Temperature Measuring Equipments 2 Flashcards
Monitor engine parameters, outside air temperatures, liquid temperatures
Monitor health of avionics systems
Purpose of Temperature Measuring equipments
Thrust is both affected by both _____ and _____
temperature and Altitude
temperature can be measured _______ and _______.
electrically and expansion of different materials
It is produced between junctions of dissimilar metals
Electromotive force (thermo-emf)
Temperature sensing that contains a liquid in a bulb
Higher temp increases vapour pressure
High pressure straightens Bourdon Tube and increases temp indicaton
Gas Expansion Temperature Sensing
Most commonly used metals for electrical type sensing
Nickel and platinum
Two methods for electrical type temp sensing:
Variable Resistance
-Wheatstone Bridge or Ratiometer type circuit
Thermoelectric
Powered electrically and consist of 3 fixed resistors and one variable resistor
As temperature increases, resistance increases
Variable Resistance Temperature Sensing (Wheatstone)
Powered electrically and consists of variable resistor (temp sensing probe) + a fixed set of resistors and a moving coil indicator
Variable Resistance Temperature Sensing (Ratiometer)
Temperature sensing used for engine temperatures (uses THERMOCOUPLE)
Independent of aircraft power
Thermoelectric Temperature Sensing
What is the voltage measured in thermoelectric
millivolts
What are the material used for CHT probes?
Iron and Constantan
What are the material used for EGT probes?
Chromel and Alumel
Two types hot junctions that are commonly used?
GASKET TYPE
- 2 rings of dissimilar metals pressed together
- typically installed in sparkplugs
BAYONET TYPE
- dissimilar metals inside a perforated protective sheath
- can be used for CHT (by installing a hole in cylinder head) and EGT
Bayonet type is sometimes called?
Immersion type
On ____ aircraft, the SAT sensor is typically a direct-reading thermometer that uses a bi-metallic or resistance type probe. Works by the expansion of a bimetallic element.
M1
On M2 aircraft, the SAT is typically derived electronically from ___ by the CADC.
TAT
TAT is static air temperature (SAT) plus any rise in temperature caused by the ______ movement of the aircraft through the air.
high speed
This increase in temperature is known as
_______.
ram rise
TAT systems have a probe which allows air to flow through, passing over a ______ element. The probe is designed such that the anti-icing heating element does not heat up the air the probe is measuring
sensing
Air temperature is an important parameter used to monitor the aircraft’s performance relating to:
- True airspeed
- Temperature control
- Thrust setting
- Fuel/air ratio settings
