Fire danger from Honeywell ELTs may exist on aircraft beyond the 787

After last month's fire involving the emergency locator transmitter (ELT) on a Ethiopian 787 in London, the FAA and other regulatory agencies around the world have ordered that these ELTs be deactivated, inspected, or removed. The ELT on that aircraft was manufactured by Honeywell, which has produced about 6,000 ELTs for use in aircraft around the world.

A recent airworthiness directive from Transport Canada airworthiness directive (AD), which takes effect on 26 August 2013, has gone a step further, requiring that Honeywell ELTs on a variety of aircraft be inspected by the end of 2013. Transport Canada stated that the AD was issued as a precautionary measure to address the possibility of a fire due to wiring installation discrepancies of the ELT system. Depending on the outcome of the AAIB investigation, Transport Canada may revise the AD or mandate additional corrective actions.

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(click here for full AD)

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Affected aircraft
Previous directives from the UK and US authorities were limited to the 787. This latest Canadian AD covers a much wider range of aircraft, including the Boeing models 717, 727, 737, 747, 757, 767, 777, 787, MD11, MD80 and MD90; and the Airbus models A300, A310, A320, A321, A330, A340 and A380.

Other countries following Canada's lead
The European Aviation Safety Agency (EASA) has also adopted the Canadian AD. According to various media reports, the FAA also plans to issue a similar AD for US-registered aircraft.

Why ELT fires are potentially catastrophic
As was described in some detail in an earlier AirSafeNews.com article on the Ethiopian 787 event, fire caused by an ELT would be particularly worrisome because these devices, unlike other systems such as engines and auxiliary power units, do not come equipped with fire suppression systems, and they are typically located in parts of the aircraft that are inaccessible from the cabin. In the event of an in flight fire, it may not be possible to put out the fire, and it may spread to other parts of the aircraft.

In the event of an onboard fire, typical emergency procedures include landing at the closest suitable airport, but if the fire occurred if the aircraft were far from a a suitable airport, which would be the case for many transatlantic or transpacific flights, passengers and crew could be exposed to large amounts of smoke and fumes for a significant amount of time.

In such a situation, emergency oxygen systems may not have been useful for passengers since these systems are typically designed to supply passenger with a combination of oxygen from the emergency oxygen system and ambient air from the cabin, including any smoke or fumes that are present in the cabin.

Disturbing implications of the recent 787 fire in London

The recent 787 fire at Heathrow Airport in London appeared at first to be a relatively minor event with a limited impact beyond the aircraft involved. However, when the investigative authority, the Air Accidents Investigation Branch (AAIB) of the UK, released its preliminary report on the event, the recommendations that were made implied that the problem had the potential to be far more serious had it occurred in flight.

Key findings of the AAIB report
The initial AAIB report, stated that the fire damage coincided with the location of the emergency locator transmitter (ELT), and although the AAIB did not state that the ELT was the source of the fire, the aircraft was unpowered at the time of the fire, and no other aircraft systems in the area contained an energy source capable of starting a fire. The ELT is designed to operate without any power from the aircraft's electrical system, and is powered by a set of chemical batteries using a Lithium-Manganese Dioxide (LiMnO2) composition. This kind of battery represents a different technology from the lithium-ion batteries associated with the fires on two different 787 aircraft in January 2013.

What the fire fighters encountered in London
According to the AAIB, when fire fighters entered the aircraft through the front left door (the 787 has four pairs of doors), they encountered thick smoke and had to open at least two other cabin doors to clear the smoke. They were unable to extinguish the fire with a handheld Halon fire extinguisher, and had to forcibly remove a ceiling panel and use water from a fire hose to put out the fire. While this was apparently not an complicated procedure for the fire crews on the ground, it could have been an entirely different situation had this occurred in the air.

