January 17, 2024- No. 03 In This Issue : Buttigieg says no timeline on Boeing 737 Max return after Alaska Air incident : Workers at a Boeing Supplier Raised Issues About Defects. The Company Didn’t Listen. : Firefly Green Fuels is making SAF from sewage : Stuck valve may have doomed private Peregrine moon lander mission, Astrobotic says : Dutch Startup Elysian Pursues Large Battery-Electric Airliner : Bjorn’ s Corner: New aircraft technologies. Part 45. Continued Airworthiness : US Treasury Department issues guidelines around a new tax credit for sustainable aviation fuel : Obstructed catalytic converter brings down experimental airplane Buttigieg says no timeline on Boeing 737 Max return after Alaska Air incident 'I have confidence in any aircraft cleared by the FAA,' Buttigieg says By Thomas Catenacci FOXBusiness Transportation Secretary Pete Buttigieg discusses the Department of Transportation fining Southwest for its Christmas meltdown and the administration's electric vehicle goals. Transportation Secretary Pete Buttigieg wouldn't put a timeline on the return of Boeing’s 737-9 Max aircraft after a door on one of the models operated by Alaska Airlines blew off mid-flight on Friday. "The only consideration for the timeline is safety," Buttigieg told reporters from the Transportation Research Board’s annual meeting on Wednesday afternoon, transportation news outlet Skift reported. "Until it is ready, it’s not ready. Nobody can or should be rushed in that process." "I have confidence in any aircraft cleared by the FAA," he continued, praising Federal Aviation Administration Administrator Mike Whitaker, according to Politico. "Every plane they deliver to an airline, every plane that goes in the sky needs to be 100 percent safe. They need to be able to demonstrate that, which means finding and fixing anything related to this issue." Buttigieg added that the images of the Alaska Airlines plane missing its door while in the air affected him. The transportation secretary's comments come days after the incident, which ultimately forced an emergency landing in Portland, Oregon, but caused no serious injuries among passengers. The plane's door panel, which covers an extra emergency exit that is only operable on planes with the maximum capacity, blew off Alaska Airlines Flight 1282 while it was at 16,000 feet and climbing to cruising altitude after departing Portland, Oregon, for Ontario, California. The loss of the panel caused the depressurization of the cabin and the plane soon made its emergency landing. Officials say two cellphones, at least one of which was still intact and in airplane mode, were found on the ground, and the door plug, considered a key component, was recovered from a Portland school teacher's backyard. While the National Transportation Safety Board continues its investigation of the incident, the FAA announced Tuesday that it had grounded every Boeing 737-9 Max with a plug door until the aircraft had been determined to be safe. "The safety of the flying public, not speed, will determine the timeline for returning the Boeing 737-9 Max to service. Every Boeing 737-9 Max with a plug door will remain grounded until the FAA finds each can safely return to operation," the FAA said in a statement to FOX Business on Wednesday. "To begin this process, Boeing must provide instructions to operators for inspections and maintenance," the statement continued. "Boeing offered an initial version of instructions yesterday which they are now revising because of feedback received in response. Upon receiving the revised version of instructions from Boeing the FAA will conduct a thorough review." Workers at a Boeing Supplier Raised Issues About Defects. The Company Didn’t Listen. BY KATYA SCHWENK DAVID SIROTA LUCY DEAN STOCKTON JOEL WARNER Weeks before the door plug blew out of an Alaska Airlines flight over Portland, Oregon, on January 5, grounding more than 150 Boeing aircraft, workers at the part’s reported manufacturer had been warning of safety concerns — but management ignored them. A plastic sheet covers an area of the fuselage of the Alaska Airlines N704AL Boeing 737 Max 9 aircraft outside a hangar at Portland International Airport on January 8, 2024 in Less than a month before a catastrophic aircraft failure prompted the grounding of more than 150 of Boeing’s commercial aircraft, documents were filed in federal court alleging that former employees at the company’s subcontractor repeatedly warned corporate officials about safety problems and were told to falsify records. One of the employees at Spirit AeroSystems, which reportedly manufactured the door plug that blew out of an Alaska Airlines flight over Portland, Oregon, allegedly told company officials about an “excessive amount of defects,” according to the federal complaint and corresponding internal corporate documents reviewed by us. According to the court documents, the employee told a colleague that “he believed it was just a matter of time until a major defect escaped to a customer.” The allegations come from a federal securities lawsuit accusing Spirit of deliberately covering up systematic quality-control problems, encouraging workers to undercount defects, and retaliating against those who raised safety concerns. Read the full complaint here. Although the cause of the Boeing airplane’s failure is still unclear, some aviation experts say the allegations against Spirit are emblematic of how brand-name manufacturers’ practice of outsourcing aerospace construction has led to worrisome safety issues. They argue that the Federal Aviation Administration (FAA) has failed to properly regulate companies like Spirit, which was given a $75 million public subsidy from Pete Buttigieg’s Transportation Department in 2021, reported more than $5 billion in revenues in 2022, and bills itself as “one of the world’s largest manufacturers of aerostructures for commercial airplanes.” “The FAA’s chronic, systemic, and longtime funding gap is a key problem in having the staffing, resources, and travel budgets to provide proper oversight,” said William McGee, a senior fellow for aviation and travel at the American Economic Liberties Project, who has served on a panel advising the US Transportation Department. “Ultimately, the FAA has failed to provide adequate policing of outsourced work, both at aircraft manufacturing facilities and at airline maintenance facilities.” David Sidman, a spokesperson for Boeing, declined to comment on the allegations raised in the lawsuit. “We defer to Spirit for any comment,” he wrote in an email to us. Spirit AeroSystems did not respond to multiple requests for comment on the federal lawsuit’s allegations. The company has not yet filed a response to the complaint in court. “At Spirit AeroSystems, our primary focus is the quality and product integrity of the aircraft structures we deliver,” the company said in a written statement after the Alaska Airlines episode. The FAA did not immediately respond to a request for comment on its oversight of Spirit. Spirit was established in 2005 as a spin-off company from Boeing. The publicly traded firm remains heavily reliant on Boeing, which has lobbied to delay federal safety mandates. According to Spirit’s own Securities and Exchange Commission filings, the company’s “business depends largely on sales of components for a single aircraft program, the B737,” the latest version of which — the 737 Max 9 — has now been temporarily grounded, pending inspections by operators. Spirit and Boeing are closely intertwined. Spirit’s new CEO Patrick Shanahan was a Trump administration Pentagon official who previously worked at Boeing for more than thirty years, serving as the company’s vice president of various programs, including supply chain and operations, all while the company reported lobbying federal officials on airline safety issues. Spirit’s senior vice president Terry George, in charge of operations engineering, tooling, and facilities, also previously served as Boeing’s manager on the 737 program. Last week’s high-altitude debacle — which forced an Alaska Airlines 737 Max 9’s emergency landing in Portland — came just a few years after Spirit was named in FAA actions against Boeing. In 2019 and 2020, the agency alleged that Spirit delivered parts to Boeing that did not comply with safety standards, then “proposed that Boeing accept the parts as delivered” — and “Boeing subsequently presented [the parts] as ready for airworthiness certification” on hundreds of aircraft. Then came the class-action lawsuit: In May 2023, a group of Spirit AeroSystems’ shareholders filed a complaint against the company, claiming it made misleading statements and withheld information about production troubles and quality-control issues before media reports of the problems led to a major drop in Spirit’s market value. An amended version of the complaint, filed on December 19, provides more expansive charges against the company, citing detailed accounts by former employees alleging extensive quality-control problems at Spirit. Company executives “concealed from investors that Spirit suffered from widespread and sustained quality failures,” the complaint alleges. “These failures included defects such as the routine presence of foreign object debris (‘FOD’) in Spirit products, missing fasteners, peeling paint, and poor skin quality. Such constant quality failures resulted in part from Spirit’s culture which prioritized production numbers and short-term financial outcomes over product quality, and Spirit’s related failure to hire sufficient personnel to deliver quality products at the rates demanded by Spirit and its customers including Boeing.” “We Are Being Asked to Purposely Record Inaccurate Information” The court documents allege that on Feruary 22, 2022, one Spirit inspection worker explicitly told company management that he was being instructed to misrepresent the number of defects he was working on. “You are asking us to record in a inaccurately [sic] way the number of defects,” he wrote in an email to a company official. “This make [sic] us and put us in a very uncomfortable situation.” The worker, who is unnamed in the federal court case, submitted an ethics complaint to the company detailing what had occurred, writing in it that the inspection team had “been put on [sic] a very unethical place,” and emphasizing the “excessive amount of defects” workers were encountering. “We are being asked to purposely record inaccurate information,” the inspection worker wrote in the ethics complaint. He then sent an email to Spirit’s then CEO, Tom Gentile, attaching the ethics complaint and detailing his concerns, saying it was his “last resort.” When the employee had first expressed concerns to his supervisor about the mandate, the supervisor responded “that if he refused to do as he was told, [the supervisor] would fire him on the spot,” the court documents allege. After the worker sent the first email, he was allegedly demoted from his position by management, and the rest of the inspection team was told to continue using the new system of logging defects. Ultimately, the worker’s complaint was sustained, and he was restored to his prior position with back pay, according to the complaint. He quit several months later, however, and claimed that other inspection team members he had worked with had been moved to new positions when, according to management, they documented “too many defects.” “Spirit Concealed the Defect” In August 2023, news broke that Boeing had discovered a defect in its MAX 737s, delaying rollout of the four hundred planes it had set to deliver this year. Spirit had incorrectly manufactured key equipment for the fuselage system, as the company acknowledged in a press statement. But these defects had been discovered by Spirit months before they became public, according to the December court filings. The court documents claim that a former quality auditor with Spirit, Joshua Dean, identified the manufacturing defects — bulkhead holes that were improperly drilled — in October 2022, nearly a year before Boeing first said that the defect had been discovered. Dean identified the issue and sent his findings to supervisors on multiple occasions, telling management at one point that it was “the worst finding” he had encountered during his time as an auditor. “The aft pressure bulkhead is a critical part of an airplane, which is necessary to maintain cabin pressure during flight,” the complaint says. “Dean reported this defect to multiple Spirit employees over a period of several months, including submitting formal written findings to his manager. However, Spirit concealed the defect.” In April 2023, after Dean continued to raise concerns about the defects, Spirit fired him, the complaint says. In October 2023, Boeing and Spirit announced they were expanding the scope of their inspections. The FAA has said it is monitoring the inspections, but said in October there was “no immediate safety concern” as a result of the bulkhead defects. “Emphasis on Pushing Out Product Over Quality” Workers cited in the federal complaint attributed the alleged problems at Spirit to a culture that prioritized moving products down the factory line as quickly as possible — at any cost. The company has been under pressure from Boeing to ramp up production, and in earnings calls, Spirit’s shareholders have pressed the company’s executives about its production rates. According to the Financial Times, after the extended grounding of Boeing’s entire fleet of 737 Max airlines following two major crashes in 2018 and 2019, “the plane maker has sought to increase its output rate and gain back market share it lost to