AC-SYS

Propellers are de-iced by electrically heated boots glued to the inner part of the blade. Electrical power is supplied through brushes and a slip-ring in the propeller hub.

This system protects the engine from ice ingestion in some turboprop aircraft. --> PC-12

Low power consumption is another positive aspect of TKS systems. Complete airframe ice protection is provided for a fraction of the power needed by electrical heating devices. Also the reduction of runback ice on the wings and tail.

The minimum anti-ice endurance is typically 2.5 h.

In this system, a microsecond duration high current electrical pulse delivered to the actuators in carefully controlled timed sequences generates opposing electro-magnetic fields that cause the actuators to change shape rapidly. This change of the actuator shape is transmitted to the erosion shield of the leading edge causing it to flex and vibrate at very high frequencies. This rapid motion results in acceleration-based debonding of accumulated ice on the erosion shield.

TMEDS addresses and resolves the icing problem by a strategic combination of electrothermal and EMEDS deicing.

The heating and flexing of the leading edge skin are applied in a coordinated fashion locally. Heat is used only to increase the temperature of the ice/skin interface to reduce the level of adhesion between the ice layer and the subjacent skin and thereby weaken the bond between the skin and ice. Once this bond has been weakened, the heat is turned off and the actuators are used to flex the skin and shed the accumulated ice.

1. The clean airplane concept, as mandated by the FAA and Transport Canada, is meant to ensure that no transport aircraft takes off when any snow, frost, or ice is adhering to the wings, propellers, or control surfaces.
2. Ground de-icing/anti-icing

Heated Type I fluid mixed with water is very effective as a deicer, but it has very little ability to keep frozen contamination from reaccumulating. In other words, Type I fluid is not effective as an anti-icer. It has a short hold-over time, or estimated time of protection in active frost or freezing rain (between 5 and 10 minutes).

They are most effective as anti-icers when unheated and undiluted (unverdünnt) and applied as the second step of a de-icing/anti-icing process.

The HOT of Type IV fluid is the longest (between 35' and 1h15') but require high airspeeds to blow off the AC during TO. Recommended rotation speed=100kts.

A quantity is a property of a phenomenon, body, or substance, where the property has a magnitude that can be expressed as a number and a reference. A reference can be a measurement unit, a measurement procedure, a reference material, or a combination of such. The generic concept quantity can be divided into several levels of specific concepts.

• Reproducibility error: The more sensitive the measuring instrument, the less likely it is that two successive measurements of the same sample will yield identical results.
• Systematic error: Suppose that you weigh yourself on a bathroom scale, not noticing that the dial reads 1.5 kg even before you have placed your weight on it. The results will be off by a constant amount.

Precision: degree of agreement between repeated measurements. A precise instrument is characterised by a low reproducibility error.

Accuracy: Refers to how close the mean measured value of quantity is to the true value. An accurate instrument is virtually free of systematic errors.

1. In an analog instrument, such as the airspeed indicator, the angular position of the white pointer on the dial is proportional to the measured airspeed value. When the airspeed changes, the speed with which the pointer moves on the dial is proportional to the rate of change of airspeed.
2. On an instrument with a digital display, such as the car speedometer, the measured value is represented as a number. A high readibility does not necessarily imply a high resolution or accuracy.

1. A detector-transducer, a sensor, which detects the physical variable and performs either a mechanical or an electrical transformation to convert the signal into a more usable form. In the general sense, a transducer is a device that transforms one physical effect into another. But mostly the physical variable is transformed into an electric signal.
2. Some intermediate stage, which modifies the direct signal by amplification, filtering, or other means so that a desirable output is available.
3. A final or terminating stage, which acts to indicate, record, or control the variable being measured.

1. Flight (airspeed indicator, altimeter)
2. Navigation (Compass)
3. Systems (Fuel, oil)

1. Warning systems that inform the crew of a critical situation
2. Protection systems that allow the crew to perform corrective actions
3. Escape systems

To ensure that they can be used during an emergency, they need separate sources of power, alternate means of operation and clear indications.

1. Red: critical condition, for which immediate action is required (warning),
2. Amber: abnormal condition requiring immediate attention, but not immediate action (caution),
3. Green: system is working normally and within its limitations,
4. other colors: status indications or reminders

Groups all indication lights in a panel placed in the center of the cockpit. (PC-12)

1. On one of the Multi Function Display (MFD) unit. I.e. on the Airbus A320 warning and caution messages are displayed by the ECAM (Electronic Centralised Aircraft Monitoring).
2. The Engine and Warning Display (EWD) and the System Display (SD)

• the EWD displays warning or caution messages,
• the master warning or master caution lamps illuminate,
• an aural signal can be heard (tone or voice callout),
• the SD shows the system page for the affected system,
• the CLR (clear) pushbutton on the ECAM control panel illuminates.

The crew not only receives clear and precise information about the system failure, bur also guidance on how to deal with it and on the other systems affected, without the need to consult the flight manual. This is obviously a great advantage in a stressful situation.

• Avoid producing false warnings as much as possible,
• quickly and accurately indicate the location of the fire,
• be able to indicate if the fire has been extinguished,
• be capable of self testing and warning the crew of a failed condition,
• operate in an adverse environment (extreme temperature changes, humidity, fuel, oil, shock, vibration),
• require as little electrical power as possible directly supplied by the aircraft electrical system without electrical inverters.

It consists of continuous sensors filled with helium under pressure. So, no electrical wiring has to be used because these would have to be protected from the fire.

The special metallic core has the unique property of quickly releasing an extremely large volume of hydrogen when any short section of the sensor is heated to a high temperature. This increases the pressure in the tube and activates the alarm pressure switch.

With two identical pneumatic detection loops (A and B) with separate resolvers, and a Fire Detection Unit (FDU).

1. Each loop monitors the engine fan section, the pylon and the engine core.
2. The FDU processes all warnings and cautions originating in the two resolvers, and issues a fire warning to the ECAM.

On the Airbus A340, the APU is protected by two parallel sensor tube loops and a dedicated FDU, similarly to the engines.