Ice and Rain Protection System

Gulfstream GVII

Eddie sez:

For a quick refresher or a good intro, be sure to see Ivan Luciani's notes: Ice and Rain Protection System.

There are also a few flash cards here: G500 Flashcards and Quizlet.

Everything here is from the references shown below, with a few comments in an alternate color.


Photo: G500 Anti-ice synoptic, PAS, P. 9-26
Click photo for a larger image

How it works . . .

Limitations and Abnormal Procedures . . .

Last revision:


How it Works . . .

Ice Detection

Ice Detection Probes (2)


Photo: G500 Ice detection probes, PAS, P. 9-2
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[PAS, P. 9-2]

  • Two installed, one below each pilot's windshields, work independently.

  • AC powered, vibrate at 40,000 Hz to detect ice. Occurs with ice accumulation of approx 0.02" on either probe, displays CAS message minimum of 3 minutes → Ice Detected, timer resets each time ice forms on probe.

  • Triggers operation of anti-ice protection system(s) set to Auto.

  • If ice accumulation < 0.02" for 3 minutes, Ice Detected CAS extinguishes, Cowl and Wing auto heat ceases two minutes after Ice Detected CAS extinguishes.


Photo: G500 Ice detector test, PAS, P. 9-19
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[PAS, P. 9-19]

  • BIT triggered with selection of FCS test switch, TSC's 1 - 4, Menu → Systems → Test tab → FCS, FCS test switch also triggers flight control test, Used first flight of day during Airplane Power Up check, Lasts approx 30 seconds.

  • System continually checks for Ice Detect failures during normal ops.

Wing Anti-Ice



Photo: G500 Wing anti-ice components, PAS, P. 9-3
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[PAS, P. 9-3]

  • Wing Anti-Ice (WAI) Control system → 2 independent systems (one for each wing).

  • Uses hot engine bleed air through two WAI valves located in the tail compartment. Each valve is a butterfly-type valve, spring loaded closed, pneumatically actuated, variable pressure regulator and shutoff valve, provides regulated hot air to its respective wing leading edge.

  • A crossover Duct allows bleed air from 1 engine to provide heat to both wings if a WAI valve fails or there is a bleed Air failure.

  • Hot air flows from the engine(s) through the leading edge of each wing, passes through main wheel well and exits through 2 screens behind main wheel well.



Photo: G500 Wing anti-ice activation, PAS, P. 9-4
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[PAS, P. 9-4]

  • Can be activated 2 ways via WAI switch on OHPTS → Anti-Ice.

    • Manually. WAI switch → On, WAI operates regardless of Altitude. There is a large thrust debit above FL450.

    • Automatically. This is the normal mode of operation, WAI switch → Auto. (Default state at power up.) WAI comes on automatically in-flight if ice detected and aircraft → 400’ AGL - FL350. WAI turns off automatically when Ice Detected removed and ice accumulation < 0.02" for 3 minutes Auto does not work on the ground.

  • Bleed Air Computer (BAC) modulates HPSOV to mix 8th stage air with 4th stage air to increase precooler inlet temperature. The high temperature set point is 700°F. WAI valves to maintain WAI duct exit temperature of approximately 130°F.

  • WAI switch → Off: WAI valves close and WAI ceases to operate.

Wing Leading Edge Fuel Vapor Ventilation


Photo: G500 Wing anti-ice ram air inlet, PAS, P. 9-5
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[PAS, P. 9-5]

  • Wing Leading Edge Fuel Vapor Ventilation provided by RAM air when WAI Off: enters through rubber check valve on leading edge near nav lights.

  • Provided by WAI when operating: rubber check valve prevents WAI from escaping through RAM inlet


Photo: ECS/Pressurization Synoptic with WAI on, FSI G500 MTM, fig. 30-12
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Cowl Anti-ice



Photo: G500 Cowl anti-ice components, PAS, P. 9-6
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[PAS, P. 9-6]

  • Consists of 2 independent systems, left and right, heat comes from on-side engine bleed air, 4th stage air, upstream of Bleed Air Valve (BAV), operates regardless of Eng Bleed Air switch position.

  • Controlled by Cowl Anti-Ice (CAI) Valve. If valve fails to open, can be locked open for dispatch in icing in accordance with MEL.

  • Travels through CAI Supply Duct to heat cowl leading edge.

  • Exhausted overboard through exhaust vent at bottom of engine cowl.



Photo: G500 Cowl anti-ice activation, PAS, P. 9-7
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[PAS, P. 9-7]

  • Can be activated two ways

    • Manually: CAI switch ON, CAI operates regardless of altitude or ice detection and is available in flight or on the ground.

    • Automatically: This is the normal mode of operation, CAI switch AUTO, default state at power up. CAI comes on automatically if ice detected and the aircraft is above 400' AGL and at or below FL 350. CAI turns off automatically when ice accumulation < 0.02" for 3 minutes. Auto does not work on the ground.