Airbus,” its European rival. Spirit, which also produces airframe components for Airbus, has felt the pressure of that demand. As Shanahan noted in Spirit’s third-quarter earnings call on November 1, “When you look at the demand for commercial airplanes, having two of the biggest customers in the world and not being able to satisfy the demand, it should command our full attention.” According to the court records, workers believed Spirit placed an “emphasis on pushing out product over quality.” Inspection workers were allegedly told to overlook defects on final walkthroughs, as Spirit “just wanted to ship its completed products as quickly as possible.” Dean claimed to have noticed a significant deterioration in Spirit’s workforce after Spirit went through several rounds of mass layoffs in the early days of the COVID-19 pandemic, despite the huge influx in government funding they received. According to court documents, Dean said that “Spirit laid off or voluntarily retired a large number of senior engineers and mechanics, leaving a disproportionate number of new and less experienced personnel.” “Over-Tightening or Under-Tightening That Could Threaten the Structural Integrity” After the Alaska Airlines plane was grounded, United Airlines launched an independent inspection of its planes. Initial reporting shows that inspectors found multiple loose bolts throughout several Boeing 737 Max 9 planes. Alaska Airlines is currently conducting an audit of its aircraft. Concerns about properly tightened equipment were detailed in the federal complaint. “Auditors repeatedly found torque wrenches in mechanics’ toolboxes that were not properly calibrated,” said the complaint, citing another former Spirit employee. “This was potentially a serious problem, as a torque wrench that is out of calibration may not torque fasteners to the correct levels, resulting in over-tightening or under-tightening that could threaten the structural integrity of the parts in question.” According to former employees cited in the court documents, in a company-wide “toolbox audit,” more than one hundred of up to 1,400 wrenches were found out of alignment. On Spirit’s November earnings call, after investors pressed the company’s new CEO about its quality-control problems, Shanahan promised that the company was working to fix the issues — and its reputation. “The mindset I have is that we can be zero defects,” he said. “We can eliminate all defects. . . . But every day, we have to put time and attention to that.” Firefly Green Fuels is making SAF from sewage by Daniela Castim Firefly Green Fuels, a company dedicated to reducing aviation’s carbon footprint, is exploring an innovative method to transform the way the world’s airlines are powered: sewage. “Sewage is interesting to work with. At the moment the only other disposal route in the UK is through agricultural spreading, a practice which will likely be outlawed as soon as a better route is secured,” he added. “Our process gives this waste a new purpose, creating SAF whilst supporting biodiversity in ecosystems currently plagued by agricultural runoff,” James Hygate, Firefly Green Fuels CEO, said. The company takes sewage sludge from water utilities and separates it into two useful materials through a high-pressure reactor process. The first product, biochar, is used as a fertilizer in the agriculture industry, while the second, bio-crude, can be refined into jet fuel. “We really do need every different route to SAF to work out if we want to meet ambitious global targets,” Hygate said. “That means that more support is needed from governments and other technologies need to also be developed alongside SAF. We really don’t have much time to make these changes if we want to make a significant impact on climate change.” As approved SAF routes cannot meet the necessary demand in the aviation industry, more solutions are required. Firefly has been in discussions with officials in a major metropolitan area who believe that their sewage-to-SAF process could power up to 80% of flights from their international airport using SAF alone. Firefly is working at pace towards the making of a first-of-a-kind plant in the UK within this decade. However, that’s just the start. As the feedstock is globally relevant, the company plans to roll this technology out around the world. The sewage-to-SAF process has the potential to significantly reduce aviation’s carbon footprint and transform the way the world’s airlines are powered. “I think that every route to SAF is incredibly innovative and will be an important part of the puzzle moving forward, but our SAF made from sewage is an incredibly effective and green solution that promises to be very cost-effective too,” Hygate continued. “When looking exclusively at biogenic wastes, the Firefly route shows potential to be the largest single source of SAF globally.” Stuck valve may have doomed private Peregrine moon lander mission, Astrobotic says By Mike Wall published 7 days ago The current hypothesis is that a valve failed to reseal properly, leading to a ruptured oxidizer tank. Astrobotic has homed in on a potential cause for the problems plaguing its Peregrine moon lander. Peregrine launched early Monday morning (Jan. 8) atop United Launch Alliance's (ULA) new Vulcan Centaur rocket, with the goal of becoming the first private spacecraft to land softly on the moon. That dream was dashed, however, by a propellant leak that sprang up shortly after Peregrine deployed from the rocket's upper stage. Astrobotic has been troubleshooting and analyzing the issue ever since, and the company may now know what happened. Sponsored Links "Astrobotic's current hypothesis about the Peregrine spacecraft's propulsion anomaly is that a valve between the helium pressurant and the oxidizer failed to reseal after actuation during initialization," company representatives wrote in a post on X Tuesday afternoon (Jan. 9). "This led to a rush of high-pressure helium that spiked the pressure in the oxidizer tank beyond its operating limit and subsequently ruptured the tank," they added. Related: 1st photo from crippled private Peregrine moon lander holds clue about anomaly Astrobotic's Peregrine moon lander is seen in a clean room before its Jan. 8, 2024 launch. (Image credit: NASA/Isaac Watson) Astrobotic has been impressively transparent about the Peregrine anomaly: Tuesday afternoon's update was the eighth one that the company has posted on X since the leak occurred. In update number seven, which Astrobotic posted earlier on Tuesday, the company announced that the fuel leak will prevent Peregrine from landing on the moon as planned. That update also stated that the lander is in a stable operating mode and has about 40 hours' worth of propellant left. Peregrine's launch marked the long-awaited debut of Vulcan Centaur, which will replace ULA's venerable Atlas V and Delta rockets. Vulcan Centaur did its job well on Monday, Astrobotic stressed. The rocket "inserted Peregrine into the planned translunar trajectory without issue," Astrobotic wrote in update number eight. "There is no indication that the propulsion anomaly occurred as a result of the launch." Dutch Startup Elysian Pursues Large Battery-Electric Airliner Graham Warwick January 10, 2024 Note: See diagrams in the original article. Elysian’s E9X concept uses battery-powered distributed electric propulsion with a turbogenerator for reserves. Credit: Elysian A Dutch startup is challenging the belief that battery-powered aircraft must be small and short-range, proposing to develop a 90-seat, 500-mi.