Instrument Systems & Fire Protection Flashcards
Minimum powerplant instruments required by CFR 91.205:
1) Tach for each engine.
2) Oil pressure gage for each engine.
3) Coolant temp for each liquid-cooled engine.
4) Oil temperature gage for each air-cooled engine.
5) Manifold pressure gage for each altitude engine.
Types of data important for monitoring the operation and performance of aircraft powerplant:
1) Pressure
2) Temperature
3) Mechanical movement.
Types of pressure:
1) Absolute pressure
2) Gage pressure
3) Differential pressure
Define absolute pressure:
Pressure referenced from zero, or a vacuum.
Define gage pressure:
Pressure added to a fluid by a pump/device. Referenced from the existing atmospheric pressure.
Define differential pressure:
The difference between two pressures.
(DeltaP)
Most common type of lubricating oil pressure measuring instrument:
Bourdon tube type.
Used to measure carb air temps, fuel temps, and oil temps:
Ratiometer instruments.
Define EPR:
The ratio of turbine discharge total pressure to compressor inlet total pressure.
How do analog instruments measure oil temps?
By measuring the vapor pressure of a liquid in a sealed tube.
Two types of instruments that measure temperature electrically.
1) Ratiometer
2) Thermocouple
How does a Ratiometer operate?
Temp sensing bulb is immersed in the targeted fluid. The resistance of the wire in the bulb varies with its temp. The voltage allowed to pass through the wire creates a magnetic field that pulls magnet-attached pointer accordingly.
Types of thermocouples for recip engines.
1) Bayonet type
2) Spark plug gasket type.
Where is a recip engine EGT thermocouple mounted?
In the exhaust stack, within 6 inches of the cylinder head.
Turbine EGT is measured how?
By several thermocouples, connected in parallel, arranged around the tail cone, whose readings are averaged together.
What are the instruments that measure mechanical movement.
1) Tachometer
2) Fuel flow indicator (vane type and mass fuel type)
3) Torquemeter.
Class A fire:
Fire with a solid combustible material.
Class B fire:
Fire with a combustible liquid.
Class C fire:
Fire which involves energized electrical equipment.
Class D fire:
Fire in which metal (such as magnesium) burns.
Class A fire zone:
Large volume of air flowing past regular arrangements of similarly shaped obstructions.
(Area where air flows over cylinders)
Class B fire zone:
Large volume of air flowing over aerodynamically clean (smooth) obstructions.
(Exhaust shrouds in recip, fireproof liner in turbine)
Class C fire zone:
Zones with small amount of airflow through them. (Behind firewall)
Class D fire zone:
Little or no airflow.
(Enclosed area inside a wing structure)
Class X fire zone:
Large volumes of air flow at an irregular rate. (Wheel well)
How does a thermoswitch operate?
When detector is heated, internal strips on which contacts are mounted distort and close the contacts, completing the circuit between loop and ground.
How does a thermocouple work?
Two dissimilar metal are welded together to form a loop. A voltage exists in the loop proportional to the to the difference in temperature between the hot and cold junctions at which the wires are joined.
Thermocouples are considered to be what type of detection system?
Rate of temperature rise
Types of Continuous loop fire and overheat detection systems:
1) Thermistor type (Kidde and Fenwall)
2) Pneumatic type (Lindbergh and Systron-Donner)
What are the types of thermistor-type continuous loop systems?
1) Kidde (double conductor)
2) Fenwall (single conductor with ceramic beads)
Types of pneumatic-type continuous loop systems:
1) Lindberg (gas absorbing element)
2) Systron-Donner (gas absorbing element and helium gas)
Two types of installed fire-extinguishing systems:
1) CO2 systems (engine compartment of older aircraft)
2) HRD (high rate discharge) systems (used on most modern jet transport aircraft)
A yellow blown out disk indicates:
Normal discharge
A red blown out disc indicates:
Thermal discharge due to an overheat condition
HRD bottles contain what?
Halon 1211 or
Halon 1301
What is used to break the frangible disk of a HRD bottle?
Powder discharge (Squib)
Pulling the fire-pull handle does what six things?
1) Shuts of fuel.
2) Trips the generator field relay.
3) Shuts off bleed air.
4) Shuts off wing or cowl anti ice.
5) Shuts off hydraulic supply.
6) Turns off hydraulic pump warning light.
Green arc:
Normal operating range
Yellow arc:
Caution range
(Time limited)
White arc:
Special operations range.
Red arc:
Prohibited range
(Damage to engine will occur)
Red radial line:
Do not exceed indication
Blue radial line:
Special operating condition
Red triangle, dot, or diamond:
Max limit for high transients (such as starting)
Yellow arc on carburetor air temp instrument:
Range where ice is most likely to form.
Instrument that indicates engine power:
Manifold pressure gage.
CFS (computerized fuel system) gives what information?
1) Pounds/gallons of fuel on board.
2) Fuel flow rate (per hour).
3) Fuel time remaining.
4) Amount used since engine was started.
EICAS (engine indication and crew alert system) does what?
Replaces many instruments and provides crew with two screens of airframe and engine parameters. Alerts crew of warnings and fully redundant in the case of one screen outage.
EICAS primary display parameters:
1) EPR
2) N1
3) EGT
EICAS secondary display parameters:
N2
Fuel Flow
Oil temp
Oil pressure
Oil quantity
Vibration
How often must instruments be calibrated according to FAR?
Annually
Far 91 minimum instrument equipment list:
Tachometer
Oil pressure
Oil temp
Coolant temp
Manifold pressure
T/F
A CO2 discharge requires expensive clean up after discharge.
False.
No clean up required.
How does Halon put out fire.
Mixes with oxygen chemically and starves the fire.
How does CO2 put out fire?
Displaces oxygen and absorbs heat through evaporation.
Life limited part on an HRD system:
The squib.
T/F
Sensing elements are powerplant items.
False.
Airframe items. Remove before sending out to engine repair shop.
Requirements for fire detection and warning systems:
1) Separate detection for each engine.
2) Must not give false alarms.
3) Must not be damaged by oil, water, vibration, temps, or handling.
4) Must operate directly from aircraft electrical system and require minimal electrical current.
What types of fire detectors are used for engine fire detection?
Overheat
Rate of rise
Flame detector
Spot
