Maintenance Practices M7.14 Sheet Metal Flashcards
How do you know which direction the grain is running on sheet metal
Same direction as the writing is stamped
When bending metal what must be remembered
Bend 90° to the grain
What stresses is sheet metal subject to when being bent
Tensile and compression forces
Where does the neutral axis run on a metal that is being bent
The centre
How is sheet metal stored
In a frame with appropriate paperwork
What is important to remember about the Neutral line
It is in neither compression or tension
What is important to remember about K factor
For every 90° bend K factor = 1
What is the mood point
Where the mold lines intersect
What is subtracted from EACH flat
Set back
What are bends inspected for after bending
Cracks
What is the bend sight line
1 bend radius from the bend tangent line
When bending ally what must you remember
Might have to go slightly over due to spring back
What is max juggle
2-3 thickness maximum
What is a room temp cure
18-25°c 48 hours to 7 days
When increasing bonding temp to 50-70°c how quick can cure time be
2-4 hours
What is hot bonding controlled with
Thermocouples
Does it take a longer time or shorter time for a cure to carry out in warm temp
Shorter time when warmer
What is a disadvantage of using a heat lamp
Can cause high surface temps
What are autoclaves
Big ovens giving ideal bonding
What is a disadvantage of heat blankets
Can’t be used on complicated shapes
What is the two wipe method
A solvent wipe and then a dry wipe before bonding
What is used for detecting sub surface flaws
Ultrasound
How are chains identified
Pitch, width between plates and roller diameter
How is a change in direction in chains achieved
A bi planer block
What are chain standards governed by
BS228
What should be done if a chain is disassembled
It should be proof loaded once reassembled
When should a chain be replaced with relation to wear
If wear is over 2%
When not being used how are chains stored
In grease proof paper
How would you know if push pull tubes are in safety
Witness hole
What is the purpose of backlash
Prevents gears from jamming and room for lubrication
What are the 2 different clearance fits
Running and free running
What is the standard of ISO system limits and fits
BS4500
If a repair is done to a control surface what must be done afterwards
It will need rebalancing
What is the definition of sealant
Confines liquids and gasses in given areas to prevent them from entering other areas
What are injection seals for
Holes
What is a seal plane
A structural boundary where fuel cannot pass
How are fuel tanks sealed
3 phase system
When scraping sealant and choosing a scraper what must be remembered
Scraper should not be any harder than 2024 T3
What altitude do lightning strikes normally occur
Between 5-15k feet during take off and decent
How much can a single bolt of lightning be
1 million volts
What are 2 types of lightning strike damage
Direct and indirect
What is HIRF
High Frequency Radiated Field
What type of aircraft are more likely to get hot with lightning strikes
Short haul
If an overweight landing occurs what must be done
An overweight landing
How is severe turbulence identified
Turbulence which causes large abrupt changes in altitude and attitude
What’s the alternative way of cutting a cable
Anvil, hammer and chisel
What must not be used to cut a cable
Oxy acetalyne torch
No more than what for a suage tool
4 role sequences
How to make sure a cable tension tester is operating correctly
Hold for 5 secs and no slips
Which side of the turnbuckle had a left hand thread
The one with a groove
How do you make sure a turnbuckle is in safety
Witness mark or hole
