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MODULE 7 MAINTENANCE PRACTICE

7.1 SAFETY PRECAUTION

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CAT B1.1

ANSWER ALL QUESTIONS

7.1.1 High-Pressure Gases

1. Compressed gases are frequently used in the maintenance and servicing of aircraft.

The use of compressed gases requires a special set of safety measures.

Q1: State safety rules apply fo r the use of com pressed g ases:

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7.2.1.1 General Notes on Calibration

2. The scope of the records maintained, are dependent upon the standards required and

the nature of the equipment. The record system can also provide a valuable reference

in case of dispute or warranty claims. These records can also indicate ‘drift’ and canhelp in reassessing calibration intervals.

Q2: L is t a min imum in format ion content of any appl iance Cal ib rat ion Record o r

Cert if icate

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 7.3.1.1 Combination Set

3. The Combination Set (refer to Fig. 4), consists of a graduated steel rule, which has a

machined groove running along the centre of its entire length. The rule can be slid into three

different ‘heads’ and secured, by a locking screw device, so that the combination of rule and

’head’ will enable certain tasks to be accomplished.

Q3 : Based on the picture d escribe the name of parts A, B, C, D, E and F

7.5.1 DRAWING IDENTIFICATION S YSTEM 

4. An aircraft engineering drawing (refer to Fig. 7), must certain data, which is used to

prove its validity (and legality). All alterations to drawings must be made in

accordance with a drawing amendment system, which will ensure amendment to

design records. If an alteration is made, a new issue number and date must be

allocated to the drawing.

To comply with legislation, procedures must be introduced to progressively amend

the total definition of the product in terms of its associated list of drawings at specific

Combination Set

AB

D

C

E

F

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issues. Each particular variant of a product and its state of modification must be

identifiable in relation to the appropriate list of drawings.

Q4 : State the inform at ion that can be foun d on th e convent io nal drawing as per

Fig. 7

 A. Summary of Recommended Drawing Information

7.6.1.1 Tolerances

5. The tolerance on a dimension is the variation tolerated and may be considered as a

numerical expression of the desired quality of workmanship. It is the difference

between the high and low limits of size for that dimension (refer to Fig. 1). Thus, a

part that should be exactly 25 mm nominal diameter, will be accepted for a certain

purpose if it is within the limits 25.1 mm, (the high limit); and 24.9 mm, (the low limit).The difference between the two (0.2 mm) is the tolerance.

DRAWING No. SHEET 

DRAWING ISSUE No. APPROVAL DATE OF ISSUE ALTERATION 

DESCRIPTION TREATMENT MATERIAL / SPECIFICATION ITEM  PART No. 

TITLE 

DRAWING No. 

1  1 TC002 RIVETING BLOCK 

TC002 

OF 

CHECKED BY. STRESS 

AIRCRAFT SCALE DIMENSIONS IN 

mm 1 : 1 N/A 

A New Drawing 

APPROVED BY. DATE 

19-09- 

uk engineering 

NORWICH AIRPORT NORWICH NORFOLK ENGLAND 

TOLERANCE USED ON: 

DRAWN BY. 

THIRD ANGLE PROJECTION 

QTY 

THIS DOCUMENT IS THE PROPERTY OF KLM uk ENGINEERING LIMITED AND MAY NOT BE COPIED OR COMMUNICATED TO A THIRD PARTY OR USED FOR ANY PURPOSE OTHER THAN THAT FOR WHICH IT IS SUPPLIED WITHOUT THE EXPRESS WRITTEN AUTHORITY OF KLM uk ENGINEERING LIMITED. ANY ERRORS SHOULD BE 

REPORTED TO THE INSTRUCTORS CAD GENERATED DRAWING - NO MANUAL ALTERATIONS  DO NOT SCALE  IF IN DOUBT ASK 

± 0.05

N/  NR6 6HB HURRICANE WAY 

TECHNICAL COLLEGE 

1  TC002-1  Mild Steel  Case Harden  Riveting Block  1 

R5  45 

WORKBENCH EXERCISE No

Note: Stamp initials on workpiece before case hardening 

25.0

65.0

N/A N/ 

N/ 

10.0

60.0

115.0

R5 

15.0

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Q5: Refer Fig. 1 and desc ribe A , B, C and D

7.8.1 T YPES OF RIVETED JOINTS 

6. The location of the riveting dictates the type of joint (refer to Fig. 3) that is

made. An ordinary lap joint is used on lightly loaded members and, to provide a flush

surface on one side, the joint may be joggled. Where one flush surface and greater

strength is required, the single butt joint is used. The strongest joint is the double

strap butt joint.

DCBA

Types of Riveted Joints

Fig. 3

DC

BA

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Q6 : Describ e the types of r iveted jo ints as i l lus trated in Fig. 3

7.9.1.1 MAINTENANCE OF PIPES AND HOSES 

7. The correct methods of installing pipes and hoses (refer to Fig. 6) must be followed if

damage (and possibly disaster) is not to result. Pipes attached to the airframe

structure, are often shielded and will not usually be liable to accidental damage. Other

pipes may be located in exposed positions, where they may be susceptible to

damage or corrosion.

