The 1600' remark can actually be attributed to (OT-IIG)
http://pogoarchives.org/m/dp/dp-V22-dote-092005.pdf
Page 35 under dual engine failure
To convert the nacelles from 60 to 0 degrees requires about 8 seconds and the aircraft must be above ground level by 1600' in order to complete the conversion prior to impact
I'm not sure how the 8 second/1600' statistic relationship is derived (a standard decent rate?), and I am even less sure how this conversion time yields a "not likely to be survivable" conclusion.
Emergency landing after the sudden failure of both engines in the Conversion/Vertical Take-Off and Landing modes below 1,600 feet altitude are not likely to be survivable
It seems to me that should read, "Full conversion from 60 to 0 degrees of nacelle tilt cannot be achieved in under 8 seconds of 1600' of decent time @ XXX fps"
SAS, where is your quoted text from?