Airframe 2 Flashcards
What prevents a nose landing gear from being retracted with the nose wheel out of the center position?
Nose wheel, centering cams, or an external track
When should a landing gear retraction check be accomplished?
During annual inspection
After landing gear replacement
After hard landings
During other programmed inspections
What methods are used for transmitting cockpit control movements to a steering control unit in a large aircraft?
Mechanical, electrical or hydraulic
What unit prevents nose wheel vibration?
Shimmy damper
What prevents a split wheel from leaking air through the inner and outer mating surfaces or the wheel assembly?
An O-ring between the halves
What is an indication of excessive heating of a wheel bearing?
Discoloration
What is the purpose of a wheel fusible plug?
To relieve air pressure to prevent tire blowout
What are some types of break actuating systems?
Independent master cylinders
Boosted brakes
Power brakes
What is the purpose of an anti-skid system?
It prevents the wheels from skidding or locking during breaking attempts
What are some methods of bleeding breaks?
Gravity and pressure
What must be accomplished before inspecting a wheel brake system for hydraulic leaks?
Pressurize the system
What is the most necessary maintenance function for safe operation and long aircraft tire service life?
Proper inflation
What are the effects of under inflation on tires?
Uneven wear near the edge of the tread and creep when the brakes are applied
What conditions should a mechanic look for during a regular inspection of the exposed piston section of a landing gear?
Cleanliness, damage, and proper extension
What safety precaution must be taken when removing a wheel from an axle or when disassembling a wheel?
Verify the tire is completely deflated before removing or disassembling the wheel
What are three types of hydraulic fluids?
Vegetable
Mineral
Phosphate esters
Which color does mineral base and phosphate, ester hydraulic fluids have?
Mineral – red
Phosphate Ester – light purple
What happens to plastic resin , vinyl compositions, lacquer and oil base paint if exposed to a phosphate base and hydraulic fluid such as skydrol?
They become damaged, softened, and/or peeled
What precautions should be taken to minimize contamination during replacement of a hydraulic unit?
All lines should be plugged or capped after disconnecting
What would cause a hydraulic filter to go into open by-pass, allowing unfiltered fluid into the systems?
A clogged filter
What are two types of engine driven hydraulic pumps?
Constant delivery
Variable – delivery
How does a gear type power pump operate?
Two meshed gears are driven by a power unit and rotate in a housing. Fluid is carried around the outside of the gears and delivered to the outlet side of the pump as the gears rotate.
What feature is built into a hydraulic pump drive system to prevent engine damage in the event of a pump, seizure or overload?
A shear section of the pump drive shaft
What is the purpose of a pressure relief valve?
Limit the amount of pressure to prevent damage to system components
What is the purpose of a pressure regulator?
Manage the output of the pump to maintain system pressure and allow the pump to turn without resistance
What is used in some hydraulic systems to supplement the power pump when several units are operated at the same time?
An accumulator
What are the different types of accumulators?
Piston
Diaphragm
Bladder
What must be accomplished with any accumulator prior to disassembling?
Make sure that the air side or preload has been discharged
For what purposes are pneumatic systems used in some aircraft?
To operate brakes, doors, drive pumps and engine starting
What are sources of pneumatic power?
Storage bottles
Vane-type pumps
Turbine engine compressor (bleed air)
What happens to excessive pressure in a pneumatic system?
A relief valve bleeds it to the atmosphere
What is the purpose of restrictions used in aircraft pneumatic systems?
To control the rate of flow
Why should a pneumatic system be purged periodically?
To remove contamination and moisture
What are the results of exposing lacquers, oil based paint, plastic, resin, and vinyl compounds to phosphate Ester based hydraulic fluid?
The materials will be damaged and/or softened, or the paint will peel
Name several sources used to develop hydraulic pressure
Hand pumps
Engine driven pumps
Electrically driven pumps
What types of components or systems are pneumatically operated in some aircraft?
Landing gear
Brakes
Flaps
Other mechanical actuators
Name several sources of pneumatic power
Storage bottles
Engine bleed air
Engine driven compressor
Vane type pumps
How does it continuous flow oxygen system operate?
Oxygen flows from a charged cylinder through a high pressure line to a reducing valve and to mask outlets
How does a basic pressure demand oxygen system operate?
Oxygen flows from a charged cylinder to a pressure demand regulator that is adjustable by each crew member
What type of oxygen must be used in aircraft?
Aviators breathing oxygen
What must be accomplished if an oxygen system has been opened to atmosphere for two hours or more?
It must be purged to remove the moisture
What is used to purge oxygen lines of moisture?
Dry air, dry nitrogen, or oxygen
What safety precautions should be observed when servicing oxygen systems?
Make sure tools, clothing and hands are clean and grease free
Do not smoke or have open flames within 50 feet
Do not use adhesive tape of any kind
What are the two groups of independent cabin compressors?
Positive displacement and centrifugal
What is a roots blower?
An engine driven compressor (it is used in old reciprocating engines for cabin pressurization)
What method is used by some turbine powered aircraft for pressurization?
Engine bleed air
What pressurization control unit will regulate the position of an outflow valve?
Cabin pressure control controller
What is the principle control for a pressurization system?
An outflow valve
What is a vapor cycle cooling?
A closed system in which a refrigerant is circulated through tubing and other components to remove heat from the aircraft
In what significant way is a vapor cycle cooling system different from an air cycle system?
Vapor cycle uses Freon
