Gefahr Lithium Battery
Self Ignition when the charging process is not properly controlled -> Thermal runaway
it is most likely to be hazardous -> with an extreme internal pressure
Definition Electric Power
P = E/t
turbo prop alpha range
flight idle to maximum power
TAT
SAT * (1 + 0,2*M^2)
Gyro Magnetic Compass
Reihenfolge vom Flux Valve zum Torque Motor
FEAT
Flux Valve -> Error Detector -> Amplifier -> Torque Motor
the principle of INS regarding accelerometers and Gyros
Gyros and accelerometers on a stabilized plattform
plattform is kept level and north aligned
uses:
two accelerometers
three gyros
längliche Verbindungsstücke rumpf
“assist the skin to absorb longitudinal compressive loads”
stringers / longerons
NRV valve meaning
Non return Valve / Check valve
Check valves stop the flow in one direction and allow free flow in the opposite direction
shuttle valve
fly by wire laws A320
normal law
alternate law
direct law
Mechanical backup
Normal law:
system mode which is active throughout the flight
Alternate Law
provides most features of the normal law
some features suchs as automatic stall protection are lost -> conventional warnings
flight envelope protection is degraded
Direct Law
failure conditions prevent operation in Alternate Law
Auto pilot funcitons are lost
no flight envelope protection anymore
Mechanical Backuo
house in vented metal box
about / around
along
drehung um die Achse
along entlang der Achse
What is a combinaton of an AC electric motor and a generator called?
a starter generator
Paralleling generators
Balancing of
real load
reactive load
Real load sharing is achieved by increasing the torque to the lower speed aleternator.
Reactive load are balanced by regulating the energizing current (exiter field current).
function impulse magneto coupling
retard the spark during engine start
provide a stronger spark on TDC
chemically correct ratio of fuel to air mixture
15:1
also the theoretical best economy
Piston Engine
Jet engine
facts regarding process and combustion
Piston engine
process is intermittent
combustion is at a constant volume
process is continous
combustion is at a constant pressure
Specific Fuel Consumption definition
SFC is the mass of fuel consumed for each unit of power output per unit of time.
Difference of impulse blades and reactive blades in a turbine…
all types of turbines rely on a stator to accelerate the airflow and to direc the air properly towards the rotor.
stator nozzle guide vane -> rotor extracts gas energy and converts it into mechanical work
impulse turbine
airflow direction changes
causes a change in the impulse of the gas flow, causing the force on the blades
constant passage of the rotor blades -> no change in temp/pressure
reaction turbine
direction of the airflow changes similar to the impulse turbine
passage between the rotor baldes convereges -> forming a nozzle
leads to aceceleration of the gas and expansion (?) druck sinkt
expansion of hot gas followed by conversion of kinetic energy (velocity) into (mechanical) work
Fail Safe
Safe Life
Fail safe:
when a structure fails there is an alternative load path privided by an adjacent part whic his able to take over the loads for a limited amount of time
-> multiple load paths
limited life time, during which the assembly will be free of fatigue or failure
-> only one load path
fly by wire
PCU
Power Control Unit
-> are operated by analagoue signals.
Rosemount Ice Detector
measures the resonant vobratoin frequency
baffles
baffle valves
baffle: damp spanwise fuel motion
baffle valves: prevent outward movements
IDG
Integrated Drive Generator
Kombination aus Generator und Constant Speed Drive
lubricated by an internal oil system
FADEC
Full Authority Digital Engine Control
-> digital control system mounted on the engine’s fan case -> performs the entire engine management task
> FADEC has a dual channel Electronic Control Unit for redundancy, with ine channel always active and a second one on standby.
single fault tolerant
Specific Fuel Consumption (SFC)
can be expressed in kg per
hour per unit of shaft power
Fuel Flow turbine engine
LP fuel pump low pressure boost pumps -> fuel-oil heat exchanger - > filtered and pressurized under high pressure pump -> delivered to a number of fuel nozzles
between fuel control unit and the fuel nozzle, a fuel flow transmitter and a fuel nozzle filter (letzter feiner Filter) a fitted.
Flat rated engine
below the Flat Rated Temperature, EGT is below its limit, thrust is strucutrally limited flat rated
limited by maximum mass flow of the engine/ of air?
