What happens to these pilots? Are they grounded with the aircraft or do they go back to their previous a/c for the time being?

 

Each contract may be slightly different as to performance guarantees; however, I think the larger issue with the Dreamliner is how Boeing handles what has become a PR nightmare. With many production delays, cost overruns, etc.,there are concerns by the airlines. With a serious safety issue, those concerns may take a back seat to an aircraft that initially may be a safety hazard.

I think Boeing shot themselves in the foot when they went to a "save weight at all costs" design philosophy, at least in the electrical system batteries. The decision to switch from a proven, albeit heavier, ni-cad battery to the lithium-ion batteries may prove to be very expensive with possible cancelled or lost orders or certainly significant performance penalties paid. The perception by the flying public public that the aircraft has "serious safety problems" alone will be very costly ! Had the Korean Air aircraft been in flight when the fire broke out, that perception would have become reality.

Y'all be careful out there

 

I hope Boeing does the right thing. This is not the time to roll out the PR machine. The best way to win back the public and prove their product is safe is by clear information as to the cause and how they will fix it. They can do it. They have some of the best engineers in the biz. Granted it is another set back, I am sure they will solve the problem quickly.

I just find it odd that what ever the cause it happened. From what I read, there are 4 safety systems around the LiIon batteries to prevent this. So it will be interesting to see what the root cause was.

 

Why jump two generations of battery back when one will do?
Absolutely no reason to entertain NiCad batteries when NiMH will do.
Besides, most (no-mechanical) Li-Ion hazards are related to the charging circuits and not the battery itself (knowing its limitations).
Why would anyone consider NiCad over NiMH ,,, in any environment?

 

I'd rather go back to lead acid. NiCads and MiMH can both go into an overcharged/overdrawn/overheated state that can lead to venting or fire. Lead acid generally do not (without actually throwing them into a fire).

Also, the nice thing about lead acid is they tend to fail slowly and have a more measurable output drop (they give warning when they are getting weak while NiCads and NiMHs do not).

 

Lithium ion batteries are a huge fire hazard. You cannot carry them on passenger airplanes if you're shipping them. They are "Cargo Aircraft Only" hazmat.

So Boeing decides to put 2 (!) 49 kg lithium ion batteries on their plastic airplane. You tube "lithium ion battery fires" for an eye opener. At least two cargo airplanes have burned to the ground because of lithium ion battery fires.

Great thinking there.

 

Charge density for NiMH is only 50% or so that of Li-ion, so presumably one would need 200 kg worth of battery... NiMH also has more self-discharge properties and would constantly need to be trickle-charged during any standby periods.

The engineers thought it would be within acceptable safety limits, and I'd bet with some modification they will ultimately be right, but it is still really scary to think about those batteries underneath the plane.

As somebody with an engineering background before medicine, took a nice look at the energy density:

100 kg of lithium battery would have about 15,000 W-h of capacity, or 54 megajoules. 54 million joules.

For reference, a stick of dynamite (200g) has about 1 megajoule.

It is energy equivalency of more than 50 sticks of dynamite... obviously, the ability to get this energy out quickly is somewhat more limited, but certain failure scenarios are concerning; have a look at this: (posted it before)

https://www.youtube.com/watch?v=pizFsY0yjss

Of course this is also concern for any electric vehicles in a crash. Time and experience will tell.

 

That's what we did...all Ni batteries replaced with Pb over the last decade.

I'm sure Li batteries can be made safe enough for aviation use, at some significant cost, but not when the manufacturing is outsourced to certain latin american countries.

 

Having been an engineer in the aircraft parts business at one point, I find it stunning that combustibility tests were goofed during thousands of hours of testing on these batteries. No doubt a story will emerge from the inquiry into supplier testing. RTCA/ DO-160 is the document that spells out necessary compliance testing for airborne equipment such as these lithium batteries, and it is pretty hard to miss a lot.

 

The T-38 had Lead-acid batteries when I was a student. Some years later, the Air Force converted them to NiCad.

Today?

Back to lead-acid, for about 10 years or more. I'm not sure if it was a thermal runaway issue, or the "sudden-death" nature of NiCads. (No warning they are about to fail).

Point is, sometimes engineering mistakes are made, and they have to be corrected....even if the correction is going back to the tried-n-true.