What On Earth Is A Pickle Fork And Why Is It Adding To Boeing’s 737 Woes?

It’s fair to say that 2019 has not been a good year for the aircraft manufacturer Boeing, as its new 737 MAX aircraft has been revealed to contain a software fault that could cause the aircraft to enter a dive and crash. Now stories are circulating of another issue with the 737, some of the so-called “Pickle forks” in the earlier 737NG aircraft have been found to develop cracks.

It’s a concerning story and there are myriad theories surrounding its origin but it should also have a reassuring angle: the painstaking system of maintenance checks that underpins the aviation industry has worked as intended. This problem has been identified before any catastrophic failures have occurred. It’s not the story Boeing needs at the moment, but they and the regulators will no doubt be working hard to produce a new design and ensure that it is fitted to aircraft.

The Role of the Pickle Fork

For those of us who do not work in aviation though it presents a question: what on earth is a pickle fork? The coverage of the story tells us it’s something to do with attaching the wing to the fuselage, but without a handy 737 to open up and take a look at we’re none the wiser.

Fortunately there’s a comprehensive description of one along with a review of wing attachment technologies from Boeing themselves, and it can be found in one of their patents. US9399508B2 is concerned with an active suspension system for wing-fuselage mounts and is a fascinating read in itself, but the part we are concerned with is a description of existing wing fixtures on page 12 of the patent PDF.

A cross-section of the aircraft wing fixing, in which we've highlighted the role of the pickle forks. (Boeing)
A cross-section of the aircraft wing fixing, in which we’ve highlighted the role of the pickle forks. (Boeing)

The pickle fork is an assembly so named because of its resemblance to the kitchen utensil, which attaches firmly to each side of the fuselage and has two prongs that extend below it where they are attached to the wing spar.

For the curious engineer with no aviation experience the question is further answered by the patent’s figure 2, which provides a handy cross-section. The other wing attachment they discuss involves the use of pins, leading to the point of the patented invention. Conventional wing fixings transmit the forces from the wing to the fuselage as a rigid unit, requiring the fuselage to be substantial enough to handle those forces and presenting a problem for designers of larger aircraft. The active suspension system is designed to mitigate this, and we’d be fascinated to hear from any readers in the comments who might be able to tell us more.

We think it’s empowering that a science-minded general public can look more deeply at a component singled out in a news report by digging into the explanation in the Boeing patent. We don’t envy the Boeing engineers in their task as they work to produce a replacement, and we hope to hear of their solution as it appears.

[via Hacker News]

[Header image: AMX Boeing 737 XA-PAM by Jean-Philippe Boulet CC-BY 3.0]

New Space Abort Systems Go Back To The Future

Throughout the history of America’s human spaceflight program, there’s been an alternating pattern in regards to abort systems. From Alan Shepard’s first flight in 1961 on, every Mercury capsule was equipped with a Launch Escape System (LES) tower that could pull the spacecraft away from a malfunctioning rocket. But by the first operational flight of the Gemini program in 1965, the LES tower had been deleted in favor of ejection seats. Just three years later, the LES tower returned for the first manned flight of the Apollo program.

Mercury LES Tower

With the Space Shuttle, things got more complicated. There was no safe way to separate the Orbiter from the rest of the stack, so when Columbia made its first test flight in 1981, NASA returned again to ejection seats, this time pulled from an SR-71 Blackbird. But once flight tests were complete, the ejector seats were removed; leaving Columbia and all subsequent Orbiters without any form of LES. At the time, NASA believed the Space Shuttle was so reliable that there was no need for an emergency escape system.

It took the loss of Challenger and her crew in 1986 to prove NASA had made a grave error in judgment, but by then, it was too late. Changes were made to the Shuttle in the wake of the accident investigation, but escape during powered flight was still impossible. While a LES would not have saved the crew of Columbia in 2003, another seven lives lost aboard the fundamentally flawed Orbiter played a large part in President George W. Bush’s decision to begin winding down the Shuttle program.

In the post-Shuttle era, NASA has made it clear that maintaining abort capability from liftoff to orbital insertion is a critical requirement. Their own Orion spacecraft has this ability, and they demand the same from commercial partners such as SpaceX and Boeing. But while all three vehicles are absolutely bristling with high-tech wizardry, their abort systems are not far removed from what we were using in the 1960’s.

Let’s take a look at the Launch Escape Systems for America’s next three capsules, and see where historical experience helped guide the design of these state-of-the-art spacecraft.

