Battery-charged trouble

The incident was quickly linked to the malfunction or failure of the aircraft’s forward main battery. It was the second incident within a week involving a battery generating smoke or acrid smells as they partially melted and sprayed their electrolyte contents across the electronics bays of the aircraft.

ANA immediately announced it was temporarily ceasing 787 operations and Japan Airlines (JAL) – the operator of the first 787 to suffer a battery fire – made a similar announcement shortly after. By the afternoon of January 17, the Federal Aviation Administration (FAA) had issued an Emergency Airworthiness Directive (EAD) suspending all 787 operations in North America.

The EAD focused on the electrical architecture of the aircraft, specifically the safety of the lithium-ion polymer battery. But what that issue specifically is remains unclear at the time of going to press.

The FAA determined that “the battery failures resulted in release of flammable electrolytes, heat damage, and smoke” and that there was sufficient enough risk of onboard fire or other electrical issues to ground the aircraft. An investigation initiated by the National Transportation Safety Bureau (NTSB) was subsequently supported by the Japan Transport Safety Board (JTSB), Boeing and airworthiness authorities of other 787-operating nations.

Ultimately aviation safety regulators in all countries with 787 operators, including Chile, Ethiopia, Europe, India, Poland and Qatar followed the FAA’s lead suspending 787 operations for an indefinite period.

Boeing’s 787-8 becomes only the third new-design commercial jet to be grounded for safety reasons. Its dream hasn’t been entirely shattered, but any ground the company’s beleaguered image had recovered after prolonged delays and development issues slid away as quickly as the passengers evacuating its Dreamliner in Tomkatsu that morning.

Timeline

The 787 programme has suffered a series of incidents during the aircraft’s test and operational life, though several of these issues including a cracked windshield, minor fuel leak and brake irregularities being common operational issues experienced by most new designs being introduced to regular service. However, during its certification period and the aircraft’s first 15 months in service, the 787 has suffered ongoing problems related to its batteries and electrical system:
2006 – A 787 battery undergoing prototype equipment testing exploded during testing in Arizona, burning down the test facility.

November 2010 – Test aircraft ZA002 suffered an inflight electrical fire, temporarily grounding the flight test program.

December 4 2012 – United Airlines UA1146 diverted enroute due to an electrical malfunction. Multiple error messages, with flight crew requesting firefighters be vigilant of fuselage aft of wing area upon touchdown.

December 13 2012 – Qatar Airways grounded one of its 787 aircraft on landing in Doha, following an inflight electrical fault.

December 17 2012 – United Airlines identifies an electrical issue in a second 787.

January 7 2013 – Japan Airlines 787 JA829J suffered an incident during turnaround in Boston after a nonstop flight from Tokyo, in which smoke filled the cabin and aft cargo compartment as a result of the APU battery in the rear electrical bay catching fire.

January 16 2013 – All Nippon Airlines (ANA) 787 JA804A operated Tomkatsu when the crew received battery fault indications and detected an acrid, burning smell in the cockpit. The aircraft was evacuated on landing.

Boeing, the FAA or NTSB as yet have been unable to trace these issues back to a single cause or fault in the electrical system.

The 787 is the first aircraft to support fully electric architecture, this replaces pneumatic bleed air systems used to drive cabin pressure and onboard systems, and operates at a significantly higher capacity 1.5MW than any other aircraft.

To support these systems the 787 requires a battery that can efficiently produce enough energy, and currently only less-stable lithium Ion polymer batteries offer that capability.

After years of testing the batteries were ultimately approved by the regulator with special conditions, and demonstrated assurances that the system could isolate and shutdown the batteries in this instance, and inflight fire would be contained.

Investigation

The FAA’s response to the 787 incidents has come under intense scrutiny worldwide. Questions have been raised as to why in the first instance the FAA allowed the aircraft to continue to fly after announcing the safety review. There has also been considerable criticism of FAA Administrator Michael Huerta, who was so emphatic in saying the 787 was safe after he had announced a review, but before the NTSB had concluded an investigation.

Responding to the FAA’s handling of the 787 situation following the JAL incident in Boston, US Transportation Secretary Ray LaHood, who has subsequently stepped down from his position, claims: “We did what we did, we did the right thing … on the day we announced the planes were safe, they were.”

The investigation has revealed that ANA has replaced ten batteries on its fleet of 17 787s and United Airlines has replaced three batteries on its fleet of six 787s since entry into service.

Boeing CEO James McNerney has defended the use of lithium-ion batteries, with no evidence yet produced that suggests the need to switch back. While he admits replacement cycles for some airlines have been higher than anticipated he said: “The replacement cycle that we’ve been experiencing there has been for maintenance reasons…there is no incident we’re aware of where a battery has been replaced due to any kind of safety concern.”

By January 23, the NTSB had confirmed the battery in each incident had not overcharged. The 787s batteries consist of eight rechargeable cells. Investigation of the flight data recorders on both aircraft has shown neither APU battery exceeded its 32.2 volt design maximum.

