Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
Were I king for a day on that line I would require labeling at each removable fastener location to indicate that a fastener is required and have a QR code to link to the part numbers and any torque requirements and a diagram showing the correct installation. The door would also have a QR code linking to a diagram and assembly process. That main QR code would also include the serial number of the door so that the QC checking the door would be recorded. They would scan the 12 capture screws and the 4 capture bolts. Each one should be linked to the assembler who scanned them as part of their completion of work record. They should all have tamper-proof stripe applied by the QC operator so that anyone removing the door will not be able to sneak it back into place.
I am pretty sure that if you take a vote from persons occupying row 0 up to the rear jump-seats, on whether this experience was "scary and terrifying", you would get an unanimous vote.
Hint: "Neuroscience research suggests that laughter or mirth is a way for us to reduce fear, anxiety, or stress."
I applaud this lady for having the presence of mind, to start communicating by text-writing on her phone, the only practicable way of communicating, when suddenly a shirtless teen dropped in an empty seat next to her, and upon seeing his skin abrasions, was compassionate enough to inquire on his state of well-being.
And this selfie will be treasured by both for a very long time....
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In another forum a Boeing worker who works on installing interiors said that the Reuters quote is not correct. He said that those doors are too small to do much interior installation work. He said that interiors are installed through the front and rear main doors as those are larger and it is much easier to get seats and bins through the main doors. We'll have to wait and see what is determined but there are conflicting rumors as to whether or not those doors are opened or removed during interior assembly.
One aspect that could have fallen through the cracks is that the bolts to fasten the bottom hinges to the door frame were not in some cases correctly fastened (not necessarily "loose" in normal parlance, but not torqued to spec). All of the doors are shipped from in place but Spirit does not consider them "fitted and final". For the main doors this is fine. Boeing removes the main doors, dresses them with slides and other hardware and then rigs them to stringent specifications. Boeing was assuming that the plug doors were "installed" and wasn't checking the fasteners that mount the hinges and this is an apparent lapse and it explains how the loose bolts could have slipped through the system. That's also a relatively simple fix in adding a procedure to inspect, and torque those bolts.
One aspect that could have fallen through the cracks is that the bolts to fasten the bottom hinges to the door frame were not in some cases correctly fastened (not necessarily "loose" in normal parlance, but not torqued to spec). All of the doors are shipped from in place but Spirit does not consider them "fitted and final". For the main doors this is fine. Boeing removes the main doors, dresses them with slides and other hardware and then rigs them to stringent specifications. Boeing was assuming that the plug doors were "installed" and wasn't checking the fasteners that mount the hinges and this is an apparent lapse and it explains how the loose bolts could have slipped through the system. That's also a relatively simple fix in adding a procedure to inspect, and torque those bolts.
I am pretty sure that if you take a vote from persons occupying row 0 up to the rear jump-seats, on whether this experience was "scary and terrifying", you would get an unanimous vote.
Hint: "Neuroscience research suggests that laughter or mirth is a way for us to reduce fear, anxiety, or stress."
I applaud this lady for having the presence of mind, to start communicating by text-writing on her phone, the only practicable way of communicating, when suddenly a shirtless teen dropped in an empty seat next to her, and upon seeing his skin abrasions, was compassionate enough to inquire on his state of well-being.
And this selfie will be treasured by both for a very long time....
We cannot make everything idiot proof as idiots are so ingenious. If the FAA wanted to put an emphasis on this they could require a logbook entry noting that the door had been opened and an additional verification of inspection and that could provide another level of redundancy, but there is not need to redesign something that works as designed. A redesign would then require additional certification testing and approvals and there is no need for that.
I wouldn't be surprised if there are months of delay getting the MAX line going again as new procedures might need to be certified. FAA will probably be okay with existing a/c being rigorously inspected and brought to spec.
QA
Were I king for a day on that line I would require labeling at each removable fastener location to indicate that a fastener is required and have a QR code to link to the part numbers and any torque requirements and a diagram showing the correct installation. The door would also have a QR code linking to a diagram and assembly process. That main QR code would also include the serial number of the door so that the QC checking the door would be recorded. They would scan the 12 capture screws and the 4 capture bolts. Each one should be linked to the assembler who scanned them as part of their completion of work record. They should all have tamper-proof stripe applied by the QC operator so that anyone removing the door will not be able to sneak it back into place.
This seems all the more relevant given the nasty sting in the tail of post #921 in which incompleteness raises the possibility that at higher altitude this could have been a catastrophic beyond design basis accident. Presumably both Boeing and the FAA (dis)missed this as an incredibility of failure item during design and certification. My guess it was worse than 10E-3
Finally, in the wake of a dreadful smoking hole event somewhere we almost always find a combination of unfortunate circumstance which contributed. This case is the exact reverse - window seat not occupied, event at low altitude, departing door did not impact the horizontal stabiliser. The whole thing screams ‘unbelievably lucky this time’ . Let’s hope that that Boeing and the FAA get it.
I’m at a total loss to understand why at least a functioning paperwork version of this was not in place for this door/plug ... Presumably both Boeing and the FAA (dis)missed this as an incredibility of failure item during design and certification. My guess it was worse than 10E-3
Regarding Risk Assessments, I have long found these to be alas a way of back-fitting likelihood values to what you have already designed, just to get things accepted.
Probability
Some thoughts in general:
In final assembly you ‘never have enough’ space and access.
Getting complete fuselages delivered (as Boeing do with the 737) may well be an overall manufacturing optimum, but reduces available space and accessibility in final assembly even more.
The most critical area with respect to space and access is the cockpit section and E-bay. Call them the “red zone”.
If you take interiors for example, you would expect galley units to be delivered to final assembly on rollers, then lifted onto the level platform outside the left hand forward pax door (the platform railings being foldable or turnable), then pushed into the cabin and rolled to their positions. You would expect cabin wall panels to be delivered in a similar manner with sets of panels on roller carts and through the same door.
These logistics moves of big parts limit available space and access, and in the most critical area.
If you get passengers in from the left and cargo/baggage from the right side of your aircraft, your cargo doors are on the right, and (smaller) service doors too.
So the left side of your plane has 2 big size pax entry door openings, plus 1 (potential) medium plug opening, plus 2 small size escape hatch openings.
So the right side of your plane has 2 medium size service door openings, plus 1 (potential) medium plug opening, plus 2 small escape hatch openings, plus 2 medium/large cargo door openings.
This means that you will be tempted to open these plugs during final assembly, and especially to open the one on the left side. So the probability that you open a plug is higher on the left than on the right.
That probability increases when you have to deal with changes in production rates, and with shortages and delays.
Don’t say this is what happened, but may explain why the left plug was ejected and not the right. Which makes it interesting to find out if on the other planes the loose bolts of AK and UA were found mostly on the left.
In final assembly you ‘never have enough’ space and access.
Getting complete fuselages delivered (as Boeing do with the 737) may well be an overall manufacturing optimum, but reduces available space and accessibility in final assembly even more.
The most critical area with respect to space and access is the cockpit section and E-bay. Call them the “red zone”.
If you take interiors for example, you would expect galley units to be delivered to final assembly on rollers, then lifted onto the level platform outside the left hand forward pax door (the platform railings being foldable or turnable), then pushed into the cabin and rolled to their positions. You would expect cabin wall panels to be delivered in a similar manner with sets of panels on roller carts and through the same door.
These logistics moves of big parts limit available space and access, and in the most critical area.
If you get passengers in from the left and cargo/baggage from the right side of your aircraft, your cargo doors are on the right, and (smaller) service doors too.
So the left side of your plane has 2 big size pax entry door openings, plus 1 (potential) medium plug opening, plus 2 small size escape hatch openings.
So the right side of your plane has 2 medium size service door openings, plus 1 (potential) medium plug opening, plus 2 small escape hatch openings, plus 2 medium/large cargo door openings.
This means that you will be tempted to open these plugs during final assembly, and especially to open the one on the left side. So the probability that you open a plug is higher on the left than on the right.
That probability increases when you have to deal with changes in production rates, and with shortages and delays.
Don’t say this is what happened, but may explain why the left plug was ejected and not the right. Which makes it interesting to find out if on the other planes the loose bolts of AK and UA were found mostly on the left.
If it does turn out to be IAM workers in Renton doing something (removing the door plug) without following the relevant procedures or doing the associated paperwork, it's going to be a huge blow to the whole IAMs mantra that "union workers do it better".
The IAM spent years (and huge dollars) claiming that the 787 line in Charleston couldn't do the high quality work that the IAM does in the Puget Sound. Before we had the huge embarrassment of FOD left in the KC-46 and other tanker QA failures - done by the IAM's 'superior' work force.
The IAM spent years (and huge dollars) claiming that the 787 line in Charleston couldn't do the high quality work that the IAM does in the Puget Sound. Before we had the huge embarrassment of FOD left in the KC-46 and other tanker QA failures - done by the IAM's 'superior' work force.
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The Max line is not stopped. The only planes affected are the -9's and Boeing only makes 3 or 4 of those a month. No one has said anything about stopping or slowing Max production. Right now there are only 2 Max-9's that have been built and are awaiting delivery and those will have to be subjected to any inspections called out by the AD. Max-9 production is a small subset of the Max line. It's about 10% of Max production. Since the -9 wasn't impacted by the Spirit bulkhead issue in the last few months they've made a higher percentage of them compared to the -8's but if they didn't make any -9's for month or so it isn't going to have an effect on production rates or Max deliveries.
If it does turn out to be IAM workers in Renton doing something (removing the door plug) without following the relevant procedures or doing the associated paperwork, it's going to be a huge blow to the whole IAMs mantra that "union workers do it better".
The IAM spent years (and huge dollars) claiming that the 787 line in Charleston couldn't do the high quality work that the IAM does in the Puget Sound. Before we had the huge embarrassment of FOD left in the KC-46 and other tanker QA failures - done by the IAM's 'superior' work force.
The IAM spent years (and huge dollars) claiming that the 787 line in Charleston couldn't do the high quality work that the IAM does in the Puget Sound. Before we had the huge embarrassment of FOD left in the KC-46 and other tanker QA failures - done by the IAM's 'superior' work force.
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I am pretty sure that if you take a vote from persons occupying row 0 up to the rear jump-seats, on whether this experience was "scary and terrifying", you would get an unanimous vote.
Hint: "Neuroscience research suggests that laughter or mirth is a way for us to reduce fear, anxiety, or stress."
People do absolutely random things in situations they never experienced before where adrenaline must have been through the roof. They didn't know if it was a bomb, they didn't know if the airplane was going to continue to fall apart, they didn't know if anyone had actually died, they didn't know if they were going to be alive in one minute. Taking selfies is one if the least strange things someone could have done.
The FAA announcement on Jan 12 begins with the following statement: " WASHINGTON, D.C. — After taking decisive and immediate action to ground approximately 171 Boeing 737-9 MAX planes, the Federal Aviation Administration (FAA) today announced new and significant actions to immediately increase its oversight of Boeing production and manufacturing. These actions come one day after the FAA formally notified Boeing that the FAA has launched an investigation into the company as a result of last Friday’s incident on a Boeing Model 737-9 MAX in which the aircraft lost a passenger door plug while in flight. "
On its own, that sounds reasonable. But I would have thought that the FAA "oversight" was already at the highest level as a result of the MCAS omnishambles. It also states: " Assessment of safety risks around delegated authority......." This is like deja vu all over again. If I was a U.S. taxpayer I would be asking Congress to point the blowtorch at the FAA, as well as at Boeing.
On its own, that sounds reasonable. But I would have thought that the FAA "oversight" was already at the highest level as a result of the MCAS omnishambles. It also states: " Assessment of safety risks around delegated authority......." This is like deja vu all over again. If I was a U.S. taxpayer I would be asking Congress to point the blowtorch at the FAA, as well as at Boeing.
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These plug doors are opened during specific inspections. Consequently the fact that they are opened and secured on a regular (although infrequent basis) is an indication that the process of closing and securing the door, when performed to the prescribed procedure is a safe process. There are literally thousands of bolts on any aircraft that if not properly installed and secured will result in the loss of an aircraft. We cannot make everything idiot proof as idiots are so ingenious. If the FAA wanted to put an emphasis on this they could require a logbook entry noting that the door had been opened and an additional verification of inspection and that could provide another level of redundancy, but there is not need to redesign something that works as designed. A redesign would then require additional certification testing and approvals and there is no need for that.
I agree with you on the bulk of your post, and a redesign likely isn't needed. IMO the cockpit and the maintenance hangar have addressed the human-factors element to a large degree, but it seems the assembly line is lagging behind. Maybe a reconsideration there, with a view of the subtleties/nuances of "effective" redundancies might mean additional layers of inspection. Or stronger visual cues - for low-tech ideas maybe contrasting paint where a fastener must go? Or for high-tech, maybe digitalized video inspections, that are processed through A.I. for abnormality detection. Maybe that would solve other problems, such as the foreign object debris problem, I mean if inspections already don't notice extra tools left in an airframe, whatever problems are happening there, it's not going to be solved by the same level of thinking and one more log book.
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All of the doors are shipped from in place but Spirit does not consider them "fitted and final". For the main doors this is fine. Boeing removes the main doors, dresses them with slides and other hardware and then rigs them to stringent specifications. Boeing was assuming that the plug doors were "installed" and wasn't checking the fasteners that mount the hinges and this is an apparent lapse and it explains how the loose bolts could have slipped through the system. That's also a relatively simple fix in adding a procedure to inspect, and torque those bolts.
It also would mean that there’s potentially both: A (manufacturing) design issue and a shopfoor discipline and oversight issue.
I am pretty sure that if you take a vote from persons occupying row 0 up to the rear jump-seats, on whether this experience was "scary and terrifying", you would get an unanimous vote.
Hint: "Neuroscience research suggests that laughter or mirth is a way for us to reduce fear, anxiety, or stress."
I applaud this lady for having the presence of mind, to start communicating by text-writing on her phone, the only practicable way of communicating, when suddenly a shirtless teen dropped in an empty seat next to her, and upon seeing his skin abrasions, was compassionate enough to inquire on his state of well-being.
And this selfie will be treasured by both for a very long time....
Glad they all ended up OK
It seems we are starting to hear that there was a competently documented process for the assembly steps, which is really what you would expect from somewhere like Boeing, but on the ground this was not being followed. I'd be pretty confident that they nevertheless have a paper audit that all was done right. The way to overcome this is called MBWA - Management By Walking Around; just seeing that reality matches.
Regarding Risk Assessments, I have long found these to be alas a way of back-fitting likelihood values to what you have already designed, just to get things accepted.
Regarding Risk Assessments, I have long found these to be alas a way of back-fitting likelihood values to what you have already designed, just to get things accepted.
Like instead of taking everything under the wings apart, workers start removing and replacing DC-10 engines directly from pylons with a forklift. Seemed like a great idea at the time, amirite?
Or the guy working on the 737 who apparently didn't reinstall a washer into a location that he couldn't actually see, during a bizarrely difficult maintenance procedure, leading to a bolt coming loose into the slat track and thence being shoved into the wing fuel tank.
Honorable mention to the inspector who pitched in and helped his guys remove the screws from their EMB 120 horizontal stabilizer, although it might have gone better if he had let the next shift know the leading edge needed to be put back together.
And to the guy who just used the screws that were handy to put the windscreen on BA111.
But anyway if you have what seems to be a Stupid Process™, people will sooner or later stop following it, possibly with dire results.
Is it Legal to Plug Emergency Exits on MAX 9?
Previously I’ve questioned ethics of plugging EEs; it seems wrong to deliberately block an available escape route. I wasn’t questioning legality of doing so, provided maximum passenger load complied with ratings of remaining EEs.
However, on reflection plugging mid-cabin EEs on MAX9 may not comply with FAR §25.813 Emergency Exit Access: “…. Emergency exit distribution must be as uniform as practical….”
If any EEs are plugged surely it should be either pair of over-wing EEs, not those at mid-cabin. Certainly, retaining mid-cabin EEs better meets intent of regulation as discussed in FAA Advisory Circular AC No: 25.807-1 UNIFORM DISTRIBUTION OF EXITS. Note regulation number has changed since AC was written.
Previously I’ve questioned ethics of plugging EEs; it seems wrong to deliberately block an available escape route. I wasn’t questioning legality of doing so, provided maximum passenger load complied with ratings of remaining EEs.
However, on reflection plugging mid-cabin EEs on MAX9 may not comply with FAR §25.813 Emergency Exit Access: “…. Emergency exit distribution must be as uniform as practical….”
If any EEs are plugged surely it should be either pair of over-wing EEs, not those at mid-cabin. Certainly, retaining mid-cabin EEs better meets intent of regulation as discussed in FAA Advisory Circular AC No: 25.807-1 UNIFORM DISTRIBUTION OF EXITS. Note regulation number has changed since AC was written.
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Distributin of exits
Is it Legal to Plug Emergency Exits on MAX 9?
Previously I’ve questioned ethics of plugging EEs; it seems wrong to deliberately block an available escape route. I wasn’t questioning legality of doing so, provided maximum passenger load complied with ratings of remaining EEs.
However, on reflection plugging mid-cabin EEs on MAX9 may not comply with FAR §25.813 Emergency Exit Access: “…. Emergency exit distribution must be as uniform as practical….”
If any EEs are plugged surely it should be either pair of over-wing EEs, not those at mid-cabin. Certainly, retaining mid-cabin EEs better meets intent of regulation as discussed in FAA Advisory Circular AC No: 25.807-1 UNIFORM DISTRIBUTION OF EXITS. Note regulation number has changed since AC was written.
Previously I’ve questioned ethics of plugging EEs; it seems wrong to deliberately block an available escape route. I wasn’t questioning legality of doing so, provided maximum passenger load complied with ratings of remaining EEs.
However, on reflection plugging mid-cabin EEs on MAX9 may not comply with FAR §25.813 Emergency Exit Access: “…. Emergency exit distribution must be as uniform as practical….”
If any EEs are plugged surely it should be either pair of over-wing EEs, not those at mid-cabin. Certainly, retaining mid-cabin EEs better meets intent of regulation as discussed in FAA Advisory Circular AC No: 25.807-1 UNIFORM DISTRIBUTION OF EXITS. Note regulation number has changed since AC was written.