Engineers scoff that Level 1 diminution is a four-letter word, but there’s nothing funny about UFOs and their potential to cause disaster.
The accident occurred on October 5 at approximately 10:25 a.m. ET, as the SpaceX platform crew was preparing the Crew Dragon. Endurance to launch the Falcon 9 rocket. With four crew 5 astronauts already inside the capsule and the hatch closed, the watchful eye spotted a single human hair in the latch seal. Designated hair FOD – the engineering term for foreign body debris – requires the pillow crew to take action.
The countdown clock had just passed after the T-90, so time was of the essence. The pillow crew has quietly reopened EnduranceSlot and remove the offending tape. They did another check, completely re-cleaned the sealing area, and sealed the hatch a second and final time. A subsequent pressure check confirmed the presence of a tight seal.
It only took a few minutes, and the launch was not affected. The Falcon 9 explosion occurred at noon as scheduled, with crew 5 astronauts – Nicole Onapo Mann, Josh Cassada, Koichi Wakata and Anna Kikina – they successfully arrived at the International Space Station the next day.
That the SpaceX board crew would take so long to remove a single hair before the rocket could be launched is perfectly clear and understandable. In the aerospace industry, first-level decay is defined as any object that does not belong to a specific location, whether that location is a hatch seal, engine, cockpit or runway. Debris in the wrong place can damage equipment, facilitate suboptimal performance of systems, and lead to complete failures.
It’s a problem in many industries, but for the aviation industry, it’s a problem that comes with a $4 billion price tag every year, according to to Boeing. NASA runs FOD At the Kennedy Space Center, its purpose is to “reduce the potential for damage or loss of flight equipment or injury to personnel due to loss of items within flight hardware components, thus conserving national resources.”
Speaking with me via video call, Tom Simon, deputy spacecraft administrator at NASA’s Johnson Space Center, said, “We’ve all been trained from day one, when dealing with flight systems, to monitor the state of Level 1 decay.” Extraneous items, such as pencils, paper clips, screwdrivers, hair and dust, “may seem simple,” he said, but could, among other things, lead to “a seal slowly seeping out of the sea.” “When we build systems, we take it very seriously,” he added.
As an engineer, FOD is “inherent in your system,” John Posey, NASA’s chief engineer at Crew Dragon, told me during the same call. It is “considered one of the most important risks in training programmes,” he explained, as the FOD holds the ability to “shoot down missiles and planes.”
Simon and Posey couldn’t speak to SpaceX’s specific policies and protocols, but they weren’t surprised by the pillow crew’s actions in removing human hair. Level 1 fade related to tightly sealing surfaces is a serious concern. “You don’t want something to press against,” Bossi said when dealing with a sealing surface, and when you have to ensure a tight seal. “Something like that – depending on its size and direction – could lead to a leak path.”
Posey said that for time-sensitive situations such as the final closing of the capsule orifice, the sudden appearance of Level 1 decay should be included in the schedule and process, as well as having a contingency plan in place should this scenario arise. The liner crews should “step back, remove the element, re-examine, even clean the seal, and then go ahead with the job you’re trying to do,” Bossi said.
It’s not just gates that are prone to first-level decay risks. Launch operators implement operations to mitigate Level 1 decay risks, such as using covers or shields when actions such as cutting or deployment are required in the vicinity of spacecraft. And of course, operators have to be clean. Posey, who worked on the space shuttle during its final days and “spent thousands of hours in the propulsion systems, working on the floor with technicians, to make sure everything was okay,” said Busy.
As Simon explained, the degree of cleanliness required often depends on the nature of the project or task itself. Each system needs its own control plan, Bossi said, with engineers setting acceptable limits and deciding what to check.
He said clean room protocols for unmanned satellite launches tend to be minimal, “to the point of washing hands and wearing gloves.” But missions involving a crew are a different story. “With crews, not only does the avionics system have to work, but you also don’t want things to fly all over the place,” Simon said, as well as keeping the seals clean. Once in orbit, microgravity can suddenly cause Level I decay to float unnoticed, including hair and dust. Filtration systems are designed to handle this kind of thing, Bossi said, “but you still want to prevent hassles,” such as ordering lids over orifice plugs, among other measures. “Even the covers should be cleaned and checked for leaks,” he added.
Busy offered some wise advice: “Always make sure you’re opening a system in a clean room, do only what you need to do, and do a check before you close it.” “If you see something that doesn’t look good, go and check it out,” he said, because it’s a “necessary burden.” He added that a second set of eyes wouldn’t hurt. “FOD will find a way to get into your system,” Bossi said, hence the term “intelligent first-level dilution.” He recounted an incident in which a shoe, or shoe cover, was suddenly discovered in the shuttle compartment. “I slipped off someone’s foot, and those kinds of things can be funny later,” Posey said, but socks or tape or anything else that doesn’t belong can be a concern about flammability.
Level 1 anti-fade measures start from entry into complex components or systems in the clean room, and each clean room has its own hygiene requirements, depending on the project. Bossi said clean rooms are “specially certified and monitored to a certain degree of cleanliness depending on what’s in there,” and items usually need to be approved before they are allowed into a clean room.
Cabinets are available to hold bulk items; Adhesive and tape floor pads can secure items that must be in the room; And the ropes can pick up anything that is accidentally dropped. The suits, known to engineers as “bunny suits,” cover the arms and legs and usually feature a hood with a hairnet. Beards are covered with beard nets, while shoes get socks.
Once you’re all set and everything ready, you step through a double door, the first of which “closes behind you and then you enter the clean room,” Posey said. In the average rooms of some double doors, “it blows air everywhere, sucking up any dust or debris,” he explained. Staff will collect any FOD found and investigate its source and whether any additional controls are needed. Bossi added that clean rooms are “never clean enough”.
These procedures are an additional but necessary headache. The good news is that detection of first-level decay improves over time. Cameras are now routinely used to monitor nearly every corner of the launch pad, while X-ray and CT scans can look inside objects and create 3D images of the interior. With these tools, engineers can “see assembly problems” and “detect first-level decay that wouldn’t be found otherwise,” Bussey said. The enhanced ability to level 1 fade wax is of increasing interest to the private sector, particularly in the era of ingredient reuse.
The human hair inside the orifice seal may or may not have caused a problem during the Crew-5 flight, but that doesn’t matter. What matters is safety and the elimination of anything that could endanger human life. Engineers will continue to look for first-level decay, regardless of the inconvenience it may cause.
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