Transportation Safety 3

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Profile Gary Charpentier Crowdfunding Project Donor*Special Project $75 donorSpecial Project $250 donor
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Message 2130949 - Posted: 8 Jan 2024, 6:39:47 UTC - in response to Message 2130901.  

They have the door.
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Message 2130991 - Posted: 9 Jan 2024, 8:00:58 UTC

Phones, headrest, and door plug that fell 16,000 feet from Alaska Airlines plane found in Portland area.
United Airlines doing maintenance checks have found loose bolts on their aircraft as well.

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Message 2130999 - Posted: 9 Jan 2024, 9:23:01 UTC - in response to Message 2130991.  

BBC report with a bit about the United B737 Max-9 plug door findings:
https://www.bbc.co.uk/news/world-us-canada-67919436

This whole story is getting quite worrying :-(
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Message 2131003 - Posted: 9 Jan 2024, 12:05:05 UTC

I heard a brief snatch of a live BBC interview with an industry specialist - unfortunately it doesn't seem to be on the repeat list or available in text yet.

His suggestion was that in previous generations of aircraft the plug would be designed as a frustum - a truncated cone, like a bathplug - fitted from the inside. That would mean that during flight the air pressure differential would simply bed the plug even more firmly into its seating. It sounds obvious, really, but he suggested that the 737 Max was a design outlier in this respect. Anybody here able to confirm that?
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Message 2131006 - Posted: 9 Jan 2024, 14:39:54 UTC - in response to Message 2131003.  

I can't comment on the earlier B737 types, but relying on a small contact area and a small number of fixings for such a vital part of an airframe looks to be a weak point looking to fail. It's hard to see the exact size of the "stop pads" on the door but they appear to be about 25mm in diameter, while the lower "locking thing" is only about 40mm in effective length, and it's sprung to open. Thus, assuming everything is lined up properly only 25mm of movement is required to release the plug from the aperture and another 15mm for the plug to become free floating & so relying on the thin "safety wires" to stop it flying off into the wide blue yonder.
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Message 2131008 - Posted: 9 Jan 2024, 15:59:09 UTC - in response to Message 2131003.  

I heard a brief snatch of a live BBC interview with an industry specialist - unfortunately it doesn't seem to be on the repeat list or available in text yet.

His suggestion was that in previous generations of aircraft the plug would be designed as a frustum - a truncated cone, like a bathplug - fitted from the inside. That would mean that during flight the air pressure differential would simply bed the plug even more firmly into its seating. It sounds obvious, really, but he suggested that the 737 Max was a design outlier in this respect. Anybody here able to confirm that?

Can't verify. However that design could then only accept a traditional door in the frame. Emergency doors are supposed to open out, not have to be hauled in. I think fire service rules have banged into pressurization rules.
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Message 2131015 - Posted: 9 Jan 2024, 19:04:15 UTC - in response to Message 2131008.  

It's very easy to get the "blanking plate" that failed to stay in place in this accident with a "door" (emergency or otherwise). This blanking plate should not be able to be opened while the aircraft in service as it requires (or at least should require) tools to dismantle part of the interior and undo a number of bolts. Emergency exits are designed to be opened by a human of "normal" strength (a monstrous handle may be used to assist the process), there is no direct regulation that says they should open outwards, but the average human can push far harder than they can pull. Thus they are designed to be pushed open, being guided by a combination of hinges and guide tracks, the initial movement is generally upwards (probably on an outward curve) then outwards and being either "thrown away" or retained by hinges.

This is quite unlike building regulations in many countries that require emergency exits to open outward, and to exit onto a basically level surface landing before any stairs or slopes to allow changes in level - many aircraft emergency exits have slides immediately outside the door so one has to stand on the edge and either drop or jump onto the slide.
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Message 2131019 - Posted: 9 Jan 2024, 20:15:31 UTC - in response to Message 2131015.  

