AIRCRAFT CONTROL CABLES

AIRCRAFT CONTROL CABLES

INTRODUCTION :

As we know, the pilot of an aircraft needs to control the surfaces that govern the attitude of flight of the aircraft. There are various methods of achieving this i.e. the use of control cables, or control rods , or electrical signals (fly by wire), etc.

Control cables provide a strong, light and flexible method of control. These cables only operate in tension, and can only be used in a pulling direction. However, cables are normally arranged in pairs, that is making a continuous loop, providing a pull in both directions.

CABLE CONSTRUCTION :

The cable is made of galvanized steel and is normally impregnated with a friction preventative lubricant during manufacture. Cable design is based on the number of strands and the number of wires in each strand.

The most common aircraft cables are 7 x 7 and 7 x 19. See figure below for typical examples of cables.

7 x 7 CABLE :

The 7 x 7 cables is of medium flexibility and is used for fairly light application like engine controls and control tabs, where there is not too much load.

7 x 19 CABLE :

The 7 x 19 cables mainly use on primary flight controls where a more flexible cable is required.

CABLE INSPECTION :

For a cable system to operate effectively the cable tension must be correct. Excessive tension imposes an unnecessary loading on the system, whereas a slack cable could cause an ineffective response to a control signal. As cable runs are some times over a large distance it may be necessary to have more then one cable in a run. The method of joining cables together is achieved by using a turn barrel arrangement as shown in figure below.

When adjusting cable control, it is important that the cable end-fittings do not foul the pulley otherwise cable movement will be restricted.

The inspection of aircraft control cables is limited to a visual survey of the cable. Particular attention must be paid to the condition of the cable with emphasis on the surface condition of the cable for corrosion and also for broken strands of wire within the cable construction.

WEIGHTS AND MEASURES TABLE

METRIC

LINEAR MEASURE :

10 millimeters  => 1 centimeter

10 centimeters => 1 decimeter

10 decimeters  => 1 meter

10 meters         => 1 decameter

10 decameters  => 1 hectometer

10 hectometers => 1 kilometer

SQUARE MEASURE :

100 sq.millimeters   => 1 sq.centimeter

100 sq.centimeters  => 1 sq.decimeter

100 sq.decimeters   => 1 sq.meter

100 sq.meters          => 1 sq.decameter

100 sq.decameters  => 1 sq.hectometer

100 sq.hectometers => 1 sq.kilometer

LIQUID MEASURE :

10 milliliters   => 1 centiliter

10 centiliters  => 1 deciliter

10 deciliters   => 1 liter

10 liters          => 1 decaliter

10 decaliters  => 1 hectoliter

10 hectoliters => 1 kiloliter

WEIGHTS :

10 milligrams    => 1 centigram

10 centigrams   => 1 decigram

10 decigrams    => 1 gram

10 grams           => 1 decagrams

10 decagrams   => 1 hectogram

10 hectograms  => 1 kilogram

10 kilograms    => 1 quintal

10 quintals       => 1 tonne

ENERGY :

10,000 ergs           => 1 millijoule

1000 milijoules    => 1 joule

1000 joules           => 1 kilojoule

1000 kilojoules     => 1 megajoule

3.6 megajoules     => 1 kilowatt hour

1000 megajoules  => 1 gigajoule

1000 gigajoules    => 1 terajoule

POWER :

1000 microwatts => 1 milliwatt

1000 milliwatts   => 1 watt

1000 watts           => 1 kilowatt

1000 kilowatts     => 1 megawatt

1000 megawatts   => 1 gigawatt

1000 gigawatts     => 1 terawatt

IMPERIAL

LONG MEASURE :

12 inches  => 1 foot

3 feet        => 1 yard

5.5 yards  => 1 rod

40 rods     => 1 furlong

8 furlongs => 1 statute mile

3 miles      => 1 league

CUBIC MEASURE :

1.728 cubic inches       => 1 cubic foot

27 cubic feet                => 1 cubic yard 

128 cubic feet              => 1 cord (wood)

40 cubic feet                => 1 ton (shipping)

