How much ice is too much?
 

A question for the pilots out there.

I was in a Q400 today right next to the LH wing (at about 19000 ft if I heard the F/O properly) when I noticed ice both around the intake(?) just behind the props but more curiously in the centre of the prop (excuse complete lack of technical knowledge) and "growing" (along the cone section rearwards) as we travelled, until the cone section in question went almost entirely white.

This isn't something I've noticed on the Q400 or other dashes before, although most of the flight (Gladstone to BNE in Oz) was in cloud, so icing would be expected I guess. I was just curious how the rotating centre of the propeller array, at such high revs, could still ice up and was also interested as too how much icing could occur before it became a concern.

:confused:

Don't know how much could build up on a spinner, but it is not rotating at "high revs" as you might think, simply because propellors become inefficient at higher revs, so are geared down to around 2000 revs. I suspect it would be impossible for enough to build up on a spinner to become a problem as it would shake off as soon as it got to any thickness ... but I've no doubt somebody will correct me.

UFO

as long as the wings stay clear you'll be ok

Thanks UFO and MatBlack:ok:.

Didn't notice any ice on the wings ... and the landing gear deployed and didn't collapse, so all in all a good flight:p

i think the dash prop is only doing about 1400rpm in the cruise. the centrifigal force close to the hub at that speed is not great, but it will fling excess ice off. as long as the ice forms evenly (as it would) balance would not be a huge issue. the hub is not anti/de iced, but the blades are, for this reason. from memory the inlet is electrically anti-iced, but ice may form behind the inlet boot.

I've seen 2 inches of ice on the leading edge of a C172, but then again any less than 1 inch doesn't allow certain de-icers to work properly.