Long Uptime Makes Boeing 787 Lose Electrical Power

jones_supa writes: A dangerous software glitch has been found in the Boeing 787 Dreamliner. If the plane is left turned on for 248 days, it will enter a failsafe mode that will lead to the plane losing all of its power, according to a new directive from the US Federal Aviation Administration. If the bug is triggered, all the Generator Control Units will shut off, leaving the plane without power, and the control of the plane will be lost. Boeing is working on a software upgrade that will address the problems, the FAA says. The company is said to have found the problem during laboratory testing of the plane, and thankfully there are no reports of it being triggered on the field.

Comments

Have you tried turning it off and on again?

[Anonymous Coward]

Finally!

IT support advice that's useful!

Control unit runs at 100 Hz?

[photonic]

I guess this might be due to a 32-bit signed integer being incremented at 100 Hz: 2^31 / 24 / 3600 / 100 = 248.5 days.

Re:Control unit runs at 100 Hz?

[TheRealHocusLocus]

I guess this might be due to a 32-bit signed integer being incremented at 100 Hz: 2^31 / 24 / 3600 / 100 = 248.5 days.

Yes, the moment the big bird would shut down was correctly prognosticated by the Connecticut Yankee in King Arthur's Court. While testing a crowbar circuit he ran out of time and came to while munching on phattened feasant at Medieval Times, in a daze of King Arthur. He noticed an unused carrion bit, and realized that birds of prayer who managed the King's affairs were hard-sinewed to pluck quills for signing and always discarded the carrion bit. He caught the underflow was heralded by the people and befriended by the King, who set him to work hacking the Code of Chivalry and cracking the Y1K problem. In that time there were only punch cards and knights on horseback only had a resolution of 1 bit, so tournaments were long the fields were full of snakes, to avoid spooking the horses the knights would dismount and cleave them with sword, leaving half-adders strewn about. It was Pendragon who had built the famous Round Table with 12 seats, two complete I Chings, where Arthur and the knights would drop in and punch out binary sums in a rudimentary form of patty-cake, which inspired the mechanical circular adder of later years. The Yankee's refinement was a 13th chair left unoccupied to mark the betrayal of Judas, and also to serve as a carrion bit.

There is a great deal more about gum-powder and 99 cent gamut of Steampunk-driven micro commerce, a Debian release called 'Guinevere' and a whole lotta Lancelot, but time is fun when you're having flies.

Re:Oh come on.

[IndigoZulu]

It could be the overflow of a counter of 10ms intervals. There are 86400 seconds per day, so 8640000 10ms intervals per day ... 2147483648 / 8640000 = 248.55

It is probably a non-issue.

[140Mandak262Jamuna]

The company is said to have found the problem during laboratory testing of the plane, and thankfully there are no reports of it being triggered on the field.

The spokesman continued, "The battery would have caught fire long before that integer overflow."

Re:Very unlikely to be triggered in the field

[confused one]

If it ever happened on a plane, then it means that the maintenance was intentionally skipped. If they reach 248 days of continuous operation then a number of significant maintenance cycles have been skipped (some 23-25 inspection / maintenance cycles that generally require shutting down the electrical system). The generators in question are attached to the engines. The engines have a overhaul schedule that is shorter than 248 days of continuous operation. If they managed to reach this point, then the major maintenance cycles have been skipped and the engines are long overdue for a tear down inspection and overhaul. Any plane which could reach this point, 248 days of continuous operation missing all of the required maintenance; this is not a plane (or an airline for that matter) which anyone should be flying on.

Enough of this

[confused one]

This story is being way overblown. Yes, it's a bug. Yes, it should be fixed. However...

248 days of continuous operation is well past the scheduled major maintenance for the aircraft. By this point, a 787 would have to go through many minor maintenance cycles which would have required shutting down the electrical system. In addition, loss of all 4 generators would not result in a loss of vehicle because there are batteries, an APU (a backup generator) and Ram Air Turbines (RATs), generators that deploy from the wing if the APU won't start. To have to rely on any of these would not make for a good day for the pilots; but, they would certainly provide the necessary power to safely land the aircraft at the nearest airport. They might even be able to continue on and finish their flight if they successfully reset the generators.

This is not the OMG Planes Are Going to Fall From The Sky! event the media is making it out to be.

Re:queue the..

[dunkelfalke]

Only theoretical, though. Windows 9x would crash long before reaching this uptime.

Re:If Boeing believed in software QA....

[Required Snark]

You have no idea what you are talking about. All FAA certified aircraft software has to conform to the DO-178B / DO-178C standard. The standard imposes design, testing, process and documentation standards that are extremely demanding.

QC isn't just a department or a step in the release process, it is built into the full life cycle of the software. Safety is the goal, and the requirement for good practice starts at the beginning of the process, with the requirement documents.

For example, there are five levels of error severity defined from A to E. E has no impact on safety and A is catastrophic, where a crash could occur. The level of software test and validation depends on the severity level.

The number of objectives to be satisfied (eventually with independence) is determined by the software level A-E. The phrase "with independence" refers to a separation of responsibilities where the objectivity of the verification and validation processes is ensured by virtue of their "independence" from the software development team. For objectives that must be satisfied with independence, the person verifying the item (such as a requirement or source code) may not be the person who authored the item and this separation must be clearly documented. In some cases, an automated tool may be equivalent to independence. However, the tool itself must then be qualified if it substitutes for human review.

Your inability to find a "QC" position is because you don't know the structure of aerospace software development and have no idea of the job titles or terminology used to describe the standards used. You are projecting your lack of knowledge into a inconceivable lapse of competence on the part of Boeing and the FAA. In what universe would there be no software safety requirements for the civilian aircraft industry? All you have shown is that you are ignorant and have a basic lack of common sense.