787 Battery Issues

[CanadianEh]

Update as of today found on AvHerald (http://avherald.com/h?article=45c377c5/0023&opt=0)

On Dec 1st 2014 the NTSB released their final report concluding the probable causes of the occurrence of JA829J in Boston were:

The National Transportation Safety Board determines that the probable cause of this incident was an internal short circuit within a cell of the auxiliary power unit (APU) lithium-ion battery, which led to thermal runaway that cascaded to adjacent cells, resulting in the release of smoke and fire. The incident resulted from Boeing’s failure to incorporate design requirements to mitigate the most severe effects of an internal short circuit within an APU battery cell and the Federal Aviation Administration’s failure to identify this design deficiency during the type design certification process.

The NTSB reported that one of the eight battery cells suffered an internal short circuit as result of design deficiencies, which led to a thermal runway propagating to other cells (which Boeing had considered but ruled out as a possibility) resulting in the fire, that fortunately occurred on the ground.

The NTSB stated: "Because the APU and main lithium-ion batteries installed on the 787 represented new technology not adequately addressed by existing regulations, the Federal Aviation Administration required that Boeing demonstrate compliance with special conditions to ensure that the battery was safe for use on a transport category aircraft. Boeing's safety assessment of the battery, which was part of the data used to demonstrate compliance with these special conditions, was insufficient because Boeing had considered, but ruled out, cell-to-cell propagation of thermal runaway (which occurred in this incident) but did not provide the corresponding analysis and justification in the safety assessment. As a result, the potential for cell-to-cell propagation of thermal runaway was not thoroughly scrutinized by Boeing and FAA engineers, ultimately allowing this safety hazard to go undetected by the certification process."

In addition the NTSB identified a number of design and manufacturing concerns:

- GS Yuasa’s cell manufacturing process allowed defects that could lead to internal short circuiting, including wrinkles and foreign object debris, to be introduced into the Boeing 787 main and auxiliary power unit battery.

- The thermal protections incorporated in large-format lithium-ion battery designs need to account for all sources of heating in the battery during the most extreme charge and discharge current conditions and protect cells from damage that could lead to thermal runaway.

- More accurate cell temperature measurements and enhanced temperature and voltage monitoring and recording could help ensure that excessive cell temperatures resulting from localized or other sources of heating could be detected and addressed in a timely manner to minimize cell damage.

- Determining the initial point of self-heating in a lithium-ion cell is important in establishing thermal safety limits.

- Boeing’s electrical power system safety assessment did not consider the most severe effects of a cell internal short circuit and include requirements to mitigate related risks, and the review of the assessment by Boeing authorized representatives and Federal Aviation Administration certification engineers did not reveal this deficiency.

- Boeing failed to incorporate design requirements in the 787 main and auxiliary power unit battery specification control drawing to mitigate the most severe effects of a cell internal short circuit, and the Federal Aviation Administration failed to uncover this design vulnerability as part of its review and approval of Boeing’s electrical power system certification plan and proposed methods of compliance.

- Unclear traceability among the individual special conditions, safety assessment assumptions and rationale, requirements, and proposed methods of compliance for the 787 main and auxiliary power unit battery likely contributed to the Federal Aviation Administration’s failure to identify the need for a thermal runaway certification test.

- Stale enhanced airborne flight recorder data could impede future accident and incident investigations by delaying the full understanding of the recorded data; stale data could also impact aircraft safety if an operator’s maintenance activities were based on these data.

- The poor audio recording quality of the enhanced airborne flight recorder could impede future aircraft investigations because the recorded conversations and other cockpit sounds might be obscured.

The NTSB released 15 safety recommendations to the FAA, 2 safety recommendations to Boeing and 1 safety recommendation to the manufacturer of the battery in addition to the safety recommendations released so far.

[Liquid Charlie]

I was not aware that lithium ion batteries were certified for aircraft use -- in fact I am suspecting a typo here and the batteries are nicads -- I base this on the explosive chance of lithium ion batteries and all the work put into having them declared hazmat -- but I have been wrong before -- once -- many years ago -- lmfaooooooo -- kidding

[whodareswins]

I was not aware that lithium ion batteries were certified for aircraft use -- in fact I am suspecting a typo here and the batteries are nicads

Batteries on board the 787 are indeed Lithium Ion.

[Liquid Charlie]

Well it seems that the battery technology of the future was not allowed to develop to the point of use -- it is obviously not completely ready -- I can remember the growing pains with nicads it took several years to sort them out with many returning back to lead acid -- I will actually consider buying an electric car once the batteries are perfected and allow 1000km between charges -- plus they haul ass

I stand corrected ---

[Longtimer]

NTSB details issues with 787 flight and data recorder
By: JON HEMMERDINGERWASHINGTON DC Source: in 5 hours
The US National Transportation Safety Board (NTSB) is recommending that regulators address newly-disclosed problems with the Boeing 787’s cockpit voice and data recorder.

In a report released 1 December, the safety agency has urged the Federal Aviation Administration (FAA) to “take appropriate measures to correct any problems found” with the 787’s General Electric-made “enhanced airborne flight recorders” (EAFR), which record flight data and cockpit voices.

