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Monday, June 9, 2003

Data Protection

The operative phrase is that if the data is of value, it should be protected. This approach has led to an increase in protection standards and testing requirements for flight data recorders over the years. The notes below equate to the numbers in parentheses in the box:

(1) 100 G can be equated to the force of stopping a vehicle traveling 60 miles per hour in 14.4 inches.

(2) Impact shock equates to a vehicle traveling 60 mph stopping in 1.4 inches.

(3) Impact shock is equivalent to a vehicle traveling 60 mph stopping in 0.4 inches.

(4) Note how coverage has increased to 100 percent, exposure to an hour, and now includes the heat load.

(5) The low intensity long duration fire was more likely to destroy the box and data therein.

(6) Corrosive liquids include hydraulic fluid and blue-colored toilet water.

Frank Doran, of L-3 Communications, which builds voyage data recorders for the maritime industry, quipped that if aviation recorders can withstand a crash, why not build the whole airplane out of the "black box material"? The weight penalty would be punitive, of course. Doran said, "In the case of a ship, we do build it out of black box material - steel."

Survival Testing for Recorders More demanding over time
Hazard 1958 TSO C51 1966 TSO C51a 1996 TSO C123a/C124a
Impact shock 100 G (1) 1,000 G, over 5 milliseconds (msec) (2) 3,400 G over 0.5 msec (3)
Static crush None 5,000 lb., 5 min per axis 5,000 lb., 5 min per axis
Fire resistance 1,000�C (1,980�F), 30 min., 50% coverage 1,000�C (1,980�F), 30 min., 50% coverage. 1,000�F (1,980�F), 60 min., 100% coverage, 50,000 BTU/hr/ft2 (4)
Heat resistance None None 10-hr at 260�C (500�F) (5)
Deep sea pressure None None 20,000 ft. for 24 hrs
Corrosive fluids None 24 hours, specified fluids (6) 48 hours, specified fluids
Source: Duncan Schofield, manager of flight recorder engineering, Honeywell
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