AMC 25.773(b)(1)(ii) Pilot compartment view in icing
conditions
ED Decision 2016/010/R
CS 25.773(b)(1)(ii)
requires that the aeroplane have a means of maintaining a clear portion of
windshield in the icing conditions defined in Appendix C and in certain Appendix O icing conditions
(corresponding to the CS 25.1420
certification option selected).
The effectiveness of all cockpit windows and windshield ice and
precipitation protective systems should be established within relevant icing
environment. Sufficient tests, including flight test in natural or simulated
Appendix C icing conditions, should be performed to validate the performance
prediction done by analysis.
When thermal ice protection systems are used (e.g. electrical heating
system), a thermal analysis should be conducted to substantiate the selected
nominal heated capacity. Past certification experience has shown that a
nominal heating capacity of 70 W/dm2 provide adequate protection in
icing conditions; such value, if selected, should anyway be substantiated by
the thermal analysis. The applicant should conduct dry air flight tests to
verify the thermal analysis. Measurements of both the inner and outer surface
temperature of the protected windshield area may be needed to verify the
thermal analysis. The thermal analysis should show that the windshield surface
temperature is sufficient to maintain anti-icing capability without causing
structural damage to the windshield.
When anti-icing fluid systems are used, tests shall be performed to
demonstrate that the fluid does not become opaque at low temperatures. The AFM
should include information advising the flight crew how long it will take to
deplete the amount of fluid remaining in the reservoir.
An evaluation of visibility, including distortion effects through the protected area, should be made for both day and night operations. In addition, the size and location of the protected area should be reviewed to confirm that it provides adequate visibility for the flight crew, especially during the approach and landing phases of flight.
For showing compliance with the CS-25 certification
specifications relative to SLD icing conditions represented by Appendix O, the
applicant may use a comparative analysis. AMC 25.1420(f) provides guidance for
comparative analysis.
[Amdt 25/16]
[Amdt 25/18]
Pilot Compartment Visibility in Icing Conditions Aircraft windshields must maintain clear visibility during icing, validated through tests in simulated or natural icing environments. Thermal systems require analysis to ensure adequate heating without structural damage. Anti-icing fluid systems must remain transparent at low temperatures. Visibility, including distortion, needs evaluation for day/night operations, ensuring sufficient view for pilots, especially during landing.
* Summary by Aviation.Bot - Always consult the original document for the most accurate information.
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