Aerospace certification is additive’s deep-end, it is the most difficult to attain but once conquered all should follow. “If something goes wrong in a car, you can pull it over to the side of the road, that’s not the case in the air,” Jeff Kowalski, Autodesk’s CTO said in a previous interview.
Several airworthiness authorities throughout the world certify aircraft, modifications and products; there’s the European Aviation Safety Agency (EASA), there’s the International Civil Aviation Organization - part of the United Nations, and even Europe’s smallest republic, San Marino, has an aviation agency. The most renowned and respected is the Federal Aviation Authority (FAA) in the U.S. That’s why when a breakthrough happens in certification the headlines always scream “First FAA Approved Part” as opposed to, “First EASA Approved Part”.
In fact, it was a headline on a press release that led me down a path to further understand what it means to get FAA approval. The complex frameworks and semantics that exist to ensure that everything on an aircraft is airworthy resulting in, by far, the safest mode of transport.
The Claim
“Norsk Titanium to Deliver the World’s First FAA-Approved, 3D-Printed, Structural Titanium Components to Boeing,” said the headline on top of April 10, 2017, press release from Norsk. I knew it was coming, I had spoken to CEO, Warren Boley two months previously with the aim of covering the story in our sister publication across the pond. Unfortunately, I couldn’t confirm nor deny it to be true before my deadline, and we didn't run with it.
Eventually, Boeing confirmed, and an FAA spokesperson got back to me with the following statement, confirming Norsk’s statement to be true, albeit in a semantically odd way: “It is accurate that Norsk Titanium is the Boeing-approved supplier for 787 galley fittings, but they are not “FAA-approved” as such. We do not approve any supplier or certify their designs. They are indirectly approved as a vendor through Boeing, and Boeing is responsible for showing that the parts comply with applicable regulations as part of the 787 type design.”
Norsk Titanium’s part delivered to Boeing
The Steps
What I hadn’t grasped was that FAA does not approve the process of making a part, it approves the aircraft, and it is up to the OEM to endorse the supplier of parts. Scott Sevcik, Head of Aerospace, Defense & Automotive at Stratasys explained in more detail:
“You either present an aircraft to the FAA, or a modification to an aircraft. There are standards, the regulations to which you must certify but every one of those projects is unique, you work with the airworthiness authority to show how you are going to comply with the regulations. What they ultimately certify is that vehicle or modification, they are not certifying a vendor or process, they will leverage qualifications that have been performed as part of a certification plan for a vehicle.”
It’s this very certification process that makes it tough for additive manufacturing (AM) to get to the point of confidence for it to be considered a norm in aerospace manufacturing. In August 2015 Terry Khaled, PhD, Chief S/T Advisor, Metallurgy at the FAA produced a presentation on AM for the FAA, which said:
“My understanding is that FAA seldom approves materials and processes as standalone entities, materials and processes approvals are implied when a particular design has been certificated regardless of whether this design is a component, an engine or an aircraft. Therefore, why is FAA attempting to regulate AM as a standalone entity?”
The desire to certificate the technology as a whole would appear to do with the sheer amount of variables involved in AM. With traditional manufacturing in the aerospace industry, you use a solid block of known material and a CNC machine to subtract the parts. With AM you have to take into account so much more: variables in the materials be it in powdered or wire form, the consistency of the energy source, the temperature of the chamber, does the machine print differently on the left-hand side to the right? Has the powder been contaminated by spatter from a laser beam? Has the part been orientated differently? Are there complex internal channels? And if so how can we ensure that they’re printing reliably time after time?
That’s not getting started on the reverse engineering of parts, and all the additional process that requires, this from the aforementioned Dr Khaled presentation is quite something:
A Different Approach
So just how did Norsk, a company without the kind of might behind a GE, whose LEAP fuel nozzle is perhaps the most well known aerospace part, get to the point of being an approved Boeing supplier?
Picasa
GE’s LEAP Fuel Nozzle is one of the first 3D printed parts to be approved by the FAA.
“What Norsk Titanium initially did is ran some 2,000 FAA tests to create specifications,” says CEO Warren Boley. “We created the Boeing specification, we then ran tests to show we were in compliance with that spec. We went through the FAA review process to show that all of our processes were in control and that the outcome was predictable. That we could comply with the spec meant that we connect with the Boeing airworthiness requirements that Boeing certifies to the FAA and then each subsequent part that we make is found to be in conformity to that.”
Norsk’s technology, which we have reported on before, uses what they call Rapid Plasma Deposition, to make near-net shapes from a Titanium wire, hugely improving on fly-to-buy ratios of titanium, but fly-to-buy ratios are nothing without certification.
“What Norsk and its investors did is decided to take a systems engineering approach,” explains Boley. “We're not trying to sell machines; we're trying to sell an FAA approved process.”
Norsk’s RPD platform
Getting AM processes approved for a wide variety of parts be they structural or internal isn't going to happen overnight. However, Stratasys’s Scott Sevcik says we’re progressing at the speed of Concorde in comparison to the 30-40 years it took composites to get certified.
“We've started to engage the whole industry in the U.S.,” says Sevcik “We are working with National Institution of Aviation research to develop a comprehensive certification of the process. This will be a materials and process specification that the FAA has already seen and understands so that everyone can leverage it. On top of that, we will create a very substantial test data set based on these specifications so that there is statistical confidence. Not every company should have to go through the qualification programme; multiple businesses should leverage the same data, the same accepted standard specs to efficiently certify parts for aircraft.”
