A Peek Inside A 747 Fuel Gauge

June 11, 2023 by Matthew Carlson 28 Comments

It isn’t that often that we civilians get the chance to closely examine the fantastic internals that make up the modern marvels of avionic engineering. Luckily for us, [Glen] got his hands on a 747 fuel gauge and tore it down for our benefit. Not only does he tear it down, but he also builds a controller to display values.

Unlike your typical automotive fuel gauge that reports the distance from the top of the tank to the fuel level, this gauge reports the number of pounds of fuel. The fact that the indicator pictured above can go all the way to 95,000 pounds of fuel hits home the sheer scale of the fuel tanks on a 747 compared to your Volvo. Of course, where this gets interesting is the teardown with the metal sleeve removed. A 400 HZ AC servo motor moves the pointer and counter through the gearing with the help of a feedback potentiometer. The resistance tolerance is only 3%, as there are adjustment knobs on the back. But the linearity spec is only 0.06%, putting this part in a different grade from most pots.

One of the indicators was in worse shape than the others, so [Glen] got to work tapping into the internals of the gauge to drive the motor directly. A custom AC power supply repurposed from another project provided power, and a Raspberry Pi Pico was the PID controller. For [Glen], it isn’t all roses. Unfortunately, a noisy spot around 22,500 prevents accurate placement around there.

The code is up on GitHub, and we love having a gauge on the desk to show whatever value we like. If you are curious about more 747 instruments, this retro control unit might interest you.

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Bad Week For Boeing: Reports Of Third Engine Failure Causes Emergency Landing In Moscow

February 26, 2021 by Mike Szczys 34 Comments

Early Friday morning a Boeing 777 performed an emergency landing in Moscow, according to Russian media. The Interfax news agency cites an anonymous source who claims the landing was caused by an engine failure on a flight from Hong Kong to Madrid. According to the Hong Kong civil aviation department this was a cargo flight. So far no injuries have been reported.

Two damaged fan blades from UA328, a Boeing 777 that returned safely to DIA shortly after takeoff

Engine failures happen, pilots train for them, and our airport infrastructure is setup to accommodate emergency landings like this. However, the timing of this reported failure is notable. This is the second engine failure on a 777 within a week, and the third to occur in a Boeing aircraft.

Shortly after takeoff on Saturday, February 20th, a United Airlines flight bound for Hawaii made an emergency landing after suffering a catastrophic failure of the right engine. The event was widely shared on social media, you likely saw the video from a passenger inside the Boeing 777-200 that shows the damaged engine on fire — if you haven’t you really should. There was also damage on the ground due to falling debris. This prompted Boeing to launch inspections of all 777-200s, and soon afterwards the NTSB published photos of the damaged engine. No injuries have been reported.

Two days later, on February 22nd, a Boeing 747-400 cargo plane operated by Longtail Aviation suffered an engine failure over the Netherlands, dropping parts that reportedly injured two people on the ground. This is a different model of aircraft but uses a Pratt & Whitney PW4000, in the same family as the Pratt & Whitney PW4070/4090 on the United 777-200.

Reports of this morning’s emergency landing in Moscow will need to be verified and investigated, and we have not seen confirmation on what type of engine the Rossiya Airlines B777-300ER used. For comparison the 777-300ERs of the United fleet and the 777-300ERs operated by Emirates both use General Electric engines rather than Pratt & Whitney models, so it is likely the Rossiya aircraft also had a GE engine.

The fact that the flights were all able to make safe landings is a testament to the redundant engineering of these aircraft. CNET did a deep dive into last Saturday’s engine failure and notes that it was an Extended-range Operations Performance Standards (ETOPS) aircraft capable of flying long distances on a single engine — necessary if an aircraft needed to make it half-way to Hawaii on one engine for an emergency landing. They also report on two other Pratt & Whitney PW-4000 engine failures in 2018 and ~~2000~~ 2020, although as mentioned before, today’s incident likely didn’t involve an engine from this maker.

[Main image source: B777-300 by Maarten Visser CC-BY-SA 2.0]

Phantom Express: The Spaceplane That Never Was

March 27, 2020 by Tom Nardi 12 Comments

Even for those of us who follow space news closely, there’s a lot to keep track of these days. Private companies are competing to develop new human-rated spacecraft and assembling satellite mega-constellations, while NASA is working towards a return the Moon and the first flight of the SLS. Between new announcements, updates to existing missions, and literal rocket launches, things are happening on a nearly daily basis. It’s fair to say we haven’t seen this level of activity since the Space Race of the 1960s.

With so much going on, it’s no surprise that not many people have heard of the XS-1 Phantom Express. A project by the United States Defense Advanced Research Projects Agency (DARPA), the XS-1 was designed to be a reusable launch system that could put small payloads into orbit on short notice. Once its mission was complete, the vehicle was to return to the launch site and be ready for re-flight in as a little as 24 hours.

Alternately referred to as the “DARPA Experimental Spaceplane”, the vehicle was envisioned as being roughly the size of a business jet and capable of carrying a payload of up to 2,300 kilograms (5,000 pounds). It would take off vertically under rocket power and then glide back to Earth at the end of the mission to make a conventional runway landing. At $5 million per flight, its operating costs would be comparable with even the most aggressively priced commercial launch providers; but with the added bonus of not having to involve a third party in military and reconnaissance missions which would almost certainly be classified in nature.

