EXAMPLES OF SYSTEM INTEGRATION

7.1) AP68TP-600 VIATOR Aircraft model Aircraft Manufacturer Aircraft weight Engine manufacturer Engine model Engine power Engine type Number of engines AP68TP-600 VIATOR Partenavia 3000 Kg

Allison Division General Motors 250B17C+

328 shp Turboprop

2

This example is interesting because it is a typical case of an aircraft equipped with an ice protection system but not certified for flight in known icing conditions. The ice protection system is not powerfull enough to cope with ice accretion and it is only sufficient to give a pilot time to divert in case of inadvertent icing encounter.

The aircraft is equipped with de-icing pneumatic boots on the wings, stabilizer and fin leading edge. The boots are pneumatically operated by engine-driven pumps. An annunciator light monitors the system operation. The deicing system is manually operated each time a de-ice cycle is desired. The switch will instantly spring back to OFF. The sequencing system inflates at the same time the tail section boots and the wing boots for approximately 6 seconds. The annunciator light will lit up when the boots reach a proper pressure. The pneumatic deicers should be activated when ice accumulates between 1/4 and 1/2 inch, but they must not be operated more than once per minute. Accumulation of ice larger than 1/2 inch can cause an increase in stall and buffet speed, and an increase in power is required to maintain cruise airspeed. Prestall buffet and stall speeds are increased also when boots are activated. Therefore, an increase in approach speed in icing condition is required.

A pitot is installed on the left side of the fuselage and an electrical heating element is installed within the pitot tube to prevent ice obstruction. In addition to static source valves mounted flush on each side of the aircraft nose, an alternative emergency valve is located on the left side of the control pedestal. The aircraft is equipped with a compressor bleed air system that is manually operated by the pilot by pulling a knob located on the left hand lower section of the instrument panel. The knob actuates the deicing system on both engines simultaneously discharging heated air into the compressor inlet vanes. Use of the compressor ice protection system will increase T.O.T. of approximately 50 °C.

The air intake is electrically heated, two switches are provided, one for each intake, on the "DE-ICE" panel located on the pilot side instrument panel. A press-to-test button is installed above the relevant air intake switch to provide advance warning of the deterioration of the insulation resistance within the de-icing heaters and protection against escalating damage. To test the system it is necessary to switch ON the battery, the air intake heating ant to press the test button. A green light will light up in the annunciator panel if the system is fully operational. When the test button is pressed again, the green light will go off. This action will also disconnect power from the heater elements until the system is reset by turning the air intake switch OFF. During air intake de-icing operation, an increase of 30 amps will be indicated in the relevant Volt/Ammeter.

The propeller de-ice system consists of electrically heated mats on the propeller blades. Each mat consists of a heating element which receives electrical power through a de-icer timer. The timer provides power to all heating elements on one propeller for approximately 90 seconds, then the power is provided to all heating elements of the other propeller. An ammeter, with a green arc from 14 to 18

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amps is provided in the center left instruments panel to monitor operation of the propeller ice protection system.

In case of inadvertent encounter of icing conditions (visible moisture and temperature below 5 °C) the following procedure must be followed:

a) Engine air intake ice protection switch ON

b) Engine compressor inlet anti-ice knob PULL OUT c) Pitot heat CHECK ON d) Ignition ON

e) Surface deicing AS REQUIRED f) Propeller ice protection switch ON

g) Oil temperature MONITOR

De-icing boots must be off for take-off, during final approach and landing.

Pre-flight inspection requires a check for tears, abrasion and cleanliness of de-ice boots; in addition a visual check of the boots functionality and of the “ON” annunciator light is required before take-off. Aircraft performances are decreased if ice has accumulated on unprotected areas. It is required to maintain extra airspeed on approach to compensate for the increased prestall buffet associated with ice on the unprotected areas and the increased weight.

Page 64 7.2) ATR 72 Aircraft model Aircraft Manufacturer Aircraft weight Engine manufacturer Engine model Engine power Engine type Number of engines 72 ATR 21500 Kg Pratt & Whitney Canada

PW 124/127 2160 - 2480 shp

Turboprop 2

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For this aircraft pneumatics boots have been installed on: wing leading edges, horizontal tailplane leading edges, engine air intakes and gas path de-icer.

Electrical anti-icing is applied on windshield, probes, propellers, wing and horizontal and vertical tail horns. An ice detector is installed on wing mid-span and an ice probe, to be used as visual cues, is installed near the left wing.

Three levels of ice protection are defined: