Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
From Flight:
That sounds to me like it's a genuine door, only deactivated (and which can be reactivated), rather than a dummy one.
Provision for the new exits – which boost the exit limit capacity from 189 to 215 passengers – “will be structurally installed as standard in all -900s, and will allow operators to decide if the door should be activated or deactivated”, says 737 chief project engineer Mike Delaney.
The deactivation feature will enhance the aircraft’s remarketability, says Delaney, adding that, when not used, the mid-exit area will be covered with a standard sidewall and overhead bin interior.
The deactivation feature will enhance the aircraft’s remarketability, says Delaney, adding that, when not used, the mid-exit area will be covered with a standard sidewall and overhead bin interior.
On a positive note: It makes the middle seat more attractive.
It is a genuine door frame, stripped of the slide, internal paneling and opening mechanisms. The locks are bolted in place and in principle should not be able to move. (Of course if any of those bolts were missing...). 'Reactivation' is a tad more than pulling a safety inhibitor pin, but still much less effort than cutting a hole in the fuselage and installing the required hardpoints.
Think of the view and the additional arm room. Plus it ends boring conversations with the middle seater. Maybe start writing notes to toss out: "I've been trying to contact you about your automobile warranty insurance" and let people guess how it got on the roof of their house.
The previous 737-900NG-ER series also had this option for an extra aft emergency exit door behind the wing to enable high-density seating.
It is more of a hatch, that drops down, has a window, and is fitted with a slide.
This exit can be used when Ditching, unlike the 2 rear main doors that must not be used when landing on water.
It's not like the larger 757 Type 1 door (doors 3L/R) with a slide.
UK's Excel Airways were the first airline to order two of the -900ER type in 2006 for delivery for summer 2008, but the airline went under soon after.
Some airlines choose not to use this extra exit option on the 737-900ER, and on the 737 MAX-9 and will have it deactivated as Alaska have done here.
Although the actual door/hatch is still fitted, but when seen on the inside (in the cabin) it is blanked off with a wall panel with a window, and Pax would not know there was a door/exit there.
It can be reactivated if the airlines want it.
The A321N cabin-flex also has this option to use the extra aft exit for high density seating, along with a choice of overwing exit hatches too, which can also be blanked off if not required.
It is more of a hatch, that drops down, has a window, and is fitted with a slide.
This exit can be used when Ditching, unlike the 2 rear main doors that must not be used when landing on water.
It's not like the larger 757 Type 1 door (doors 3L/R) with a slide.
UK's Excel Airways were the first airline to order two of the -900ER type in 2006 for delivery for summer 2008, but the airline went under soon after.
Some airlines choose not to use this extra exit option on the 737-900ER, and on the 737 MAX-9 and will have it deactivated as Alaska have done here.
Although the actual door/hatch is still fitted, but when seen on the inside (in the cabin) it is blanked off with a wall panel with a window, and Pax would not know there was a door/exit there.
It can be reactivated if the airlines want it.
The A321N cabin-flex also has this option to use the extra aft exit for high density seating, along with a choice of overwing exit hatches too, which can also be blanked off if not required.
Ahh - bottom hinge - now that I have a name for them:
I would not expect the bottom hinge to be in place for the substitute fixed door.
Seeing in the video that they don't have moving latches, the exit version of the doors are slid up to unalign the retaining features. Without the operating lever having someone pry the door up against the pressure it should not have moved.
Putting on a speculators cap - there were fatigue cracks in the retaining features / fingers on the door. Had only one let go I would not expect the door to do more than leak loudly. But if several had cracks then when one finally crossed the finish line the rest go in a rapid cascade.
Seeing in the video that they don't have moving latches, the exit version of the doors are slid up to unalign the retaining features. Without the operating lever having someone pry the door up against the pressure it should not have moved.
Putting on a speculators cap - there were fatigue cracks in the retaining features / fingers on the door. Had only one let go I would not expect the door to do more than leak loudly. But if several had cracks then when one finally crossed the finish line the rest go in a rapid cascade.
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Assuming the door is fully installed but deactivated and the aircraft hasn’t been through a heavy mx check then it looks like a Quality issue from build. It would be interesting know if any reports previously of door indication / noise/ pressurisation problems. Maybe even a certification issue with the length of the fuselage flexing on landing. Going to be an interesting investigation with as always a lot of Swiss cheese hazards leading to the event. Luckily the seat was empty as could have been far worse.
Putting on a speculators cap - there were fatigue cracks in the retaining features / fingers on the door. Had only one let go I would not expect the door to do more than leak loudly. But if several had cracks then when one finally crossed the finish line the rest go in a rapid cascade.
"On a Wing and a Prayer" by Al Jazeera, years ago......subcontraced construction by lowest bidder
There was this debate during the 777 development about doors - having a potential weak spot and either being redesigned to include a re-inforcing plate internally - or to wait, tell the end user to inspect the outside periodically for cracking and then face the prospect of fitting the plate externally with the concomitant delays and additional parasitic drag, etc.
In the end they just got on and redesigned the damn door to be stronger in the first place.
In the end they just got on and redesigned the damn door to be stronger in the first place.
There are two sorts of fatigue - low cycle and high cycle.
Low cycle fatigue is typically a material issue where the material strength is far below the requirement, such as from an improper heat treatment or incorrect alloy. It can also happen if the manufacturing process has left a fatigue initiator such as using a sharp corner end mill instead of a fillet end mill. Low cycle is found in the 5.0 -100 cycle range. This can be typified by flexing a paper clip. It is from a load near or above the yield strength.
High cycle fatigue is the more typical for manufactured goods. It is typified by a load that is far below the yield strength and is nearly independent of yield strength and can run from 100,000 cycles to well into the millions. If there is a manufacturing process problem it can be as simple as a surface texture that's a bit rougher or an internal inclusion of contamination.
At only 3 months - that is no bueno.
Low cycle fatigue is typically a material issue where the material strength is far below the requirement, such as from an improper heat treatment or incorrect alloy. It can also happen if the manufacturing process has left a fatigue initiator such as using a sharp corner end mill instead of a fillet end mill. Low cycle is found in the 5.0 -100 cycle range. This can be typified by flexing a paper clip. It is from a load near or above the yield strength.
High cycle fatigue is the more typical for manufactured goods. It is typified by a load that is far below the yield strength and is nearly independent of yield strength and can run from 100,000 cycles to well into the millions. If there is a manufacturing process problem it can be as simple as a surface texture that's a bit rougher or an internal inclusion of contamination.
At only 3 months - that is no bueno.
The quality and safety genes acquired from McAir in 1997 have time and again been proven robust and utterly dominant, and the Boeing genotype is essentially extinct.
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Hopefully they can locate the missing door as the aircraft was over land for the duration but unfortunately the area is heavily forested, thankfully though no reports of injuries on the ground.