AIRCRAFT ENGINE FRAGMENT BARRIERS

SRI International is performing research under contract to FAA to protect critical aircraft components against fragments resulting from uncontained failure of a turbine engine. In our fuselage impact tests, we have examined the placement of high-strength fabric ballistic barriers within the fuselage walls, as shown below, to mitigate the hazard from fragments released in an uncontained engine burst.

FRAGMENT BARRIER DESIGN

The figure below illustrates the concept of hazard mitigation. The solid black line shows cumulative number of fragments above a given kinetic energy. There are many fragments with energies above 300 ft-lbs and only a few fragments with energies above 3000 ft-lbs.

MITIGATION DESIGN CONCEPT

From fuselage impact tests, we have measured the effectiveness of the fuselage wall in stopping fragments. As shown by the light blue lines, the fuselage wall, at a weight of 1.48 lb/sq. ft., stops all fragments with energies below 350 ft-lbs. As shown by the pink lines, a single layer of zylon fabric, weighing only 0.03 lb/sq. ft., stopped fragments with energies below 750 ft-lbs. As shown by the dark blue lines, three layers of Zylon fabric, weighing only 0.10 lb/sq.ft., stopped fragments with energies as high as 3600 ft-lbs. This was more than 10 times the amount of energy absorbed by the unfortified fuselage wall, at an increase in weight of only about 6%