Roll tendency with a failed slat

[JammedStab]

I always figured that if a slat did not extend on one wing, the aircraft would want to roll toward the failed slat, but I was assured that the aircraft will roll toward the wing with all slats extended.

Anyone care to confirm.

[Feather #3]

Having had a couple on the B742 and B74SP, just as you'd think, it rolls towards the failed slat. Disregard the moron who told you otherwise???

G'day

[Mad (Flt) Scientist]

Agree with very little effect at normal (low) angles of attack.

At high AoA it would get quite exciting though!

[Old Smokey]

At high speed and low angles of attack, the aircraft will roll rapidly towards the wing with the most slats extended.

About minimum clean speed, assymetric slats will have negligible roll effect.

At approach angles of attack, the aircraft will have a small tendancy to roll towards the wing with the least slats extended.

At high angles of attack, stand by for the roller coaster ride as the wing with the least slats stalls first, associated with rapid roll towards the "least slats" wing.

NOTE 1 - Most slats and least slats terms used here to differentiate between "fail" extended and "fail" not extended.

NOTE 2 - DC9 operators will be familiar with the pronounced back elevator required to compensate for lift loss when slats are extended at high speed.

Regards,

Old Smokey

[JammedStab]

I seem to have conflicting responses. Anyone have a quote from a flight manual.

Thanks.

[Mohit_C]

This reminds me of an exam question.

"Concerning flap and slat asymmetry, which statement is correct?"

ANSWER: "Flap asymmetry will cause a large rolling moment at all speeds; slat asymmetry will cause a large difference in Cl max"

[JammedStab]

Originally Posted by Cosmos2

TWA 841 was an extreme case because speed was over Mach 0.80 and pilots handled it badly, leading to loss of control.

The TWA thing is a separate issue. My original question referred to a failure of a slat to extend when the rest do. More specifically I am referring to low speed situations such as during normal selections.

[Feather #3]

Indeed, so was I.

G'day

[777fly]

From actual experience:

DC10-30
Decelerating on base leg, approx 210 kts & 5 degrees NU, Flap 0/EXT selected (extends slats). Left outboard slats did not extend. Full right aileron input plus about 2/3 of full right rudder required to keep approx straight & level. After cycle back to UP/Retract and back again, normal conditions returned. Scary moment....