View Full Version : Wing anti ice B744
A bit of a geeky question this so here goes: on the B744 I thought that there was note that when the Wing Anti Icing (WAI) failed open there was a increment to be applied to Vref, 10 knots I believe.
However, I cannot find it referenced anywhere not least on the QRH. Maybe I am just going a bit(!) senile or does it ring any bells with anyone else. Anything similar on any other Boeings?
regards
BBK
zerozero
4th May 2012, 09:27
I'm away from all my reference material but I'd be hard pressed to believe the 744 could be dispatched with the WAI valves OPEN.
I've been 744 qualified for just 2.5 years, but have never come across this scenario.
Doesn't ring any bells with me either. It's while back since I operated the 744 but as I recall it there could be serious (?) structural issues with the wing LE if the LE flaps were retracted on the ground and the WAI was running, so AFAIK it was no despatch if stuck open, and bleeds off on the effected side ASAP after landing if a valve stuck open in the air.
Don't remember anything about Vref additives.
MarkerInbound
4th May 2012, 13:40
Looking at the QRH for WAI VALVE LEFT, RIGHT, if the valve is stuck open everything remains normal until the after landing. No speed additive. As wiggy says, bleeds off on the affected side and close the isolation valve on that side after landing.
gas path
4th May 2012, 13:43
Certainly not allowable 'Dispatched Open'. And if it is jammed/failed open it will put a nice kink in the leading edge 'bullnose' just immediately outboard of the outbd pylon. So as wiggy says 'bleeds off' on the affected side please ASAP!
IIRC the MEL doesn't give any crew ops. requirements except no dispatch into known icing conditions with the valve locked closed.
Old Fella
5th May 2012, 02:01
Certainly on the Classic there was no action required during flight, however after landing the affected wing isolation valve would be closed and the engine bleed valves for the engines on the affected wing would be closed also. Only other consideration was to ensure that an operational hydraulic system was available to supply brake system pressure.
When I asked the question I meant in flight, not dispatch, but thanks for all the answers anyway.
Looks like my memory was playing tricks after all.
regards
BBK