Week 8:
The large project that started this week was an inventory of the O-ring cabinet. The cabinet contains thousands of O-rings, in hundreds of sizes, made of four different materials, and in three different styles. It’s quite a large selection, ensuring the team has all the O-rings required for Alvin components and, hopefully, to fix any tools or machines used to maintain the sub as well.
Monday’s highlight was the start of testing the in-sphere emergency lights. These lights would, unsurprisingly, provide illumination in the sphere during an emergency involving loss of main battery power. Testing was a simple process of charging all the lights to maximum capacity and then verifying they stayed lit for the minimum required amount of time. Followed by general inspection of the lights to check for any damage or failing parts.
On Tuesday, I helped electrical engineer Scott inspect and measure the wires that connect to the Power, Data, and I&I bottles. These bottles are titanium pressure vessels that contain electronics related to power conversion, data processing, imaging, and other instruments that do not fit in the main sphere. The wires travel through polyurethane tubing filled with oil to create what are called Pressure Balanced Oil Filled (PBOF) tubes. The electrical signal of the wires enter the bottles through specially designed penetrators made of titanium, ceramic, gold plated copper pins, and other materials to maintain pressure differences and keep water/oil out of the bottles. We performed initial inspections of the wires, tubes, and penetrators for obvious flaws, with further inspections to occur later. We also measured the wires and tubes to ensure we have enough material for replacing parts if needed.
There was a faulty DC power supply that Ben began troubleshooting on Wednesday. I was able to observe some of his troubleshooting while discussing PCB design and related topics. Ultimately, the repair was fairly simple, consisting of a failed capacitor that had also damaged an inductor.
On Thursday, we had a meeting to review the Navy’s findings from their visit the month prior. As I had heard previously, the visit went very well, with the Navy finding no major issues.
Throughout the week, I continued inventorying O-rings in between other tasks. Friday brought an interesting one. It was time for the mechanical team to begin inspecting the sphere, and a dial indicator used for precise measurement of surface dimensions was in need of calibration. As the calibration lab was located in Boston, it was easier for me to make the drive there than to arrange for the tool to be shipped.
Week 9:
The mountain of O-rings from last week stretched into this week as I continued to catalogue them. It was not a simple process of counting, as I was also disposing of any that were past their shelf life or would reach it before the next overhaul, along with reorganizing the cabinet for easier use. To properly categorize and sort the O-rings, I had to dig into some research, as I was not familiar with many of the materials and styles. I spent some time reading through Parker’s O-Ring Handbook and SAE’s AS5316 standard on O-ring storage.
I was tasked with troubleshooting a faulty battery charger on Monday. As we were preparing for maintenance of the main batteries, it was time to repair or replace a charger that had failed some time ago. The unit would power on but would not begin the charge cycle. Prior to the task being handed to me, the first person to notice the fault thought it was a broken button, but then Ben noticed that the voltage reading the charger uses for feedback was not accurate. My initial troubleshooting began by swapping components with a known good charger until I was able to isolate the issue to the main board. From there, further troubleshooting was made difficult by a clear protective conformal coating applied to the entire PCB and by the lack of any obvious failed component, as in the DC power supply repair. Ultimately, I was not able to locate the root fault, but I was able to treat the symptom by adjusting a trim potentiometer related to voltage feedback until the unit once again had accurate voltage readings. After that, the battery charger was back in service. It will require monitoring to see if the issue returns.
Tuesday, I was able to spend some time with the mechanical team making hydraulic hoses using Swagelok fittings. It is a fairly simple process if you have the correct tools and dies, but it was a fun task since I had not worked with the Swagelok brand before. It was also informative, as I had previously inspected a number of hydraulic hoses for faults and had to double-check with the mechanical team because I did not yet know enough about Swagelok fittings at the time to verify they were acceptable.
On Wednesday, I finally wrapped up my work on the O-ring extravaganza and started my next multi-day project, inspecting and measuring the 35 PBOF tubes that connect to the various wire junction boxes throughout Alvin. Similar to my previous PBOF inspections with Scott, this involved measuring the length, outer diameter, and inner diameter of the tubes and inspecting them for discoloration, hardening, or other faults. Work continued on this into the following week.
The end caps for the Power, Data, and I&I bottles returned on Thursday from inspections by outside vendors. They were among the first major items to return and signaled that reassembly was on the horizon. The end caps are large titanium discs, roughly 2 to 3 inches thick and 9 to 11 inches wide. I helped Scott carry them up to the electrical office for receipt inspections.
Later that night, we had our usual D&D adventure. The special event for the evening was that I cooked dinner for the group. I made fresh chana masala, dhal, and basmati rice, along with an assortment of frozen samosas and other pastries.
Rick had begun disassembly of the main batteries earlier in the week, and on Friday I helped for a bit. The batteries, like many components on Alvin, are filled with oil to compensate for the pressures experienced during dives. This creates an interesting situation in which the lead-acid battery cells, of which each battery contains 60, with each cell being roughly half the size of a normal car battery, can accumulate oil at the top during normal operation. Part of reconditioning the cells involves removing the oil to top up the electrolyte solution. I helped siphon oil from the cells using a vacuum pump and collection chamber.
