Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

AV Laet QC > NDT vibration HUMS > Flashcards

NDT vibration HUMS Flashcards

1
Q

what is the definition of NDT

A

its a method of testing, examination or inspection that does not render, the material, equipment, system or structure unserviceable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

aims of NDT

A

to improve flight safety by ensuring the structural integrity of the aircraft

to increase aircraft and equipment availability

to reduce servicing cost

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what methods of NDT are there

A

visual and visually assisted

penetrant testing

eddy current testing

ultrasonic testing

radiographic testing

magnetic particle testing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

where are NDT reports written up?

A

rendered on an MF 762 IAW map - 01

whenever a fault id found using an NDT L2 WI

at each radiographic inspection (xray)

when specifically required by a work instruction in the relevent aircraft topic 5G or equivalent publication

on first use of a provisional WI

when any change is found whilst monitoring an existing fault indication

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what faults will NDT testing find

A

fatigue cracking

overload failure

sub surface flaws

corrosion

loose articles

incorrect assembly

secondary impact damage

residue build up on internal bores e.g. carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the action on finding a fault?

A

if a fault is found with an NDT technique IAW 5G - examination standard in the technique will state the acceptable fault size if any

fault found as casual inspection - topic 6 should be consulted for repair information, advice from station NDT team should be sought,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what are the two types of visual aids used for inspection

A

magnifiers (maginifiers can be used in accessible areas to find surface breaking faults)

remote viewing instruments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the construction / make up of an endoprobe

A

they consist of a complex optical system surrounded by a fibre light guide,

contained in a tube of plated brass/stainless steel

the viewing end of the probe is fitted with an eye piece cup and a right angled sleeve to accept the end fitting of the light guide

at the objective end are the light outlet and objective lenses

individual probes give one angle of view and are reliable to give forward, oblique, lateral or retrograde view

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

fibrescope construction

A

fully flexible instruments used where complexity of shape precludes the use of rigid endoprobes,

they consist of two bundles of glass fibre containing tens of thousands of strands,

the light guide bundle of non- coherent strands transmit light from a light source box to the object being viewed

the image guide is a coherent bundle, which transmits the image of the viewing eyepiece,

the distal end can be angled with operation of the angular controls

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the basic PT(penetrant testing) procedure

A

clean

apply penetrant and allow contat time

remove excess penetrant

apply developer and allow development time

examine indications

record

clean and restore surface protection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the advantages of PT

A

carried out by squadron/unit personnel after further specialist trainng (TEM)

results available after specified time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

PT disadvantages

A

surface finish has to be removed

liquids used are de-fatting agents

liquids used are flammable

this method can only detect surface breaking flaws

can only be used in accessible areas

time consuming

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what are the principles of magnetism

A

if a piece of ferrous material has been magnatised there is an area of energy surrounding the material known as a magnetic field,

this field is made up of a series of lines of force that flow from one pole of the magnet to another

they are characterised as being elastic in nature and tend to contract

they never cross and are defined by other lines of force

they form a complete magnetic circuit running from north poles to south poles outside and south to north inside the magnet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the theory of magnetic flaw detection

A

if a magnetic force is applied to a closed circuit of magnetic material the lines of force will flow in parallel lines from one side to the other.

if a flaw occurs cutting the lines of force, it will form “free poles”

magnetic particles applied to the surface of the components will follow the lines of force and will concentrate around the srongest area of attraction, the area of free poles, the gathering of particles will indicate flaws

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the detecting media used in magnetic detection

A

minute particles of oxide iron suspended in kerosene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

why must demagnatisation of material being tested be carried out and when

A

components must be demagnetised before, intermediately (when changing the direction of magnetic flux) and after testing

initial and intermediate testing is carried out to rid of any stray residual magnetism that would give spurious readings

final de-magnatisation is necessary so not to cause a reduction in accuracy of aircraft instruments

stray voltages dont induce into adjacent electrical circuits

adherence of metalic partical to moving parts that could cause excessive damge and wear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is the test procedure of maganetic detection

A

clean and degrease components

fully demagnitise the components

magnetise using the selected method

apply detecting ink and view for flaw indications

demagnetise

if serviceable, prepare the component for service

18
Q

what are the advantages of ultrasonic testing

A

ultrasonic is a very sensitive detection method

can be used on both metallic and non-metalic materials, penetrating to many feet in steel and many metres in aluminium

19
Q

briefley describe the concept of UT operation

A

the pulsed echo method is uded to detect flaws within a component

a focused pulsed beam of high energy sound is transmitted into dense material

ultrasound attenuates in air this will cause the wavefront to be refelcted back

pulses of highh frequency (0.5-20MHz) are introduced into a material

the signal will reflect back from the boundary of the material and any flaws and will show up on the display

20
Q

what couplants (UT) are used and why do we use them?