-range all-electric airliner. Breaking with traditional design principles, Delft-based Elysian says it has found design space where a large electric aircraft looks viable with near-term battery technology. Because of severe limitations on battery energy density, all-electric aircraft are viewed as only suited to new forms of air mobility and short-range regional connectivity. But Elysian believes it is possible to build a bigger battery-electric aircraft that can decarbonize a larger share of aviation. • Aircraft could fly 500 mi. on near-term batteries • Maximum takeoff weight would be as much an Airbus A320 “If you want to make a significant impact on the sector as a whole, then you need to electrify flights up to 1,000 km [620 mi.]. Then you’re talking about roughly one-fifth of aviation emissions and about half of all passenger flights,” says Reynard de Vries, director of design and engineering at Elysian. “We found design space where we believe that, with the right design, a battery-electric aircraft can fly much farther than most studies suggest and also carry many more passengers,” he says. “It’s not crazy, hocus-pocus science, new technology or complex materials or anything like that. It’s looking in the right corner of the design space.” “Instead of a turboprop aircraft, we considered first-generation narrowbody jets as a reference point,” says Rob Wolleswinkel, co-CEO and chief technology officer. “While those jets were fuel-inefficient, they were designed for long ranges and carried a high energy mass. That served as inspiration for our electric aircraft design.” At the American Institute of Aeronautics and Astronautics’ SciTech conference in Orlando on Jan. 10, Elysian presented its design principles and parametric designs for a feasible battery-electric aircraft to accommodate 40-120 passengers with a cruise range up to 1,000 km. “These numbers start meaning that if you can also get the costs down, if you can get enough people on the plane, then perhaps from a cost perspective it makes sense not to operate on new segments of mobility and in new markets but to compete with current aircraft,” de Vries says. The concept originated with Wolleswinkel, a management consultant who embarked on a career change to professional pilot only to be interrupted by the COVID-19 pandemic. “Since I could not continue my flight training, I had ample time to study. That was the moment I dusted off my old books and started studying this idea of sustainable aviation. “That is where the idea was born,” Wolleswinkel explains. “Because if you look at the academic research, then battery-electric aviation was quickly dismissed as a niche thing. You can’t make it big, and you can’t fly far. And if you look at the reasons why people were saying that, sometimes the analyses behind it were plainly wrong, but in many cases the analyses were right.” But the starting point was always current aircraft designs. “People took an ATR 72 and tried to electrify it on paper, and guess what, it didn’t work,” he says. “I said, ‘Let’s turn the problem around. If I want to fly as far as possible with a sizable group of people—I started with 40 and later 80 passengers—what’s that going to look like?’ To my surprise, here came a solution out of my spreadsheets.” In 2021, Wolleswinkel presented his ideas to the late Jaap Rosen Jacobson, longtime aerospace investor and founder and CEO of Panta Holdings, which owns Fokker Services. Rosen Jacobson formed a project team to develop the top-level requirements and business case for the aircraft. “Fokker Services supports the Fokker fleet worldwide but also has developed supplemental type certificates for older aircraft. There’s quite an engineering base. They were of great service to us,” Wolleswinkel says. In November 2021, the team approached Delft Technical University (TU Delft) to develop a conceptual design. “It’s fair to say that, at the start, they were skeptical. They said that cannot be done. The academics all agreed it is not feasible, because of all the old arguments I had already seen,” he says. But after “an afternoon of intense discussion,” TU Delft conceded the idea looked promising and agreed to take on conceptual design. The task was led by de Vries, then a postdoctoral researcher, with Wolleswinkel and TU Delft professors Maurice Hoogreef and Roelof Vos. After six months, the team presented the conceptual design for a battery-powered 90-passenger aircraft. In January 2023, Panta launched the next phase, founding Elysian and providing initial funding to enter a two-year risk-reduction phase for the proposed E9X electric airliner. The startup initiated 10 projects to address technology challenges—“hot potatoes” identified during conceptual design that require further research to ensure technical feasibility. “We want to solve the key technical issues first. And we do that together with renowned research institutes,” Wolleswinkel says. Elysian is working with German aerospace center DLR as well as Royal NLR, TU Delft and Twente Technical University in the Netherlands. “The idea is to make sure those projects give us the green light to go into detail design. We want to finalize these projects by the end of 2024 or early 2025,” he says. “We’re in risk reduction now. We are doing research on the hot potatoes, a list of elements that during the conceptual design we said are the technical challenges that can maybe make or break the design, but at least have a large impact,” de Vries says. The 10 projects cover battery cell assessment, wing/battery-pack integrated design and structural sizing of the wing for loads with batteries installed, design of the reserve energy and high-voltage systems, sizing of the thermal management system, low-noise propeller design for distributed propulsion, propeller-wing aerodynamic performance in cruise and high-lift conditions, stability and control with distributed propulsion and the weight and power consumption of low-voltage nonpropulsive systems. “We want to make sure before we go out and make big claims that what we’re saying is feasible. Let’s clarify the