There are two types of doors on large PAX aircraft today. Those normal ones that hinge on the side and they drive they drive the ramps or stairs up to. Once the aircraft pulls away from the terminal building the cabin crew is supposed to arm them as emergency exits so the slide deploys if opened. The other doors are the over wing emergency exits. They generally do an up and out because they don't have a cabin crew there to operate it. Some aircraft seating designs to meet the 90 second rule have to add additional doors in between the normal rear exit doors and the over wing exits. They also are of the over wing design.
On the max9 they can be 1) Operating, 2) Deactivated, 3) Plug. The airframe doesn't change, just the door. To open a plug you need to remove interior trim, cut safety wire (cotter pin), use a wrench to remove bolts, then you can operate the door. The operating ones have a handle that assists in the up and out. The deactivated ones don't have a handle but would have a safety wire and all covered by interior trim so PAX don't mess with them.

As to the report the bolts weren't found, that is good. Bolts didn't shear. [that would be a big problem] Examination of all the maiting surfaces might be able to tell if it was vibration that had them fall out or if they were even there in the first place.

BTW loose bolts is only an issue if the castle nut did not have a cotter pin. As long as that safety is there the nut can't come off and the bolt will be in place and the door can't move.
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Message 2131028 - Posted: 9 Jan 2024, 22:08:19 UTC
Last modified: 9 Jan 2024, 22:09:22 UTC

Now that I've seen this pic of the inside of the plug I've got to wonder if it was held in by anything at all as the only damage that can be seen on that plug is some witness marks left by the trees when you'd expect to see at least a little bit of tearing somewhere from at least a couple of those bolts.


It looks like it could just be bolted back into place.
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Message 2131055 - Posted: 10 Jan 2024, 5:26:13 UTC - in response to Message 2131003.  
Last modified: 10 Jan 2024, 5:34:21 UTC

I heard a brief snatch of a live BBC interview with an industry specialist - unfortunately it doesn't seem to be on the repeat list or available in text yet.

His suggestion was that in previous generations of aircraft the plug would be designed as a frustum - a truncated cone, like a bathplug - fitted from the inside. That would mean that during flight the air pressure differential would simply bed the plug even more firmly into its seating. It sounds obvious, really, but he suggested that the 737 Max was a design outlier in this respect. Anybody here able to confirm that?
I'm wishing i'd kept a copy of the link- when searching on information on aircraft exit doors i found a site showing how these newer doors worked & why.

My understanding is that the design was changed when they ran emergency evacuation tests with people that had just been briefed in how to open the emergency exit (eg just like a passenger), and not actually trained in their operation, and found they significantly impeded the evacuation of the aircraft.
The old style of over wing emergency exit doors are like the main cabin doors- the door has to be pulled into the cabin before it can be opened. In the case of the over wing exits, the entire door has to be pulled into the cabin far enough to turn it on it's side to then push it outside of the aircraft so as to not impede the other passengers trying to get out.
When untrained people tried to operate such doors as a part of a drill, often they struggled to open the door and get it outside the aircraft within the specified time frame.

From memory the newer overwing exits require the door to drop slightly after the lock has been released, then it should fall outward/easily be pushed outward, being hinged on the bottom. This allows people that aren't actually trained in how to use the door to open it quickly enough to make it possible to evacuate the aircraft within the time limit specified.
I suspect (but don't actually know) that such mechanisms can't be operated at altitude due to the pressurisation of the aircraft (such as with the main doors). Only once the internal & external pressures have normalised can the locking mechanism be released.
Grant
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Message 2131063 - Posted: 10 Jan 2024, 10:02:48 UTC - in response to Message 2131055.  

Is it possible for the human brain to hold two separate concepts in the foreground at the same time?

We have a hole designed into the side of an aeroplane, with two purposes:

1) to hold a quick-release emergency door, which they would like to open outwards.
2) to hold a semi-permanent blanking plate, which can be removed for major servicing, but cannot be removed in flight.

The solution would seem to be to build a combined door+frame assembly, carrying both components of the quick-release mechanism: but designed, like its matching blanking plate, to be installed from the inside where heavy-duty ground handling equipment is available.
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Message 2131102 - Posted: 11 Jan 2024, 11:34:06 UTC

A little more about how the plug door works.
https://youtu.be/WhfK9jlZK1o?si=y1VZuiEck6d5sH-S

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Message 2131107 - Posted: 11 Jan 2024, 12:58:43 UTC

Thankfully no injurues have been reported., no bridge involved this time.
Oh dear

On the other side of the pond...
Boeing jets won't fly until safe
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Message 2131110 - Posted: 11 Jan 2024, 15:29:49 UTC - in response to Message 2130895.  

