022 Instrumentation
Instruments of an A/C
Instruments of an A/C
Kartei Details
| Karten | 53 |
|---|---|
| Sprache | English |
| Kategorie | Verkehrskunde |
| Stufe | Andere |
| Erstellt / Aktualisiert | 01.08.2022 / 13.06.2025 |
| Weblink |
https://card2brain.ch/box/20220801_instrumentation
|
| Einbinden |
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On-Board Clock
Commercial ACFT
- Normal time indication
- GPS based
- Used for ACARS
Small ACFT
- Normal time indication
- HOBBS or Flight time measurement
Variant 1: Connected to the battery. Measures time as of which the battery is used until shut down
Variant 2: Connected to the engine. Measure time as of which the engines runs until shut down
Variant 3: Starts and stops at defined airspeed (50 to 60kt) - Used for maintenance
Static ports
Measure static pressure PS
One on each side of the plane --> Increases accuracy
Ports are subject to Position error influenced by:
- Pitch attitude
- Speed changes
- Configuration changes
Pitot tube
Measures total pressure PT
One attached at the front of the wing to keep it in undisturbed air flow.
Subject to total pressure error if pitch > 20° up or down
Definition of Altitudes
Altimeter
Capsule: Very low pressure (vacuum)
Case: Static pressure
Contains a bimetal temperature compensator
Tolerances:
- up to 30'000ft +/- 60ft
- up to 50'000ft +/- 80ft
Types of Altimeters
- Simple altimeter
One aneroid capsule - Sensitive altimeter
Multiple aneroid capsule enhance accuracy - Servo assisted altimeter
Pressure measurement is connected to a circuit, translating contraction/expansion of capsules into electric signals. --> Eliminates the lag error and makes it the most accurate altimeter
Altimeter errors
- Position error
- Instrument error
- Barometric error
- Temperature error
- Lag error
Vertical Speed Indicator
Capsule: Static pressure
Case: Static pressure
Static pressure is directly fed to the capsule while the case has a restricted passage through which static pressure enters. --> The instrument measures the difference between static pressure in the capsule and case.
Once leveled-off the pressure in the case reaches the static pressure in the capsule and the VSI indicates 0 again.
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Vertical Speed Indicator errors
Static system errors
- Blocked static port
- Leakage of static line
- Position error
Instrumentation error
Time lag
Instantaneous Vertical Speed Indicator
Working principle is the same as for the regular VSI but an acceleration pump is added which helps to pass the pressure quicker and hence reduces the time lag of the indication?
Air Speed Indicator
Case: Static pressure
Capsule: Total pressure
Air Speed Indicator errors
...
Air Speed Indicator markings
VS0 = Stalling speed in landing configuration
VS1 = Stalling speed in a specified configuration
VFE = Max. speed with flaps full down
VLE = Max. landing gear extended speed
VLO = Max. landing gear operating speed
--> VS0 bis VFE = White sector
VNO = Max. Normal operating speed
--> VFE bis VNO = Green sector (normal operating range)
VNE = Never exceed speed
--> VNO bis VNE = Yellow sector (caution range)
VX = Best rate of climb
VY = Best angle of climb
VMC = Minimum control speed, one engine inoperative, take-off configuartion, landing gear retracted, running engine at T/O power, max. 5° bank.