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MCAS And The 737: When Small Changes Have Huge Consequences

When the first 737 MAX entered service in May of 2017, it was considered a major milestone for Boeing. For nearly a decade, the aerospace giant had been working on a more fuel efficient iteration of the classic 737 that first took to the skies in 1967. Powered by cutting-edge CFM International LEAP engines, and sporting modern aerodynamic improvements such as unique split wingtips, Boeing built the new 737 to have an operating cost that was competitive with the latest designs from Airbus. With over 5,000 orders placed between the different 737 MAX variants, the aircraft was an instant success.

But now, in response to a pair of accidents which claimed 346 lives, the entire Boeing 737 MAX global fleet is grounded. While the investigations into these tragedies are still ongoing, the preliminary findings are too similar to ignore. In both cases, it appears the aircraft put itself into a dive despite the efforts of the crew to maintain altitude. While the Federal Aviation Administration initially hesitated to suspend operations of the Boeing 737 MAX, they eventually agreed with government regulatory bodies all over the world to call for a temporary ban on operating the planes until the cause of these accidents can be identified and resolved.

For their part, Boeing maintains their aircraft is safe. They say that grounding the fleet was done out of an “abundance of caution”, rather than in direct response to a particular deficiency of the aircraft:

Boeing continues to have full confidence in the safety of the 737 MAX.  However, after consultation with the U.S. Federal Aviation Administration (FAA), the U.S. National Transportation Safety Board (NTSB), and aviation authorities and its customers around the world, Boeing has determined — out of an abundance of caution and in order to reassure the flying public of the aircraft’s safety — to recommend to the FAA the temporary suspension of operations of the entire global fleet of 371 737 MAX aircraft.

Until both accident investigations are completed, nobody can say with complete certainty what caused the loss of the aircraft and their passengers. But with the available information about what changes were made during the 737 redesign, along with Boeing’s own recommendations to operators, industry insiders have started to point towards a fault in the plane’s new Maneuvering Characteristics Augmentation System (MCAS) as a likely culprit in both accidents.

Despite the billions of dollars spent developing these incredibly complex aircraft, and the exceptionally stringent standards their operation is held to, there’s now a strong indication that the Boeing 737 MAX could be plagued with two common issues that we’ve likely all experienced in the past: a software glitch and poor documentation.

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When New Space Loses Out To NASA Pragmatism

You’ve got to admit, things have been going exceptionally well for SpaceX. In the sixteen years they’ve been in operation, they’ve managed to tick off enough space “firsts” to make even established aerospace players blush. They’re the first privately owned company to not only design and launch their own orbital-class rocket, but to send a spacecraft to the International Space Station. The first stage of their Falcon 9 rocket is the world’s only orbital booster capable of autonomous landing and reuse, and their Falcon Heavy has the highest payload capacity of any operational launch system. All of which they’ve managed to do at a significantly lower cost than their competition.

United Launch Alliance Atlas V

So it might come as a surprise to hear that SpaceX recently lost out on a lucrative NASA launch contract to the same entrenched aerospace corporations they’ve been running circles around for the last decade. It certainly seems to have come as a surprise to SpaceX, at least. Their bid to launch NASA’s Lucy mission on the Falcon 9 was so much lower than the nearly $150 million awarded to United Launch Alliance (ULA) for a flight on their Atlas V that the company has decided to formally protest the decision. Publicly questioning a NASA contract marks another “first” for the company, and a sign that SpaceX’s confidence in their abilities has reached the point that they’re no longer content to be treated as a minor player compared to heavyweights like Boeing and Lockheed Martin.

But this isn’t the first time NASA has opted to side with more established partners, even in the face of significantly lower bids by “New Space” companies. Their decision not to select Sierra Nevada Corporation’s Dream Chaser spaceplane for the Commercial Crew program in 2014, despite it being far cheaper than Boeing’s CST-100 Starliner, triggered a similar protest to the US Government Accountability Office (GAO). In the end, the GAO determined that Boeing’s experience and long history justified the higher sticker price of their spacecraft compared to the relative newcomer.

NASA has yet to officially explain their decision to go with ULA over SpaceX for the Lucy mission, but in light of what we know about the contract, it seems a safe bet they’ll tell SpaceX the same thing they told Sierra Nevada in 2014. The SpaceX bid might be lower, but in the end, NASA’s is willing to pay more to know it will get done right. Which begs the question: at what point are the cost savings not compelling enough to trust an important scientific mission (or human lives) to these rapidly emerging commercial space companies?

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The Photo Lab That Flew To The Moon

When planning a trip by car these days, it’s pretty much standard practice to spin up an image of your destination in Google Maps and get an idea of what you’re in for when you get there. What kind of parking do they have? Are the streets narrow or twisty? Will I be able to drive right up, or will I be walking a bit when I get there? It’s good to know what’s waiting for you, especially if you’re headed someplace you’ve never been before.

