196 An unseated test specimen passes the prevailing torque specification only when the measured removal  torque is within the 3.5 to 30 in- lb (0.40- 3.4 N -m) range over the entire removal angle range from break away  to 360 degrees. When all measured removal torque values from all test samples  for a combination of  fastener material  and adhesive are with this range, the test combination has 100% pass rate.  

Table 1 lists the pass rates with respect to the 3.5 to 30 in- lb (0.40- 3.4 N -m) prevailing torque specification  for unseated pla in grade 8 threaded fasteners. The first entry in the table shows 100% pass rate for all  initial use tests of plain grade 8 fasteners with Loctit e 222MS in unseated assembly. Reuse without  additional adhesive tests for this c ase have only a 10%  pass rate. An unseated test specimen passes the  prevailing torque specification only when the measured removal torque is within the 3.5 to 30 in- lb (0.403.4 N -m) range over the entire removal angle from breakaway to 360 degrees. Reuse with additional  adhesive tests for this case have an 80% pass rate.  

Table 1.  Unseated plain grade 8 specification pass rate   Plain Grade 8  Loctite 222MS  Loctite 242  Loctite 243   Initial use  100%  90% 10%  Reuse w/o additional adhesive  10% 80% 0%  Reuse w/ additional adhesive  80% 80% 100%  

The same analyses has been performed for unseated grade 8 fasteners with Loc tite 242 and Loctite 243  [11]. The pass rates for these cases are included in Table 1.  This data shows the effect of different  adhesives for the same fastener material in the initial use and reuse conditions.  Reuse with additional  adhesive outperforms reuse without additional adhesive for this fastener material.    Similar results are found for the unseated tests with yellow -zinc grade 8 fasteners and A286 fasteners. The  plots for the unseated A286 aerospace fasteners with Loctite 243  adhesive  are shown in Figure 2 . This  combination of fastener and adhesive is shown because A286 is an inactive material and the Loctite 243 has activator or primer included to improve cure. This adhesive performs the best for the unseated A286  fasteners as shown in Table 2 which lists pass rates for all  unseated A286 fastener tests. Note that the low  pass rate for unseated initial use tests for A286 fasteners with adhesives lacking pri mer or activator (e.g.,  222MS and 242) is due to the fact that A286 material is inactive which inhibits cure.  

Table 2.  Unseated A -286 specification pass rate   A-286 Loctite 222MS  Loctite 242  Loctite 243   Initial use  0% 0% 100%   Reuse w/o additional adhesive  60% 50% 10%  Reuse w/ additional adhesive  78% 78% 100%    The unseated test results reveal several combinations of fastener material and adhesive that provide prevailing torque within specification for initial use and r euse with additional adhesive. This proves using  adhesive to provide prevailing torque locking within specification is a viable option.    Conclusions  

This work assessed the use of anaerobic adhesive to provide a prevailing torque locking feature. Test  procedures were developed for this assessment that can be used in practice to assess any fastener and  adhesive combination and joint conditions. Tests were conducted with different threaded fastener materials and anaerobic adhesi ves in unseated assembly condi tions. Initial use, reuse without additional adhesive,  and reuse with additional a dhesive cases were tested. A 48- hour cure time was used for all initial use and  reuse tests.