As reluctant as I am to get involved in a mxmanic thread, the information
you provide is outdated. Goodyear says that it was originally based on the
DC-3, which had large tubes and low air pressure. It is now officially an
Old Wives Tale. The approved procedure today is to turn on the boots at the
first sign of ice.

Bob Gardner

"T o d d P a t t i s t" wrote in message
...
Ron Garret wrote:

I read that turning on icing protection before "sufficient ice has
accumulated" may prevent the protection from working to remove the
ice. Why?

That applies only to boots. If the ice layer is too thin it may remain
adhered to the boot.

To expand upon this (a bit of a play on words here) The
boots work by expanding outward and breaking the ice. If
the thin ice adheres to the boot, it can get pushed outward,
but not cracked and blown off as pieces. The pushed outward
ice can freeze with the boot inflated forming a cavity
between the subsequently deflated boot and the ice. The ice
then builds up on the outside of this ice cavity and the
boot can't break it off because it doesn't push against the
inside of the ice cavity. The boot just inflates and
deflates between the ice and the wing without doing
anything.

--
Rule books are paper - they will not cushion a sudden meeting of stone and
metal.

- Ernest K. Gann, 'Fate is the Hunter.'