Visible external damage to 787 in London

Why a fire in flight would have been much more dangerous
The AAIB investigation is ongoing, and the organization has not identified the ELT as the source of the fire. However, if the ELT turns out to be the source of this particular fire, it raises the very disturbing possibility that this kind of fire could have occurred not just on the ground in an empty aircraft, but also while the aircraft was in the air. This could potentially be a far more serious event in the air for the following reasons:

• Unlike on the ground, opening one or more doors to evacuate smoke is not an option in flight,
• While there are handheld fire extinguishers in the cabin that flight attendants can use in an emergency, equipment or other tools suitable for removing ceiling panels are not typically available to cabin crew.
• While the fire fighters in the London incident had access to water hoses to put out the fire, no such option would be available to an airborne 787.
• in the event of an onboard fire, typical emergency procedures include landing at the closest suitable airport, but since the 787 often flies on routes that are an hour or more from a suitable airport, passengers and crew could be exposed to large amounts of smoke and fumes for a significant amount of time.
• Emergency oxygen systems may not have been useful for passengers since these systems are typically designed to supply supplemental oxygen, in other words, passenger would be breathing a combination of oxygen from the emergency oxygen system and ambient air from the cabin, including any smoke or fumes that are present in the cabin.

A nightmare scenario
Simply put, the aforementioned conditions imply that had this event occurred in the middle of a flight, the cabin crew may have been unable to reach the source of the fire, and even if they did, they may not have been able to put the fire out. The aircraft involved in the fire at London's Heathrow airport sustained damage to the composite structure of that airplane's fuselage. Conceivably, if the fire had been allowed to burn for a significant amount of time, a situation that could have occurred had the airplane been inflight, the fire could have led to significant damage to the aircraft's systems, or could have caused the aircraft to lose its structural integrity. Either outcome could have led to the loss of the aircraft and all on board.

An additional twist to this story
While the previous scenario may be disturbing to the average passenger, what may cause additional concerns, especially to aircraft manufacturers and airline operators, is the possible role of the ELT in the fire in London. This is a system that is noteworthy for not being a source problems that could lead to the loss of an airliner. In fact, according to the AAIB, the manufacturer of the ELT involved in the London fire, Honeywell, has produced some 6,000 ELT units of the design used in the Ethiopian 787 involved in the London fire event, and that event is the first incident where the ELT system generated a significant level of heat.

Actions taken to deal with the threat
Following the recommendations of the AAIB, the FAA and other regulatory agencies around the world have ordered that 787 ELTs be deactivated, inspected, or removed. Until the AAIB, Boeing, and Honeywell figure out the role played by the ELT in the London fire, questions will remain as to whether the 787 ELT represents an unexpected and potentially fatal risk to 787 passengers.

AAIB releases bulletin on 787 fire plus additional 777 crash interviews

On 18 July 2013, the UK's Air Accidents Investigation Branch (AAIB) released a special bulletin related to the 12 July 2013 fire on an Ethiopian Airlines 787 at London's Heathrow airport. The AAIB made two safety recommendations, the first was to advise the FAA to initiate action to have 787 operators deactivate the emergency locator transmitter (ELT), and the second was to have the FAA conduct a safety review of the installation of ELTs in other aircraft where the ELTs are also powered by lithium batteries.

While the AAIB does not have any authority to implement these recommendations, it is very likely that the FAA, Boeing, and all of the 787 operators will respond relatively quickly to the recommendations.

AAIB summary of the fire
The AAIB special bulletin contained the following key information about the events leading up to the fire:

• The Ethiopian Airlines 787 landed at Heathrow at 0527 hours on 12 July 2013 after an uneventful flight, with no technical problems reported by the crew.


• After it was towed to a parking area, external power was turned off, and the aircraft was left unpowered.


• An employee in the air traffic control tower noticed smoke coming from the aircraft at 1534 hours, and fire fighters arrived about one minute later.


• After a fire crew entered the aircraft, they observed indications of fire above the ceiling panels, and had to move a ceiling panel in order to put out the fire.


• A later examination revealed extensive heat damage in the rear fuselage in the crown area, just to the left of the centerline, an area which coincided with the location of the ELT.


• The ELT, which was powered by a set of chemical batteries containing a Lithium-Manganese Dioxide composition, was the only aircraft system in that area that had the potential to initiate a fire when the aircraft was unpowered.

About emergency locator transmitters
ELTs are battery-powered radio transmitters that are carried aboard airliners, other civil aircraft, and most military aircraft. Thay are designed to survive most accidents, and to transmit a signal that can be used by rescue crews and even satellite-based monitors to locate a crash site. The FAA requires the use of ELTs on commercial airliners.

According to the AAIB, the manufacturer of the ELT associated with the recent 787 fire (Honeywell) has produced about 6,000 ELTs for use in a wide range of aircraft, and this the first time the manufacturer has what the AAIB calls a 'thermal event.'

The ELTs used by Boeing in the 787 are all made by Honeywell, and they are powered by a set of five non-rechargeable batteries, each of which is roughly the size of a common household "D" cell battery.

What's next for the 787
There are currently 68 787 aircraft flying with 13 operators around the world. Although the FAA has not made a formal request for airlines to implement the AAIB recommendations, it is likely that Boeing and the airlines will take action relatively quickly. If the recommended actions are taken, in the short term 787s may be flying without ELTs.

While flying without ELTs may make it harder to find an aircraft that has an emergency in an unpopulated area, the FAA can allow airliners to fly for short periods of time without a working ELT, so implementing these AAIB recommendations will likely not cause the FAA to ground the 787. Other regulatory bodies around the world typically follow the actions of the FAA in situations such as this one.

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Media interviews with Dr. Todd Curtis about the Asiana 777 crash
The following three interviews with Dr. Curtis were made in the days immediately following the crash of Asiana flight 214

- WGN radio - The Dean Richards show on 8 July 2013
- Bloomberg television interview 8 July 2013

CCTV America 8 July 2013

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Additional information

• AirSafeNews.com 15 July 2013 article with common questions about the 777 investigation


• AirSafeNews.com 13 July 2013 summarizing the two prior NTSB press conferences


• AirSafeNews.com 10 July 2013 article on the role of the autothrottle


• AirSafeNews.com 8 July 2013 article on early findings of the crash investigation


• Dr. Todd Curtis and Capt. Tomm Bunn discuss the crash on 7 July 2013


• Other Asiana plane crashes
• Other 777 plane crashes
• Accident details from Aviation Safety Network
• Wikipedia page on this accident

Update on 787 fire in London plus radio interview on 777 crash

Update on the 12 July 2013 787 fire in London
On 12 July 2013, an Ethiopian Airlines 787 caught fire while parked on an apron at London's Heathrow Airport. There were no passengers on the aircraft at the time of the fire, and no one was injured or killed.

The initial witness and physical evidence shows that this event resulted in smoke throughout the fuselage and extensive heat damage in the upper portion of the rear fuselage. The photo below shows that the fire burned through the top of the fuselage in the rear of the aircraft between the two rear doors and near the base of the vertical fin.

(click to enlarge)

The British Air Accidents Investigation Branch (AAIB) is investigating the fire, and has not yet released any statement about the likely causes of the fire. However, several things are known about the investigation:

• The aircraft had arrived from Addis Ababa, Ethiopia about nine hours before the fire was discovered.


• In addition to the AAIB, participants in the investigation include the FAA, NTSB, the Civil Aviation Authority of Ethiopia, Boeing, Ethiopian Airlines, and Honeywell International.


• Honeywell is the manufacturer of the emergency locator transmitter (ELT) used in the 787.


• The battery in the ELT is based on a lithium manganese-dioxide technology and not on the lithium-ion technology associated with the batteries that caught fire on two different 787 aircraft in January 2013.


• The fire was in the rear of the fuselage, and was remote from the areas of the aircraft containing the main battery and the auxiliary power unit batteries, the batteries associated with the grounding of the entire 787 fleet earlier this year.

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Dr. Todd Curtis interviewed by eFM radio in South Korea
In the following July 15, 2013 interview on the South Korean eFM radio show Prime Time with Henry Shinn, Dr. Todd Curtis discussed several issues associated with the ongoing investigation into the July 6, 2013 crash of an Asiana 777 in San Francisco, CA, including speculation about the cause of the crash, the role of automated systems in the cockpit, and the NTSB investigative process. Many of the issues raised in this interview included questions about the 777 crash answered in a previous article.

(Listen to the interview)

Additional information

• AirSafeNews.com 15 July 2013 article with common questions about the 777 investigation


• AirSafeNews.com 13 July 2013 summarizing the two prior NTSB press conferences


• AirSafeNews.com 10 July 2013 article on the role of the autothrottle


• AirSafeNews.com 8 July 2013 article on early findings of the crash investigation


• Dr. Todd Curtis and Capt. Tomm Bunn discuss the crash on 7 July 2013


• Other Asiana plane crashes
• Other 777 plane crashes
• Accident details from Aviation Safety Network
• Wikipedia page on this accident

New AAIB and NTSB 777 Safety Recommendations

In early March 2009, the AAIB released findings from the investigation of the January 2008 British Airways 777 accident that point to ice buildup in the fuel system as the key factor in the crash in London. On March 11th, 2009, the NTSB called for a redesign of the fuel system, and for the affected aircraft to have those changes installed within six months after the redesign is complete. Watch or listen to the AirSafe.com report on these updates below, or read the transcript.

