7.9 Pipes And Hoses Flashcards
What is a tubes dimensions determined by?
External diameter, wall thickness
What’s is the pressure of a high pressure line
Above 1500 psi
What is the pressure of a medium pressure line?
Under 1500 psi
What is a low pressure line?
Suction and return
What can be used instead of hoses?
Flexible metal pipes
What must be taken into account when installing tubes?
Vibration and movement
How is a tube cleaned internally?
Pressurised air
What are support clamps used for?
Securing tubes to the aircraft
What are the two most common clamps?
Rubber cushioned clamp, plain clamp
What is an advantage of rubber cushioned clamps?
Limit vibration
What material should the cushion clamps use when around liquid?
Teflon
What is a bonded clamp used for?
Securing hydraulic, fuel and oil lines
How does a flareless tube fitting achieve its seal?
Ball bush principle
What is an MS fitting?
Sleeve of malleable steel shaped over pipe
What is a Harrison fitting?
Sleeve of solid steel which the tube seals onto from inside using swaging
What is required for a flare type fitting?
Specialised tool
Why are flare type fittings used in engines?
Low vibration
What is the standard flare angle of flare type fittings?
37
What are the 2 types of flare fitting?
Single, double
What is the diameter of a double flare?
3/8 or smaller
Why is a double flare better then single flare?
Better seal, resistant to shearing/torque
What is a permaswage fitting?
Steel sleeve squeezed onto pipe using press
What affects the tool you use when bending pipes?
Diameter
When inspecting tubes and pipes what defects do you look for?
. Nicks
. Scratches
. Cracks
. Scores
. Bends
. Corrosion
Why are hoses uses?
Flexible, withstand high vibration
What is a low pressure in a hose?
Up to 600 psi
What is a medium pressure in a hose?
Up to 3000 psi
What is high pressure in a hose?
3000 plus psi
What run along the length of the hose?
Lay lines
What does a lay line indicate?
Twisting
What do you inspect a hose for?
Length, cleanliness, damage
What do you check a hose label for?
Part number, cure date, assembly date
What should hoses be fitted with if they could bend or move?
Clamps
What colour are lay lines
Yellow, red or white
What’s are advantages of a pemerswage fitting
It can be made quickly in situ, light and gives a good steal
What’s a disadvantage of a permerswage fitting
The fitting cannot be separated
What are the two most common clamps used
Rubber cushioned clamp and plain clamp
What do rubber cushioned clamps do
Secure lines which are subject to vibration
Why do we used bonded clamps
Has an electrical lead secured to aircraft structural, bonding it. Contains, hydrolic oil or fuel
What fitting does a Harrison fitting have
Ball bush fitting
What are the two methods of making a single flare
Impact type - one with hammer
Roller type - no hammer/ preferred one
What is the difference between AN fitting and AC (name all An things for this one)
37 degrees
Has a recess
Coarser
Blue/black
Longer
What is the difference between AN fitting and AC (name all ACthings for this one)
35 degrees
No recess
Finer
Grey or yellow
Shorter
What is a swage/Harrison fitting suited too
Thin walled tubes as almost completely vibration resistant
Why would you use a hose
to connect stationary to moving parts
Or in high vibration areas
When fitting a hose assembly it should be fitted every …..
24 inches
What is recommended before commencing a bend using a hand tube bender
Lightly lubricate the bend point
Why does a hose need to slack and what percentage is required
They reduce their length by 2-4% and expand when under pressure so 5-8% manufactured longer
What system is used to protect hoses assemblies from chafing and temps
Protective sleeves
- heat shrink
- nylon spiral wrap
- Teflon