assumptions we made on a subsystem level in the design process with people who know more about it. We’ve outsourced most of these research programs,” de Vries says. “The objective is not to design the systems. The objective is: Can it be done?” he says. With input from the projects, Elysian will perform another design iteration in the second half of 2024. “That will be the final conceptual design. And then in Phase 3, which is to start in January 2025, we will do preliminary design and work with ground-based demonstrators and scaled flying prototypes,” he notes. Elysian’s concept differs dramatically from existing designs for small electric aircraft and hybrid-electric regional turboprops. The E9X is large, with about the same maximum takeoff weight as an Airbus A320—and almost half that weight is batteries. Eight propellers are mounted on the wing, which has a longer span than an A320 wing, so the tips must fold to fit the same airport gates. “The idea is to not take turboprops as a starting point, because turboprops are designed for short range and therefore have a low fuel fraction,” Wolleswinkel says. “You have to turn the logic around and say, ‘I need to carry a lot of fuel, so I have to look at aircraft that had the same problem as we have.’ And that’s the old jet airliners, the Boeing 707 and Douglas DC-8, which were gas-guzzlers with poor aerodynamics. “You have to take that as a starting point in terms of weight fractions and what is feasible in terms of payload fractions, energy weight fractions and empty weight fractions,” he says. Using this approach, Wolleswinkel and TU Delft produced a conceptual design that challenges beliefs about electric aircraft. De Vries had worked on hybrid-electric aircraft design at TU Delft. “Myself, I was a bit pessimistic when we started this study,” he says. “I said, ‘Whoa, I’m not sure it is possible.’ But we did the design study and were positively surprised. It looked very promising.” Designers use the Breguet range equation to estimate the range of an aircraft. Adapted for electric aircraft, this says range is driven by the efficiency of the powertrain and propulsors, the lift-to-drag (L/D) ratio of the aircraft and the battery weight fraction. “Basically, the two levers you want to play with as an aerospace designer are the battery weight fraction and the lift-to-drag ratio,” de Vries explains. Using current design rules, a “best possible” regional turboprop would have mass fractions of around 20% for payload, 26% for fuel and 54% for empty weight with an L/D of 19 allowing for future technology developments such as laminar flow. Putting those values into the range equation with a battery-pack-level energy density of 300 Wh/kg gives a maximum range of 405 km. “But then you have your reserves, which are always a killing blow for most electric aircraft design exercises,” he says. The required energy reserves are set by the certification basis, which for Elysian is Europe’s CS-25 transport category for large aircraft. “For CS-25, about 350 km reserves is a reasonable proxy for diversion to alternative plus loiter and contingency. You quickly end up with a story that says: ‘Even if I take the best possible turboprop and manage to make an electric aircraft just as light, I can only have 55 km of useful range, so what’s the point? I’m not going look into this any further,’” de Vries says. But Elysian says this analysis is wrong because of these four misconceptions about electric aircraft: Energy mass fraction has to be 20-25% as in turboprops; realistic maximum L/D is 14-19 as in turboprops; reserve requirements result in a practical range close to zero; and negative scale effects make batteries more suitable for small aircraft than large. Distributed propulsion minimizes power-to-weight ratio and maximizes propulsive efficiency, Elysian says. Credit: Elysian concept Maximum range is achieved by maximizing battery weight fraction. “The aircraft only cares how many kilograms of battery it carries per kilogram of aircraft. It doesn’t care how many kilograms it carries in an absolute sense,” de Vries says. “If I have 1 kg of battery or thousands, that does not say anything about how far the airplane flies. It’s about the percentage of batteries.” Battery weight fraction is maximized by minimizing empty weight fraction. “It’s really big, two or three times heavier than the turboprop. The wing is heavier, the landing gear is heavier, but the percentage is lower, and that’s the only thing that matters,” he says. “And that’s because of how things scale.” The weights of crew and cabin furnishings, for example, do not change. Elysian made several design choices to reduce weight and drag: distributed propulsion with more and smaller propellers reduces the power-to-weight ratio and increases propulsive efficiency; placing the batteries in the wing minimizes bending moment and weight; a relatively large and lightly loaded wing reduces takeoff power required; and a low-wing configuration reduces landing gear weight. “If you make a few smart design choices, like placing the batteries in the wing to make sure you have load alleviation, you end up with an aircraft that easily can have 45% batteries. And the side effect of this—and you must imagine a heavy aircraft with a small number of passengers—is you end up with an aircraft that has big wings but a small fuselage,” de Vries says. “You start approaching a flying-wing concept, and because of that you get a lift-to-drag ratio of 20-23. We were careful here because the handbook told us 23. Including heat exchangers, etc., we said that looks way too optimistic. But in recent results my colleagues at DLR got—and I’m not kidding—22.99,” he says. “We said, ‘This is not possible. We’re doing something wrong here.’ But you can get sort of a free L/D gift purely because of how the components scale. It has nothing to do with crazy tech or laminar flow. It’s purely because you have a flying wing,” he concludes. “The L/D is a free gift without any weird tech,” Wolleswinkel agrees. “Also, the empty weight fraction of 42% doesn’t require any weird tech. It is pretty similar to a Russian Ilyushin built in 1960. And that was not really high tech. This is just how things scale. If you add technology, it only gets better.” “The battery weight fraction looks ridiculous. How can you fly something that’s almost 50% batteries?” de Vries says. “But you can look at the old jet aircraft. Many of them had fuel weight fractions of 40-50%. The reason some widebodies have high fuel fractions is because they fly far. The reason why we have a high fuel fraction is because the batteries are so heavy. But you get the same kind of scaling effects.” The third misconception the team tackled was the reserves. “The reserves are a safety feature. It must always work, but it’s almost never used. That means