Audio: MP3 | Video: iPod/MP4 | WMV | Google Video | YouTube

Report on March 2009 AAIB and NTSB Updates

For more videos, visit the AirSafe.com YouTube channel.

Fixing the Problem That May Have Caused the British Airways 777 Crash

Recent findings from the AAIB accident investigation point to ice buildup in the fuel system as the key factor in the January 2008 crash of a British Airways 777 in London. On March 11th, 2009, the NTSB called for a redesign of the fuel system, and for the affected aircraft to have those changes installed within six months after the redesign is complete.

You can hear this information in the podcast here or at at podcast.AirSafe.org

In the January 2008 crash, the flight from Beijing to London was routine until the the aircraft was on final approach, when both engines had an uncommanded power reduction, or engine rollback, which caused the plane to land short of the runway. Although the aircraft was seriously damaged, only one of the 136 passengers was seriously injured, and there were no serious injuries among the 16 crew members.

The Air Accidents Investigation Branch in the UK headed the investigation, with the help of several other organizations, including the aircraft manufacturer Boeing, the engine manufacturer Rolls Royce, and British Airways.

The series of updates and interim reports from the AAIB, the most recent of which was released in early March 2009, revealed that the likely cause of the dual engine rollback was ice blockage in a critical fuel system component that led to a reduction of fuel flow to the engine.

These findings didn't come easily. The AAIB focused its efforts on the fuel system because of the unusual conditions of the accident flight. That flight was exposed to rather cold atmospheric conditions, so cold that the crew changed altitudes at one point to fly through warmer air.

The AAIB reviewed the minimum fuel temperature data from over 141,000 777 flights. About 13,000 of these flights were on aircraft operating with the Rolls Royce Trent 800 series engine, the same kind as on the accident aircraft. Of those 13,000 flights, only 118 had fuel temperatures at takeoff that were at or below the takeoff fuel temperature of the accident flight, and during the approach phase, only 70 had fuel temperatures that were as low or lower than the fuel temperature on the accident flight.

The two most likely accident scenarios that were investigated by the AAIB both involved ice formation within the fuel system, leading to a reduction of fuel flow. This ice formation was possible because the aircraft fuel did contain some water. This kind of contamination is normal, and in fact the fuel from the accident aircraft was tested, and found to be in compliance with the appropriate fuel specifications.

After an extensive analysis of the fuel system, the AAIB concluded that the most likely scenario for the engine rollback was that ice formed in the fuel pipes within the main fuel tank, and that during the latter part of the approach phase of the flight, factors such as turbulence, aircraft pitch changes, and increasing temperatures could have contributed to the sudden release of accumulated ice into the fuel feed system of both engines. This ice would have restricted the fuel flow through a component called the fuel oil heat exchanger and would have led to the engine rollbacks.



The AAIB recommended that Boeing and Rolls Royce review the aircraft and engine fuel system design, and make changes that would prevent ice from restricting fuel flow through the fuel oil heat exchanger.

In the US, the National Transportation Safety Board went further, recommending that within six months of completing the redesign, that it be incorporated in all 777 aircraft using the Trent 800 engines. Some of the airlines that fly Trent 800 equipped triple sevens include Air New Zealand, American Airlines, British Airways, Cathay Pacific, Delta Airlines, El Al, Emirates, Kenya Airways, Malaysia Airlines, Singapore Airlines, and Thai Airways. There are about 220 such aircraft currently in service.

The NTSB's recommendations were influenced by a second 777 rollback event. On November 26, 2008, a Delta 777, powered by two Trent 800 series engines, experienced a single-engine rollback while in cruise on a flight from Shanghai to Atlanta. The crew was able to address the issue and continued the flight without incident. Later analysis indicated that there was a blockage of the fuel oil heat exchanger on that engine that was likely due to ice accumulation. Although the engine rollbacks on the British Airways accident aircraft and the Delta Airlines incident aircraft occurred during different phases of flight, the fuel temperatures at the time of the rollbacks were about equal.



