Reference to the CASA incidents here..
http://www.ntsb.gov/recs/letters/1990/A90_181_182.pdf
and the Fokker 50 at Luxembourg incident..
http://aviation-safety.net/database/...?id=20021106-0
http://www.iasa.com.au/folders/Safet...embourg-0.html
Seems to be some question over the reliability of inflight beta prevention on several types?