that it doesn’t have to be efficient. It can emit carbon dioxide. We don’t care because it’s only required on less than 1% of flights,” de Vries says. “What you want is a reserve energy system that can cover your diversion, loiter and contingency but is as light as possible,” he continues. “Guess what? One of the lightest sources of energy is fuel. So we use batteries only for the main mission and carry a range extender or reserve energy system, a fuel-based turbogenerator that creates electricity only in an emergency. “We’re talking about something that weighs several tons and that’s not negligible,” de Vries notes. “But when we do the calculations, it ends up in the 42% empty weight. It’s so much lighter than trying to cover your reserves with batteries that it’s worth carrying that dead weight in the aircraft. And if you run these numbers through the same range equation, you get 830 km instead of 405 km, and the reserves are covered by something that’s already bookkept in the empty weight fraction.” As for battery technology, the team compared three scenarios: conservative, with 300-Wh/kg battery cells available today; first generation, with 450-Wh/kg cells expected to be available in 5-10 years; and second-generation with 550-Wh/kg cells that Elysian calculates would meet its vision of 1,000-km range. The analysis assumes a 25% packaging overhead, a maximum depth of discharge of 90% in case of emergency and retiring the battery when it has 90% capacity left, which corresponds to about 1,500 flight cycles. Batteries would be replaced every 6-12 months, and the maximum charging time is 45 min. “That is also the limiting power demand on the battery. The highest C rate that the battery must be able to provide or absorb is during charging. It’s about 1.4 C,” says de Vries. “On takeoff, it’s actually less because we have such a high energy capacity in total. The energy we extract per cell is really low. Compared to eVTOL applications, the power demands on the battery are quite modest.” The 300-Wh/kg conservative scenario results in a range of 500 km. Elysian’s design is based on the first generation. “We think that assuming 450 Wh/kg for a new cell in five years, six years plus, is realistic. We know there’s a risk, but we think that’s the number to work with where we get 800 km range,” he says. “Ideally, we think future battery-electric aircraft must be able to reach 1,000 km. That needs 550 Wh/kg. That’s something we haven’t seen on any realistic development road map, but lithium sulfur seems to be going in that direction. That’s a bit too risky to depend on, so we stick to the middle scenario,” de Vries adds. “The middle scenario is confirmed by the companies we have spoken to thus far. They don’t get too excited about these numbers and say they are impossible. This is on the five-year horizon of their road maps. If there’s one thing that bothers them, it is not the energy density—it’s the 1.4 C charging,” Wolleswinkel says. “That surprised us a bit. So charging might need 55 min. That could be the thing that changes, the charging time and not so much the range.” Elysian’s conceptual E9X seats 90 passengers, four-abreast. Maximum takeoff weight is 75,000 kg (165,350 lb.) compared with 73,500 kg for the A320neo, and the battery accounts for 46%. A 450-Wh/kg cell results in a 360-Wh/kg energy density at the pack level. Wingspan is 42 m (137.8 ft.)—36 m with the tips folded—compared with the A320’s 35.8 m. “The electric aircraft weighs as much as an A320 even though it flies less distance and has fewer passengers. But the grid energy consumption per passenger kilometer to power the aircraft is substantially lower,” de Vries says. The E9X’s grid energy consumption is less than 200 Wh/passenger kilometer, 80% lower than the A320neo assuming the narrowbody uses power-to-liquid synthetic kerosene (eSAF) produced using electricity. “With eSAF, for 1 kWh of useful energy at the shaft we need 6-8 kWh from the grid. With battery-electric, for every 1 kWh at the shaft we need about 1.5 kWh of energy from the grid.” The team strove for an electric aircraft design efficient at decarbonizing aviation and appealing to airlines. “In 2021, when Jaap formed the project team, we were driven by the fact that narrowbodies, not regional jets and turboprops, are the most used aircraft even on short ranges,” Wolleswinkel says. “We ended up at 90 passengers. And the reason is, if you want to operate in today’s markets, you need to be cost-competitive with narrowbodies,” he says. “Maybe you rely on carbon taxes or landing fees or some tax-free thing because you’re zero emissions. But at the end of the day, it must be profitable for the airlines to operate this aircraft. We believe that’s very difficult with a low passenger count.” To compete economically with narrowbodies, Elysian needs two things to happen. One is for air traffic control fees in Europe to be based not on aircraft maximum takeoff weight but on number of passengers, as they are in the U.S. “But this is not the biggest driver. We can work around that,” Wolleswinkel says. “The biggest thing is the price of fossil fuel must double to $1,800 per ton. That’s the order of magnitude we need. Be it by a carbon tax or another tax, we don’t care how, but doubling the price will be great news.” When Panta founded Elysian, it also committed €4 million ($4.4 million) in funding and brought in an external French investor. “They invested an amount based on milestones,” says Daniel Rosen Jacobson, Elysian co-CEO and chief business officer as well as director for aerospace and technology at Panta. “We are well-funded for this phase to the end of 2024. And we have started the preparation for our second funding round. We want to raise €50-60 million and will be starting in the first quarter,” he says. The program has been divided into two-year phases so funding can be raised in stages. “The total cost picture looks around €7 billion,” Rosen Jacobson says. Elysian is in contact with KLM, and through Fokker Services has access to Fokker operators such as Air Nostrum and Alliance Airlines. “It’s good to be part of the Panta group,” Wolleswinkel notes. “It provides us a source of seasoned engineers coming from the days of producing airplanes who keep our feet on the ground and also have a lot of detailed knowledge.” With those engineers and an outside advisor, Elysian has launched a project to draft a CS-25 certification plan for the E9X. The company is targeting entry into service between 2032 and 2035. “I think it is doable only given the fact we are a startup in an ecosystem that is knowledgeable of aviation,” he says. Panta also invested in a second startup, Fokker Next Gen, to pursue development of a single-aisle airliner with liquid-hydrogen combustion engines. Design is underway on modifying a Fokker 100 into a