De-Icing/Anti-Icing Inspection
De-Icing/Anti-Icing Inspection
Surface contamination means any deposit on the aeroplane surfaces which could degrade aeroplane performance and control, if not removed. Such contaminants may be in any solid form of water adhering to the aeroplane surfaces. Snow, ice, frost, frozen water droplets and ice pellets fall into this category.
“Clean Aircraft” concept may be determined through pre-flight inspections using visual, tactile (by touch or feel) or sensor-based procedures.
Critical surfaces (wings, horizontal stabilisers, control surfaces, high lift devices, spoilers/speed brakes, air data probes, static vents, fuselage, landing gear and wheel bays) are to be checked for possible frost, ice, slush, or snow accumulation. Clear ice, which is very difficult to detect, may have formed on the upper side of the wing due to:
Ice can build up on aeroplane surfaces when descending through dense clouds or precipitation during an approach. When ground temperatures at the destination are low, it is possible for flaps to be retracted and for accumulations of ice to remain undetected between stationary and moveable surfaces. It is, therefore, important that these areas are checked prior to departure and any frozen deposits are removed.
Important: Heavy freezing has been reported during drizzle/rain even at temperatures up to +15ºC due to cold fuel.
It shall not be assumed that light snow will blow off the wings during acceleration. It can be anticipated, that partly frozen ice or snow patches on the wing will have a severe effect on aerodynamic efficiency. It shall always be expected that below a snow/slush layer there can be clear ice.
As clear ice is very difficult to detect visually, a tactile examination may have to be made of the surface area to be inspected.
During snow fall, freezing rain and drifting snow, the possibility exists that snow and melting ice could penetrate into slots, balance bays, drainage openings, hinges and operating linkage and then refreeze. Therefore the above-mentioned areas have to be checked with special attention especially when the aeroplane has been parked outside for a long period under freezing conditions. The same is applicable for landing gear areas, including landing gear-latching mechanism, operating mechanism and electrical switching elements, inlet scoops, pitot probes, air inlets and outlet, openings of the APU and the airconditioning as well as their adjacent areas.
Low wing temperatures associated with Clear Ice build-up normally occur when large quantities of cold fuel remain in wing tanks during the turnaround/transit and any subsequent re-fuelling does not cause a sufficient increase in wing temperature.
The Commander shall conduct an inspection to determine the need for de-icing. He will, based on his judgment, initiate de-icing/anti-icing and will be responsible for the correct and complete de-icing/anti-icing of the aeroplane.
A pre-flight external inspection of critical surfaces may also be conducted by a qualified person, to determine if the surfaces are contaminated by frost, ice, slush or snow. Under conditions of ground icing, this inspection is mandatory. The critical surface inspection phase is of prime importance in the overall de-icing/anti-icing process and is directly related to the safety of the aeroplane during take-off.
An aeroplane shall not be dispatched after a de-icing/anti-icing operation until the aeroplane has received the visual check by a trained and qualified person responsible for post de-icing/anti-icing check.
This check shall cover wings, horizontal stabiliser, vertical stabiliser and fuselage, plus all other parts of the aeroplane on which a de-icing/anti-icing treatment was performed according to the requirements identified during the contamination check. The check shall be performed from points offering sufficient visibility of all prescribed surfaces (e.g. from de-icer itself or other equipment suitable for gaining access). Any contamination found, shall be removed by further de-icing/anti-icing treatment and the check must be repeated. After the visual check for any contamination (and/or clear ice check/tactile check) of all critical surfaces, post de-icing/anti-icing check provides the Commander with all the necessary information to make an appropriate request for further possible de-icing/anti-icing treatment of the aeroplane.
The company carrying out de-icing/anti-icing treatment, which is responsible for the treatment of an aeroplane, shall pass all information about the treatment to Commander.
The Commander shall be notified of the type of the de-/anti-icing treatment performed – anti-icing code which shall enable him to estimate hold over time (HOT). Anti-icing code providing by post de-icing/anti-icing check shall be recorded (voice recorder) and communicated to the Commander referring to the start of the last step of the treatment.
The anti-icing code contains:
Once the post anti-icing inspection has been completed and is satisfactory, the aeroplane should be released for take-off as soon as possible.