The NTSB report stated: “Investigators have also examined several other components removed from the airplane, including wire bundles and battery management circuit boards”. Test plans had also been developed for components removed from each aircraft including “battery management unit (for the APU battery), the APU controller, the battery charger and the start power unit.” A failure of any of these components can lead to a sequence of reactionary events inside the battery.

The abundant energy of lithium ion batteries, also makes them efficient fire starters. Thermal runaway triggered by a short-circuit, overcharging or collateral domino of effects causes an increase in temperature of the battery. If the temperature passes 80°C the thin layer separating electrolytes from the carbon anode breaks down. Passing 110°C the polymer separator melts causing a short circuit between electrodes. This reaction releases flammable gases causing pressure inside the cell to increase. As the reaction continues, ignitable metallic lithium forms. The battery becomes highly exothermic passing 200°C as the metal oxide cathode material breaks down. An explosion and fire ensues which spreads to other cells as they heat up or are punctured by debris.

While some analysts have criticised the lack of fire suppressants in either electrical bays of the 787, it is likely they would be of little use. Chief 787 project engineer Mike Sinnett said: “You have to assume it’s not going to go out. You have to assume that it’s going to go and that it’s going to expend all of its energy”.

By the end of week two of the grounding, Japan’s transport ministry official Shigeru Takano announced that investigations show the battery manufacturer GS Yuasa is not to blame. It is now clear the battery suffered from thermal runaway and short-circuiting, but ruled out the manufacturer or charging issues narrows a possible cause down to intermittent faults which are much harder to determine. It is these faults that remain the focus of attention.

Sinnet explained Boeing’s design philosophy for the 787 battery system. “I design a cell to not fail and then assume it will and then ask the ‘what-if’ questions. And then I design the batteries that if there is a failure of one cell it won’t propagate to another. And then I assume that I am wrong and that it will propagate to another and then I design the enclosure and the redundancy of the equipment to assume that all the cells are involved and the airplane needs to be able to play through that.”

In this instance the issue did propagate, but the 787’s redundancy didn’t take over as it was engineered to. By late January, the JTSB and NTSB had announced the battery fire was not the result of overcharging and efforts had now moved to the batteries’ associated components with the NTSB seeking the assistance of the US Naval Surface Warfare Centre. Experienced in using lithium-ion technology since the 1970s, the centre ran tests on the undamaged forward battery from the Japan Airlines 787 at the group’s Carderock Division, in West Bethesda. The NTSB reported that these tests reported no anomalies in any of the eight cells in the undamaged batteries.

Japan Airlines Chairman Masaru Onishi said: “It seems like Boeing’s investigation hasn’t reached the stage where they can come to us and reassure us about anything yet. Their investigation hasn’t progressed to the stage where they can identify the root cause of this problem”.

For now there is no end in sight for the investigation, as Boeing moves to begin testing components of the wider electrical system which interface with the battery.

A350 programme

Airbus remains committed to using lithium-ion batteries on the A350, but remains open-minded about the implications of the investigation on its own programme, stating: “Airbus will carefully study recommendations that come out of the 787 investigation and evaluate whether they apply to the A350.”

Thus far Airbus has made it clear it sees no reason to change the electrical architecture of the A350.

At a press conference shortly after the 787’s grounding Airbus CEO, Fabrice Brégier offered his support for his competitor, saying “I firmly believe that it is the role of new aircraft to fly. I don’t ever want to bet on building Airbus’s success on the difficulties of a competitor.”

Uncharted territory

The 787 programme is by no means a disaster – innovation was always a difficult business.

Like the A380, the 787 represented a technological leap forward in the way aircraft are designed, built and flown. And every revolution has its problems, exemplified by the A380, 747, Comet and Lockheed Electra.

These aircraft all suffered significant problems following their entry into service. Who remembers the 747 having significant engine problems? All were eventually rectified. It is part of the natural development of aircraft that changes are made, and redesigns worked in, and changes made again. The number of airworthiness directives in worldwide circulation for all aircraft types demonstrates this. Indeed, the more resources pushed into engineering the 787 now, the better it will become.

No customer is yet to cancel a 787 order as a result of the recent incidents and none is likely too. In fact current operators have been stoic in their support of Boeing and the 787.

Ethiopian Airlines CEO Tewolde Gebremariam said: “The Dreamliner is a highly capable and safe aircraft,” he said. “However, like any new technology aircraft entering into service it is normal to encounter some minor bugs here and there.” Both British Airways and Thomson Airways in the UK have also reiterated their public support for the aircraft.

Closer to home and Japan Airlines Chairman Onishi and Qantas CEO Alan Joyce have commended Boeing’s proactive communication with customers updating them on the investigation. Joyce said: “We are always confident about what Boeing is doing. They are very proactive with daily calls to the operations people and regular calls with the senior management”.

As with the DC-10 and more recently the A380 after QF32, it’s no surprise travellers will book away from the 787 for a period. But they will come back. They have loved the 787 to date. With the high level of regulatory and developmental scrutiny, airlines and travellers alike are going to end up with an exceptionally safe next generation aircraft. It’s a matter of when – not if – that happens.