6.5 Flashcards
Screws are the most commonly used fastener since they differ from bolts how?
They are made of lower strength materials
What fitting is screws and what are there head shapes made for
Loose fitting thread and the head is to engage a screwdriver or wrench
What are the following
Machine screws:
Structural screws:
Self-tapping screws:
Machine: most widely used
Structural: same strength as screws
Self-tapping: used to join light weight materials
What are machine screws used for?
Attaching fairings, inspection plates, fluid line clamps and structural parts.
What process are structural screws gone through to have similar characteristics to bolts?
Heat treated to have the same shear strength as a bolt.
What are the 4 types of self tapping screws?
Round
Truss
Counter sunk (flat top)
Counter sunk (oval)
What are dowels used for?
To align/correct two mating surfaces.
What is present in aircraft operation that can make parts loose?
And what can we use to stop the fasteners from coming loose?
Vibration is always present in aircraft.
To prevent use locks for the fasteners.
There’s are various methods to secure items in the aircraft industry what are some examples?
Safety wires
Split and cotter pins
Lock washers (tab, spring and shake proof)
Self locking nuts
Quick release fasteners
In places where self locking nuts and split pins can’t be used lock washers are used what are some examples?
Spring, tab and shake-proof
They are made of steel and twisted when the nut is against it which creates friction.
What is the counter sink angle from the head to the shank
100’ between the shank and head
What metal washer with two or more tabs where one is bent over the edge of a component or hole and the other against the nut
Tab washer
What washer bites into the nut to not allow it to uh tighten
Shakeproof washers
What is a pal nut?
Resilient spring locking action nut made of steel provide vibration proof action while small sized.
What plates are manufactured from mild steel used to secure parts (bolts securing it can be equipped with shake proof and spring washers)?
Locking plates secure making sure nothing comes loose can be re used
What fastener is held by a cross pin and a floating fastener?
Airloc
What fastener is quick release by a quarter turn and consist of a stud washer and receptacle
Camloc fasteners
What Simple’s secure fastener can be quickly inserted and removed with at tools?
Pip pin the pin with the button and ball bearing (thing that as remove before flight thing)
What pins provide a lock which is pushed into a Hole (place where not likely removed)?
Roll pins
What charteristics of Clevis pin
Goes in 1/16 inch incremets
What shaped piece of metal fits into ____ways in wheels discs sprockets or gears.
Aligns items and helps by spreading out load on what is being driven.
Keys
woodruff, square, pratt and Whitney, gib head key
What metal are rivets with no identifying marks and designated by letter A (in rivet code)
1100 Aluminium
What Rivets with code AD and a simple dimple also referred to as field rivets?
2117 Aluminium Alloy
What rivet has a raised cross and rivet code B
5056 Aluminium Alloy
What rivet has raised dot and rivet code D
2017 Aluminium alloy
What rivets identified by DD and two raised dashes
2024 aluminium alloy
What rivet has raised ring and letter E
7050-T73
What rivet is F
Corrosion resistant steel
What the diffrence between hi lite and hi lok bolt?
Hi lite is lighter and less threads
What are the 3 types of lock bolts
Pull type
Blind type
Stump type
What materials are standard airfrane bolts made of?
Cadmium plated steel, corrosion resistsant steel and 2024 aluminuim alloy
What load occurs for clevis bolts to be used?
Shear
What featrues do a clecvis bolt have near its threads
A hole for pins
What bolts are used in applications of external tension loads
And what is attached to them?
Eye bolts (used for the attachments of turnbuckles)
What is special about the head of hex headed nickle steel bolts?
Holes drilled into them
An173 and 186 are manufacturesd tk what tolerance?
+ or - 0.0005 inchs
Ms20004 to ms20024 internal wrenching bolts sre high strength steel bolts where are they primarly used?
In areas subjected to high tensile loads (washers must be used under the head to provide needed bearing area)
Nas bolts cant be replaced by AN 1/16 longer than AN
What are the dash numbers in nas even or odd
Even
Where are all bolts but AN bolts measured from?
The grip length not overall
What dash numbers do MS issue bolts have?
If grip length is too long or short odd dash bolts are available.
Even
Use of circlips
Used for internal and external locking
What is the term of the thread on a screw
The pitch (use a screw thread pitch gage)
What are the 5 classes of fit
Class 1 loose
Class 2 free
Class 3 medium
Class 4 close
Class 5 Tight
What is the diffrence of a theard on a external surface and formed inside a cylinder or cone
External is a male thread and cone is a internal/ female thread
What is the diffrence between a thread on a cylinder or conical part?
Cylinder is straight or parallel thread
Conical part is taper thread
Multiple threads are not often used but are found on what?
Industrial machines, vavles, fire hydrants and aircraft landing gear
Screws and bolts have 4 types of lead threads what are the four?
Single one groove
Double two grooves
Triple three grooves
Quadruole four groves
Double, triple and quadruple threads are known as what?
Multiple lead threads
Where should a single thread be used?
Where locking power is required
What advantages do multiple lead threads offer
They furnish more bearing surface
They have larger minor diameters
Provide rapid movement
What is the lead?
The distance a nut travels in a revelution
In a single lead screw how much does a nut move in one turn
And in a double lead how far?
Forward the pitch (one thread) in single lead
And double lead 2 threads in 1 rotaion etc
What are the three most common standard thread forms
British standard thread forms
American nations thread forms
Unified thread forms
What thread angle is british standard coarse (BSW)
55°
BSF is a fine version always having 2.5cm turns than a bsw and offer greater resistance to?
Resitance to vibrations
What is the BA (british assosiation) fine pitch sizes below?
6.35mm / 1/4 inch
What is BA thread angle
47.5°
What angle are anc and anf
60°
United thread firms are univeral containing what 3 (what is UNC UNF and UNEF)
Unified National Coarse
Unified National Fine
Unified National Extra Fine
Two screw threads may have similar major diamters but diffrent what?
Depths of thread
If a screw has a deeper cut thread what will it have fewer of?
Fewer threads
What are the 3 thread types
Square
Buttress
Acme
What perk do square threads have
Very powerful root (handle heavy loads)
What perk do buttress threads have?
Triangular section and have great pulling power
What are the perks of acme threads
Tapered version of square easier to fix or unscrew when cutting nuts and considerbly stronger
What is the crest a of screw?
Most prominent point of the thread
What is the helix angle of a screw
Referes to areas of the screw angle in degrees
What is the run out
Where minor diameter increases to major
What are A and H bolts
A holes bolt heads
H for locking wire
If a bolt is has no markings what should it be
Cadmium nickle plated
What markings do close tolerance bolts have?
Triangular mark on the head
Internal wrenching bolts are used in areas of what?
Areas subjected to high tensile loads
What is the thread?
The angle between two adjacent flanks
