Located, riveted and bolted HB-21A aft wraparound brackets onto top of sidegirder assemblies using H-14 1/8" rivets, HH-19 and -5 (AN3 locknuts and bolts) and HH- 11 and -2 (AN4 locknuts and bolts.
Tightened remaining nuts and bolts on L & R sidegirders.