Above the Flat Rated Temperature, EGT is at its limit and limits the the Thrust of the engine temperature limited
constant amount of thrust up to a certain temperature, then thrust decresases
power reduced, because the air is less dense -> less performance
unterhalb der Temperatur muss der thrust konstant gehalten werden, da sonst Belastung für den Engine zu groß werden würde
Compressor Stall
some part of local disruption of airflow occurs
individual compressor blades stalling
-> when the stall spreads out other turbine blades and stages -> full surge of the compressor
-> disruption of airflow in a compressor stall reduces the cooling airflow into the turbine, causing a rise in TGT (turbine Gas temp)
(before and between the individual turbines)
> RPM of the turbines/compressors will fluctuate, and the EPR will drop
was sind turbine nozzle guide vanes
stators in der turbine
Bypass Ratio
Bypass Mass Flow / HP compressor mass flow
immer mass flow
Engine Pressure Ratio (EPR)
it is the ratio between the low pressure turbine exhaust total total (the engine’s last stage) and the engnine inlet total pressrue (the fan’s pressure)
durck hinten durch Druck vorne
höhere Machnumber, mehr druck vorne -> geringeres EPR
höhere Höhe -> geringere Dichte -> weniger thrust bei gleichem EPR (total pressure Verhältnis bleibt gleich, vllt durch höhere Geschwindigkeit bei geringerer Dichte ?)
on condition maintenance
hard time maintenance
predictive manintance that involces replacement or ovehaul of components before failure happens. regular inspections
“monitoring of ciritcal parameters of a component or a piece of equipment and its replacement if a limit value is exceeded”
hard time maintenance: component is replaced after a fixed amount of hours
Rudder ratio changer
variable stop system
blow back
the rudder deflection is reduced at higher IAS, despite the pedal being able to move the same amount all the time
Variable Stop System
the movement of the rudder pedals and rudder is always proportional. The distance the pedals and rudder can move reduces with higher IAS
Ice Detection Systems
advisory
primary
automatic
manual
the crew activates ice protections systems based in the standard flight manual critera if total temperature reading and the sighting of moisture
ice detector signal (kann auch der stab sein?) serves as a back up indicator
monitor icing using primary methode as stated in the AFM
ice detector system automatically activates ice protection systems at the optimal moment.
takes full advante of the ice detector’s capabilities and proved the most benefit to the operator
the flight crew manually activates ice protection systems based on ice detector signals
=> relying on indications of ice detectors rather than observing potential icing conditions (advisory)
colours
AVGAS 100LL
AVGAS 100
AVGAS 115
blue
green
Fuel control unit
= Governor pump / hydro mechanical unit
there is always a fuel filter before the FCU, either only before the HP pump or before and after the HP pump.
The FCU or governor pump comes after the HP pump
Piston engine specific fuel consumption
SPFC = mass of fuel required to produce unit power for unit time
static load
dynamic load
static load:
constant loads, that do not change in size, position or direciton
dynamic load:
are laods that do change in size, position and direciton
DC generators are connected in … in order to
parallel to provide maximum power
primary inout signals for a hydro machanical gas turbine engine fuel control system
N2
compressor discharge pressure
compressor inlet temeprature
fuel shut off
thrust lever angle
how is a torsion box formed
a torsion box is formed by wing spars, ribs and wing skin reiforced by stringers
former
stringers/ longerons
vertical
longitudial
check valve
Fluss nur in eine Richtung
Flussrichtung muss gecheckt werden
system with low pressure fluid when the system actuating mechanisms are idle
open centre hydraulic system
pressure transducer
wandelt den gemessenen Druck in eine Anzeige um
zero force position trim irreversible flight controls
neutral position changes for ailerons, rudder
remains constant for: elevator
wind screen heating with
AC 3 phase at 400HZ
brauch viel Strom
Freezing Point
Flash point
Jet A
Jet A1
Jet B
Jet A: -40
Jet A1: -47
Jet B: -60
Flash Point
Jet A: 38
Jet A1: 38
Jet B: -20
Density:
Jet A1 0.8kg/l
AND gates / OR gates
bus tie breaker
zwischen generator and bus
How to determine torque of an electric motor?
simpel, wie bei einem Verbrennungsmotor
P = torque * RPM
(U * I) / RPM = Torque
RPM and manifold pressure procedures
throttle control:
controls the Power output of the engine manifold pressure indication
RPM lever:
controls the Engine RPM by changing the blade angle
in order to reduce power when reaching the desired altitude:
reduce manifold pressure and adjust RPM to a lower RPM
dry sump system
scavenge pump, pumps the oil from the sump into a tank
pressure pump, from tank to engine
scavenge pump must have a greater volume in comparison
to maintain a constant mixture in a piston engine, a carbutettor is fitted with a
diffuser (compensating jet)
glaube das ist einfach das Hauptrohr
hung start
hot start
hung start:
N2 stabilizing at a lower than normal RPM and a subseqeuent increase in EGT.
The engine fails to accelerate sufficiently because of a too low peneumatic starter pressure before fuel is supplied to sustain combustion.
