Tear straps

Skins with bonded doublers have been used successfully on a large number of civil aircraft and are still used on new designs. The only widespread in-service problem with bonded doubler assemblies has been delamination caused by unstable surface preparation. Early fuselage skins with bonded doublers and inadequate surface preparation experienced severe delamination and subsequent corrosion. A majority of these delaminated doublers were the fail-safe tear straps (Fig. 27). Although the tear strap bond does not cany structural load, the bond... 

Fig. 12. A tear-strap inspection sample problem showing in the proper time domain gated region the decrease in amplitude and signature change for the poorly bonded tear strap and the loss of signal amplitude for the debonded tear strap, (a) Ultrasonic pulse-echo approach for tear strap inspection, (b) Underside of a tear strap, (c) Ultrasonic signals for the sample tear strap inspection (pulse-echo) / = 1.1 MHz, 6 = 45° (i) good adhesion, (ii) poor adhesion and (iii) bad adhesion (debonded).

Rose, J.L., Barshinger, J, and Meyer, R, Ultrasonic guided wave inspection of a 747 tear strap structure. ASNT Fall Conference and Quality Testing Show, 1997. 

In the sporting goods industry, considered here as in the health field, there is appreciable use of strapping tapes designed to prevent injury as well as to support injured joints or muscles. These athletic tapes, with deformable cloth backings to facilitate ease of wrapping and easy tear, must also have adhesive masses that permit facile removal. The sports industry also consumes tapes for wrapping hockey stick blades and baseball bat handles. 

Tears or cuts appear in the nylon straps or webbing of the internal suspension. 

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