The Commander shall continually monitor the environmental situation after the performed de-icing/anti-icing treatment. Prior to take-off, he, or a designated flight crew member, shall assess whether the applied hold over time is still appropriate.
Note: Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce hold over time below the lowest time stated in the range. Hold over time may also be reduced when aeroplane skin temperature is lower than OAT.
When the minimum hold over time in the HOT block has been exceeded and/or the Commander cannot effectively assess the condition of the critical surfaces of the aeroplane from inside the aeroplane just prior departure, the aeroplane has to be checked to be free of frozen contaminants. This check is performed from the outside of the aeroplane by qualified ground personnel. If this check cannot be done, take-off shall not be attempted. Whenever the Commander is in doubt about the aerodynamic cleanliness of the aeroplane, a visual inspection has to be performed (from inside or outside of the aircraft) or return to the ramp made.
Representative surfaces are intended to be used, as a tool in gauging the contaminated state of critical surfaces on an aeroplane after having used de-icing and anti-icing fluids to clean the aeroplane and then protect the aeroplane from the freezing precipitation occurring during ground icing conditions.
An aeroplane’s representative surface is a portion of the aeroplane that can be readily and clearly observed by the flight crew from inside the aeroplane and is used to judge whether or not the surface has become contaminated. By determining the state of the representative surface, it can then be reasonably expected that other critical surfaces will be in the same (or better) condition. For the flight crew, the ice indicator in front of the cockpit window is a good representation and indication of a condition of the ice build-up.
Under certain conditions, a clear ice layer or frost can form on the wing upper surfaces when the aeroplane is on the ground. In most cases, this is accompanied by frost on the underwing surface. Severe conditions occur with precipitation when sub-zero fuel is in contact with the wing upper surface skin panels. The clear ice accumulations are very difficult to detect from ahead of the wing or behind during walk-around, especially in poor lighting and when the wing is wet. The leading edge may not feel particularly cold. The clear ice may not be detected from the cabin either because wing surface details show through.
The following factors contribute to the formation intensity and the final thickness of the clear ice layer:
The areas most vulnerable to freezing are:
In some cases, ice may form on the aeroplane’s skin even if the OAT is above freezing, particularly in a case of the short turnaround:
Under freezing fog conditions it is necessary for the rear side of the fan blades to be checked for ice build-up prior to start-up. Any deposits discovered should be removed by directing air from a low flow hot air source, such as a cabin heater, onto the affected areas.
When slush is present on runways, inspect the aeroplane when it arrives at the ramp for slush/ice accumulations. If the aeroplane arrives at the gate with flaps in a position other than fully retracted, those flaps, which are extended, shall be inspected and, if necessary, de-iced before retraction.
It is important to note that the rate of ice formation is considerably increased by the presence of an initial depth of ice. Therefore, if icing conditions are expected to occur along the taxi and takeoff path, it is necessary to ensure that all ice and frost is removed before flight. This consideration shall extend the awareness of flight crew to include the condition of the taxiway, runway and adjacent areas since surface contamination and blown snow are potential causes for ice accretion equal to natural precipitation.
An aeroplane shall not be operated in expected or actual icing conditions at night unless it is equipped with a means to illuminate or detect the formation of ice. Any illumination that is used shall be of a type that will not cause glare or reflection that would handicap crew members in the performance of their duties.
Surface contamination means any deposit on the aeroplane surfaces which could degrade aeroplane performance and control, if not removed. Such contaminants may be in any solid form of water adhering to the aeroplane surfaces. Snow, ice, frost, frozen water droplets and ice pellets fall into this category.
“Clean Aircraft” concept may be determined through pre-flight inspections using visual, tactile (by touch or feel) or sensor-based procedures.
Critical surfaces (wings, horizontal stabilisers, control surfaces, high lift devices, spoilers/speed brakes, air data probes, static vents, fuselage, landing gear and wheel bays) are to be checked for possible frost, ice, slush, or snow accumulation. Clear ice, which is very difficult to detect, may have formed on the upper side of the wing due to:
- Freezing rain,
- Cold fuel causing cold wing surface,
- Precipitation (e.g. rain) freezes above tank area,
- Snow melting on a warm wing, but refreezing as the wing cools down,
- Melted snow running to a colder part of the wing.
