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OCR for page 81
81 Table 48. SAE Type I deicing fluid application procedures. Source: Table 6 of TC Holdover Time Guidelines Requirements: Deicing Only and First Step of Two-Step Deicing, use with the described dilutions. The enhancement in holdover and in TP14714E, Evaluation of Fluid Freeze Points in First-Step time is not significant as a result of using richer glycol mixes of Application of Type I Fluids. Type I fluid nor when using a 100/0 mix of Type II/III/IV fluid Type II/III/IV fluid holdover times are derived from versus a 75/25 mix. It can thereby be concluded that fluid dilu- endurance time tests of fluids that are in pre-set concentra- tions provide an opportunity to reduce glycol without a signif- tions: these are 100/0, 75/25, and 50/50. What is interesting icant loss of holdover time. with Type II/III/IV fluids is that in many cases the holdover times of the 75/25 fluids are equivalent to the holdover times Findings of the Focus Group Survey of the 100/0 fluids; in a few cases the holdover time of the 75/25 dilution is slightly higher. Many fluids are designed The detailed results of the focus group survey are pro- such that the viscosity is higher at the 75/25 dilution than the vided question by question in Appendix C. For multiple viscosity at the 100/0 dilution; this fluid design characteristic choice questions, the percentage of respondents selecting provides the enhancement in the holdover times of the 75/25 each response is listed. For most multiple choice questions, dilution. the responses are also additionally broken out by organiza- Type I and Type II/III/IV fluid holdover times have been tion type (i.e., airlines, DSPs, others). Each response pro- developed at the concentrations that are described above. vided for the short answer questions and comment areas is From a safety perspective, the holdover times are suitable for provided.
OCR for page 82
82 Table 49. SAE Type II, Type III, Type IV anti-icing fluid application procedures. Source: Table 7 of TC Holdover Time Guidelines Some key findings from the survey include: · The top five factors given for influencing use of fluid dilu- tions were: fluid storage requirements, prevailing OAT · De/anti-icing fluid use varies considerably from an approx- during the winter deicing season, cost of fluid, cost of imate average of 100 liters for frost removal on a small blending equipment, and replacement cost of modern turbo-prop transport to 1,500 liters for an operation in light deicing equipment. freezing rain on a super jet transport. · Of all anti-icing fluid types (Type II/III/IV) and dilutions · The majority of respondents (75%) feel that the current (100/0, 75/25, 50/50) available, Type IV fluid 100/0 is used guidance material is adequate for conducting operations almost exclusively; diluted Type II/III/IV fluids are not com- with diluted fluids. monly used.