-> shut down engine -> cranking -> cooling
hung -> to low
Hot start:
early starter cut out or fuel messcheduling (excessive fuel in the combustion), strong tailwinds
light up ath ery low rpm > sudden increase in EGT
continues to accelerate
pulling the fire handle
turning the fire handle
arming
executing
oxygen
Emergency -> pressuirzed 100% oxygen
-> should be used when there is smoke on the flight deck
n position: diluter demand ->mixed with surrounding air and on demand
100%: pure oxygen -> on demand
Emergency: continous flow of 100% oxygen at positive pressure
magneto ground
strain
deformation caused by the action of stress on a material
-> stress is the internal force per unit area inside a structural part as a result of external loads
tensile load
Zugfestigkeit
stress corrosion
occurs as a result of the combined effect of sustained tensile stresses and a corrosive environment
plastic deformation
Verformung die bleibt
im Gegensatz zu elastic deformation
stack pipe
stand pipe
Emergency use, weil noch fluid enthalten ist.
normal use
short cylindrical probe mounted on a vibrator housing
prssire hydraulic system
3000 PSi and higher
autobrake goal
a specific decelration rate, if this cannot be achieved because of slippery RWY, brake pressure is increased
only in the RTO mode, maximum brake pressure is applied, so here not the deceleration rate, but the pressure is decisve (?)
no selection of autobrake -> no takeoff warning
for a given touchdown speed, no reverse, dry RWY and a given ABS setting -> constant deceleration rate
MOGAS in relation to AVGAS
higher risk of ice in carburettor
lower octane -> higher risk of detonation
computer life expactancy
10 degrees increase > double life
Work
Joule
pole pair formula
AC Gen Putput frequency [Hz] = (Rotor RPM) * (number of pole pairs) / 60
Öl Kreislauf
pressure indicator nach der pressure pump und vor dem Motor
Oil cooler nach dem Motor
Waste gate supercharger
waste gate controls the amount of exhaust gas that goes to the turbine -> fully open -> no supply to the turbo charger
Thrust equation
Thrust = M * (Vjet - Vflight) + A (P - P0)
M mass of the air
Vjet exhaust nozzle gas velocity
Vflight flight forward speed
A nozzle area
P nozzle static pressure
P0 ambient static pressure
-> static thrust
F = (M x V) + (A x P)
compression ratio centrifugal compressor
4:1
compressor stall
entsteht wenn die axial velocity im Verhältnis zur RPM zu klein ist.
Emtscheidend ist dabei aber die axial velocity und nicht die RPM bei den Fragen
geringe axial velocity
entsteht bspw. durch zu starkes Gas geben, rise in the combustion chamber pressure -> kann zu zu starker Durck zunahme in der combustion chamber führen und dadurch den axial airflow verlangsamen zum Stall
Die luft muss entlang des compressors immer weiter komprimiert werden. Das design compression ratio wird dabei bei der design RPM erreicht.
at low compressor RPM, compression is low, reduciton in volume of air reicht nicht aus to pass through the small section at the end of the compressor -> airflow restriction in the rear stages -> axial velocity in the front stages is reduced -> compressor stall in the frontal stages
fuel flow measurement position
just before the soray nozzle, after the passage of the fuel control unit
torsion
verdrehung des Flügels bspw.
Why is the reservoir pressurized?
to prevent cavitation in the pump
cavitation -> air bubbles
cavitation
vapour lock
hydraulic system air bubbles at high altitudes for example
fuel system -> Wasserdampf entsteht
fully powered primary flight controls
no direct linkage between control column and control surfaces
either mechanically actuated fully powered flight control system
control column moves valves which then controls the pressure onto the hydraulic actuators
redundancy can here be achieved for jammed or broken controls
one control axis on two separate control runs which translate the pilot’s movements into useful movements of the servo valves via the power control units.
electrically actuated fly by wire control system
input is given into a computer, which eletronically transmits the actuation signals to the hydraulic actuators
bleed air pressure reference
atmospheric pressure
fuel pressure measurement where
at the outlet of the low pressure fuel pump (booster pump) or at the outlet of the the outlet of the high pressure filter
AC generators operated in parallel must have the same
voltage and phase
wet sump system
only pressure pump and filter
difference turbocharger and supercharger
supercharger is powered by the engine
turbocharger is powered by exhaust gases
smith ice detector
der mit Löchern
small holes vorne und ein großes vorne, hinten größere Löcher
der differential pressure, vorne total pressure hinten ambient pressure wird gemessen.
