Apollo 14 Docking Ring Pyrotechnic Charge Holder

Two MDF (Mild Detonating Fuse) Charge Holders, when joined, make a 33 inch diameter ring. Each having a yellow North American Rockwell (NAR) Temporary Parts Removal Tag, reading in part: “Charge Holder, S/C 110.” One charge holder is marked “V36-596031-7 B, SN (Serial Number) 157” and the other “V36-596031-9 “C,” SN 155, MR 374060” with a NAR inspection stamp, number 330. Both have a white label NAM 14 inspection stamp. There are twenty ½ inch bolts attached to the outer circumference with “NAS 1101 C3” marked on the head of each bolt. Included is a plastic bag with a blank yellow NAR tag having a manuscript note on the reverse side of: “Hardware for Charge Holders.”

Additionally, two spacer and pins contained in an unopened plastic bag that has a yellow NAR tag reading in part: “Part Number V36-596041, Spacer & Pins, 2 ea., S/C 110.”
Three of the NAR tags have the manuscript date of “2/14/72” and a green circular label with a date stamp of “SEP 12, 73.”

Pyrotechnic devices on the Apollo vehicles provided a convenient system to preform flight operations such as initial pressurization of spacecraft propellant systems, Lunar Module (LM) landing gear deployment, LM ascent/descent stage separation, and the final separation of the Command/Service Module (CSM) and LM. There were over 200 pyrotechnic devices used on each Apollo lunar mission.

All of the above hardware is associated with tests conducted after docking problems which occurred on the Apollo 14 flight of 1971. Charge holders like these were used on Apollo flights to make the final separation between the CSM and LM prior to leaving lunar orbit and returning to the Earth. This represents last major set of hardware used in tests described below which included an actual docking ring and docking ring flange assembly.

On Apollo 14, docking problems between the CSM and LM almost scrubbed the lunar landing. Finally after six attempts and some 2 hours of effort, the vehicles finally linked-up properly. Fortunately, when Alan Shepard and Edgar Mitchell returned from the lunar surface, the docking system worked correctly on the first attempt. However, Mission Control had the crew return the docking probe for post flight inspections. The probe was mechanism that makes the first connection with the LM.

From the NASA MSC 05101 post flight report titled: “Apollo 14 Mission Anomaly Report No. 1 - Failure To Achieve Docking Probe Capture Latch Engagement,” states that “the failure to achieve capture-latch engagement has been narrowed to either foreign material restricting the normal function of the capture latch mechanism or jamming of the translation cam.” Modifications for future flights included improved cleanliness requirements, using a removable cover for the probe head to minimize foreign contamination prior to flight, and certain probe mechanical modifications.

To describe the charge holders and testing, a paraphrase from NASA Technical Note TN D-7141, Spacecraft Pyrotechnics Systems, March 1973 follows. The docking ring separation system core charge consisted of two strands of 6-grain Hexanitrostilbene (HNS) Mild Detonating Fuse (MDF) with an adhesive to assist potting (setting) of this explosive material into the charge holder. On December 8, 1971, during verification tests, a failure to completely sever the docking ring occurred. As a result, the design of the docking ring separation system and its redundancy capabilities were investigated. This analysis discovered the possibility of cross-sectional voids developing during the potting process into the charge holder groove. Additional tests were performed afterwards and in the next year (1972) to verify the results of corrective action.

Included is a copy of NASA MSC (now JSC) internal records (Voucher # 6093-003, page 54 of 60) listing these components including an ART (Artifact) number, description, part number, serial number (if any), and from which associated spacecraft. In this case the spacecraft (S/C) was is 110, being Apollo 14. It most probable that these charge holder components were used in either the above docking ring separation tests or companion tests with the flown Apollo 14 docking probe, the docking ring listed, and docking ring flange listed. Both the flange and charge rings retain residual smearing from the explosive tests. It is believed a recording error has the wrong part number for the holders listed on this paperwork. Hardware was transferred to the National Air and Space Museum (NASM) via number 6341-001 in 1977 and later deaccessed by NASM (NASM number 5809).