225 their manufacturer was not yet certified in compliance with ISO 9001. At the time, material certifications  were not required as a part of purchase orders (which is a requirement now). A perfect storm of conditions  set the stage for the application of the cold temperature black oxide to be missed, despite the long duration  they were possessed. If the units had  been part of a lot that was intended to be used in short order, the  discovery would have been made during testing of the other projects. The use of hardware drives being  purchased as a solitary lot, intended to be immediately shelved, and the minimal involvement from the  quality organization at the time of purchase, meant the discrepancy snuck in, undetected, to be discovered  instead during the development of the next generation of MDDAs decades later. As a result of this  discovery, a recommendation is made for heightened inspection to be completed of hardware that was  either received before quality process changes, or before any significant changes in the ownership of or  certifications obtained by the supplier.  

References  

1. Packard, Douglas T.; “Dual Drive Actuators”; Proceedings, 16th Aerospace Mechanisms  Symposium; May 13- 14, 1982; NASA CP -2221.  

2. Conley, Peter L. and Bohner, John J.; “Experience with Synthetic Fluorinated Fluid Lubricants”;  Proceedings, 24th Aerospace Mechanisms Symposium; April 1 1990; N ASA- CP-3062.  

3. Herman, Jason and Davis, Kiel; “Evaluation of Perflouropolyether Lubricant Lifetime in the High  Stress and High Stress -Cycle Regime for Mars Applications”; Proceedings, 39th Aerospace  Mechanisms Symposium; May 1, 2008; NASA/CP -2008- 215252.  

4. Venier, Clifford; Casserly, Edward W.; Jones, William R., Jr.; Marchetti, Mario; Jansen, Mark J.;  Predmore, Roamer E.;  “Tribological Properties of a Pennzane- Based Liquid Lubricant  (Disubstituted Alkylated Cyclopentane) for Low Temperature Space Applications”; Proceedings,  36th Aerospace Mechanisms Symposium; April 1, 2002; NASA/CP -2002- 211506.  

Acknowledgments  

This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, under a  contract with the National Aeronautics and Sp ace Administration. Reference herein to any specific  commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not  constitute or imply its endorsement by the United States Government or the Jet Propulsion Laboratory,   Pasadena, California. © 2020. California Institute of Technology. Government sponsorship acknowledged.  

The author would like to thank JPL chief engineer, and original delivering engineer of the MDDA, Michael  R. Johnson, from the Jet Propulsion Laboratory  (JPL), for patiently providing his never ending technical  guidance and mentorship. Also, thanks to Allison Ayad, for her tireless support during the failure  investigation and her valuable data reduction, also through JPL. Thank you to Duval Johnson, of the  Laboratory for Applied Tribology at JPL, who spearheaded the disassembly, cleaning, and detailed  inspection of the Wave Generator subassemblies, and skillfully completed the Braycote removal and  rewetting of the Harmonic Drives and duplex bearings with P ennzane. Thank you to the expertise of Mark  Balzer, also of the Laboratory for Applied Tribology at JPL, who identified the cold temperature black oxide  coating. Many thanks also to the Analytical Chemistry Laboratory at JPL, namely Nick Heinz, Mark  Anders on, and Bill Warner, who performed all chemical grease analysis described in this paper.  

Lastly, but not least, the author would like to make a special acknowledgement of Harmonic Drive, LLC.  Harmonic Drive, under their current ownership, has successfully  provided flight hardware to JPL for  decades. In recent years, the author of this paper, specifically, has received more than thirty pancake style  HD units (in size 14) which have been inspected and approved by JPL QA, and have been integrated into  high reliability flight actuators for multiple projects, including successful life test completion. No anomalies  related to any of the HD units have resulted during these program developments.