Ice can build up on aeroplane surfaces when descending through dense clouds or precipitation during an approach. When ground temperatures at the destination are low, it is possible for flaps to be retracted and for accumulations of ice to remain undetected between stationary and moveable surfaces. It is, therefore, important that these areas are checked prior to departure and any frozen deposits are removed.
Important: Heavy freezing has been reported during drizzle/rain even at temperatures up to +15ºC due to cold fuel.
It shall not be assumed that light snow will blow off the wings during acceleration. It can be anticipated, that partly frozen ice or snow patches on the wing will have a severe effect on aerodynamic efficiency. It shall always be expected that below a snow/slush layer there can be clear ice.
As clear ice is very difficult to detect visually, a tactile examination may have to be made of the surface area to be inspected.
During snow fall, freezing rain and drifting snow, the possibility exists that snow and melting ice could penetrate into slots, balance bays, drainage openings, hinges and operating linkage and then refreeze. Therefore the above-mentioned areas have to be checked with special attention especially when the aeroplane has been parked outside for a long period under freezing conditions. The same is applicable for landing gear areas, including landing gear-latching mechanism, operating mechanism and electrical switching elements, inlet scoops, pitot probes, air inlets and outlet, openings of the APU and the airconditioning as well as their adjacent areas.
Low wing temperatures associated with Clear Ice build-up normally occur when large quantities of cold fuel remain in wing tanks during the turnaround/transit and any subsequent re-fuelling does not cause a sufficient increase in wing temperature.
The Commander shall conduct an inspection to determine the need for de-icing. He will, based on his judgment, initiate de-icing/anti-icing and will be responsible for the correct and complete de-icing/anti-icing of the aeroplane.
A pre-flight external inspection of critical surfaces may also be conducted by a qualified person, to determine if the surfaces are contaminated by frost, ice, slush or snow. Under conditions of ground icing, this inspection is mandatory. The critical surface inspection phase is of prime importance in the overall de-icing/anti-icing process and is directly related to the safety of the aeroplane during take-off.
An aeroplane shall not be dispatched after a de-icing/anti-icing operation until the aeroplane has received the visual check by a trained and qualified person responsible for post de-icing/anti-icing check.
This check shall cover wings, horizontal stabiliser, vertical stabiliser and fuselage, plus all other parts of the aeroplane on which a de-icing/anti-icing treatment was performed according to the requirements identified during the contamination check. The check shall be performed from points offering sufficient visibility of all prescribed surfaces (e.g. from de-icer itself or other equipment suitable for gaining access). Any contamination found, shall be removed by further de-icing/anti-icing treatment and the check must be repeated. After the visual check for any contamination (and/or clear ice check/tactile check) of all critical surfaces, post de-icing/anti-icing check provides the Commander with all the necessary information to make an appropriate request for further possible de-icing/anti-icing treatment of the aeroplane.
The company carrying out de-icing/anti-icing treatment, which is responsible for the treatment of an aeroplane, shall pass all information about the treatment to Commander.
The Commander shall be notified of the type of the de-/anti-icing treatment performed – anti-icing code which shall enable him to estimate hold over time (HOT). Anti-icing code providing by post de-icing/anti-icing check shall be recorded (voice recorder) and communicated to the Commander referring to the start of the last step of the treatment.
The anti-icing code contains:
- Type and concentration of the ADF (with commercial name);
- Local time and the date of the start of one-step of de-/anti-icing treatment; or
- Local time and the date at the start of the second step of two-step de-/anti-icing treatment.
Once the post anti-icing inspection has been completed and is satisfactory, the aeroplane should be released for take-off as soon as possible.
The Commander shall continually monitor the environmental situation after the performed de-icing/anti-icing treatment. Prior to take-off, he, or a designated flight crew member, shall assess whether the applied hold over time is still appropriate.
Note: Heavy precipitation rates or high moisture content, high wind velocity or jet blast may reduce hold over time below the lowest time stated in the range. Hold over time may also be reduced when aeroplane skin temperature is lower than OAT.
