Final Exam Review (Kimbo)

two individuals credited with creating the jet engine

Frank Whittle and Hans Von Ohain

first country to fly a jet powered airplane

Germany

what year did Britain fly their first jet aircraft?

1941

When did the U.S. fly their first jet aircraft?

1942

First all-American company to create a jet engine

Westinghouse

What type of jet engine was Westinghouse’s jet engine?

axial flow

Maximum number of stages on a centrifugal compressor?

two

What would happen if there were more stages on a centrifugal compressor?

a third stage would turn so fast that shockwaves would form on the blades

does the turbofan or pure turbojet have a more efficient engine?

turbofan

are modern jet engine spools single or multi spool?

multi spool

how many spools do modern U.S. jet engines typically have?

two

how many spools do modern British jet engines typically have?

three

what is the name of the sound that a severe compressor stall makes?

surge

what are the two basic types of combustion chambers

annular and can

which type of combustion chamber is the most common today?

annular combustion chamber

which engine that we saw in the lab had a can combustion chamber?

Mark 102 type engine

How many minutes do you need to warm up the engine before takeoff?

5 minutes

What are the six major sections of a jet engine on an airliner?

inlet, compressors, diffuser, combustion, turbine, jet nozzle/thrust reverser

do any airliners today have afterburners?

no

which airliner had an afterburner?

Concorde

principal advantages of a high bypass engine?

fuel efficient and quiet

What percent of thrust is from the bypass engine?

90%

What percentage of the air in a jet engine is used for combustion?

25% or less

What percentage of air in a jet engine is used for cooling?

75%

What causes the noise on jet engines?

shear

shear

core air coming out of the engine and mixing with the static air outside

Newton’s first law

law of inertia - an object in rest will remain in rest and an object in motion will remain in motion unless acted on by an external force

Newton’s second law

F = ma (force equals mass times acceleration)

Newton’s third law

for every action there is an equal and opposite reaction

after a flameout occurs in flight, what is the first thing you try to do to restart your engine?

airstart

after a flameout occurs in flight, what is the second thing you try to do to restart your engine?

try a starter assisted start (APU)

on earlier engines, shrouded blades were designed to minimize losses of what?

pressure on the tips of the turbine blades

on modern engines, what is done to minimize loss of pressure on the turbine blades?

active clearance control (ACC)

two types of nozzles on the back end of the engine

convergent/divergent and convergent

Which type of nozzles are used on afterburner engines?

convergent/divergent nozzles

which type of nozzles are used on regular engines (without afterburner?)

convergent

T/F: U.S. airliners mostly have convergent/divergent nozzles on their engines

FALSE

What type of nozzles do U.S. airliners have?

convergent nozzles

which type of engines have convergent/divergent nozzles?

only engines with afterburners

what is the purpose of convergent nozzles on airliners?

straighten out some of the flow to get more thrust

in a two spool engine, which stage of turbines drives the N1 compressor?

low pressure turbines

N1 compressor

the low pressure compressor

N2 compressor

high pressure compressor

which compressor is used to start the engine?

N2 compressor

which engine condition instrument in the cockpit uses thermocouples?

EGT gauge

What is the N2 gauge?

gives the high pressure compressor speed

What is the N1 gauge?

gives the speed of the fan blades

old gauge used for pressure

EPR: engine pressure ratio

most common combustion chamber byproduct?

nitrogen oxide

annular combustor

takes air in at the front dome area of the liner and discharges it at the rear

thrust reversers provide what percent of the braking force under normal runway conditions?

20%

are axial flow compressors or centrifugal flow compressors more susceptible to damage?

axial flow

normal operating procedure for thrust reverse

select reverse after touchdown at ground idle speed and reapply power to appx 75% N2 speed

Once the engine is fully started, do the igniter plus continue to fire or do they shut down?

they shut down because there are limitations on the starter

why is overtemp such a problem when starting up the engine?

there is no airflow through the engine so it needs to be kept cool when getting it started

which pump provides oil to the bearings in the engine?

lubrication pump

scavenge pump

pulls oil off the bearings and recycles it through the oil tank again

is the scavenge pump or oil pump stronger? by how much?

scavenge pump; 1.5x

what type of oil system is in jet engines?

dry system

besides being burned in the combustion chamber, what does fuel do in the jet engine?

guide vanes, fuel oil heat exchanger, operates compressor bleed mechanisms

fuel oil heat exchanger

uses fuel to cool off oil

when are times that you would have the igniter plugs running normally (continuous ignition)?

takeoff and landing, moderate turbulence, rain, icing conditions

borescope

an instrument used to inspect the inside of a structure through a small hole

what does the reverse flow combustion chamber do?

drives turbines

where are the reverse flow combustion chambers found?

after centrifugal flow compressors

three types of power sources on airliners?

AC, DC, battery (emergency power source)

which component in the electrical system provides normal DC power on an airliner?

transformer/rectifier

what does the transformer/rectifier do?

transforms AC to DC power

what type of power do generators provide?

AC power

what changes battery power into AC power?

static inverter

what does the static inverter do?

used in emergency situations to get AC power

if you are flamed out and have 2 igniter plugs, both powered by AC, one on an emergency AC bus, where does it get its energy from to start firing?

battery from the static inverter or emergency AC bus power source in an electrical emergency

when does the engine produce more pollutants than other times?

taxi because there is less airflow through the engine

what is the new inlet put on during maintenance/test stand to get accurate readings off the engine?

bell mouth inlet

which is used to get really meticulous, fine readings during maintenance?

bell mouth inlet

what is the primary way to start engines on the ground?

APU

what is the secondary way to start engines on the ground?

ground cart

if you are pushing back and engine fails, what do you do as you are taxing out to the runway? How do you start the second engine? 

you cannot start it; there is no way to get it started on the ground

how many air turbine starters are on each engine?

one

for how many starts are air turbine starters good for?

5000

which engine studied in the lab was a 3 spool engine?

ATF 3 (advanced turbofan 3)

which engine studied in the lab was a 2 spool engine?

Rolls Royce Mark 102

old form of fire detection on airliners? (pre 1950s)

point fire detectors

form of fire detection on airliners since mid 1950s?

continuous loops

how does an engine technician rotate the engine?

through a tool in the gearbox

which is the first aircraft in the world to have something similar to an APU?

Boeing 727

what device did the B24s have (similar to an APU)?

putput (10 HP gasoline powered motor)

what is the primary task of jet ignition systems?

to light off the combustion chamber during start

what is the secondary task of jet engines?

relight combustion chamber if needed

Is jet fuel or avgas easier to ignite? why?

avgas because it has higher volatility

T/F: Jet engines have 4 igniter plugs

false

how many igniter plugs do jet engines have?

2 (or 3 but rare)

method of fuel control?

electronic

what do afterburners use to function that is already existing in the engine?

air

If an engine has been overhauled and is short of making the thrust it is supposed to make, what does Honeywell (or whatever company) do to get it up to speed/improve efficiency of compressor blades?

engine wash

first company to solve compressor stalls by using two stages?

Pratt & Whitney

second company to solve compressor stalls by using two stages?

Rolls Royce

does the thrust reverser that is used on all modern airplanes use bypass or core air?

bypass air

which engine studied in the lab uses an axial flow compressor?

J85 (T38 engine)

which engine studied in the lab uses a centrifugal flow compressor?

J69 (T37 engine)