2,150.42 cubic inches => 1 standard bushel

231 cubic inches         => 1 U.S. standard gal

1 cubic foot                 => about 0.8 of a bushel

SQUARE MEASURE :

144 sq.inches    => 1 sq.foot

9 sq.feet            => 1 sq.yard

30.25 sq.yards  => 1 sq.rod

40 sq.rods         => 1 rood

4 roods             => 1 acre

640 acres         => 1 sq.mile

ANGULAR MEASURE :

60 seconds => 1 minute

60 minutes => 1 degree

30 degrees  => 1 sign

90 degrees  => 1 quadrant

4 quadrants or  

360 degrees => 1 circumference or great circle

LIQUID MEASURE :

4 gills => 1 pint

2 pints => 1 quart

4 quarts => 1 gallon

31.5 gallons => 1 barrel

2 barrels => 1 hogshead

AVOIRDUPOIS WEIGHT :

27.34 grains => 1 dram

16 drams      => 1 ounce

16 ounces     => 1 pound

28 pounds     => 1 quarter

4 quarters     => 1 cwt

2,000 pounds => 1 short ton

2,240 pounds => 1 long ton

TEMPERATURE CONVERSION :

Celsius        => 5(F-32)/9

Fahrenheit => 9C/5 + 32

LATEST AVIATION NEWS

(*) Malaysian Airline shares sink to record low on rights plan:

Shares in Malaysian Airline System Bhd (MAS) tumbled more than 20 percent to an all-time low on Wednesday as the national carrier's 3.1 billion ringgit ($1 billion) rights issue p

lan triggered fears of share dilution and uncertainty over the move.
MAS was down 17.8 percent at 83 sen as of 0254 GMT, after falling as much 20.8 percent earlier, its biggest single-day drop in about 14 years.
MAS also said it will reduce the par value of its shares to 90 sen from 1 ringgit in order to build a credit reserve of 8 billion ringgit. The company raised 2.7 billion ringgit in a rights issue in 2010.
The company saw its performance improve on lower fuel costs after it cut unprofitable routes, asserting that cost management remained a priority going forward.
MAS shares are down about 22.5 percent since the beginning of the year. In February, the company reported its worst-ever loss of 2.5 billion ringgit for 2011, surprising analysts who had expected its restructuring to limit losses.
Source: Reuters

(*) Aircraft's tyre bursts while taxiing :
Around 125 passengers on board a Muscat-Chennai Oman Air flight had an escape after nose wheel of the aircraft burst while taxiing after landing at Chennai airport on Monday. Nobody was injured in the

 incident. The aircraft was later towed to the parking bay.

Airport sources said that the flight landed at 6.30am and was taxiing near cargo terminal when a tyre burst and the aircraft was halted. The pilot informed the air traffic control about the incident. Controllers closed the taxi way and alerted the apron from where a pushback vehicle was brought and the aircraft was towed to the parking bay.

Source: Times of India

(*) India’s Jet, SpiceJet in stake talks with Etihad, AirAsia: 
Struggling Indian carriers Jet Airways and SpiceJet are in talks with Abu Dhabi’s Etihad Airways and Malaysia’s AirAsia Bhd to sell minority stakes, a senior government official w

ith direct knowledge of the talks said.

Jet shares rose about 14.3 per cent and SpiceJet jumped as much as 19.2 per cent on Monday, continuing their rallies from last week amid speculation that they may become the first Indian carriers to secure foreign investment.
India changed its rules in September to allow foreign carriers to buy stakes of up to 49 per cent in local airlines, which have been battered by fierce competition and high operating costs.

The Jet-Etihad tie-up would be the biggest of the two deals, with a possible value of up to nearly $440 million (Dh1.62 billion), but the government official provided no details on the stakes involved or costs.

Talks between Etihad and Jet, which has 100 planes and is India’s largest airline by total passengers carried, have been the subject of recent media reports citing unnamed sources.

“The talks are on. This is more or less final. It may take around a month and half,” the government source told reporters, referring to the Jet-Etihad negotiations.