Q7 : Refer to Fig. 6 describe state of ho se insta l lat ion

A

C

Structure

B

Fig. 6

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7.10.1 INSPECTION AND TESTING OF SPRINGS 

8. Springs will generally require little in the way of maintenance. Those that are in

exposed areas can become corroded over time and those in areas of high

temperature can, if they become overheated, lose their temper and cease to have the

necessary mechanical compliance to satisfy the task for which they were designed.

Q8 : State the types of check c arr ied out in ord er to establ ished the cond it ion or

serv iceab i l ity o f sp r ing?

7.11.1.1 Installation and Misalignment

9. Installation damage is usually the result of an impact that occurs when a bearing is

fitted incorrectly. This may be due to a sharp strike from a drift or pressing the wrong

raceway when mounting the bearing.

Q9 : Describe how to d etect misal ignment of bearing ins ta l lat ion and what kind o f

ef fect o n th e bearing.

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7.12 TRANSMISSIONS

10. There are various types of transmission mechanisms which served variable purposes

used in aircraft systems. Some of which are as listed below.

 Gears

 Belts and Pulleys

 Chains and Sprockets

 Screw Jacks

 Levers

 Push-Pull Rod Systems.

Q10. : State the purpo se or funct io n of gear transmiss ion sys tem

7.13.1 INSPECTION OF CONTROL CABLE PULLEYS 

11. When inspecting cables for the previously mentioned wear and breakages, the

complete cable runs must be examined for incorrect routing, fraying, twisting or wear

at fairleads, pulleys and guards.

Pulleys must be inspected for wear (refer to Fig. 2), to detect indications of seizure, flat

spots, embedded foreign material and excessive tension. Any signs of contact with

adjacent structure, pipe-work, wiring and other controls must also be thoroughly

investigated.

Q11: Refer to Fig. 2 below and state the reason for defect on the pul leys

Types of Pulley Wear

Fi . 2

A

C

B

D

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7.14.1 SHEET METAL

12. While the majority of metals can be rolled into sheet form, consideration is confined

here solely to the working with sheets of the light alloys, which are encountered on

aircraft and, in particular, those formed from aluminium alloy ingots.

By definition, sheets of aluminium alloy are comparatively thin in cross-section and,

as such, they not only pose a health hazard, through cuts, when being handled but

they are, also, prone to buckling and creasing if handled carelessly.

Q12 : Describe the method o f stor ing and h andl ing o f sheet metal

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7.16 AIRCRAFT WEIGHT AND BALANCE

13. The main purposes, of monitoring the mass and balance of aircraft, are to maintainsafety and to achieve efficiency in flight. The position of loads such as passengers,

fuel, cargo and equipment will alter the position of the Centre of Gravity (CG) of theaircraft.

Q13. : Describe th e effect or d irect result of inc orrect loadin g o n aircraf t

per formance

7.17.1 AIRCRAFT FUELLING PROCEDURES 

14.The use of the term ‘fuelling’ can include both refuelling and defueling procedures and

these notes contain examples of the essential points to be considered when refuelling

and defueling aircraft.

There may, however, be some further, local instructions, regarding the responsibilities

of the various personnel involved in fuelling procedures and these will always take

precedence in conjunction with the relevant Maintenance Manual.

Q14 : State typ es of aircraft refuell in g

7.18.1 T YPES OF DEFECTS 

15. An operational aircraft can suffer from many defects and these can be defined as any

event or occurrence, which reduces the serviceability of the aircraft below 100%.

The manufacturer should specify the inspection areas and the faults, which are

expected to be found. In most instances the inspector is looking for indications of

abnormality in the item being inspected.

Q15 :

List ou t inspect ion and d efect as appl icable to all metal parts, bod ies or casings

of units in systems and in electr ical , instrum ent and radio insta l lat ions, metal

p ipes, duct in g, tubes, rods and levers.

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7.19 ABNORMAL EVENTS

16. All aircraft are designed to withstand the normal flight and landing loads expected

during a typical flight cycle. These loads will include the normal manoeuvres the

aircraft is expected to make. The designer will build in a safety factor to compensatefor loads slightly larger than normal. Sometimes extreme circumstances occur which

causes stresses outside the normal design limits.

If the design limits are exceeded, then damage may occur to the aircraft. If it is known

or suspected that the aircraft has been subjected to excessive loads, then an

inspection should be made, to ascertain the nature of any damage that may have

occurred. The manufacturer will normally have anticipated the nature of some of

these occurrences and detailed special checks for these ‘Abnormal Occurrences’. 

Q16:

The aircraf t maintenance manual wi l l norm al ly l ist the types of abnorm al

occ urrences needing s pecia l inspect ion. The l ist may vary, dependin g on the

a i rcra f t. L is t the abnormal events m ost common ly encou ntered.

7.20.1 CONTROL OF LIFE-LIMITED COMPONENTS 

17.On almost any aircraft, there will be a number of components that have a stated ‘life’,usually quoted in flying hours, cycles, calendar time or operating hours.

The correct terminology for ‘life’ is Mandatory Life Limitation. The   components will

have been given a life for various reasons. For example, a fatigue life on a structural

component in flying hours; the landing gear legs due for retirement after 10,000

landings, the batteries due for replacement after 3 or 4 months and a retirement life

on an APU measured in hours running time.

Q17:

Who are respon sib le for mon i tor ing and cont ro l of l i fe components and how the

procedures are be ing carr ied out?