How often do aircraft get an external clean?

[AerocatS2A]

Originally Posted by cee cee

Actually they can be deployed while the aircraft is still flying. I have seen them deployed for short periods when descending on approach to the airport. Wikipedia says

Airliners are almost always fitted with spoilers. Spoilers are used to increase descent rate without increasing speed.

It is true that they are only deployed fully and for a sustained period after touchdown.

The details of exactly how much spoiler is available in flight as opposed to on the ground varies with aircraft type.

The point the others are making is that if you don't know why an aeroplane has done something, in this case a go-around, please don't try to pretend you do. What's that famous quote? "Better to remain silent and be thought a fool than to speak and to remove all doubt."

To the OP: I fly freighters and they get cleaned very rarely, maybe once every C check.

Edit: Even when they do get cleaned, the flap tracks etc don't get cleaned as when they are cleaned the flaps and airbrakes are all closed up.