NASA was very much of this mind in the 1960s, except the trip they were planning for was 238,000 miles each way and would involve parking two humans on the surface of another world that we had only seen through telescopes. As good as Earth-based astronomy may be, nothing beats an up close and personal look, and so NASA decided to send a series of satellites to our nearest neighbor to look for the best places to land the Apollo missions. And while most of the feats NASA pulled off in the heyday of the Space Race were surprising, the Lunar Orbiter missions were especially so because of how they chose to acquire the images: using a film camera and a flying photo lab.

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Hackaday Links: May 28, 2017

Boeing and DARPA are building a spaceplane. Right now it’s only a press release and a few concept images, but it looks like this is an air-launched system kind of like a Tristar/Pegasus, only much higher and completely unmanned. It’s a ton and a half to low earth orbit, with a goal of 10 flights in 10 days.

Up in Albany? There’s a new hacker con happening in a few weeks. Anycon is a hacking, infosec, and cyber security conference happening June 16 & 17th in Albany, NY. The organizers of this con ([Chris], and his company Leet Cybersecurity) are loosely modeling this con after Derbycon. [Dave Kennedy] of TrustedSec will be attending as the keynote speaker.

GOOD NEWS! [Casey Neistat] is under investigation by the FAA. [Casey Neistat] is the YouTuber that flies drones right in the middle of the Hudson River corridor, and is a menace to general aviation around NYC.

This is neat. The Supplyframe Design Lab is the Hackaday Mothership right in the middle of Pasadena where we host our designers in residence, host a few meetups, and slowly fill every cubic inch of space with either dust or tools. The Design Lab just won a design award. You can check out the ‘design’ part of the Design Lab here, but keep in mind it will never be that clean ever again.

Here’s an interesting Twitter to follow. Alitronik is a curator of the weird and wonderful cheap crap that can be found on AliExpress. Need an Altera Cyclone dev board? Here you go. A desk-mountable OLED inspection microscope? Done. A seven dollar Tesla coil? Dude, you can totally fit this inside a hat.

[Drygol] had a nice old Commodore C16 with a broken TED chip. A shame, really. He did what anyone would do: put a C64 motherboard in the case for a fancy stealth upgrade.

Is the great crowdfunded 3D printer boom over? Some would say that ship sailed after dozens of 3D printer crowdfunding projects failed to deliver, or delivered very low-quality machines. These people were wrong. This Polaroid-branded 3D printing pen might not get funding. A year ago, this project would have been funded on day one. There would have been writeups in The Verge on how Polaroid is turning the corner after decades of wasted opportunities. Now, the Crowdfunded 3D printer boom is finally over.

The Hackaday crew was at the Bay Area Maker Faire last weekend and holy crap did we have a blast. Everyone came to the meetup on Saturday except for the fire marshall. The secret OSHPark bringahack on Sunday was even more impressive. We also saw a Donkey Car capable of driving around a track autonomously, but the team behind it didn’t have their work up on the Internet at the time.

Boeing’s New Microlattice, Now The Lightest “Metal” Ever

Mr McGuire: I just want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr McGuire: Are you listening?
Benjamin: Yes, I am.
Mr McGuire: Plastics.

You may recognize the above dialog from the movie “The Graduate” starring a young [Dustin Hoffman], whose character is getting advice about what line of work he should get into after university. Maybe Mr McGuire’s advice should have been “Microlattice.”

If you take a step back for a moment and survey the state of materials, you’ll see that not much has changed in the last 50 years. We’re still building homes out of dead trees, and most cars are still made out of iron(although that is starting to change.) It’s only been just recently has there been advances in batteries technology – and that only came about with the force of a trillion-dollar mobile phone industry behind it. So we’re excited by any new advance we see, and Boeing’s new “Microlattice” tickles our fancy.

Boeing isn’t giving away the recipe just yet, but here is what we know: it’s 99.99% empty space, making it extremely light. It’s so light, that if you drop it, it floats to the ground. It’s also compressible, giving it the ability to absorb energy and spring back (you can see it in action in the after the break.) It’s made by creating a sacrificial skeletal structure the shape of the final lattice, then coating that template with nickel-phosphorus alloy. The temporary inner structure is then etched away, leaving a “microlattice” of tiny interconnected hollow rods with wall thickness of about 100 nanometers. Of course it doesn’t take a rocket surgeon to figure out why Boeing is interested in such materials, they are eye it as an extremely lightweight building material for planes and spacecraft.

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