1
Q
How can you measure screw thread pitch ?
A
- Screw thread pitch gauge
Match thread on gauge to thread on screw/bolt and check if alined
2
Q
Name all 5 classes of fit with threads
A
Class 1- loose fit
Class 2- free fit
Class 3- medium fit
Class 4- close fit
Class 5- tight fit
3
Q
Explain a lock washer ?
A
- Used between joint surface and nut
- Made of steel
- Spring loaded washer which with friction, doesn’t allow vibration to loosen the nut which has been tightened on
4
Q
What are 3 types of lock washer ?
A
- spring
- tab
- shakeproof
5
Q
Explain spring washer ?
A
- Fitted beneath nut which compresses the spring creating friction when nut is tightened
6
Q
Explain tab washer ?
A
- One of the flat sides is bent against the nut and other bent side is places into hole on surface
- Stops vibration loosening bolt
7
Q
Explain shake proof washer ?
A
- Spring steel washer
- Tendency for nut to unscrew is prevented by the sharpe sides bitting into underside nut
- Can be repeatedly used
8
Q
What is the diameter of lock wire measured in ?
A
1/1000 of an inch
9
Q
What happens to end of wire once twisted final time ?
A
End is cut of then wire is bent backwards preventing injury
10
Q
Where is locking wire used ?
A
- Used in critical areas where inspection intervals may be in frequent
- Areas prone to vibration
11
Q
What’s the two locking wire techniques ?
A
- By hand
- Locking wire pliers
12
Q
Explain lock plates ?
A
- Can be used repeatedly
- Secured to adjacent part of structure
13
Q
Where are pal nuts used ?
A
Used where frequent load changes tend to loosen nuts
14
Q
Why is quick release fasteners useful to use on aircraft ?
A
- They provide vibration resistant joining solution for panels which will repeatedly need removing and attaching using minimal effort.
15
Q
What is the three common types of quick release fasteners ?
A
- Dzus
- Airloc
- Camloc
16
Q
What are the Two types of dzus fasteners ?
A
- Heavy duty
- Light duty
17
Q
What’s the difference between the heavy duty and light duty Dzus fastener ?
A
- Heavy duty fastener has a grommet
18
Q
Two types of airloc fasteners ?
A
- Fixed type
- Floating type
19
Q
What does a Airloc fastener consist of ?
A
- Stud
- Cross pin
20
Q
What’s the advantages of a Camloc fastener ?
A
- used in confined areas
- Vibration resistant
- Connects quickly
21
Q
What three parts does a quick turn fastener consist of ?
A
- Stud (male)
- Washer
- Receptacle
22
Q
What is a pip pin ?
A
- Non-threaded fastener allowing rapid installation and removal of parts without tooling
23
Q
What two types are a pip pin available in ?
A
- Locating pin
- Locking pin
24
Q
What is a Circlip ?
A
- Spring clip used for external and internal locking
- Used for retaining seals and bearings
25
What is used to remove circlip ?
1. special pliers
26
What loads does a taper pin carry ?
Shear
27
How is a plain taper pin (AN385) held in place ?
1. Held by friction in reamed hole
28
What the difference between the AN385 and AN386 taper pin ?
1. AN386 has its small end threaded
29
Why are roll pins used ?
1. To provide locking for a joint where pin in unlikely to be removed
2. To lock something Onto shaft or handle
30
How is a roll pin inserted ?
Pin compresses then when pushed into hole springs out holding securing it against edge of hole
31
How do you remove roll pin ?
Tap with pin punch
32
What’s the size of a Clevis pin measured in ?
1/16 inch increments
33
What’s the purpose of a “key” ?
1. Used to align wheels and disc sprockets and gears onto a shaft
34
What’s the 4 types of keys ?
1. Woodruff
2. Square key
3. Prat and Whitney
4. GiB headed
35
Whats happens to the cross sectional area of a rivet after it has been driven ?
It increases
36
What head type on a rivet is an AN426
Countersunk
37
What type of head on a rivet is AN470 ?
Universal
38
How far shall a rivet extend beyond material prior to being driven ?
1.5 x rivet diameter
39
How much does the Bucktail expand from its original diameter after driven ?
1.5 x original diameter
40
What two systems of rivets are used today ?
1. Airforce navy
2. Military standards (MS20)
41
What is the length of a rivet measured in ?
1/16 inch
42
What is the diameter of a rivet measured in ?
1/32 inch
43
What’s the countersink angle of the head ?
100 degrees
44
Why does the universal rivet replace round,flat and brazier rivets ?
Has better fatigue strength
45
Once countersunk, how much should a rivet head protrude surface ?
