PPRuNe Forums - View Single Post - 787 Batteries and Chargers - Part 1
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Old 19th Feb 2013, 18:20
  #744 (permalink)  
RR_NDB
 
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No powered plane without fire*

Hi,

Dtype:

Aeroplanes have been living with fire (in their engines) for over 100 years. This COULD be a precedent for permitting (inadvertent) fires in another power source, the batteries, provided it was as well contained as the engine combustion???


You introduce an important point: We operate (and live with) machines with contained fires. What is not accepted is:

A company introduce a new design (under special "conditions") and in an interval of days two planes suffer incidents with HEAT, SMOKE and FIRE (BOS). The second (TAK) was bound to be much worse. A short circuit saved Boeing discharging the battery thus avoiding an in flight fire in a compartment with important electronics. (This is a model posted and commented earlier)

The technical answer is:

A dependable and safe battery (one that not is transformed suddenly in a dragon: heat, smoke and even fire) is absolutely required. A battery (that could caught fire) well contained with "normal" MTBF will be certified.

Problem now is not only technical. Became almost a "political" issue with not small technical challenges.

(*) No powered plane without fire. There are powered planes (electric motor) with these batteries.

saptzae:

IMHO will draw less than 7.5KW (300A x 25V).
Good estimate

These LiCoO2 cells are de-rated to 4.025V, and should not show any anomalies after a few months / a few hundred flight hours.
What really happened? Just random? Coincidence?

FlightPathOBN:

In the re-design, go back from 32V to 24V..
32 V was designed due BDM (diode module)

ITman:

I am sure that these issues were considered in Mr B's design,...
We detected errors so, we are not so confident on that.

Hi_Tech

2. Is it just a coincidence that we have 2 fire incidents in one month.
One fire incident in BOS (Logan) TAK had heat, smoke and hot chemical spray (battery lost 5 Kg)

3. Surely the battery would have gone through a rigorous testing before manufacture and it is difficult to imagine that there were no problems at all with this compact design of a highly volatile chemistry.
We donīt know. This is a Testability issue.

TURIN:

Someone at Boeing got their wires crossed.
The disconnection seems not just between engineers at Seattle and Chicago high rocks.

cockney steve:

Some bean-counter's being grossly overpaid for a stupendous level of incompetence!


green granite:

It then has the ability to recharge in a relatively short period of time so that it is available for the critical backup role that it plays during flight.
Logical question!

Last edited by Jetdriver; 19th Feb 2013 at 19:14.
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