
(Source: YouTube, composite of two frames)
I came across this interesting, probably unique, solution:
With the heavier engines on the MD-90 compared to the MD-80, MDC added flaps on the engine pylons that activate (deflect 30°) to assist in recovering from deep stalls.
The first warning of stall onset comes from the stick-shaker, followed by a red light and aural/vocal warning, and the stall is finally corrected by a stick-pusher. The nacelle strakes and large engine pylon assist natural pitch- down at the stall. The pylon trailing edge also deflects 30° down when the control column is pushed fully forwards: this deflection takes about 2s (Flight, 1994).