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Malcolm

Investigators Stumped In Air Canada E190 Avionics Failure

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Malcolm    646

The following is a news article on the incident, if you want to read the full very detailed report here is the goto: http://www.tsb.gc.ca/eng/rapports-reports/aviation/2016/a16o0066/a16o0066.asp

Investigators Stumped In Air Canada E190 Avionics Failure

Sep 11, 2017John Croft | Aviation Daily
 

WASHINGTON—Canadian air safety investigators remain stumped as to the source of the coffee or soft drink that caused a crucial avionics electronics box in the belly of an Air CanadaEmbraer 190-100 to short-circuit and catch fire during a May 2016 flight.

Air Canada Flight 361, en route from Boston to Toronto with 61 passengers and four crew members, was cruising at 36,000 ft. in visual weather conditions when a series of electric-system-fault messages appeared in the cockpit, shortly followed by a total loss of electrical power from both engines.

While the pilots were able to restore power and continue the flight, the source of the failure and the pilots’ response highlight the need for safety improvements, according to the Transportation Safety Board of Canada (TSB).  

“The autopilot disconnected, three of the five cockpit display panels went dark, and several more engine-indication and crew-alerting system (EICAS) messages appeared,” the TSB said in a newly published final report on the incident.

Following the failure, the aircraft’s ram air turbine (RAT) automatically deployed, supplying power to the “essential” busses while the crew followed emergency checklists and descended to 30,000 ft. in order to start the auxiliary power unit (APU) to provide electrical power. Without the RAT or the APU, the fly-by-wire aircraft must draw power from its batteries, which are guaranteed to last only 10 min.

The pilots started the APU and ultimately were able to reset the engine-driven generators, restoring power to most of the aircraft’s systems as it leveled off at 24,000 ft. The crew’s initial announcement to the passengers and flight attendants during the descent was drowned out by the noise of the RAT, according to the TSB. The cabin crew then contacted the flight deck and relayed the information to the passengers.

What the crew would find out later—that there had been a fire in the right integrated control center (RICC) avionics box located in the middle avionics compartment in the aircraft’s belly—might have caused them to reconsider their decision to refrain from declaring an emergency and continuing the flight to Toronto. Once the pilots reconnected to the generators, the E190 was approximately 100 nm from Boston and 170 nm from Toronto. When power was lost, a fan that would have circulated the smoke toward a smoke detector (and the cabin) did not work, so no fire alerts were issued to the cockpit.

“There were several suitable options that would have been closer [than Toronto],” the TSB said. “Although the checklist guidance is specific—to land at the nearest suitable airport—the aircraft operating manual gives the captain discretion to consider operational constraints in the decision-making process,” the agency said. Based on the incident, Embraer submitted a proposal to change the operating manual to begin with the instruction to “land at the nearest suitable airport” for cases of electrical emergencies.

The TSB also noted in its “findings as to risk” that when flight crews do not declare an emergency, “There is increased risk that should the situation worsen, the flight will still be airborne due to a lack of priority handling,” and that emergency services will not be present when the aircraft lands.

What initiated the fire remains a mystery. TSB investigators determined that a “fluid contaminant” caused “severe arcing,” melting and fire in the RICC. “A sample of the dried fluid contaminant was examined, and it was determined that the fluid was a beverage, possibly coffee or a soft drink,”  the TSB said.

Investigators determined that the liquid spilled in the previous 6 hr., and there was “no evidence” of contaminants in the drip trays above the RICC that prevent liquids from leaking down from the cabin. The report infers that the liquid must have come from a maintainer working in the middle avionics compartment, which has to be accessed on the ground from underneath the aircraft. However at New York LaGuardia Airport, where the aircraft overnighted the night before the occurrence, a “routine check” by Air Canada maintenance staff did not “require anyone to enter the middle avionics compartment,” said the TSB.

Investigators determined that the most recent maintenance that would have required entry into the compartment occurred in October 2015, almost seven months earlier. The TSB said a “general inspection” of the middle avionics compartment after the incident “did not reveal any debris or beverage containers.”

While not issuing a recommendation related to the contaminant, the TSB noted that Air Canada’s policies do not restrict “outside fluids” in areas where they may cause harm to sensitive equipment, leading to a continued risk of “contamination causing component malfunctions or failures.”

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boestar    600

What Mechanic would take a drink into a confined space while performing maintenance.  in 30 years I have NEVER seen that.

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Vsplat    286

Hmmm.  Avionics bay door SHOULD not have been opened.  No sign of whatever leaked in there. 

The conspiracy theorist in me wonders if it was contraband that leaked.  Hard to know without knowing that aircraft's itinerary.

