Figure 5. The reason the leads were splayed apart during assembly was that an existing circuit board,  designed for HED’s with different lead spacing, was used for the Capture Latch motor to minimize  development costs. While NASA processes do allow for forming of leads in situations like this, a minimum  distance must be maintained between bends in the leads and any joints. In this application, the minimum  distance was not maintained for the solder joint at the body of the HED, resulting in stress concentrations  at the solder joint and ultimately crack formation over time.  The second contributing factor and root cause was thermal induced stresses in the HED and its lead wires  caused by voids in the potting material. These voids allowed for large thermal gradients between the  exposed and unexposed portions of the HED, leading to large component stresses and crack formation.  The voids were a byproduct of the process for applying and curing the potting material which did not  sufficiently eliminate entrained air bubbles prior to curing. The voids were caused by weaknesses in the  degas process, and by difficulties containing the potting material prior to curing in the small surrounding  volume. Additionally, it was found that differences in the Coefficient of Thermal Expansion (CTE) of the  potting material and adjacent materials contributed to the high stresses in the HED.  Corrective Action  There were a number of corrective actions performed to resolve this issue. First, the primary root cause  was addressed by changing the potting material to a  new type that was easier to remove entrained air  bubbles and with a CTE that was more compatible  with the encapsulated materials. The degas process  was improved to ensure bubbles were removed from  the potting material and the HED was also encased in RTV silicone to cushion it during thermal expansion.  Additional measures were also taken to ensure that if  a motor with large voids was produced in spite of the  improved processes, it would be flagged and removed  from use. To that end, inspections of the potting  material were implemented so motors with large voids  are rejected. Additionally, the motor testing process  was revised (both at the supplier and at Boeing) to  include oscilloscope-based current monitoring to  confirm all HED operate nominally. Furthermore, a  secondary corrective action changed the circuit board  design to allow for installation of the HEDs without lead forming.  Results  The redesigned motor was subjected to qualification testing and no issues with the HEDs were identified.  Additionally, all twelve flight motors successfully completed all Acceptance Testing, at the component,  subsystem, and system levels, without any issues.  Secondary Release Mechanism Failures During Qualification Testing  Description of Development Test Failure  The initial failure of the CCLR occurred during testing of the development Capture Latch. Prior to the failure  the CLA had been subject to a suite of tests for the Capture Latch, including functional tests, random  vibration, thermal cycling, and thermal vacuum. The secondary release test was the next to last test, to be  followed only by an ultimate load test.   The CCLR failure was the first significant issue that occurred during the CLA development test although  one off-nominal condition was noted earlier in test which later proved to be a missed indication of the  eventual failure. During the random vibration test, the spherical bearing located on the NEA pushed its way  out of the NEA housing. After investigating, it was determined that the issue was caused by the development  Figure 6. HED Image Showing Body Crack AB NASA/CP—2018-219887 492