Source: Reuters/Gulf News

(*) Air India eyes over Rs.2,500 crore from sale of Boeing 777s :
After failing to find any lessor for its five Boeing 777s, the debt-laden Air India is now planning an outright sale of these aircraft to raise up to about Rs 2,500 crore, airli

ne sources said.

The state-run airline will soon appoint a consultant to help it find a suitable buyer besides taking the assistance from Boeing on the issue, they said. The move is to trim over Rs 68,000-crore debt, they added.

“These are surplus aircraft after the induction of the latest Dreamliners in our fleet which we have decided to dispose of,” Air India sources told PTI on Monday.

Earlier, the carrier had sought to ‘sale and lease back’ the fuel-guzzling five Boeing 777-200 LR planes, which are of 2007 and 2009 make.

However, despite repeated attempts, Air India did not find any taker for them, eventually forcing to put them on the block.

Source: The Hindu

(1) SAA and Mango fleet details for FY2011/12:South African Airways (SAA) 
operated (26-Nov-2012) a fleet of 55 aircraft as of 31-Mar-2012, comprising 14 Boeing 737-800s, 11 A319-100s, nine A340-600s, eight A340-300s, six A330-200s,two A320-200s, one A340-200, two 737-300Fs and two 737-200Fs.

Mango operated a fleet of five 737-800s.

SAA plans to increase its long-haul fleet from 24 to 31 aircraft and replace its 737-800s with A320s in the next five years.

Source; SAA

(2) Oman Air planning expansion of Germany routes:

Oman Air plans to expand services to/from Germany. The carrier plans to increase Muscat-Frankfurt service, currently operated six times weekly, to daily. Munich will also see a frequency increase from four times weekly to daily. The carrier will also feature Berlin Brandenburg in its network upon its opening.

Source: fluege.de



(3) British Airways is to allow passengers to watch and listen to in-flight entertainment from boarding through to landing, following an assessment of safety considerations.

Chief executive

 Keith Williams, speaking at a BA event in London on 26 November, said the airline would no longer "pull the plug" - typically about 20min from touchdown - on passengers who wished to continue using the IFE.

BA will introduce the new policy on 1 December.
The airline says it carried out safety assessments in collaboration with the Civil Aviation Authority on a number of flights including services to Moscow and Tel Aviv. A spokesman for the carrier says these "went extremely well".

Passengers will be allowed to continue using the IFE but only if they are using BA's own headsets, to ensure that they can hear cabin announcements. BA says passengers will still be able to use their own headsets during cruise.

The precise point at which the IFE will be switched off will depend on the aircraft type. Most of the long-haul fleet is already capable of supporting the new scheme, but BA is still upgrading cabins on eight older Boeing 777-200s.

Source: Flightgloble

(4) Qatar 787 to make Heathrow debut on 13 December:
Qatar Airways will launch Doha-London Heathrow services using its new Boeing 787 on 13 December.
It will be the first airline to serve the UK using the new Boeing.
Initially, one of the air

line's five daily flights will be operated with the Dreamliner. Flight QR075 will depart Doha at 06:25 local, arriving at Heathrow at 11:05. The return flight, QR076, leaves Heathrow at 15:05, arriving in Doha at 00:45.

The airline took delivery of its first 787 earlier this month and the twinjet has been operated on intra-Gulf routes to allow Qatar's staff to familiarise themselves with the new aircraft.

Its second of 60 Dreamliners has also arrived in Doha, the airline says.

Source: Flightgloble

(5) Volga Dnepr Airlines and HNA Group seen as key potential candidates for Cargolux stake:

Russia’s Volga Dnepr Airlines and China’s HNA Group reportedly lead the list of potential candidates to replace Qatar Airways as a 35% shareholder in 

Cargolux.

As previously reported, Qatar Airways earlier this month announced it would be relinquishing its 35% stake as a result of differences with other shareholders over strategy and the appointment of interim CEO Richard Forson on a permanent basis.

Source: lloydsll.com

ATA CHAPTERS

ATA CHAPTERS

AIRCRAFT GENERAL :

This information is peculiar to maintenance manuals and occupies chapters 5 through to 12.

Chapter 5   => Time Limits/Maintenance Checks.

Chapter 6   => Dimensions and Areas.

