106 Through Exam 3 Flashcards
What is feathering
increasing or decreasing the angle of attack
What is an aerodynamic downside of rotors
there is an imbalance of lift along the span of the blades
tip produces more lift as it is going the fastest
highest forward speed comes from the ____ blade
advancing
What is washout
a design where the blade has the lowest angle of incidence between the blade root and blade tip
In forward flight, the sped of air over the blades is _____ on the advancing and reatreating blade and in hover the speed is _____
different, the same
Where is there greater force on the helicopter (right or left)
right side
What is gyroscopic precession in relation to helicopters
a helicopter pitches up rather than rolling over
What do flapping hinges do
equalizes lift on each side of the helicopter
Hinge up where there is more lift and down with less lift
how does flapping equalize lift
changes relative wind approaching blades - changes AoA and therefore CL
What happens to the CG of a helicopter when a blade flaps up
CG shifts more toward center - results in bad rotor vibration and pitching up tendency
what was the purpose of lead/lag hinges
to reduce the vibration caused by the advancing blade wanting to go faster and retreating blade wanting to go slower - ended up creating worse vibrations
How does a semi-rigid rotor work
uses central pivot to allow rotor to teeter at the center
allows advancing blade to rise and retreating to fall
relative wind change produces desired AoA on each side
How does the semi rigid rotor system get affected by Coriolis
CG of blades appear to move towards the center at the same time, so Coriolis doesn’t need to be messed with ~as much~
What is a fully articulated rotor head
has flapping hinges
has lead lag hinges
has lead lag dampeners
(common in helicopters with +2 rotors)
How are semi rigid rotors designed in regards to the pivot point
rotors hang below pivot point so CG does not shift in/out board as like a fully articulated rotor
Explain CG and semi rigid rotors
instead of flapping up: underslung, see-saw type pivot moves whole blade outboard as the system tilts, keeping the CG in the same place laterally
instead of flapping down: underslung, see-saw type pivot moves whole blade inboard as the system tilts, keeping the CG in the same place laterally
Advantages of rigid rotor elastomeric bearings
improved control response
substantial improvements in vibration control
no risk of ground-resonance as with fully articulated
(very expensive though)
Advantages of the star flex system
centrifugal force is contained by flexible arms so “star” arm can be connected by polymer fitting
allows whole blade and plate to flex so blade can lead and lag
no hinges that require lubrication: no additional lead lag dampener, no hydraulic fluid, easily exposed parts for inspection
To move forward, which blade moves up? (If 12 o’clock is forward)
9:00 blade increases in pitch causing disk to rise to highest point at 6
to move backward, what happens with the blades (back is 6)
blades at 3:00 increase in pitch, making spinning disk rise to highest point at 12
What are aluminum alloys for compared to straight aluminum
they add strength
may be as much as 15% of alloy by weight
iron, silicon, copper, magnesium, manganese, zinc
a metal’s strength is directly related to its ___
grain size, orientation, and heat treatment (temper)
what is a composite material
material that is produced from two or more materials
What is AC 43.13 1B
methods/techniques “acceptable” for repairing aircraft when there are no manufacturer repair or maintenance instructions
What are some of the different specifications of aircraft hardware
National Aerospace standard (NAS)
Army-Navy (AN)
Military Standard (MS)
What is yield strength
amount of stress a material can withstand without permanent deformation
what countersink does aviation have
100 degree
drill bits are selected based on
the rivet shank diameter
What is De-Burring
to remove rough edges of a hole or sheet after it has been drilled or cut
Solid rivets
oldest and most reliable
first used in Bronze Age
used almost everywhere
how is a washer measured
by the inside diameter and thickness
What are cotter pins used for
to secure bolts, screws, nuts, pins
what are hi-lock fasteners
two part structural fastener - breakout in collar provides uniform preload torque values by breaking when correct torque level is reached
What is GMAW/WIG
gas metal arc welding
spool or wire as filler that constantly moves through the gun to create a spark and melts to form weld
Like a hot glue gun
what is gas welding
done by heating the ends/edges of metal parts to a molten state with a high temperature flame
what is GTAW
Tungsten inert gas welding
weld produced by an electric arc
electrode doesn’t touch work
long rods fuse two metals
before 1957 how did aviation laws get passed
the civil aeronautics board (CAB) presented to congress and enforced laws passed by congress
14 CFR Part 21
Certification procedures for produces and parts
what is the purpose of the type certificate data sheet
configuration control
document that records type certification data of a product
what needs a TCDS
aircraft, engine, propellor
What is an STC
supplemental type certificate
certificate approving modification for aircraft, engine, or propeller
what are the two types of airworthiness certificates and what are some categories they follow
Standard
normal, utility, acrobatic, commuter…
Special
primary, restricted, limited, light-sport…
important items of airworthiness certificates
issued by the FAA when built
good for life of aircraft
must be visible to passengers/crew
What is a TSO
Technical Standard Order
an FAA approval of the design and manufacture of commonly interchangeable parts on an aircraft
What is a PMA
parts manufacture approval
far approval of the manufacture only of noncommonly interchangeable parts on an aircraft
What are ADS
airworthiness directives are issued by the FAA and must be complied with by owner/operator
what are service letters
sent by manufacturers as a means of providing non-critical information or for clarifying maintenance manuals or pilot handbooks
Operational Specification
commercial airline creation that is submitted to FAA
Contains rules for operations and maintenance where not specifically covered by Federal Regulations
If there is no MEL what should be referenced
14 CFR part 91.213
Aircraft aluminum (alloy # 2XXX) is what
copper
What is an important note about aircraft registration
registration does not prove ownership, just operator
What is the data plate
it is the aircraft (theoretically)
contains serial number
maintenance records must include
Description of the work performed
Date of completion of work
Signature and certificate number of person approving aircraft for return to service
Total aircraft time and time on life-limited parts
Current AD status
What is an important security reminder about your certificate/rating
the TSA can has the authority to tell the FAA to hold, deny, suspend, or revoke certificate
What happens when cheating on an official test
- You will not be eligible to take any sort of test for any airman certificate or rating under this chapter for a period of 1 year after the date of that act
- Commission of that act is a basis for suspending or revoking any airman or ground instructor certificate or rating held by that person
When must you alert the FAA of a change of address
30 days
