Ethiopian plane crash

[snotrag]

Lemming Train said:

https://www.seattletimes.com/business/boeing-aeros...

Good on EASA, although I suspect there are some politics at play here to demonstrate that they aren't the FAAs European puppet.

FAA said:

On Wednesday, the FAA declined to clarify if the EASA requirements are stricter or in line with its own.

“We aren’t going to comment on specific details about ongoing discussions,” the FAA said in a statement. “The FAA has a transparent and collaborative relationship with other civil aviation authorities as we continue our review of changes to software on the Boeing 737 MAX … Each government will make its own decision to return the aircraft to service based on a thorough safety assessment.”

The FAA appear to be a bit.. rattled.

Edited by Lemming Train on Thursday 5th September 19:13

Good. I was at a Boeing Reliability Conference a while back, Boeing obviously were bigging up their ongoing work alonside the FAA. Most of the European customers where keen to point out that it is not just the FAA they need to answer to, its EASA, ANAC etc...



As for pressure testing, here is a great story used in training related to pressure testing - doing a leak down test on an American Refueller, a mech managed to pressurise the aircraft to more than double its maximum allowable pressure differential and subsequently, BURST it!



http://www.discity.com/kc135/

[eharding]

snotrag said:

http://www.discity.com/kc135/

Article said:

The technician's gauge didn't even have a max "peg" for the needle and so it was no surprise he missed it when the needle went around the gauge the first time. As the technician continued to pressurize the aircraft, and as the needle was on its second trip around the gauge the aircraft went "boom" - the rear hatch was blown over 70 yards away, behind a blast fence!

Outstanding bit of work.

[Starfighter]

I was thinking about this incident, it comes up periodically in the metrology world. The pressure gauge did not have a physical stop on it and went all the way around twice.
As I recall, one of the passenger door ended up around 50m away behind the jet blast deflectors.

Edited by Starfighter on Monday 9th September 11:22

[Starfighter]

Ah, beaten to it!

[jshell]

IanH755 said:

El stovey said:

jshell said:

eliot said:

I thought the cabin doors are plug doors and therefore impossible to blow open under pressure. Maybe it was a cargo door?

Used to be but not now. Now many rely on locking mechanisms rather than interference fit!!!

Which doors? The ones with locking mechanisms I’ve seen are still held closed by positive cabin pressure differential. I.e. once locked and pressurised they still can’t be opened.

The door didn't "open" as such as that is impossible in the pressurised A/C. Instead the door was blown out of the airframe. This used to be difficult as the door was shaped as an interference fit so it couldn't be physically pushed out of the airframe as an extra safety measure but this design style has been replaced by simply "locking" the door into the airframe with a latch mechanism.

With all the extra flexing and pressure during the test a latch was probably compromised and the lack of a door interference fit meant that, once the latch failed there is nothing to prevent the internal pressure pushing the door out of the airframe.

I think that answers it for me too. I look at the doors, latching etc - maybe being an engineer who did his 76th flight this morning for the year. It looks like the newer 320 doors are not interference, but the internal pressure pushes the door against the locking lugs on the door frame.

[JuniorD]

snotrag said:

Good. I was at a Boeing Reliability Conference a while back, Boeing obviously were bigging up their ongoing work alonside the FAA. Most of the European customers where keen to point out that it is not just the FAA they need to answer to, its EASA, ANAC etc...



As for pressure testing, here is a great story used in training related to pressure testing - doing a leak down test on an American Refueller, a mech managed to pressurise the aircraft to more than double its maximum allowable pressure differential and subsequently, BURST it!



http://www.discity.com/kc135/

The front half of the aircraft looks all right

[anonymous-user]

jshell said:

IanH755 said:

El stovey said:

jshell said:

eliot said:

I thought the cabin doors are plug doors and therefore impossible to blow open under pressure. Maybe it was a cargo door?

Used to be but not now. Now many rely on locking mechanisms rather than interference fit!!!

Which doors? The ones with locking mechanisms I’ve seen are still held closed by positive cabin pressure differential. I.e. once locked and pressurised they still can’t be opened.

The door didn't "open" as such as that is impossible in the pressurised A/C. Instead the door was blown out of the airframe. This used to be difficult as the door was shaped as an interference fit so it couldn't be physically pushed out of the airframe as an extra safety measure but this design style has been replaced by simply "locking" the door into the airframe with a latch mechanism.