Taken together, these developments are good news for the aviation community, especially passengers and crews flying on 777s equipped with Trent 800 engines. The investigative authorities have determined the likely cause of the event, the changes to the fuel system that are needed are well understood, and the engine and aircraft manufacturers are well on their way to developing solutions that will prevent similar occurrences in the future.

For more on this investigation, or for information about aviation safety or aviation security issues, please visit 777.AirSafe.org.

Investigation Update #4 for the British Airways 777 Crash of 17 January 2008

This is the fourth update from AirSafe.com on the ongoing investigation into the accident at London's Heathrow Airport involving a British Airways 777. This update is based on information released by the AAIB the week of 11 May 2008.

This article is based on the AirSafe.com podcast published on 20 May 2008. The podcast, available at http:/podcast.airsafe.org, presents the highlights of the most recent update from the Air Accidents Investigation Branch concerning the status of the investigation. There is a brief review of the details of the accident, followed by a discussion of the new information provided by the AAIB report, and an analysis of the progress of the investigation.

The accident aircraft was a scheduled international flight from Beijing, China to London, England, and the flight was routine until about two miles from touchdown. The engines would not respond to commands to increase thrust, and as a result the aircraft touched down about 1000 feet short of the runway. There was a significant fuel leak, but no post-crash fire. All 136 passengers and 16 crew members were able to successfully evacuate the aircraft, and the most serious injury was a broken leg suffered by one passenger.

The three previous AAIB updates in January and February 2008 provided detailed information about the flight, including the state of the fuel and fuel systems, and the condition of the engines and their associated control systems. You'll find details about the previous updates, as well as links to previous podcasts describing the accident sequence, at http://777.airsafe.org.

For the last several months, the AAIB has focused on the fuel and fuel systems of the aircraft. Extensive examination of the aircraft and detailed analysis of information from the flight data recorder and other onboard recording systems have revealed no evidence of an aircraft or engine control system malfunction.

The fuel was extensively tested, and showed no evidence of contamination or excessive water content. Although the aircraft had experienced very cold temperatures, the fuel temperature remained well above freezing. Detailed examination of the fuel system revealed a loose connection in one of the fuel lines as well as the presence of small pieces of debris, but these conditions led to no unusual deterioration or physical blockages.

The ongoing investigation has also found no evidence that a wake vortex encounter, bird strike, engine icing, or electromagnetic interference played a role in the accident. The focus of the investigation continues to be the fuel system and the engines, with the goal of understanding why neither engine responded to demands for increased power even though all of the engine control functions operated normally.

Under the direction of the AAIB, the engine manufacturer Rolls-Royce and the aircraft manufacturer Boeing are conducting further tests on the engines and fuel system with the goal of replicating the fuel system performance seen in the accident flight. Additional work is being conducted to gain a more complete understanding of the dynamics of the fuel as it flows from the tank to the engine.

No individual parameter associated with the accident flight was outside of previous operating experience. However, the AAIB is using a data analysis team to review data from a large sample of flights on similar aircraft to see if there was a combination of parameters that was outside of previous experience.

Unlike the last AAIB interim report issued in February 2008, this report did not contain any recommended operational changes for the 777.

I'd like to take a moment to share my opinion about the progress of this investigation. This crash investigation has not yet come up with an explanation for what happened. This is in spite of having a largely intact aircraft, a large volume of data from the accident aircraft and comparison data from similar flights, and the combined resources the engine manufacturer, the aircraft manufacturer, and the British government. This probably means that if the AAIB does come up with an explanation for why the accident happened, the explanation will include a combination of circumstances that had not been previously anticipated by aircraft designers or aircraft operators.

The suggestions made in previous AirSafe.com podcasts about how to evaluate what's being published about this investigation are still valid .

If you're interested in following the investigation online or in the news media, keep in mind that prior to the completion of the investigation by the AAIB, anyone outside of the investigation, including aviation safety experts and the largest news media organizations, will have access only to a fraction of the relevant information.

The AAIB will likely provide several more updates prior to publishing a final report, and these updates represent the most authoritative sources of information about the ongoing investigation.

Podcast Audio and Video
Audio: MP3 | Video: iPod/MP4 | WMV | Google Video | YouTube

Podcast Transcript
http://www.airsafe.com/podcasts/show48.htm

Additional Accident Details and Related Podcasts
http://777.airsafe.org