Airspeed Color Markings & System Blockages

Summary

This video explains the color-coded markings on an aircraft's airspeed indicator and how it reacts to different blockages in the pitot-static system. The script covers key speed ranges such as the flap operating range, normal operating range, caution range, and never exceed speed, with specific focus on the variations in twin-engine aircraft. It also delves into the effects of pitot tube and static port blockages, detailing how the instrument behaves in different blockage scenarios. The video emphasizes the importance of understanding these indicators for safe aircraft operation and how to manage blockages effectively.

Takeaways

• 😀 The airspeed indicator in light aircraft uses color-coded arcs: white, green, yellow, and red, to represent different operating ranges and speed limitations.
• 😀 The white arc represents the flap operating range, between the stall speed (vso) and the maximum speed with flaps extended (vfe).
• 😀 The green arc represents the normal operating range, between the stall speed in a clean configuration (vs1) and the maximum normal operating speed (vno).
• 😀 The yellow arc represents the caution range, starting at the maximum normal operating speed (vno) and ending at the never exceed speed (vne).
• 😀 The red line represents the never exceed speed (vne), which must never be exceeded under any circumstances.
• 😀 In twin-engine aircraft, two additional markings are present: a blue radial line for the best single-engine rate of climb (vyse) and a red radial line for the minimum control speed (vmca).
• 😀 The vyse speed varies depending on conditions like sea level, standard conditions, and maximum certified weight.
• 😀 The vmca speed also varies depending on factors such as sea level, standard conditions, maximum certified weight, and the operative engine's power.
• 😀 When the pitot tube intake is blocked, the airspeed indicator will read zero due to a lack of dynamic pressure.
• 😀 If both pitot tube and static port holes are blocked, the airspeed indicator will freeze and act like an altimeter, showing changes in speed with altitude adjustments.
• 😀 In case of blockages, pitot heat or alternate static sources can be used to solve the issue and restore accurate readings, with necessary adjustments based on correction tables.

Q & A

What do the color-coded markings on the airspeed indicator represent?

The color-coded markings on the airspeed indicator represent specific operating ranges and speed limitations. These colors are: white (flap operating range), green (normal operating range), yellow (caution range), and red (never exceed speed).

What does the white arc on the airspeed indicator indicate?

The white arc represents the flap operating range, which denotes the speed range within which the flaps can be operated without causing structural damage or overstress. The white arc starts at the stall speed in landing configuration (Vso) and ends at the maximum speed with flaps extended (Vfe).

What is the difference between Vso and Vfe?

Vso is the stall speed of the aircraft in a landing configuration with flaps fully extended and power idle, while Vfe is the maximum speed at which the flaps can be extended without causing structural damage or overstress.

What does the green arc on the airspeed indicator represent?

The green arc represents the normal operating range, where the aircraft can be operated in clean configuration (landing gear and flaps fully retracted). It starts at Vs1, the stall speed in this configuration, and ends at Vno, the maximum normal operating speed.

What is Vno and why is it important?

Vno is the maximum normal operating speed, sometimes referred to as the maximum structural cruising speed. Flying above Vno requires extra caution as the aircraft has more limited structural tolerances at higher speeds.

What is the significance of the yellow arc on the airspeed indicator?

The yellow arc represents the caution range. This range should only be flown in smooth air and with caution, especially during maneuvers. The yellow arc starts at Vno and ends at Vne, the never exceed speed.

What is the never exceed speed (Vne) and its importance?

Vne is the never exceed speed, represented by the red radial line on the airspeed indicator. It is the maximum speed an aircraft should ever exceed under any circumstances, as flying above Vne could result in permanent structural damage.

What additional markings are found on the airspeed indicator of twin-engine aircraft?

In twin-engine aircraft, there are two additional markings: the blue radial line representing Vyse (best single engine rate of climb) and the red radial line representing Vmca (minimum control speed with one engine inoperative).

How does the airspeed indicator react in case of a main intake blockage in the pitot tube?

If the main intake of the pitot tube is blocked, dynamic pressure can no longer enter the tube, and the residual pressure escapes through the drain hole. This causes the airspeed indicator to drop to zero, as only static pressure remains inside the tube.

How does the airspeed indicator behave in the event of a static port blockage?

If the static port gets blocked, the airspeed reading will remain unaffected as long as the aircraft maintains a constant altitude. However, if the aircraft climbs or descends, the instrument will behave like an altimeter: it will show a higher airspeed during descent and a lower airspeed during climb.

How can a blocked pitot tube or static port be corrected?

For a blocked pitot tube, activating the pitot heat is typically the solution, as blockages are often caused by ice. For a static port blockage, using an alternate static source is necessary. The corrected speed values must be taken from the aircraft's correction tables, considering the aircraft's configuration.