  • CAI switch OFF, closes CAI valve.

Probe Anti-ice


Photo: G500 Probe anti-ice, PAS, P. 9-12
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[PAS, P. 9-12]

  • Provides protection against ice accumulation on Multifunction Probes and Total Air Temp (TAT) Probes.

  • Electrically heated, automatic ON.

    • Multifunction Probes. After first engine start, below 60 kts → Heated to approx 150°C, above 60 kts → Full heat, Airborne → Full heat regardless of engine status.

    • TAT Probes. On ground, below 100 kts → OFF (power up default setting), switch → white. Above 100 kts → ON / full heat, switch grays out. Airborne, ON / full heat, switch → Gray.

  • Manual: TAT Probes only via soft guarded TAT Probe Heat switch. Airborne: inhibited. On ground: when selected ON and Accept, Switch → Green, Full heat applied → 1 minute.

Windshield Heat


Photo: G500 Windshield heat, PAS, P. 9-8
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[PAS, P. 9-8]

  • Electric powered heating elements within each windshield, L and R Main AC, heat windshields slowly to avoid rapid temperature changes.

  • On ground. Windshield Heat switch on OHPTS → Anti-Ice page. Selected OFF, default on power up, switch is white. Selected ON, switch is green, allows electric power to windshield heating elements.

  • In Flight. Defaults to ON. switch grays out.

Cabin Window Heat


Photo: G500 Cabin window heat, PAS, P. 9-11
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[PAS, P. 9-11]

  • Electrically heated, automatically when ≥ 60 knots. OHPTS switch grays out upon auto activation.

  • Manual override on ground only via Cabin Window Heat switch on OHPTS → Anti-Ice page. Default at power up → OFF / white. When selected ON, switch → green and cabin window heat applied → 10 minutes Irreparable damage to cabin windows can occur if heat remains ON for extended period on ground due to lack of air flow across windows

EVS Window Heat


Photo: G500 EVS window heat, PAS, P. 9-10
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[PAS, P. 9-10]

  • Automatic. Airborne and Ice Detected, cyclic heat applied to EVS window. Gear Handle UP → 1 min ON / 7 minutes OFF, Gear Handle DOWN → 1 min ON / 1 min OFF.

  • Manual. Via EVS Window Heat switch on OHPTS → Anti-Ice page. Power up switch state → White / OFF. When selected, blooms cyan then switch returns to white, overrides auto logic in EVS controller, forces EVS Window Heat to turn ON → 5 minutes.

  • EVS Window Heat Graphic on OHPTS → Anti-Ice page, displays status of EVS Window heat application. Grayed out → OFF, Green → ON

Limitations and Abnormal Procedures


Wing Anti-Ice

[G500 AFM, §01-30-10, and PAS, p. 9-34]

  • If required for takeoff, WAI must be selected on at least 3 minutes prior to setting takeoff power and normal system operation must be verified prior to takeoff (wing temperature stabilized at 130°F +/- 10°F.)
  • I am told the reason for this is that if the wing is cold the system will open the valves wide open until the temperature reaches 130°F and adding takeoff thrust runs the risk of overpressurizing the wing's leading edge.

  • AI ON in-flight with TAT < -7°C

    • Results in increased engine idle, approximately 47% N1.

    • Throughout descent and arrival, anticipate the need for speed brakes and increased airspeed to achieve desired profile.

    • Normal engine idle restored with TAT > -5°C or Landing gear down.

  • WAI ON and Flaps Up: 200 KCAS min until ready to configure for landing.

  • WAI operations with single bleed air system operating: WAI Auto mode prohibited, maximum altitude 32,000’, maximum airspeed → 0.85M, WAI activation and wing temp > 100°F required prior to entry into icing conditions.

  • Use of flaps in icing conditions restricted to takeoff, approach and landing only. Prior to flap extension: WAI ON / confirmed operating in norm temp range. Note: The use of speed brakes is approved in icing conditions and will assist energy management during descents, especially during ambient conditions resulting in elevated engine idle. If flaps extended during takeoff, approach or landing > 10 minutes, do not retract flaps < 10° until flap leading edge verified clear of ice by 1 by visual inspection of flaps on ground or visual inspection of winglet leading edges in flight. If winglets are visually clear of ice, it can be expected that flap leading edge is also clear.

Cowl Anti-Ice

  • Required for taxi and takeoff if SAT ≤ 10°C (50°F) and any of following: visible moisture, precipitation, or a wet runway.

  • Operation prohibited when cowl anti-ice valve locked open or TAT > 15°C (59°F). Note: CAI will be auto inhibited on ground when TAT > 15°C with engine operating > 72% N1.

See Also:

Gulfstream GVII-G500 Airplane Flight Manual, Revision 4, August 29, 2019

Gulfstream GVII-G500 Production Aircraft Systems, Revision 3, July 15, 2019