1. Birdcaging of Wire Strands

These wires were tinned however the solder did not flow between the strands resulting in birdcaging of the wires. This could have been the result of improper cleaning of the conductor prior to tinning or not using flux which is required to achieve a good solder flow. In addition the wires on this flight connector assembly were damaged due to improper handling. The birdcaging of the wires contributed to the breakage of the conductors resulting in the failure.

Reference :
NASA-STD-8739.3
6. Conductor Tinning Product Control. Conductor tinning personnel shall ensure that the tinned surfaces exhibit 100 percent coverage. Wire strands shall be distinguishable.

13.6 Inspection Criteria
2. Rejection Criteria. The following are some characteristics of unsatisfactory conditions, any of which are cause for rejection: (3) Improper tinning of part leads or conductors. (4) Separation of wire strands