Arianespace: Cause of Vega launch failure “human error”
According to Arianespace officials, today’s failure of their Vega rocket likely occurred because of “human error” in the installation of cables.
Engineers concluded that cables leading to thrust vector control actuators on the upper stage were inverted, apparently a mistake from the assembly of the upper stage engine, according to Roland Lagier, Arianespace’s chief technical officer. The thrust vector control system pivots the upper stage engine nozzle to direct thrust, allowing the rocket to control its orientation and steering.
The cabling problem caused the engine to move its nozzle in the wrong direction in response to commands from the rocket’s guidance system. That resulted in the rocket losing control and tumbling just after ignition of the upper stage engine around eight minutes after launch.
Lagier characterized the inverted cables as a “human error,” and not a design problem.
The next obvious question is the source of the error. The answer was not revealed, I think partly because of the number of contractors involved in building that upper stage:
The AVUM upper stage’s structure is produced by Airbus, and the Ukrainian rocket contractors Yuzhnoye and Yuzhmash supply the AVUM stage’s main engine, which consumes hydrazine and nitrogen tetroxide propellants. Avio, the Vega rocket’s Italian prime contractor, oversees final integration of the AVUM upper stage.
The goal of the investigation that will now follow will be to point that source among these contracts, and how their interaction might have contributed to it.
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According to Arianespace officials, today’s failure of their Vega rocket likely occurred because of “human error” in the installation of cables.
Engineers concluded that cables leading to thrust vector control actuators on the upper stage were inverted, apparently a mistake from the assembly of the upper stage engine, according to Roland Lagier, Arianespace’s chief technical officer. The thrust vector control system pivots the upper stage engine nozzle to direct thrust, allowing the rocket to control its orientation and steering.
The cabling problem caused the engine to move its nozzle in the wrong direction in response to commands from the rocket’s guidance system. That resulted in the rocket losing control and tumbling just after ignition of the upper stage engine around eight minutes after launch.
Lagier characterized the inverted cables as a “human error,” and not a design problem.
The next obvious question is the source of the error. The answer was not revealed, I think partly because of the number of contractors involved in building that upper stage:
The AVUM upper stage’s structure is produced by Airbus, and the Ukrainian rocket contractors Yuzhnoye and Yuzhmash supply the AVUM stage’s main engine, which consumes hydrazine and nitrogen tetroxide propellants. Avio, the Vega rocket’s Italian prime contractor, oversees final integration of the AVUM upper stage.
The goal of the investigation that will now follow will be to point that source among these contracts, and how their interaction might have contributed to it.
Readers!
Please consider supporting my work here at Behind the Black. Your support allows me the freedom and ability to analyze objectively the ongoing renaissance in space, as well as the cultural changes -- for good or ill -- that are happening across America. Fourteen years ago I wrote that SLS and Orion were a bad ideas, a waste of money, would be years behind schedule, and better replaced by commercial private enterprise. Only now does it appear that Washington might finally recognize this reality.
In 2020 when the world panicked over COVID I wrote that the panic was unnecessary, that the virus was apparently simply a variation of the flu, that masks were not simply pointless but if worn incorrectly were a health threat, that the lockdowns were a disaster and did nothing to stop the spread of COVID. Only in the past year have some of our so-called experts in the health field have begun to recognize these facts.
Your help allows me to do this kind of intelligent analysis. I take no advertising or sponsors, so my reporting isn't influenced by donations by established space or drug companies. Instead, I rely entirely on donations and subscriptions from my readers, which gives me the freedom to write what I think, unencumbered by outside influences.
You can support me either by giving a one-time contribution or a regular subscription. There are four ways of doing so:
1. Zelle: This is the only internet method that charges no fees. All you have to do is use the Zelle link at your internet bank and give my name and email address (zimmerman at nasw dot org). What you donate is what I get.
2. Patreon: Go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation.
3. A Paypal Donation or subscription:
4. Donate by check, payable to Robert Zimmerman and mailed to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
You can also support me by buying one of my books, as noted in the boxes interspersed throughout the webpage or shown in the menu above.
The simple solution would be individually shaped plugs.
Then no one could ever mix them up again.
Exactly, which makes it a design induced human error.
