BAe146 Icing Limitation
 

Quick question for the 146 drivers out there. We all know the 26000ft limit for flight in known or forecast icing conditions but is that FL260 or 26000ft? Reason being we regularly fly at FL260 in icing conditions but not above.However on days with large differences between QNH and standard setting actual aircraft altitude could be a lot closer to 27000ft and hey presto we've exceeded airframe limitations.....time for rollback!!! Maybe I've made it about as clear as mud but I think you catch my drift! Any feedback appreciated especially from anyone at Avro?

[This message has been edited by Deep Stall (edited 15 February 2001).]

I think you may interested in reading the following report....it documents how all 4 engines on a 146 rollbacked in flight and bacame a very expensive glider with passengers onboard.

"The investigation determined that during high altitude cruise, the aircraft entered an area of moist air significantly warmer than the surrounding air. This resulted in a need to select engine and airframe anti-ice which in turn placed high bleed air demand on the engines. Under these conditions the fuel control units were unable to schedule sufficient fuel to the engines, thereby causing them to lose power, a phenomenon known as ‘roll-back’."

Summary : http://www.basi.gov.au/acci/jjp.htm
Report : http://www.basi.gov.au/pdf/vh-jjp.pdf

I think that F260 would meet the requirement.
As the problem is associated with the density of the air, then to stretch the point you would really have to work out the density altitude each time.

Our company imposed a furthur limitation of F250 though.

Deep Stall

Placard says 26000 FT in our cockpits and NOT FL 260.


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It's not easy having fun; even smiling makes my face hurt.

The BAe imposed limitation states clearly 26000 feet.....and that is what all placards in the ccockpits all over the world have to say, unless the mod is fitted....

I believe the problem is above 28000 and 26000 is a buffer zone figure.

And to show much the RJ series has been improved, we have no icing level restrictions on those :)

Anything to thank the -507 engines for?

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... cut my wings and I'll die ...