0.005-0.007 of an inch ( 5-7 thow)
46
Why does the head of a countersunk rivet protrude surface ?
To allow all of the rivet guns energy to be transferred onto the head
( if rivet is flush, it lowers the energy transferred onto the head from gun )
47
How is a pure aluminium rivet identified ?
By the letter A in the rivet code as they have no markings on the rivet itself
48
How are 2024 rivets identified ?
Two raised dashes on head
49
What are stainless steel rivets used for ?
Fastening corrosion resistant steel sheets
( identified by letter F )
50
4 types of mechanical rivets ?
1. Cherry max
2. Olympic locks
3. Cherry lock
4. Huck locks
51
Why Is special fasteners used over ordinary bolts/screws ?
1. As when driven, there shank doesn’t change in dimension
2. When driven the fastener doesn’t come under tensile
52
How can you remove mechanical lock rivets ?
Pin punch through middle then drill rest of shank out
53
Whats the 3 types of lock bolts ?
1. Pull type
2. Blind type
3. Stump type
54
With shear lock bolts, is there 1 or 2 grooves to place locking collar onto ?
2
55
How is hi-lock bolt installed ?
Placing bolt into hole with a shear collar on other end which snaps off at a set torque ?
Ps. Made from strong material
56
Whats different of a hi-lite bolt to hi-lock ?
Hi-lite is made from lighter material and shorter thread
57
Whats the strongest special fastener used in aircraft construction ?
Taper-lock - because of its cork like shape which holds well on the walls in the hole
58
What force is exerted on area around the installation of a hi-Tigue ?
Radial
59
What is the length of a bolt measured In ?
1/8 inch
60
What is the diameter of a bolt measured in ?
1/16 inch
61
What part of the bolt is its grip length ?
Un threaded part of the shank
62
What must be added if the unthreaded part of the bolt extends further than the thickness oof th material ?
Washer
63
What is the letter which identifies a corrosion resistant steel bolt ?
C
64
What letter identifies a aluminium bolt ?
DD
65
What load does clevis bolts hold ?
Shear
66
What does the long grip length On a clevis pin increase ?
The shear strength.
67
On a part number, what does an A signify ?
It signifies that there is no hole on the thread for a pin to go into.
68
Why is the eye at the top of an eye bolt there ?
To allow a turnbuckle to be inserted !
69
What is stamped on the head of a close tolerance bolt to show its identification ?
A triangle
70
What is the tolerance for a close tolerance bolt ?
0.000-0.0005 inch
71
Where is internal wrenching bolts used and made of ?
Made from steel and used in areas with high tensile loads
72
Who developed precision airfare bolts ?
NAS
73
What loads are eye bolts used for ?
External tension loads.
74
What
75
Does military standard bolts have even dashed number, true or false ?
True
76
What are the 3 classifications of screws ?
1. Machine screws
2. Structural screws
3. Self-tapping screws
77
What are machine screws primarily used for ?
Attaching fairings and structural panels
( thread runs full length of shank )
78
What class of fit are screws normally ?
Class 2 ( free fit )
79
How many degrees is a flat head screws head ?
100
80
Whats the two types of nuts ?
1. Self locking
2. Non self locking
81
Whats the tree types of self locking nuts ?
1.Metal - only used when temp reaches above 121 degrees
2.Nylon
3. Fibre
82
Whats the 2 types of self locking nuts ?
Metal - only used when temp reaches above 121 degrees
Nylon
83
Can nylon self locking nuts be used on engines ?
Yes. Only in locations specified by engine manufacturer !
84
Why is the end of a metal self locking nut smaller in diameter than its body ?
As it allows the thread to grip the bolt providing the location methord.
85
When would you use a castle nut ?
Under shear and tensile loads
86
Whats the difference between a shear castle nut and ordinary castle nut ?
Shear castle nu is shallower and can only take shear loads
87
Whats the 3 common thread standards ?
1. British standard
2. American national thread form
3. Unified thread form
88
Whats the 4 British standard thread form ?
1. British standard whitworth (BSW)- has thread angle of 55 degrees.
2. British standard fine (BSF)
3. British standard pipe (BSP)
4. British association (BA)- thread angle of 47.5
89
Whats the two American standard threads ?
ANC - American national coarse
ANF - American national coarse fine
( both have thread angle of 60 degrees )
90
Whats the three unified thread forms ?
UNC - coarse
UNF - fine
UNEF - extra fine
( All have angle of 60 degrees )`
91
Whats the 3 thread profiles
1. Square thread
2. Buttress threads
3. Acme threads
92
What does the letter H signify in a bolts code ?
The bolt is used for wire locking.
93
What’s the two classes of self tapping screw ?
Class A - sharpe
Class B - blunt
