Essay Topics Flashcards
What is the problem with a ‘dry joint’ when soldering?
They are fragile and have a high resistance
When arranging the contacts for soldering, in what direction should they be placed in the solder bucket?
Facing upwards
What should not be present on the outside of a soldering bucket?
Excess solder
If, when soldering, the strands aren’t held in position, what can be created?
A dry joint
What are the four types of self-fluxing solder?
Single-core
Tri-core
Perforated-core
Multi-core
What is soft (tin-lead alloy) solder recommended for?
It is the recommended solder for electrical and electronic applications.
What is the purpose of using a flux?
It removes the oxide from the surfaces to be soldered and promotes a good flow of solder in the joint.
What is conducive to a good soldering result?
A well equipped soldering station
What is bonding?
It is the electrical interconnection of metallic parts (normally at earth potential) for the safe distribution of electrical charges and currents.
How is the aircrafts earthing system automatically connected to the ground upon landing?
Via the noise wheel tyre (impregnated with an electrically conductive compound)
What are braided copper or aluminium cords fitted with lugs used for when bonding?
Bonding connections between moving parts or parts subjected to vibration
What should all bonding connections ensure?
They should be properly locked to prevent intermittent contact which may be caused by vibration.
(Intermittent contact is worse than no contact at all)
When installing bonding connections, what must be considered?
Surrounding/adjacent equipment as they must not interfere.
They should also not be excessively tight or slack
Before installing bonding connections to insulating materials, what must be done?
Anodic finishes and/or paint is removed from contacting faces.
What are the checks completed before carrying out bond testing?
- a full scale deflection of the meter is obtained when the two spikes of the 6-foot cable are shorted.
- the meter reads zero when the single spike 60-foot probe is connected
What is the process of solid rivet removal?
Step 1 = File Flat
Step 2 = Centre punch
Step 3 = Drill through the head
Step 4 = Insert drift punch to break off the head
Step 5 = Drive out the river shank whilst supporting the back (bucking bar)
What safety precautions are carried out prior to solid rivet removal?
- Eye protection
- Check what is behind the rivet
- Warn people in the vicinity
- Prevent FOD as far as possible
- Cleaning work area
When lifting as an individual, what is the maximum load that can be lifted?
20kg
Even light loads when individually lifting can cause what type of problem?
It can obscure your vision
What can be damaged if the loads are incorrectly lifted?
The lumbar disks (slipped disks)
What is the correct way to lift a load individually?
- Take a balanced squatting position.
- Legs should be at hip width apart with one foot slightly ahead.
- Load should be held close to the body (head up, chin drawn in to keep the back straight and rigid)
- The load should be raised by thigh muscles and bones. The bone structure should support the load.
When team lifting, who is responsible for the safe completion of the task?
The team leader
What are the things that the team leader should ensure prior to the team lift?
- everyone should understand what the job involved
- path is clear of obstructions
- each member is a similar height and physique
- the weight of the load is evenly distributed
- that he/she has the best all-round view of the area
- all moved equipment is put back to the original position after the move
What does COSHH stand for?
Control of Substances Hazardous to Health
What safety concerns do oils and chemicals present?
- inflammable
- noxious fumes
- presents slip hazards
- cause skin diseases (dermatitis)
What is POL?
Petrols, oils and lubricants.
Who is responsible to produce the MSDS?
The manufacturers responsibility
The COSHH law requires employers to control substances in the workplace. How can they prevent or reduce workers’ exposure to it?
- Health hazards & Risk assessments
- Control measures (in good working order)
- Providing training, information and instruction
- Planning for emergencies
- Minimise possibilities of combustion
- Minimise effects of fumes
- Clean up or contain spillages promptly
- Prevent contamination of dermatitis
What is the main advantage of using cascade charging?
Avoid wastage of gases
What are used for the initial charge when cascade charging?
The partially exhausted ones first
What is the advantage of a cascade manifold?
