I'm just concerned that this may rob the industry of not just the valuable information that may forestall re-occurence, but also status and integrity of our maintenance systems.
It may have been a chance event that the FDR was genuinely destroyed in the post crash fire but what if some one deliberately ensured the data became unreadable by exposing it to it's design sustained temperature 1100 degrees centigrade for 30 minutes. This is not easy to achieve except:
- Dana had installed an unserviceable FDR which did not meet the specifications detailed in ICAO annex 6: Operations of aircraft. OR
- Some interested parties have some data they want to conceal.
After 1990, these devices are designed to withstand at least these minimum requirement:
- Fire (High Intensity) - 1100°C flame covering 100% of recorder for 30 minutes. (60 minutes if ED56 test protocol is used)
- Fire (Low Intensity) - 260°C Oven test for 10 hours
- Impact Shock - 3,400 Gs for 6.5 ms
- Static Crush - 5,000 pounds for 5 minutes on each axis
- Fluid Immersion - Immersion in aircraft fluids (fuel, oil etc.) for 24 hours
- Water Immersion - Immersion in sea water for 30 days
- Penetration Resistance - 500 lb. Dropped from 10 ft. with a ¼-inch-diameter contact point
- Hydrostatic Pressure - Pressure equivalent to depth of 20,000 ft.