With all the extra flexing and pressure during the test a latch was probably compromised and the lack of a door interference fit meant that, once the latch failed there is nothing to prevent the internal pressure pushing the door out of the airframe.

I think that answers it for me too. I look at the doors, latching etc - maybe being an engineer who did his 76th flight this morning for the year. It looks like the newer 320 doors are not interference, but the internal pressure pushes the door against the locking lugs on the door frame.

Just to say again it was a cargo hold door not a passenger door that failed.

[Cupramax]

Because a cargo door blowing out is just.....great

[Pesty]

9 passengers died in that.

Horrendous.

[jshell]

El stovey said:

jshell said:

IanH755 said:

El stovey said:

jshell said:

eliot said:

I thought the cabin doors are plug doors and therefore impossible to blow open under pressure. Maybe it was a cargo door?

Used to be but not now. Now many rely on locking mechanisms rather than interference fit!!!

Which doors? The ones with locking mechanisms I’ve seen are still held closed by positive cabin pressure differential. I.e. once locked and pressurised they still can’t be opened.

The door didn't "open" as such as that is impossible in the pressurised A/C. Instead the door was blown out of the airframe. This used to be difficult as the door was shaped as an interference fit so it couldn't be physically pushed out of the airframe as an extra safety measure but this design style has been replaced by simply "locking" the door into the airframe with a latch mechanism.

With all the extra flexing and pressure during the test a latch was probably compromised and the lack of a door interference fit meant that, once the latch failed there is nothing to prevent the internal pressure pushing the door out of the airframe.

I think that answers it for me too. I look at the doors, latching etc - maybe being an engineer who did his 76th flight this morning for the year. It looks like the newer 320 doors are not interference, but the internal pressure pushes the door against the locking lugs on the door frame.

Just to say again it was a cargo hold door not a passenger door that failed.

I'm not disagreeing and I can see that the motorised cargo doors are certainly not an interference fit, but I don't think the passenger doors are now either.

[Gameface]

Pesty said:

9 passengers died in that.

Horrendous.

Some went into the engines apparently.

Nasty.

[bmwmike]

Gameface said:

Pesty said:

9 passengers died in that.

Horrendous.

Some went into the engines apparently.

Nasty.

Be quick though! Better than a few minutes sky diving to the ocean? Not a great choice either way i guess.. as i get older i'm inclined to fly less.

[Pesty]

JuniorD said:

snotrag said:

Good. I was at a Boeing Reliability Conference a while back, Boeing obviously were bigging up their ongoing work alonside the FAA. Most of the European customers where keen to point out that it is not just the FAA they need to answer to, its EASA, ANAC etc...



As for pressure testing, here is a great story used in training related to pressure testing - doing a leak down test on an American Refueller, a mech managed to pressurise the aircraft to more than double its maximum allowable pressure differential and subsequently, BURST it!



http://www.discity.com/kc135/

The front half of the aircraft looks all right

“An incident like this is never funny”

Is it though?

[Starfighter]

Pesty said:

“An incident like this is never funny”

Is it though?

Funny, No. hilarious, yes.

[jshell]

bmwmike said:

Gameface said:

Pesty said:

9 passengers died in that.

Horrendous.

Some went into the engines apparently.

Nasty.

Be quick though! Better than a few minutes sky diving to the ocean? Not a great choice either way i guess.. as i get older i'm inclined to fly less.

Me too, had my 76th flight on Monday - since Dec 2018.

[M4cruiser]

Cupramax said:

Because a cargo door blowing out is just.....great

The fact that landed safely after that shows (i think) what a good design the 747 is.

[Pesty]

M4cruiser said:

The fact that landed safely after that shows (i think) what a good design the 747 is.

Wiring on the other hand......


Short opened the lock

[George Smiley]

Back when they were over engineered

[JuniorD]

Starfighter said:

Pesty said:

“An incident like this is never funny”

Is it though?

Funny, No. hilarious, yes.

US Military aircraft
on the ground
tail end exploded off
by a numptie with a homemade pressure gauge
no one injured
aircraft left like this

[surveyor]

M4cruiser said:

Cupramax said:

Because a cargo door blowing out is just.....great

The fact that landed safely after that shows (i think) what a good design the 747 is.

Unless you were in one of the seats sucked out....