Each engine, with all icing protection systems operating, must:
Table 1-Conditions That Must Be Demonstrated by an Engine Test
Condition | Total air temperature | Supercooled water concentrations (minimum) | Median volume drop diameter | Duration |
1. Glaze ice conditions | 21 to 25 °F (-6 to -4 °C) | 2 g/m3 | 25 to 35 microns | (a) 10-minutes for power below sustainable level flight (idle descent). |
(b) Must show repetitive, stabilized operation for higher powers (50%, 75%, 100%MC). | ||||
2. Rime ice conditions | -10 to 0 °F (-23 to -18 °C) | 1 g/m3 | 15 to 25 microns | (a) 10-minutes for power below sustainable level flight (idle descent). |
(b) Must show repetitive, stabilized operation for higher powers (50%, 75%, 100%MC). | ||||
3. Glaze ice holding conditions (Turbojet, turbofan, and turboprop only) | Turbojet and Turbofan, only: 10 to 18 °F (-12 to -8 °C) | Alternating cycle: First 1.7 g/m3 (1 minute), Then 0.3 g/m3 (6 minute) | 20 to 30 microns | Must show repetitive, stabilized operation (or 45 minutes max). |
Turboprop, only: 2 to 10 °F (-17 to -12 °C) | ||||
4. Rime ice holding conditions (Turbojet, turbofan, and turboprop only) | Turbojet and Turbofan, only: -10 to 0 °F (-23 to -18 °C) | 0.25 g/m3 | 20 to 30 microns | Must show repetitive, stabilized operation (or 45 minutes max). |
Turboprop, only: 2 to 10 °F (-17 to -12 °C) |
Table 2-Demonstration Methods for Specific Icing Conditions
Condition | Total air temperature | Supercooled water concentrations (minimum) | Mean effective particle diameter | Demonstration |
1. Rime ice condition | 0 to 15 °F (-18 to -9 °C) | Liquid-0.3 g/m3 | 15-25 microns | By engine test. |
2. Glaze ice condition | 20 to 30 °F (-7 to -1 °C) | Liquid-0.3 g/m3 | 15-25 microns | By engine test. |
3. Snow ice condition | 26 to 32 °F (-3 to 0 °C) | Ice-0.9 g/m3 | 100 microns (minimum) | By test, analysis or combination of the two. |
4. Large drop glaze ice condition (Turbojet, turbofan, and turboprop only) | 15 to 30 °F (-9 to -1 °C) | Liquid-0.3 g/m3 | 100 microns (minimum) | By test, analysis or combination of the two. |
14 C.F.R. §33.68