When the minimum hold over time in the HOT block has been exceeded and/or the Commander cannot effectively assess the condition of the critical surfaces of the aeroplane from inside the aeroplane just prior departure, the aeroplane has to be checked to be free of frozen contaminants. This check is performed from the outside of the aeroplane by qualified ground personnel. If this check cannot be done, take-off shall not be attempted. Whenever the Commander is in doubt about the aerodynamic cleanliness of the aeroplane, a visual inspection has to be performed (from inside or outside of the aircraft) or return to the ramp made.
Representative surfaces are intended to be used, as a tool in gauging the contaminated state of critical surfaces on an aeroplane after having used de-icing and anti-icing fluids to clean the aeroplane and then protect the aeroplane from the freezing precipitation occurring during ground icing conditions.
An aeroplane’s representative surface is a portion of the aeroplane that can be readily and clearly observed by the flight crew from inside the aeroplane and is used to judge whether or not the surface has become contaminated. By determining the state of the representative surface, it can then be reasonably expected that other critical surfaces will be in the same (or better) condition. For the flight crew, the ice indicator in front of the cockpit window is a good representation and indication of a condition of the ice build-up.
Under certain conditions, a clear ice layer or frost can form on the wing upper surfaces when the aeroplane is on the ground. In most cases, this is accompanied by frost on the underwing surface. Severe conditions occur with precipitation when sub-zero fuel is in contact with the wing upper surface skin panels. The clear ice accumulations are very difficult to detect from ahead of the wing or behind during walk-around, especially in poor lighting and when the wing is wet. The leading edge may not feel particularly cold. The clear ice may not be detected from the cabin either because wing surface details show through.
The following factors contribute to the formation intensity and the final thickness of the clear ice layer:
- The low temperature of fuel that was added to the aeroplane during the previous ground stop and/or the long airborne time of the previous flight resulting in a situation that the remaining fuel in the wing tanks is below 0°C.
- The abnormally large amount of remaining cold fuel in wing tanks causing the fuel level to be in contact with the wing upper surface panels as well as the lower surface, especially in the wing tank area.
- The temperature of fuel added to the aeroplane during the current ground stop, adding (relatively) warm fuel can melt dry, falling snow with the possibility of re-freezing.
The areas most vulnerable to freezing are:
- The wing root area between the front and rear spars,
- Any part of the wing that will contain unused fuel after flight,
- The areas where different structures of the wing are concentrated (a lot of cold metal).
In some cases, ice may form on the aeroplane’s skin even if the OAT is above freezing, particularly in a case of the short turnaround:
- Ice can build up on aeroplane surfaces when descending through dense clouds or precipitation during an approach.
- If fuel has become cold soaked during a long flight and is in contact with the skin, frost may form after landing.
- Similar to the fuel tank, heavy pieces of structure can become cold soaked and promote frost formation after landing.
Under freezing fog conditions it is necessary for the rear side of the fan blades to be checked for ice build-up prior to start-up. Any deposits discovered should be removed by directing air from a low flow hot air source, such as a cabin heater, onto the affected areas.
When slush is present on runways, inspect the aeroplane when it arrives at the ramp for slush/ice accumulations. If the aeroplane arrives at the gate with flaps in a position other than fully retracted, those flaps, which are extended, shall be inspected and, if necessary, de-iced before retraction.
It is important to note that the rate of ice formation is considerably increased by the presence of an initial depth of ice. Therefore, if icing conditions are expected to occur along the taxi and takeoff path, it is necessary to ensure that all ice and frost is removed before flight. This consideration shall extend the awareness of flight crew to include the condition of the taxiway, runway and adjacent areas since surface contamination and blown snow are potential causes for ice accretion equal to natural precipitation.
An aeroplane shall not be operated in expected or actual icing conditions at night unless it is equipped with a means to illuminate or detect the formation of ice. Any illumination that is used shall be of a type that will not cause glare or reflection that would handicap crew members in the performance of their duties.
De-Icing/Anti-Icing Inspection
Reviewed by Aviation Lesson
on
8:54 AM
Rating:
Reviewed by Aviation Lesson
on
8:54 AM
Rating:
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