Monday, June 9, 2003
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|