Frost only on 737 spoiler panels
Join Date: Sep 2002
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It may be that the thermal mass of the spoiler panels is less than that of the other wing components - the flaps are physically larger, and the wing skin is both better attached to the spars and may also be touched by wing fuel.
If so, then the spoilers will cold soak faster than the rest of the airframe, and perhaps reach a frost-forming temp first.
Another possibility is that the energy in the boundary layer has dropped as the flow moves aft, such that there is less kinetic heating of the surface on the after portions of the wing, and this just happens to be where the spoilers are.
Both effects might be present, too.
If so, then the spoilers will cold soak faster than the rest of the airframe, and perhaps reach a frost-forming temp first.
Another possibility is that the energy in the boundary layer has dropped as the flow moves aft, such that there is less kinetic heating of the surface on the after portions of the wing, and this just happens to be where the spoilers are.
Both effects might be present, too.
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I would suggeted that the panels have delaminated and that cold air has gotten into the core of the spoiler causing condensation to form on the outer surface of the spoiler. At altitude the condensation freezes (forms frost).
If you notice the ice does not cover the entire spoiler, only the delaminated areas.
If you notice the ice does not cover the entire spoiler, only the delaminated areas.
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Happens often on the A32S too. Propable cause is, as mentioned already before, structural: spoilers are thin and freeze faster than the rest of the wing leading to frost and ice accumulation.
Olabade.
Olabade.
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So why is there no frost or ice on the flaps? Are they not made from the same composite material?
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Spoiler Rams & fittings
underneath the panel are the fittings and rams that are made of heavy duty castings. This causes the surrounding area to become significantly colder (freezing) than the other areas.
rgds
rgds
Scenario #2: The aircraft took off with the wings frost covered (i.e. wasn't de-iced), and the frost has sublimed ahead of the separation point, leaving the frost on the rear of the wing.
