce .... that act to ... . |
* helical gears @ reduction gearbox
* axial thrust * pressurize oil |
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Early vibration transducers
Type : ... . units of vibration : .... . |
* moving coil
* Relative Amplitude |
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Vibration Indication Systems
2nd type a ... and a ... inside a casing Principle : |
* piezo-electric crystal
* mass * small AC current > freq = freq of vib. |
