Re: How much "rust" is tolerated and landing light question?

Date:         13 Oct 98 02:48:28 
From:         Trevor Fenn <trevfenn@erols.SPAMOUTcom>
References:   1
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John S. Maddaus wrote:
> OK number one, flying UAL from Denver to San Antonio in an older 737S.
> First I noticed that the top (couldn't see the bottom) of both
> ailerons were nice shiny metal.  Thought that was an odd area to be
> replaced.  Then as flaps were extended for take-off I noticed rust
> stains running back approximately in the middle of the flap.  As we
> flew along, I reminded myself that most of the ac is not made from
> steel.  On landing, the source became clear.  Looked to be coming from
> perhaps a steel cover plate (screwed or riveted in place) on the flap
> and rust stains were evident all around it.  Also on deploying the air
> brakes, the undersides of those showed rust stains as well
> particularly at hinge points and hydraulic actuator connection points.

I suspect that what you saw particularly at hinge points and hydraulic
actuator attachment points was not rust but grease. The grease used in
lubricating the moving parts of the wing/flaps/slats is a bright orangy
rusty color and often after being freshly applied can be blown all over
the place. remember that the airflow past slats and over flaps can be
quite turbulent and fast.

Trevor Fenn