Wenn die kleinen Löcher vorne zu eisen sinkt der total pressure ?, difference in differential pressure -> ice indicaiton
will smith likes small holes
decrease in dynamic pressure
maximum continous power synonym
rated power
calculation of density altitude flight calculator
AIRSPEED indicator: PA and OAT
DEnsity altitude window: density altitude
120ft adjustment per degree off the isa
electrical engines and curren / torque
rotor seizure: current and torque increase to try and get it going faster
rotor runaway: current and troque decrease to dry to slow it down
testing a fire detection loop
Fire warning should sound
if system is broken: either no indication or fault alert
CS 23 aircraft catergories
Normal
Utility
Aerobatic
Commuter
hydraulic fluids desired properties
low compressiblity
good lubricaiton and anti corrosion
high flashpoint and low falmmability
low volatility
adequate viscosity
thermal stability
shielding
insulation
shielding: no electromagnetic interference
-> braided wire
insulation: no short circuit etc
low propeller pitch setting of the propeller lever position
low pitch -> forward
high pitch -> rearward.. feather position -> full rearward
mixture ratio is defined as
mass of fuel and mass of air entering the cylinder
secondary gear boxes are usually connected to
the low speed shaft
first accessory gearbox -> high pressure shaft
der zweite ist immer langsamer
Difference generator to alternator
Gernerator:
fixed / stationary magnetic field and rotating amarture (where the current is induced)
Alternator:
stationary amature and rotating field
fire detection system with loop
either
resistance
capicatance
change with temperature
the other of the two is used for testing
-> when both values are low -> fault
AC generators in parallel
same voltage and phase
Difference knocking/detonation and preignition
Knocking / detonation
mixture is ignited
fuel burns at a normal rate
all of a sudden all explodes at once
preignition
the fuel air mixture explodes before the ignition of the fuel air mixture because of a hot spark plug for example
what is never corrosive?
fuel
Power = Torque * RPM
power is proporitonal to torque
advantage of nickel cadmium over lead acid batteries
nickel cadmium maintain a constant output voltage during discharge
Nickel Cadmium batteries
made of a potassium hydoxice solution
constant voltage during discharge
more prone to thermal runaway
lower internal resistance
require venting
beta range turbo prop
range of power lever positions between flight idle and mx reveresse
from just below flight idle to full reverse
alpha range -> fwd
APU
presurized air and electrical power
when is peak EGT reached
when the fuel and air are completely used up
piston engine
turbine engine
constant volume
constant pressure
ventialtion system tank
pressurized tank
drain tanks
prevent low or over pressure
to prevent vapour lock
to check the fuel
cut out valve
im Falle einer constant displacement pump
regelt den Druck in einem System mit einer constant delivery pump
jet transport a/c cabin differential pressure
8 to 9 psi
cantilever wing
keine zusätzliche Verbindung zum Flügel
hydraulic selector valve
direct system pressure to either side of the piston of an actuator
components greatest exposure to thremal loads
first stage tubine nozzle guide vanes
first stage of the HP turbine
activation of the fire extinguishing system
how is the squib fired
electrically detonated
power settings piston
1: Takeoff
2: max. Power
3: Economy Rich
4: chemically correct (EGT max)
5: econonmy lean
electric air pneumatic system advantage
increased range due to more efficient transfer of energy
feed box
it increases the fuel level at the boost pump location
carburettor heating, the mixture becomes…
richer
thrust and SFC with altitude turbine
Thrust decreases
TSFC: remains fairly constant
advantages gaseous system cabin instead of chemical oxygen generator
flow can be regulated
greater capacity
circuit breakers must be ale to withstand the transient overcurrents that occur when switching on
electric motors (inductive load)
what is opened in case of:
imbalance
underspeed
all else
imbalance: tie breaker
underspeed: gen breaker
all else: gen exceiter breaker
what happens when air is tapped from the HP compressor of a gas turbine which has its N2 RPM controlled
ERP decreases (beim Gas geben, more air at the inlet than at the outlet) and EGT increases (weil weniger cooling)
effect of using external bleed air without countermeasures
mass flow through the engine is lower -> lower thrust
higher EGT because the amount of cooling air in the combustion chamber is reduced
-> lower thrust can be compensated by more fuel as long as the engine operates below its maxiumum EGT limit
decrease the airflow across the rear stages whilst that across the early stages is increased
fusible plug
im Rad gegen Explosion
how to assess the state of charge lead acid
off load and on load battery voltage check
corrosive
hydraulic fluid
specific fuel consumption
turbo prop
turbine powered
turbo prop:
fuel flow per unit of power kg/h per unit of power
turbine:
fuel flow per unit of thrust
tip shroud turbine
increases turbine efficiency
1 hPA = 100 Pa
1 Pa = 1 N*m
bei der Thrust Formel muss Nm als Einheit für den Druck verwendet werden
function hydraulic selector swith
direct system pressure to either side of the actuator
exhaust nozzle function
convergent duct which accelerates the airflow
auch exhaust-propelling nozzle
-> increases the airflow thus the thrust
hydraulic low pressure alert is the first indication of
the pump pressure output being insufficient
rain repellent
a hyprobhobic layer is created causing the water to form beads and roll off the window
unusable fuel is sometimes minimized by
tank sump pads
Last changed2 years ago