The report also urges the FAA to require operators of 787s to update maintenance manuals with guidance that would prevent so-called “stale data” from being using for maintenance activities.

The NTSB uncovered problems with the 787’s EAFRs during its investigation into the 7 January 2013 lithium-ion battery fire aboard a Japan Airlines 787 in Boston.

The 1 December report attributes the fire to a thermal runaway resulting from faulty oversight and manufacturing issues.

But the investigation was hindered by problems with the aircraft’s two EAFRs, which recorded seemingly valid data after the source stopped providing valid data, says the NTSB.

It notes that the system is designed so that a “flight data acquisition function” receives data from various sources, then sends the data at scheduled intervals to the EAFR’s flight data recorder function.

However, if the flight data acquisition function does not receive new data, it continues to transmit the last-received data, which can generate what the NTSB calls “stale data”, according to the report.

The system flags some, but not all, of the data that might be stale, it adds.

“The recording of stale data impacted the early stages of this investigation because significant additional effort was required to identify stale data when possible as well as those parameters for which it was not possible to determine whether the data samples were stale,” says the board.

“This process delayed the NTSB’s complete understanding of the recorded data,” it adds.

Neither Boeing or GE immediately responded to a request for comment from Flightglobal.

The NTSB report says the fault could also mislead aircraft maintenance personnel, resulting in decisions based on incorrect data.

“The safe operation of an aircraft could be impacted if stale EAFR data were unintentionally used by an operator to assess and resolve maintenance issues,” writes the NTSB.

The board also found problems with the EAFR’s cockpit voice recorder function, although voice recordings were not central to its investigation.

“During the airborne portion of the flight that was captured on the recording, almost all of the individual crew conversations were completely obscured by the ambient cockpit noise,” says the NTSB.

The report recommends that the FAA require Boeing to improve the quality of the microphones and that the agency issue specific recorder-related guidance.

[CID]

I base this on the explosive chance of lithium ion batteries and all the work put into having them declared hazmat

There are a few different formulations of L-Ion batteries. Some are quite dangerous when ruptured but the rechargeable types used in aircraft are not the same as the ones you see in Youtube videos of batteries bursting into flames. Having said that, there are safer formulations of L-Ion batteries than the type used in the 787.

I can remember the growing pains with nicads it took several years to sort them out with many returning back to lead acid

The big problem with Ni-Cad was the refusal of the operators to consider how serious a thermal runaway was. Ni-Cads were used because the lead-acid technology of the day couldn't put the same amount of power with rapid re-charge in the same space as a ni-cad. The technology finally caught up with the high density VRLA (Valve Regulated Lead Acid). They are maintenance free for their operational life (about 2 or 3 years) but they can also suffer thermal runaways.

[plhought]

I remember talking about this battery issue with a visiting engineer from Concorde.

They had bid on the 787 battery project with a derivative of a sealed-lead acid battery they make for many US Navy aircraft. They were told it was too heavy for the performance required and offered no substantial weight savings vs. previous technology etc etc.

6-7 years later nice 'light' Lithium batteries are catching fire in the back of the airplane. Damn near writes a brand new plane off. So Boeing rather than re-engineer a proven battery solution with known and safe technology, engineer a complex and heavy containment/control apparatus which easily negates the weight and performance benefits of Li-Ion batteries and still leaves you with a missing battery should one begin to cook...

[Shadowfax]

I base this on the explosive chance of lithium ion batteries and all the work put into having them declared hazmat

There are a few different formulations of L-Ion batteries. Some are quite dangerous when ruptured but the rechargeable types used in aircraft are not the same as the ones you see in Youtube videos of batteries bursting into flames. Having said that, there are safer formulations of L-Ion batteries than the type used in the 787.

There are many types of "lithium" batteries period - not just individual "lithium-ion". As usual the media does a superb job of differentiating.....and educating the masses - pylots included apparently.

http://batteryuniversity.com/learn/arti ... ithium_ion

[Liquid Charlie]

I for one am always needing further education -- damn not so lone ago I could not even spell pylottt but all arguments and education aside the facts are still there -- boeing choose a insufficiently tested technology and had an incident -- why you might ask -- well likely for the same reasons the dc10 had such a dramatic and unfortunate introduction to service - hopefully this is fixed before someone pays the ultimate price --

[Alberta_x51]

It's a tragic reality that batteries were put into aircraft without proper design protections be them of any form since they were
first put in aircraft.

The latest 787 reports on their battery show a delinquent design that failed to have the minimum level of acceptable safety.

Each cell needs in a higher risk type of battery, be it Nicad or lithium, needs individual monitoring on all aspects of the cell's health especially temperature.

It is generally one cell in a battery that goes into thermal escalation, and the warning signs can provide enough time to first bring the battery under control and interim use or to be shut off and or cooled or hit with Co2 where its needed.

I've yet to see or hear about any new lithium battery that has those kinds of features that can be reasonably predicted will
happen.

That means battery size will increase and a small increase in wt for the same performance.