Frost only on 737 spoiler panels

[stendec]

Wondering why the frost or ice is only on the spoiler panels.

[Speedwinner]

Anybody experience with light frost on ailerons and the engine pillon?talking about the 737

thanks guys

[Mad (Flt) Scientist]

Originally Posted by stendec

Wondering why the frost or ice is only on the spoiler panels.

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.

[VinRouge]

materials used perhaps?

[glhcarl]

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.

[Jetstream Rider]

Delamination is very common in spoliers on the 75/76 so I assume to 73 too. Most of our aircraft have regular inspections of allowable delamination in the spoilers.

[Olabade]

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.

[ACMS]

Are the spoilers made of composite matertial?

[WindSheer]

Me thinks its alot simpler than all that.

The warm fuel is keeping the 'tanked' part of the wing frost free.
As the fuel cools, so will the wing.

[cessna24]

Could be delam. Or the paint is flaking off.

[glhcarl]

So why is there no frost or ice on the flaps? Are they not made from the same composite material?

They are not made of the same material. Spoilers are have a honeycomb core with bonded skins. Flaps are built like other structural parts with spars, ribs and riveted skins.

[vascani]

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

[HAWK21M]

Looks like the composite Spoliers are delaminated & getting soaked.Time for a coin tap test.
regds
MEL

[captjns]

I've seen it on all Boeings from the 727 through the 767. It is a delam problem relating to moisture seepage and extreme tremperature changes.

[Checkboard]

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.