Chapter 5 - Ground Crew Supplement

Fluid Application Procedures

56.  SAE document ARP 4737 and the fluid manufacturers recommendations should be consulted in establishing sound operations de/anti-icing procedures.

57.  The deicing/anti-icing operation should be performed as close in time to the takeoff procedure as possible. This generally means that the location chosen on an airport for deicing is as near to the end of the operational runway as is possible.

58.  De/anti-icing near the beginning of departure runways reduces the interval between the anti-icing process and take off. It is this interval that determines whether takeoff can be achieved prior to fluid failure. Once the fluid has failed, the aircraft must be de/anti-iced again. Under no circumstances shall a second application of anti-icing fluid be applied over a contaminated anti-icing fluid layer.

59.  Research has indicated that if the fluid is not applied correctly, the HOT Guideline values are not achievable.

Caution:

Types II, III & IV fluids, in particular, must be applied using specialized equipment. If these fluids are not applied in the correct manner and with the correct equipment, as recommended by the fluid manufacturer, they will NOT function as designed and will therefore NOT provide the expected protection as indicated in the HOT tables.

Fluid application procedures from SAE ARP 4737 Caution and Fluid Application Reminder, are outlined in the Table entitled: "Type I Deicing Fluid Application Procedures for Type I fluids", and in the Table entitled:  "SAE Type II/IV Anti-Icing Fluid Application procedures" for Types II, III and IV fluids, available at the Transport Canada HOT website.

60.  Depending on the prevalent weather conditions, available equipment, technology, fluids and the desired holdover time, a one step or a two step de/anti-icing procedure may be appropriate. The aircraft must be treated symmetrically for aerodynamic reasons, as recommended in ARP 4737.

61.  Individual aircraft manufacturers provide guidance on specific anti-icing or deicing procedures for their particular aircraft models. An Air Operator must obtain and follow the aircraft manufacturers' guidance.

62.  It is also necessary for the Air Operator to understand aircraft deicing and anti-icing standard practices, such as those published in SAE document ARP 4737. The Regulations, Standards and Guidance published by Transport Canada must also be followed.

63.  The effectiveness of anti-icing fluid in protecting the aircraft's critical surfaces from the adherence of frozen contaminants is dependant upon the correct execution of the deicing process. The proper procedures and equipment must be employed to ensure that when both deicing and anti-icing with fluids have been accomplished the aircraft is safe for take off. This assurance requires that a thoroughly qualified and trained deicing crew accomplish the tasks.

64.  Cold soaked wings can be considerably below the ambient temperature therefore frost can build up in localized wing areas. When active frost is anticipated, SAE Type II or IV may be applied to the surfaces to prevent frost accumulation. Both wings should receive a symmetrical treatment for aerodynamic reasons.

Note:  The following guidance is general in nature and is not intended to be fluid manufacturer specific.