Well this is certainly a troubling development in your excellent continued coverage of this, Chuck. Considering the number of battery incidents that occurred so quickly in succession, I would say this was a gross underestimation on their part. I would expect more from a company like Boeing, especially when lives are at stake. It's not like they started making airplanes yesterday.
I'm sure that NTSB will implement a test with a "thermal runaway battery state" to check B787 for the worst scenario again.
There was a lot of information about the battery but nothing about the plane maintenance procedures. The Li-ion batteryes require complex electronics control which are in standby or switched off during " while the aircraft was being cleaned after a flight".
It also seems that more questions keep coming up about these incidents and the initial testing/certification. At this point, I would be very worried at Boeing as this seems to be an issue that will not go away with some simple changes!
Thank you Charles for keeping us at DN updated regularily!
I think the NTSB and Boeing would get a whole lot more frequent flyer mileage with the general public if they gave just a bit more disclosure on the cause and effect of the fire. Driving nails thru cells to sim shorts and desktop analysis of fault probabilities doesn't go too far with road warriors. Either excess load or unregulated charge made those batteries fail unless they really are unreliable chemistry. They weren't that old. So either the electrons going inny or outy weren't being properly managed and that's outside the battery; not where the fire happened. The longer the answer isn't focused on, the more people lose confidence in the whole design. Not fair but reputation and confidence in equipment is 98% perception and only 2% direct experience.
When our Li-Ion battery failed in our aftermarket radio several years ago, many of the symptoms were the same as with the 787... much heat, vapor, venting, smoke... These were NOT the result of poor charging, overloading of the circuit... none of that! You say that shorting the cell with a nail is not a satisfactory test... What do you suggest is a more appropriate test? Easy to armchair quarterback this... For us, it turned out that the nail test was a fairly accurate predictor of the results of a short circuit... And gee, guess what? Our issue turned out to be the result of an internal cell short circuit... Really, the 787 issue sounds exactly like ours, only a scale difference... I would be looking very carefully at dendrite growth causing out-gassing internal to the cell, making the cell swell. internal parts can then slide and cause unforseen shorts and it is all downhill from there!
Most machine design engineers will survey existing component manufacturers for standard linear guide products, limiting what they can do with their designs. Using extruded aluminum profile guides can customize machine designs while shrinking the bill of materials.
Practically all electronic devices today contain metals that may
be coming from conflict-ravaged African countries. And political pressures will increasingly influence how these minerals are sourced and used in products.
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.