testbed for hydrogen propulsion with the goal of flying it in 2028 under the Dutch government-funded Aviation in Transition program. A new-design hydrogen aircraft is planned to fly in 2033, leading to entry into service in 2035. “From a Panta perspective, we see this as betting on two key technologies that are going to push innovation forward in sustainable aviation,” Rosen Jacobson says. “We don’t have the illusion that as Panta we’re even going to be running one aircraft development program, let alone two. There’s going to be a moment sooner rather than later in the next few years where Panta is no longer the largest shareholder in these projects. “But we feel we have a good structure as a company to bring in the knowledge and capital needed to take both to the next level,” he continues. “We think there is space for both of them because one is a shorter-range and pretty unique electrical aircraft that can really push that technology forward, and the other has potential for longer range and bigger aircraft to address a much bigger part of the problem. We’ll see what happens in the future and who will partner with each. But they are completely separate programs.” Discover the skies with Leonardo's AW609 - where speed and elegance meet at 316 mph! Interesting Engineering Published: Jan 11, 2024 01:00 PM EST In the world of civil aviation, the Leonardo AW609 stands as a testament to innovation and engineering excellence. This remarkable aircraft features a distinctive tilt-rotor system, powered by Pratt & Whitney turboshaft engines, making it a true pioneer in the field. Its ability to seamlessly transition from vertical takeoff to airplane mode at an astonishing speed of 316 mph is nothing short of awe-inspiring. But what sets the AW609 apart, and why is it generating so much excitement in the aviation industry? The Leonardo AW609 isn't your typical aircraft; it's a versatile marvel that caters to a wide range of clientele. From VIPs seeking luxury air travel to oil and gas operators requiring efficient transportation, and even discerning individuals with unique needs, the AW609 has it all. Its key selling point lies in its customizable cabin layouts, offering options like a VIP executive configuration, a nine-passenger setup, and even a mockup search and rescue model. The journey to bring tilt-rotor technology to civilians has been a long and arduous one, with roots dating back to the 1950s. Bell Helicopter's experimental XV-3 marked the initial steps in this ambitious endeavor, evolving into the XV-15 in 1977. However, it was Bell-Boeing's V-22 Osprey, born out of a Pentagon requirement in the 1980s, that became the world's first military tiltrotor aircraft. This groundbreaking achievement was not without its challenges, as tragic crashes during testing revealed the phenomenon known as vortex ring state (VRS). VRS presented a significant risk to the safety of tilt-rotor aircraft, prompting the implementation of enhanced safety measures. These measures included the development of VRS warning systems and rigorous pilot training programs, all aimed at mitigating the associated risks. With a price tag ranging from $20 to $30 million, the Leonardo AW609 represents a substantial investment in cutting-edge aviation technology. While the cost may seem high, the anticipation surrounding the first civilian tiltrotor aircraft on the market remains palpable. The aircraft's success is intrinsically linked to pilot training, especially in navigating challenges like VRS. However, there is a silver lining. The journey of the AW609 hints at a promising future for tiltrotor technology. As advancements continue to be made in both technology and safety protocols, the path appears clear for more tiltrotor aircraft to grace our skies in the years to come. The Leonardo AW609 is not just a pinnacle of innovation; it is a harbinger of a new era in civil aviation. In conclusion, the Leonardo AW609 represents the epitome of innovation and progress in the field of civil aviation. Its unique features, versatile configurations, and the legacy of tilt-rotor technology development make it a symbol of the future. With the commitment to safety and ongoing advancements, the AW609 paves the way for a new chapter in aviation, where the sky is no longer the limit. Bjorn’ s Corner: New aircraft technologies. Part 45. Continued Airworthiness By Bjorn Fehrm January 12, 2024, ©. Leeham News: We are discussing the different phases of a new airliner program. After covering the Design and Production, we now look at the Operational phase of a new airliner family. For the operational phase, the airplane must pass scrutiny for Continued Airworthiness. Today, we discuss the different means available to the Regulator, such as Airworthiness Directives ( ADs) and System Bulletins (SBs) to the OEM to make sure any detected issues get noticed and corrected. Figure 1. The Boeing MAX 9 Door Plug Emergency AD issued last week. Source: FAA. Airworthiness Directives During its operational life (which is around 25 years compared to the two years in production), there is regulatory oversight and certification of all aspects of the operation of the aircraft. We have a fresh example from last week with the Airworthiness Directive that the FAA issued for the Boeing 737 MAX 9. A possible manufacturing lapse to ensure four stop bolts were fitted had the rear plug door on the lefthand side of an Alaska 737 come loose and leave the aircraft during climb-out from Portland International Airport. The FAA issued an Emergency AD number 2024-2-51 on the 6th of January (Figure 1) to ground all US MAX 9s until inspections have verified they are safe to fly. The Emergency AD is the highest form of escalation in the Safety Monitoring and Reporting (14 CFR 21.3, 14 CFR Part 39) part of the FAA regulations. The different levels of actions demanded of the operator by the OEM and the Regulator are summarized in Figure 2. Figure 2. Safety Monitoring and Reporting (14 CFR Part 21.3, 39). Source; Boeing. The Airline, OEM, and the Regulator are obliged to continuesly monitor the delivered product in its operation. Depending on the safety risk, different actions are initiated if an issue is suspected or detected: • OEM Service Letter: The OEM sends the operator formal information about something to observe or know about the airplane. • OEM Service Bulletin: The OEM sends the operator a formal action to be performed on the aircraft within a specified time. It can be an inspection or modification that shall be performed with a prescribed modification kit. • FAA SAIB: The Regulator issues a Special Airworthiness Information Bulletin about the aircraft. • FAA NPRM: The Regulator issues information on a changed or new regulation that the operator will have to comply with. The Regulator accepts comments to the NPRM and then