It automatically fills from the lowest source and the auto cascade switches to the next bottle.
What should oxygen be avoided coming into contact with?
Oils and greases because it can spontaneously combust without the application of heat
What should be avoided immediately after working with oxygen?
Smoking as the oxygen can be absorbed into the clothing and the naked flame could ignite the clothing.
What type of tools should be used when working with oxygen?
Only correct tooling as normal tooling can cause sparks and should not be used.
Before working with oxygen on an aircraft, what should be done prior?
The aircraft should be correctly bonded and grounded
What can be used for leak tests on oxygen systems?
Prescribed oil-free solutions
Not soapy water
What should be done before charging breathing oxygen systems on aircraft?
The oxygen should be smelled to ensure it’s not contaminated.
When checking the soldering, what should be looked for as far as possible?
Solder has flowed between the conductor strands
What must undesignated wires be dead ended with?
Caps or sleeves
How far must dead ending be accomplished from connectors?
Within 4-6 inches
After isolation, where should dead ended wires be stowed?
Visible outside of the bundle, wrapped, tied and stowed near unused terminations.
What should be used to fasten re-insulated circuit breaker terminal insulation?
Waxed string or plastic ties
What is the minimum fold-back amount of a flexible sleeve of a dead ended wire?
1 inch
What is the minimum amount of shrinkable sleeve that is pinched with pliers?
1/4 inch or 5mm
What is the preferred method when a coaxial cable is damaged?
Replacement
If a repair of a coaxial cable is absolutely necessary, what must be used?
Coaxial plug and receptor
Where is a coaxial repair not permitted?
- low range altimeter
- glide slope
- a coaxial cable with a previous repair
Where must splices not be installed?
- inside metal or flexible tubing
- within 12 inches of termination devices
- under clamps
- inside fuel tanks
- in wire harnesses that are frequently bent
How must splices be presented in a wire bundle?
Staggered
What is the maximum number of splices allowed in a wire?
3
What is the preferred option for a damaged wire?
Replacement
Outside the pressurised areas of an aircraft what type of tape is used?
Aircraft fluid resistance tape
In high temperature areas what grade of insulation tape is required?
Grade D
How is chafed or broken insulation repaired?
Splicing
If a wire has been subjected to heat damage, what may be necessary to prevent it reoccurring?
Changing the wire routing
When repairing a shielded cable what must the repair ensure?
It is fully closed and electrically continuous
Where are splices considered a temporary repair and must be replaced at the next maintenance check?
Engine harness wires or fire warning wires
What is the most common method for attaching a shield ground wire to a shielded cable?
A solder sleeve pigtail
What is the method of installing a solder sleeve pigtail?
- Strip the wire to the correct dimensions
- One end of the sleeve is slightly wider to accommodate for the the ground wire
- Heat shrink gun is used to shrink the sleeve into position and enable solder the run
- Creates an electrical connection between the ground wire and the cable shield
What is acceptable when inspecting a solder sleeve pigtail?
Dark areas or slight discolouration provided solder can be inspected and the sleeve is not ruptured or split
What must be ensured when inspecting a solder sleeve pigtail?
The seal rings have melted providing an environmental seal
What is a continuity consisting of?
A low voltage battery 2.5V and a test lamp or low-reading voltmeter
What must be done prior to a continuity test?
The main electrical supply should be switched off or disconnected
When testing a circuit, how should it be worked through?
Progressively through the circuit starting from relevant fuses or circuit breakers
When is a millivolt drop test carried out?
When a loose terminal connection or poorly swaged end is suspected. There is a excessive amount of resistance.
If testing a continuously-rated circuit with a millivolt drop test what should the test current be?
The normal operating current flowing
For short-rated circuits what is used as a test current instead of the normal electric load?
A suitable resistance or dummy load. The current should be scaled down to avoid overheating
What is the approximate guide of current and amps flowing for the millivolt drop test?
5mV or 10amps