Chapter 7   => Lifting and Shoring.

Chapter 8   => Laveling and Weighing.

Chapter 9   => Towing and Taxying.

Chapter 10 => Parking and Mooring.

Chapter 11 => Required Placards.

Chapter 12 => Servicing.

AIRFRAME SYSTEMS :

Several chapters are dedicated to various airframe systems. These occupy Chapter 20 through to 49.

Chapter 20  => Standard Practices.

Chapter 21  => Air Conditioning.

Chapter 22  => Automatic Flight.

Chapter 23  => Communications.

Chapter 24  => Electrical Power.

Chapter 25  => Equipment and Furnishings.

Chapter 26  => Fire Protection.

Chapter 27  => Flight Controls.

Chapter 28  => Fuel.

Chapter 29  => Hydraulic Power.

Chapter 30  => Ice and Rain Protection.

Chapter 31  => Instruments.

Chapter 32  => Landing Gear.

Chapter 33  => Lights.

Chapter 34  => Navigation.

Chapter 35  => Oxygen.

Chapter 36  => Pneumatics.

Chapter 38  => Water and Waste.

Chapter 49  => Airborne Auxiliary Power.

STRUCTURES :

Chapter 51 through 57 are dedicated to structures. This information is available in the Maintenance Manual further detailed repair information is to be found in the structural repair manual.

Chapter 51  => Structure General.

Chapter 52  => Doors.

Chapter 53  => Fuselage.

Chapter 54  => Nacelles/Pylons.

Chapter 55  => Stabilisers.

Chapter 56  => Windows.

Chapter 57  => Wings.

PROPELLERS/ROTORS :

These sections will contain a separate chapter for each part.

Chapter 60  => Standard Practice Propellers/Rotor.

Chapter 61  => Propellers.

Chapter 65  => Rotors. 

POWER PLANT :

This section contains a separate chapter for each system, allocated numbers 70 to 82.

Chapter 70  => Standard Practices-Engine.

Chapter 71  => Power Plant.

Chapter 72  => Engine Turbine.

Chapter 73  => Engine Fuel and Control.

Chapter 74  => Ignition.

Chapter 75  => Air.

Chapter 76  => Engine Controls.

Chapter 77  => Engine Indicating.

Chapter 78  => Exhaust.

Chapter 79  => Oil.

Chapter 80  => Srarting.

Chapter 82  => Water Injection.

GENERAL PRECAUTIONS WHILE WORKING ON AIRCRAFT

BELOW ARE LISTED SOME GENERAL PRECAUTIONS YOU MUST OBEY WHEN WORKING IN AND AROUND AIRCRAFT:-

(*) Before operating any system, be aware of the implications, the operating of one system could influence another.

(*) Before moving flight controls ensure the area around the control surface is clear of ground equipment and personnel.

(*) When items are being hoisted by crane, do not walk under suspended loads, and don't leave loads unattended.

(*) Take care with oxygen equipment, ensure no oil or grease comes in contact with pipe line threads. You should wear clean overalls and have grease free hands when replenishing oxygen systems.

(*) Any bounding wire disturbed during maintenance must be replaced to avoid the build up of static electricity. A bonding test must then be carried out.

(*) Grommets and seals particularly in fire zones must be in a serviceable conditions.

(*) Smoke only in designated areas set a aside for that purpose.

(*) Observe and obey "NO SMOKING" signs on maintenance area.

(*) Do not carry non-safety matches and do not wear steel tips on shoes as they can create sparks.

(*) When operating petrol powered ground equipment have a form fire extinguisher handy.

(*) Flammable liquids like paints and dope should be kept in an approved store outside the hanger or workshop.

(*) If using heat torches in a hanger such as blow lamps,the flame should be directed towards fire bricks when not in immediate use.

(*) You should find out where fire extinguishers and fire buckets are located in your place of work.

(*) When refueling or defueling an aircraft no electrical system should be switched on or off. Ensure the aircraft is bounded before starting work.

(*) When fuel tanks have been completely emptied, the fire risk is still present due to the fumes, always use flameproof torches when entering tanks.