issues a regulation where input from comments has been considered. • FAA IAR: The Regulator issues a changed or new regulation that comes into force without a previous consultation via an NPRM. • FAA AD: The Regulator issues an Airworthiness Directive, AD, which stipulates an action for the operator to be performed before a time limit, or the aircraft loses its airworthiness. The Emergency AD, which was issued in the MAX 9 case, was an AD that required immediate action. As can be seen, the certification of an aircraft is the approval of the design. The production certificate is an approval that if the production is done according to the design certificate and with methods and procedures as stipulated in the production certificate, it’s considered safe for use when delivered. But from the instance of delivery, the airplane is subject to the above monitoring and can at any time receive an SB and AD that require further action to keep the aircraft certified as safe to fly. Part of the actions to keep the aircraft safe to fly is acted upon during maintenance. Many SBs and ADs are structured so these can be executed at the next hangar maintenance of the aircraft. We look deeper into the maintenance part of Continued Airworthiness in coming Corners. US Treasury Department issues guidelines around a new tax credit for sustainable aviation fuel The Treasury Department on Friday, Dec. 15, issued long-awaited guidance around tax credits for aviation fuel that reduces emissions of greenhouse gases compared with conventional fuel. BY DAVID KOENIG Updated 2:39 PM CST, December 15, 2023 The Biden administration released long-awaited guidance on Friday around tax credits for aviation fuel that reduces emissions of greenhouse gases compared with fuel made from crude oil. Some environmentalists expressed concern that the Treasury Department guidelines could allow credits for fuel made from corn and other crops that they consider poor choices because of the water and other resources needed to grow them. Midwest lawmakers and companies that produce corn-based ethanol praised the guidelines, although their enthusiasm could be short-lived. Congress approved the credits as part of President Joe Biden’s Inflation Reduction Act of 2022, which included provisions designed to boost cleaner energy. The credits are designed to increase the supply and bring down the current high price of sustainable aviation fuel, or SAF. Obstructed catalytic converter brings down experimental airplane By General Aviation News Staff January 8, 2024 · Photo courtesy of Spanish Fork Police Department The pilot reported that this was his first flight in the experimental amateur-built Zenith CH 750 Cruzer since he was involved in a landing incident that took place in the same airplane about 18 months earlier. Before the accident flight, he fast-taxied the airplane down the runway at the airport in Spanish Fork, Utah, to check the operability of the flight control system and engine controls and did not observe any anomalies. Shortly after takeoff when the airplane was about 5 nautical miles away from the airport, the pilot observed a slow decay in engine power and was suddenly unable to maintain altitude. He immediately started a left turn to return to the airport. He advanced the throttle to the full power setting but was unsuccessful in restoring power to the engine. According to a witness, the airplane entered a steep left turn at approximately 80 feet above ground level that quickly transitioned into a nose-down dive before it disappeared from view behind obstacles. The pilot reported that the airplane slowed during the turn and hit the roof of a building. The airplane sustained substantial damage to the fuselage and both wings, while the pilot sustained serious injuries. Post-accident examination of the airplane’s Honda VTEC automotive engine revealed that mechanical continuity was established throughout the rotating group, reduction gearbox, engine flywheel, crankshaft and accessory section as the crankshaft was manually hand rotated at the prop hub. Thumb compression was achieved at all four cylinders. Examination of the cylinders combustion chamber interior components using a lighted borescope revealed normal piston face and cylinder wall signatures, and no indications of a catastrophic engine failure. The ignition coils were tightly secured to their respective spark plugs and the ECU harnesses were connected to each coil. The coils were all normal in appearance and did not exhibit any debris or discoloration when visually inspected. All four of the spark plugs were gray in appearance, consistent with normal wear and the center electrodes were unremarkable. The engine was equipped with a catalytic converter that was used to convert toxic exhaust gases produced during combustion. The converter was comprised of a honeycomb ceramic substrate secured within the case that directed the exhaust gas airflow towards the tailpipe. Although the converter remained securely attached to the engine case, the bottom half of the internal ceramic substrate had broken into numerous large pieces. The pilot told investigators that following a landing incident 18 months before the accident, he noticed gray fragments coming from the tailpipe, which was bent as a result of impact damage. The pilot repaired the tailpipe by straightening it and re-welded it back to the catalytic converter. He reported he noticed small white particles come out of the tailpipe the first time he started the engine after the incident and then a piece that was the size of a quarter to a half-dollar came out on the second or third engine start. He did not inspect, repair, or replace the catalytic converter before the accident flight. According to a representative of the engine manufacturer who reviewed the engine examination report, as back pressure is required for the engine to function, an obstructed exhaust can affect engine back pressure and result in a partial loss of engine power. The engine kit manufacturer, and company responsible for retrofitting the automotive engine for aviation applications, also stated that an obstructed catalytic converter could prevent the engine from producing power. Probable Cause: A partial loss of engine power due to an obstructed catalytic converter, which most likely resulted from the pilot’s failure to properly repair or replace it after it was likely damaged during a previous incident. Contributing to the accident was the pilot’s failure to maintain adequate airspeed during the forced landing, which led to an exceedance of the airplane’s critical angle-of-attack and an aerodynamic stall. NTSB Identification: 104529. To download the final report. Click here. This will trigger a PDF download to your device. This January 2022 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others. Curt Lewis