Or at least, that was the idea. Flight tests were originally scheduled to begin this year, but earlier this year prime contractor Boeing abruptly dropped out of the program. Despite six years in development and over $140 million in funding awarded by DARPA, it’s now all but certain that the XS-1 Phantom Express will never get off the ground. Which is a shame, as even in a market full of innovative launch vehicles, this unique spacecraft offered some compelling advantages.

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A Honeycomb Patching Robot Powered By Arduino

March 3, 2020 by Tom Nardi 13 Comments

No, it’s not the kind of honeycomb you’re probably thinking of. We’re talking about the lightweight panels commonly used in aerospace applications. Apparently they’re rather prone to dents and other damage during handling, so Boeing teamed up with students from the California State University to come up with a way to automate the time-consuming repair process.

The resulting machine, which you can see in action after the break, is a phenomenal piece of engineering. But more than that, it’s an impressive use of off-the-shelf components. The only thing more fascinating than seeing this robotic machine perform its artful repairs is counting how many of its core components you’ve got laying around the shop.

Built from aluminum extrusion, powered by an Arduino Due, and spinning a Dewalt cut-off tool that looks like it was just picked it up from Home Depot, you could easily source most of the hardware yourself. Assuming you needed to automatically repair aerospace-grade honeycomb panels, anyway.

At the heart of this project is a rotating “turret” that holds all the tools required for the repair. After the turret is homed and the condition of all the cutting tools is verified, a hole is drilled into the top of the damaged cell. A small tool is then carefully angled into the hole (a little trick that is mechanical poetry in motion) to deburr the hole, and a vacuum is used to suck out any of the filings created by the previous operations. Finally a nozzle is moved into position and the void is filled with expanding foam.

Boeing says it takes up to four hours for a human to perform this same repair. Frankly, that seems a little crazy to us. But then again if we were the ones tasked with repairing a structural panel for a communications satellite or aircraft worth hundreds of millions of dollars, we’d probably take our time too. The video is obviously sped up so it’s hard to say exactly how long this automated process takes, but it doesn’t seem like it could be much more than a few minutes from start to finish.

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2019: As The Hardware World Turns

December 27, 2019 by Tom Nardi 31 Comments

Well, this is it. The end of the decade. In a few days the 2010s will be behind us, and a lot of very smug people will start making jokes on social media about how we’re back in the “Roaring 20s” again. Only this time around there’s a lot more plastic, and drastically less bathtub gin. It’s still unclear as to how much jazz will be involved.

Around this time we always say the same thing, but once again it bears repeating: it’s been a fantastic year for Hackaday. Of course, we had our usual honor of featuring literally thousands of incredible creations from the hacking and making community. But beyond that, we also bore witness to some fascinating tech trends, moments that could legitimately be called historic, and a fair number of blunders which won’t soon be forgotten. In fact, this year we’ve covered a wider breadth of topics than ever before, and judging by the record setting numbers we’ve seen in response, it seems you’ve been just as excited to read it as we were to write it.

To close out the year, let’s take a look at a few of the most popular and interesting stories of 2019. It’s been a wild ride, and we can’t wait to do it all over again in 2020.

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Boeing’s Starliner Fails To Reach Space Station

December 20, 2019 by Tom Nardi 89 Comments

After a decade in development, the Boeing CST-100 “Starliner” lifted off from pad SLC-41 at the Cape Canaveral Air Force Station a little before dawn this morning on its first ever flight. Officially referred to as the Boeing Orbital Flight Test (Boe-OFT), this uncrewed mission was intended to verify the spacecraft’s ability to navigate in orbit and safely return to Earth. It was also planned to be a rehearsal of the autonomous rendezvous and docking procedures that will ultimately be used to deliver astronauts to the International Space Station; a capability NASA has lacked since the 2011 retirement of the Space Shuttle.

Unfortunately, some of those goals are now unobtainable. Due to a failure that occurred just 30 minutes into the flight, the CST-100 is now unable to reach the ISS. While the craft remains fully functional and in a stable orbit, Boeing and NASA have agreed that under the circumstances the planned eight day mission should be cut short. While there’s still some hope that the CST-100 will have the opportunity to demonstrate its orbital maneuverability during the now truncated flight, the primary focus has switched to the deorbit and landing procedures which have tentatively been moved up to the morning of December 22nd.

While official statements from all involved parties have remained predictably positive, the situation is a crushing blow to both Boeing and NASA. Just days after announcing that production of their troubled 737 MAX airliner would be suspended, the last thing that Boeing needed right now was another high-profile failure. For NASA, it’s yet another in a long line of setbacks that have made some question if private industry is really up to the task of ferrying humans to space. This isn’t the first time a CST-100 has faltered during a test, and back in August, a SpaceX Crew Dragon was obliterated while its advanced launch escape system was being evaluated.

We likely won’t have all the answers until the Starliner touches down at the White Sands Missile Range and Boeing engineers can get aboard, but ground controllers have already started piecing together an idea of what happened during those first critical moments of the flight. The big question now is, will NASA require Boeing to perform a second Orbital Flight Test before certifying the CST-100 to carry a human crew?

Let’s take a look at what happened during this morning’s launch.

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

September 30, 2019 by Jenny List 89 Comments

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]