Pzatchok, the problem with “foolproof” is that there is always a more impressive fool. For example, the famous Proton failure, where a factory worker couldn’t get the “only fit one way” attitude sensors to fit the way he thought they were supposed to go, so he “persuaded” them in to place with a hammer, upside-down. And that booster promptly did some nice aerobatics and smashed into the ground in a glorious fireball.
Cross-connected controls have plagued aeronautics since the Wright Brothers! Many years ago I was the brand new Chief Flying Instructor for a gliding club, and instituted the practice of positive control checks by two people, one the pilot and the other holding the control surfaces, before every flight.
The students were not a problem, but some of the older members who had been on the stick longer than I had been on Earth had some bad habits. One was not confirming the proper direction of control surface movement… just give the stick a wiggle and if the outside guy felt the surface move, you were good to go!
Now in almost all manufactured glideR’s, it is not possible to connect controls backward, but one member had a home-built with rudder cables that could be switched. After a maintenance session during which the rudder was removed, sure enough they got reversed, and he had a very short, very sideways sideways takeoff that wiped away the landing gear.
He was unhurt, but when he had to explain to the rest of us what had happened, and why the preflight had not prevented the problem, I am pretty sure he wished he was dead!
A similar error caused a crash of an F117 Nighthawk back in the day:
“The first crash of a production F-117A occurred on April 20, 1982 during its first test flight, flown by Lockheed test pilot Ltc Bob Ridenhauer. The flight control system on the aircraft had been assembled incorrectly at the factory in Burbank.“
While embarrassing, at least this IS a simple problem to fix and avoid going forward, so good for Arianespace. And as with RVD’s pre-flight story it’s a great lesson to all in the industry to beware the human condition and sweat these details. So in the end this will hopefully inspire better design for assembly, better assembly procedures, and better post assembly verification tests..
It also strikes me that flight control software can and should ultimately get smarter to deal with issues like this. I remember a story from Chuck Yeager’s autobiography where he avoided a crash once because when his flight controls locked up once (due to an incorrect mechanical assembly as it happens), he saved himself by un-intuitively reversing the controls instead of persisting to try and force them to function as expected. This in fact freed up a mechanical bind in the linkage so he was able to regain control and recover.
In a case such as this upper stage problem, given that modern flight controls update position 100s to 1000s of times per second I expect it is quite possible to enable dynamic control adjustments that would detect issues like this and then correct for them automatically much as a gifted musician can reverse how they hold an instrument and still play it.
I recall another F-117 crash during an air show flyby, caused by the improper re-attachment of a wing after maintenance. It fell off. Pilot ejected okay. IIRC, they had been wondering why the plane was out of trim… duh.
Ah but David that was not a simple human error.
That was a on purpose. He went out of his way to make something fit.
I don’t build aircraft yet but I do rebuild old cars. I have found that if your have to force something or remake something, stop and find out why first.
Assuming this was because of crossed electrical connectors the blame goes straight to the designers. The key way in nearby connectors of same configuration is always clocked differently from its neighbors to prevent things like this. Murphy Proof is paramount in any design.
I agree with Jerry and others. The designers could and should have used keyed connectors to help prevent such errors. However, the error was made by the technician, who should have done the job right, and was missed by the inspector, whose job is to find such errors. I do not know why there was not a test to make sure that the workmanship was good.
From the article:
The design had the cables wired correctly, and the error was elsewhere. The corrective action should include improving assembly, inspection, and test processes, but it may also recommend keyed connectors in this and other locations. Early in my career, a mentor drummed into our heads that quality must be designed in because it cannot be inspected into a poor design.
As for the improperly installed accelerometers in the Proton rocket, that was a failure on multiple levels. The tech was not well trained, and the inspection and test levels failed to find the error.
Around 1990, a colleague of mine had just come back from the Rocky Mountains with photographs of newly discovered “Sprites” (he didn’t discover them). Orange flashes that look a bit like carrots appear above lightning flashes, and he had photographs of some. Lost on this Vega launch vehicle was the Taranis satellite, which was going to study this phenomenon as well as another flash of blue jets that appear above the sprites.
I am particularly sorry to learn of the loss of this particular experiment.
I once worked with another scientist who was studying another phenomenon associated with lightning. Electrons seem to be emitted from lightning into space, and these electrons follow the Earth’s magnetic field lines, bouncing back and forth between the Northern and Southern Hemispheres. This phenomenon was also studied by the Gallileo satellite as it orbited Jupiter.