Would not have been the first time someone tried to move stuff in an aircraft avionics bay.

Vs

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boestar    600

Not familiar with the Embraer.  Is the Middle compartment door just a latched door or is it screwed on?

VSPLAT has a point if it is a simple latched door.  Much contraband has been found in easily accessible areas of aircraft in the past.

 

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conehead    248
6 hours ago, boestar said:

Not familiar with the Embraer.  Is the Middle compartment door just a latched door or is it screwed on?

VSPLAT has a point if it is a simple latched door.  Much contraband has been found in easily accessible areas of aircraft in the past.

 

To access the mid bay, one must first open a panel on the belly, then remove a "plug" type hatch. For the unfamiliar, it is not easy to close up when exiting. There is no basic servicing that would require access. If someone wanted to stow some contraband, it would be much easier to throw it in the fwd e/e bay.

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boestar    600

thanks Conehead  That's exactly what I was wondering

 

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DEFCON    684

The report doesn't discuss wx conditions at any of the 'suitable' airports?

Why are some pilots so reluctant to declare an emergency when one exists?

I can't glean anywhere near enough information from the report, but a guess says crew experience likely played a role in their decision to continue?

 

Edited by DEFCON
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Southshore    7

Not to put too fine a point on it but one doesn't always need to declare an emergency ie 'mayday'. You use that when on fire or falling out of the sky etc. The 'pan' call will get you lots of attention. The Qantas 380 event used only the 'pan 'call.  I had a serious hyd failure but not life threatening and called 'pan'. A manager later said I should have called 'mayday'. Not so. The distinction is clearly related in the manual. These guys didn't know they had a fire so under the circumstances a 'pan' call would have very appropriate. Had they known about the fire I expect the first words out of their mouths would have been 'mayday'. But the 'pan' call does up the ante very nicely.

Edited by Southshore
duplicate word

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J.O.    807

Well said, Southshore. From a response perspective, ATC and airport authorities tend to treat MAYDAY and PAN-PAN as one and the same. 

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Southshore    7

Well , the response may be the same I suspect the feeling may be different. I was in the air when Porter had an emergency descent into YQY due to smoke (very well done by the crew btw). When the crew declared mayday, you could palpably hear the anxiety in the controllers voice. Good job by him too. Cleared the airway and gave them what they needed. But I think he went for a li'l poop after that.

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mo32a    284

If you don't declare PAN or Maday and just explain you have a problem the controller will ask you if you are declaring an emergency. If your response is yes you will get priority handling as though you declared either of the above. If you say no, you  will be treated as routine traffic and take your place in line.

Declaring PAN or Mayday just speeds up the response a little.

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conehead    248
8 hours ago, boestar said:

thanks Conehead  That's exactly what I was wondering

 

Also;  the lab report says there was an unidentifiable fluid spill on top of the RICC. I've worked in there; it's a pretty tight space, not very comfortable. You want to get in, do your work, and get out. It's not like you're gonna take a cup of coffee in there to enjoy.

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We very seldom hear PAN PAN or MAYDAY but they sure get our attention!

As far as how they are treated, there are three levels we recognize although only two are official.

-  The first will be a crew advising us they are declaring an emergency and will require the equipment.  This is usually what happens in Canadian airspace and carries the same meaning as PAN PAN although the degree of response will vary depending on the crews requests.  A flap problem or a landing gear issue would definitely be considered critical but not in terms of urgency to get on the ground.

-  The more formal PAN PAN although having the same meaning will probably be treated with more formality initially even though the issue might be the same. We don't hear it often and it means to us, rightly or wrongly, that it's a little more urgent.  I suppose it has to do with the formality of using the words (a sort of STOP WHAT YOU'RE DOING AND LISTEN TO THIS) that grabs our attention.  THE MEANING, however, is the same to us as declaring an emergency in plain language.  If you're not sure you're being treated as such, confirm in plain language or use the formal PAN PAN.

-  If I hear MAYDAY, you have my undivided attention.  The meaning to us is that you life is in danger RIGHT NOW!  We will act accordingly.

So we do apply a certain nuance depending on how the emergency is communicated to us.  In the end, though, apart from being attention grabbers, the words only mean so much.  Regardless of the one you chose to use, the rest of the message will tell us how to act.  If you tell me your engine is on fire, you don't have to say MAYDAY.  On the other side, I remember a story of BA unable to lock the gear UP and wanting to return to LHR.  Upon being told he had to go to his alternate as this was not a critical emergency, he called MAYDAY.... (I wish I could say he was denied but alas).

 

Felix

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