You will be relieved to know there are no models of this plane in the UK. They are mainly used for internal domestic flights within the U.S.
Hmmm, Icelandair operates four Max 9 together with their Max 8 fleet. They occasionally fly to London, Manchester and Glasgow, also in previous days. Their Max 9's haven't been grounded. Icelandair has certainly checked doorplugs, if any are installed.
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Message 2131139 - Posted: 11 Jan 2024, 23:18:33 UTC - in response to Message 2131110.  

You will be relieved to know there are no models of this plane in the UK. They are mainly used for internal domestic flights within the U.S.
Hmmm, Icelandair operates four Max 9 together with their Max 8 fleet. They occasionally fly to London, Manchester and Glasgow, also in previous days. Their Max 9's haven't been grounded. Icelandair has certainly checked doorplugs, if any are installed.

https://www.reuters.com/business/aerospace-defense/what-airlines-regulators-are-doing-about-boeing-737-max-jets-2024-01-07/
ICELANDAIR

Icelandair said on Monday its aircraft were not affected by the FAA grounding. "It has been confirmed that the issue is related to equipment that is not a part of Icelandair's Boeing 737 MAX 9 configuration," said a spokesperson for the airline, which operates four of the aircraft.
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Message 2131173 - Posted: 12 Jan 2024, 14:39:35 UTC

Not sure if this was already posted as things related to the door are split in two or 3 forum topics.

Maybe a moderator can try to merge the various posts into one new topic??
NTSB: All 12 stop fittings disengaged on Alaska plane door plug causing blowout
Clint Crookshanks, Aerospace engineer at NTSB, explained what caused the door plug of the B737-9 MAX to expel from the fuselage.

“The exam to date has shown that the door in fact did translate upward. All 12 stops became disengaged, allowing [the door plug] to blow out of the fuselage. We found that both guide tracks on the plug were fractured,” Crookshanks said.

Crookshanks added: “We have not yet recovered the four bolts that restrain it from its vertical movement and we have not yet determined if they existed there. That will be determined when we take the door plug to our lab in Washington DC.”

The NTSB also said that although it is not key to the investigation, the board is still looking for the door plug’s bottom hinge fitting and a spring, issuing a call to the public to notify the NTSB if the items have been seen.
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Message 2131377 - Posted: 17 Jan 2024, 9:18:51 UTC

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Message 2131428 - Posted: 19 Jan 2024, 0:51:55 UTC

Just a short update. David's obituary will appear in the Naperville Sun in the coming days. It was written by David's godfather who has known the family since the late 1950s. So please pardon any errors. It is as follows:

David W. Streeter, 57, passed away on December 26, 2023, in Palos Hills, after nearly six months’ hospitalization resulting from a serious fall he suffered at home in July 2023. David was a lifelong resident of Naperville; he was born December 3, 1966 to Paul Streeter and Gail (Grote) Streeter. David attended District 203 schools and graduated from Naperville North High School in 1984 and College of Dupage in 1992. After graduation, he worked for many years at Naperville North High School as a media technician. Like his late father Paul, David was a railroad and model railroading enthusiast. David’s interest in railroading subsequently led him to a job ferrying train crews, picking them up at the end of their shift, or driving them to the origin location of a shift. His unfortunate accident occurred while returning home from work late one July evening.

David was predeceased by his parents, both of whom died in 2011; by his grandmother, Grace Grote, of Winfield, who passed away in 2013; and by his aunt, Kathy Fermo, of West Chicago, who died in July 2023. He is survived by some family on his father’s side, but also by loyal friends including other railroad fans. David’s remains, along with those of his parents, will be interred at a later date at Wheatland Township Cemetery. Donations in David’s memory may be made to the Illinois Railway Museum in Union, Illinois, of which David was a member.
~Sue~

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Message 2131429 - Posted: 19 Jan 2024, 1:11:11 UTC

It's so sad when such young people pass away. :-(
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Message 2131600 - Posted: 22 Jan 2024, 5:51:18 UTC

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