022 Instrumentation

Stall speed landing configuration

Stall Speed specified configuration

Max. Flaps extended speed

Normal Operating limit speed

Never Exceed speed

Maximum landing gear operation speed

Maximum landing gear extended speed 

• Static Pressure in Case
• Very low pressure/vacuum in capsule
  • Capsules are pressed or expand and thus indicate the altitude 
• Error: Blocked Static Ports: Alt stays 

Vertical Speed indicator

• Static Pressure in Capsule, direct static
• Static pressure in case, delayed static
• Difference between direct and delayed static pressure gives the vertical speed
• Error: Blocked static port: shows zero

• Zu hohe Querbeschleunigung, das Heckbricht aus
• In rechts Kurve Nase nach rechts --> SKID TO THE LEFT
• T/C-Kugel in Kurvenaussenseite

• Zu tiefe Querbeschleunigung, das Heck hängt in die Kurve
• In rechts Kurve Nase nach links --> SLIP TO THE RIGHT
• T/C-Kugel in Kurveninnenseit

• Airspeed indicator
• Altimeter
• Vertical speed indicator

• Attitude indicator
• Turn indicator
• Direction indicator

Green: Safe and normal range

Blue: Allowable range under unique circumstances

Yellow: Precautionary range of time limited operation

Red: Maximum or minimum safe operating limit

Used to measure low pressures (up to 5 bar)

Measures absolute and differential pressure

Application: Alt, VSI, ASI, MAP

Used to measure medium pressure (up to 10 bar)

Measures absolute or differential pressure

Application: MAP, Fuel, Fuel-flow pressure

Used to measure high pressure (up to 7000 bar)

Measures absolute and differential pressure

Application: Oil, hydraulic, fuel, oxygen and cabin pressure, air pressure and EPR

Contains 2 aneroid capsules (1 for the MAP itself, 1 for the altitude compensation)

Two metal strips attached to each other with different thermal properties

--> Differing elongation of material under varying temperature causes pointer to move

Low temperature range

Airstream is captured by the probe and decelerated to reduce measurement error.

Inside the probe the temperature is measured by a PTC/NTC element.

Aspirated Rosemount Probe
The probe is fed with bleed air to overcome errors at low or zero speed (Rosemount probe relies on an airflow, otherwise erronous measurements result).

The resistance of materials varies with temperature which is a property used to measure temperatures up to 400°C

PTC: Resistance increases with temperature increase

NTC: Resistance decreases with temperature increase

Application: Oil temperature, carburator heat

Two different metal wires form a circuit connecting at the voltage source and a junction. When the junction is heated, a current flows and hence temperature can be measured in relation to the flowing current.

Max. measurable temperature > 1000°C

Application: EGT, CHT

Used to measure low to high pressures (also negative pressures)

Measures absolute or differential pressure

Subject to measurement error --> Affected by Attitude, Accelerations and Temperature

Measures electromagnetic flux between two condensator plates. In a full tank the condensator plates are fully emerged in fuel. With increasing fuel consumption the mixture between air and fuel is altered which changes the flux and translates into the fuel quantity. --> Not affected by: Attitude, Accelerations, Temperature (almost)

Kelvin / Degree Celsius / Degree Fahrenheit

K -> C° :  \(T_C = T_K - 273.15\)

°C -> °F :  \(T_F = {9 \over 5}* T_C + 32\)

1 US gal = 3.79 litres

1 Imp gal = 4.55 litres

1 kg = 2.2046 lbs

1 lbs = 0.4535 kg

Fuel flows through the measuring vane with a paddel. Depending on the fuel flow the paddel rotates. The rotation is translated via a rotor and stator to the indicator.

Pressure sensor after the fuel pump measures the pressure in the injector line which translates into a fuel flow.

The fuel supply line contains a small turbine. Fuel flow is then derived from the RPM of the turbine.

Within a drag cup there is a magnet which rotates with the engine RPM and causes the drag cup to rotate. The rotation of the cup is then indicated on the RPM-indicator.

A permanent magnet in a stator coil rotates at the engine's RPM. An electrical signal is created which lets a second permanent magnet rotate at identical speed. The second magnet is connected to a third magnet in a drag cup that translates the rotation into an indication on the RPM indicator (as in the magnetic drag indicator). --> Produces its own electricity / independant from ACFT electric system

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A phonic wheel rotates at the engine's RPM. Next to the wheel a speed probe with a permanent magnet is installed. The magnetic field of the magnet is disturbed by the rotating wheel. Therefore, the magnetic field depends on the rotating speed of the wheel and hence can be translated into a RPM. --> Requires electrical power from an aircraft source

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For multi-engine ACFT:

• Avoid discomfort and fatigue from noise
• Detects and indicates difference in RPM
• Uses the engine tachometer (RPM)
• Does not need electrical power

--> Ensures that all engines run synchronously

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