Locking Devices

Question 1

Why is safteying important?

Answer 1

It ensures bolts, screws, nuts, pins and other fasteners do not shake loose during flight

Question 2

In lockwire material identification, what does the letter code C represent?

Answer 2

CRES (Corrosion resistant steel)

Question 3

What percentage of alloying elements are in CRES?

Answer 3

19% Chromium

9% Nickel

Question 4

In lockwire material identification, what does the letter code F represent?

Answer 4

Carbon Steel (zinc plated)

Question 5

What percentage of alloying materials are contained in zinc plated carbon steel

Answer 5

0.18-0.23% Carbon

Question 6

In lockwire material identification, what does the letter code N represent?

Answer 6

Nickel Chromium Iron alloy

Question 7

What percentage alloying elements does Nickel Chromium Iron alloy contain?

Answer 7

15.5% Chromium

8% Iron

Question 8

In lockwire material identification, what does the letter code NC represent?

Answer 8

Nickel Chromium Alloy (Monel)

Question 9

What percentage of alloying elements does Nickel Chromium alloy (Monel) contain?

Answer 9

30% Chromium

Question 10

Only where can single-wire locking be used?

Answer 10

On small screws in a closely spaced closed geometrical pattern, on parts in electrical systems and in places difficult to reach

Question 11

What method of wire locking is most common?

Answer 11

Double-twist

Question 12

How is the number of twists per inch in locking wire determined?

Answer 12

Depends on the gauge of the locking wire and is given in the AMM Chapter 20

Question 13

How do spring washers work

Answer 13

• A single or double-coil spring washer fitter beneath nut.
• Spring compresses when nut is tightened.
• This sets up friction and preventing the nut from undoing.

Question 14

What type of nut are tab washers suitable for?

Answer 14

Plain nut

Question 15

How does a tab washer work?

Answer 15

• One tab is bent against the flats of the nut

- The other tan is bent over an edge of the component or into a machined hole in the component

Question 16

Can a tab washer be reused?

Answer 16

No

Question 17

How does a shakeproof washer work?

Answer 17

• Has slanting serrations on it’s internal or external circumference
• Angle allows nut to be tightened but serrations bite into it and prevent it coming undone

Question 18

Can a shakeproof washer be reused?

Answer 18

Yes, as long as it remains springy

Question 19

When are locking plates used?

Answer 19

In replacement of tab washers when bolt must be repeatedly removed

Question 20

How many times can split pins be used?

Answer 20

Once

Question 21

When can Centre punching/Burring be Used?

Answer 21

Only when detailed in the aircraft document set

Question 22

What do pip pins allow?

Answer 22

Rapid installation and removal of parts without tooling

Question 23

What is the difference between Ring pull decent pins and Double acting steel pins?

Answer 23

Double acting pins can be removed by pushing or pulling the ring handle, ring pull detent pins are simply pulled out

Question 24

What are the 4 principle parts of a Camloc fastener?

Answer 24

1. Receptacle
2. Grommet
3. Retaining ring
4. Stud assembly

Question 25

What 4 parts does a stud assembly consist of?

Answer 25

1. Stud 2. Cross pin 3. Spring 4. Spring cup

Question 26

Where are lightweight Camlocs usually used?

Answer 26

Internal, lightly loaded access panels

Question 27

What are the two types of Dzus fasteners and where are they used?

Answer 27

Light duty: -Used in box covers, access hole covers and lightweight fairing Heavy duty: -Used in cowlings and heavy fairings

Question 28

What is the main difference between the two types of Dzus fastener?

Answer 28

The heavy duty Dzus fastener has a grommet

Question 29

What are the 2 types of Airloc fastener available?

Answer 29

1. Fixed type | 2. Floating type

Question 30

Where are stainless steel cotter pins (split pins) used ?

Answer 30

In locations where non-magnetic material is required

Question 31

What type of nut should be used with a cotter pin?

Answer 31

Castellated that have been drilled for the pin