Quote:Sir Brian Appleton after Piper Alpha:“Safety is not an intellectual exercise to keep us in work. It is a matter of life and death. It is the sum of our contributions to safety management that determines whether the people we work with live or die”.

LOCKING DEVICES

"LOCKING DEVICES"

When an Aircraft is subjected to vibration and stress it tends to loosen its various parts. to prevent this stress or loads, various of locking  devices are used. some of these listed below.

COTTOR PINS

These are steel or nickel alloy steel pins of different diameter and lengths.

USE : They are used with slotted or castle nuts to lock the bolts or studs.

FITTING :  Align the nearest slot of the nut with the hole provided in the bolt or stud,insert the cotter pin through the slot of the nut and the hole of the bolt,or stud and bend legs of the cotter pin around the nut.

REMOVAL : Straighten the legs of the cotter pin with the help of cotter pin extractor and pull it out from head side.

NOTE : "COTTER PINS ARE USED ONCE ONLY" 

SAFETY WIRES 

Safety wires are made of non-corrosive steel or copper. Different guage of wires are available for use with different sizes of fasteners.

USE : It is use to look nuts,bolts head,oil caps, wheel caps,drain cocks,turn buckles and pipe unions.

FITTING : It differs with components,double twisted method of safety wiring is the most common method used. The wire may be twisted by hand except for the final few twists which should be made with twister. Single wire method may be used on screw in a closely spaced or closed geometrical pattern such as triangle.

REMOVAL : Cut or break the wire and pull in out.

NOTE : "Safety wire is used once only"

TAB WASHERS

Tab washers are available in various sizes and consist of tabs which are used to the nut.

USE : They are used to safety the plain nuts or bolts heads.

FITTING : They are placed under the nuts,once tab in bent into the hole of the structure and the other tabs are bent around the nut.

REMOVAL : Straighten the tabs and remove the nut and tab washers.

NOTE : "TAB WASHERS IS USED ONCE ONLY"

LOCK PLATE

These are thin steel plates with six or twelve sizes to fit around a nut or bolt head.

USE : To lock nuts or bolts.

FITTING : Position the nut or bolt,so that the plate fits around it and lock the plate with set screws and spring washer.

REMOVAL : Removal the set screw remove the plate and remove the nut.

SPRING WASHER

It is under the head of machine screw or with the plain nuts where the self locking or slotted nut is not appropriate. The spring tension will keep the nuts or screws from loosening.

CHECK NUTS

Check nuts are used as locking devices for non self locking plain nuts. They are used to lock the eye ends of a tie rod.

SAFETY PRECAUTIONS

1) The safety wire shall not be used to secure the emergency device such as handle and switch table.

2) When safety wire is used, particular care should be exercised to ensure that it will not prevent emergency operation of the emergency devices.

3) Do not loosen or tighten the properly tightened nut to align with safety wire holes.

4) lock pins and cotter pins should fit snugly in the hole provided.

5) Cotter pin, lock wire and tab washers are used once only.

AERO PLANE AND AIRCRAFT

LIGHTER THEN AIR

Lighter than air aircraft (known as "aerostats") use buoyancy to float in the air in much the same way that ships float on the water. They typically have one or more large balloons or bags, filled with a relatively low density gas such as helium, hydrogen or hot air, which is less dense than the surrounding air.

Examples of lighter-than-air aircraft include non-steerable balloons, such as hot air balloons and gas balloons, and steerable airships (sometimes called dirigible balloons) such as blimps (that have non-rigid construction) and rigid airships that have an internal frame.

HEAVIER THEN AIR

Heavier-than-air aircraft (known as "aerodynes") must find some way to push air or gas downwards, so that a reaction occurs (by Newton's laws of motion) to push the aircraft upwards. The most common way to do this is by propelling the craft forwards (typically via an engine) and using a wing to displace the air so that there is greater air pressure below the wing than above it. This is the principle behind all modern aircraft. The other way of achieving lift is known as "engine lift", which is to vertically fire an engine downwards so as to push the craft upwards, which is how rockets and missiles operate.In heavier-than-air aircraft, there are two ways to produce lift aerodynamic lift and engine lift