A

ultrasound cannot travel through air so we use couplants to aid this

fluorescent orange - for metals (thixotropic)

blue gel - for composites

bright orange - thicknes gauging applications

21
Q

list the correct applications of ultrasonic testing

A

major structures

large forgings/casting

bolts

around bolt holes

22
Q

describe the theory of eddy currents

A

an alternating current is passed through a coil this causes a magnetic field to form in the vicinity of the AC coil,

the polarity of the magnetic field will reverse at the same frequency as the AC that produces it,

when the probe is placed near a conducting medium the primary field and medium couple (magnetic coupling)

this causes a magnetic field to flow at 90º to the primary field, causing circulating induced magnetic currents (eddy currents)

the eddy currents produce a secondary magnetic field that opposes and modifies the primary field

23
Q

how is the fault interpreted when using eddy currents testing

A

as the probe is moved towards the material being tested, any flaw will cause the eddy current to be distort, this will alter the strength of the secondary field, causing the strength of the primary field to alter

any changes in the primary field cause the AC to change in the coil and show an indication on the instrument

24
Q

state the principles of eddy current testing

A

in aerospace application the coil is normally incorporated into the tip of a probe,

connected to a suitable instrument to balance the primary and secondary magnetic fields,

this will cause the probe when moved to indicate any changes in eddy currents due to flaws to indicate an imbalance in magnitude of the magnetic fields

these changes can then me displayed electronically

25
Q

what are the current applications of eddy current testing

Girls that take cock freely

A

used for surface and sub-surface faults

gearboxes

tail and main rotor blades

tail pylon hinge fittings

compressor casings

fuselage

26
Q

what are the advantages of radigraphic inspection

A

can be used to reveal faults such as

cracks

corrosion

internal defects (without dismantling)

inspection of enclosed structures

examination of a faulty component in the condition of which it failed(failure can be lost during dismantling)

correct assembly of item “in-situ”

27
Q

properties of xrays

A

penetrate matter opaque to light

they travel in straight lines but cannot be focused as can visible light

chemical effec on photgraphic film

ionise gases

cause certain salts to lumise

they damage or kill cells

28
Q

safety precautions of radiographic hazards

A

thorough medical examination prior and during woking/ operating xray equipment

personal checks using thermo luminescent dosimeter TLD or electronic personal dosimeter

care taken with equipment due to high voltages of xray

cordon of the area where xrays are being used and display warnings bearing special symbol

not classified workers are not permitted to work or enter cordoned area without authorisation from senior operation

29
Q

what components are susceptable to excessive vibration wear

A

out of balance rotating components

damaged rotor blades

poor servicing, with respect to purging and removal of excessive grease

incorrect rigging of flying controls

defective blade dampers

component wear

shaft mal-alaignment

bowed shaft

defective flying control jacks

damaged or defective resilient mountings

30
Q

what defects can vibration cause

A

reduce fatigue life

accelerated wear

reduced systems and weapons accuracy

reduced equipment reliability and performance

aircrew fatigue

31
Q

what two vibration measurements are currently used

A

source measurement

remote measurement

32
Q

remote measurements

A

remote measurement

normal practice to measure vibration levels at set positions.

set positions are laid down for aircraft by type and must always be used

any deviation will cause inaccurate results

reliance is placed on the fact that the airframe will transmit any vibrations from its source to measuring point

33
Q

source measurement

A

source measurement

measures vibration on, or near as possible to the component under test.

signal is filtered overe a narrow bandwidth to detect relevent frequencies of item being tested

limitied applications due to difficult access and special equipment required

34
Q

why is it important to have blade (stroboscopic) tracking

A

it is important to have blades flying within the same tip path plane

heavy vibration occurs when one blade follows in the disturbed wake of another

a blade flying high is producing more lift giving a constantly changing lift pattern around the rotor disc and consequennt vibration

35
Q

list contaminents in a hydraulic and lubrication systems

A

dirt left from manufacture and relased by vibrations

compnents wear

atmospheric dirt and moisture during maintenance

incorrect fluid replenishment

corrosion products

36
Q

list containment in fuel system

A

dirt left from manufacture and released by vibration

atmospheric dirt and moisture during maintenance

water from condensation and poor refueling practices

microbiological growth on fuel/water interface

seals and sealant detaching

37
Q

what precautions must be observed during hydraulic and oil replenishment

A

all replen containers must be checked for correct fluid specifications before introdusing it into the system

extreme care and attention to cleanliness should be observed in any servicing which involves removal/installation of components

pipes and orifices are to be covered or blanked during any serviceing and covers should only be removed just prior to installation

only authorised equipment is to be used for replen

all equipment used in connection with oil wetted systems must be kept scrupulously clean, and not used for any other purposes. must be dry before use

orifices and areas around filler caps on aircraft replenishment equipment and containers must be kept scrupulously clean

filler caps must be in place and properly secured except during replen. pipe ends must be blanked and properly stowed when not in use

38
Q

what programmes are used to monitor the health and usage of oils and hydraulics systems

A

routine fluid sampling programmes such as SOAP and LCM 20

39
Q

what are fitted to system to detect particles

A

magnetic and chip detectors

40
Q

in great detail state how a fuel sample is taken from the aircraft

A

fuel/water checks are carried out as a routine operation on aircraft and when fuel is suspect,

these checks are normally carried out using water detection capsules in conjuction with a syringe, after drawing a small amount of fuel from the aircraft fuel tanks,

via the fuel sampling points or drain valves, into a cleen, clear container.

water will be seen in the container as globules in suspension or as a layer in the bottom of the container once the sample has settled

AV Laet QC (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions