717 winter ops question
 

How exactly would a 717 get contamination of flight surfaces (flaps in particular) during arrival/taxi or during frozen precipitation overnight that would cause the flaps unable to be set for takeoff setting following deicing/anti-ice operation.

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Next time you land on a contaminated runway, then taxi is “slush” to the gate at midnight, for the jet to sit til the 6am departure…. It’ll make sense. Spent 5 years on that puppy, only a handful of times had to actually leave flaps out, but it made sense when it occurred.

Behind the tires (and shoved up into the flaps) would be a snowcone of yuckiness, frozen, into the extended flaps.

I understand, But would you not expect after deice/anti ice operation and required inspection that the aircraft would be clean and then dispatched or deiced again if was still contaminated to the point flaps would not deploy?

I'm confused, where are you seeing this procedure that you can't set T/O flaps after being deiced? All I see is Vol 1 5.16.2.11 (Cold Weather After Landing Procedure) that says after prolonged operation in icing conditions with the flaps extended or when landing on a slushy/icy runway do not retract the flaps until the flaps have been checked to be free of contaminants. If you get to the gate and the flaps are contaminated just leave them down and whenever the next crew gets to the plane they will taxi out with the flaps down until getting deiced. A deicing spray down and contamination check satisfies the Vol 1 requirement and the flaps can then be set for takeoff.

If I understand what you’re asking, on top of the issue of slush while taxiing.. the issue would be the leading edges icing up and then once retracted remain frozen and stick/freeze to the interior of the wing that can’t be sprayed. Just a guess though, had similar issues on another plane I’ve flown.

In some heavier icing the unheated portions of the wing can get significant buildup. Especially areas near the wing root and tips where the slats retract against. I’ve seen 2+ inches build up in there on the -88 before. Also the underside of the flap tracks from the tires as others have mentioned.

So you land flaps 40, suck everything up to flaps zero (slats up too). Lots of moisture in there, plus crushing ice along the way of retraction, then only set flaps to 5/13/18 (if memory serves) for the next T/O. That’s a lot of extra potential crud iced up into the system. Land at 40 flaps, and all the gunk gets collected/frozen. Easier for the next crew to have all of that cleared out of the flaps/slats at full droop/mess and start fresh after. Not on the fleet anymore, but that’s the answer that likely hasn’t changed since the airframe design of the 60’s.

Heck that was the procedure on the CRJ as well.

Thanks, just never came across this situation