Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
I had no doubt they were recorded and visible, if one zoomed up on them; but on a cell phone screen they are small dots no one is looking for, so no pinching and zooming and scrolling.
Shrink that image to 2 inches wide and those are gone. Also, perhaps adding blue circles to the installation process would have made them stand out?? I kid, I kid.
I am more disturbed by the graffiti than that someone glancing and seeing a door where a door should be did not further investigate that every other item is in place.
Another thing to note is that to detect the bad rivets they would have to be visible, but it looks like the interior was almost completely done - carpet, seats, insulation, interior wall. So that means the defect was on the outside of the fuselage. WTF Spirit. W.T.F.
Shrink that image to 2 inches wide and those are gone. Also, perhaps adding blue circles to the installation process would have made them stand out?? I kid, I kid.
I am more disturbed by the graffiti than that someone glancing and seeing a door where a door should be did not further investigate that every other item is in place.
Another thing to note is that to detect the bad rivets they would have to be visible, but it looks like the interior was almost completely done - carpet, seats, insulation, interior wall. So that means the defect was on the outside of the fuselage. WTF Spirit. W.T.F.
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NY Times:
"Four bolts used to secure the panel that ultimately blew off an Alaska Airlines plane during a flight last month were removed — and appear not to have been replaced — at Boeing’s factory in Renton, Wash., according to a preliminary report released Tuesday by the National Transportation Safety Board."As evidence, the N.T.S.B. provided a photograph of the door plug after it was reinstalled but before the plane’s interior was restored. In the image, three of the four bolts appear to be missing. The location of the fourth bolt is covered with insulation.
"The report said the image had been attached to “a text message between Boeing team members on September 19, 2023.” The Boeing employees “were discussing interior restoration after the rivet rework was completed during second shift operations that day,” the report said."
"Four bolts used to secure the panel that ultimately blew off an Alaska Airlines plane during a flight last month were removed — and appear not to have been replaced — at Boeing’s factory in Renton, Wash., according to a preliminary report released Tuesday by the National Transportation Safety Board."As evidence, the N.T.S.B. provided a photograph of the door plug after it was reinstalled but before the plane’s interior was restored. In the image, three of the four bolts appear to be missing. The location of the fourth bolt is covered with insulation.
"The report said the image had been attached to “a text message between Boeing team members on September 19, 2023.” The Boeing employees “were discussing interior restoration after the rivet rework was completed during second shift operations that day,” the report said."
If you look at fig 11, there is paint in a guide fitting hole that is pristine. It really doesn't look like a bolt was ever there. The bolts are probably very loose fitting but still.
To me, the takeaway from the report is that the NTSB hasn't found any documentation to cover the opening/closing of the plug. No worksheets to cover the work. Possibly the techs just put it back the way they found it. That's not the way to do airplanes.
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Im not sure the Times read the report correctly. I don't think the report specifically says they removed 4 bolts, it just says they opened the plug. If the bolts weren't there to begin with they wouldn't have removed them.
If you look at fig 11, there is paint in a guide fitting hole that is pristine. It really doesn't look like a bolt was ever there. The bolts are probably very loose fitting but still.
To me, the takeaway from the report is that the NTSB hasn't found any documentation to cover the opening/closing of the plug. No worksheets to cover the work. Possibly the techs just put it back the way they found it. That's not the way to do airplanes.
If you look at fig 11, there is paint in a guide fitting hole that is pristine. It really doesn't look like a bolt was ever there. The bolts are probably very loose fitting but still.
To me, the takeaway from the report is that the NTSB hasn't found any documentation to cover the opening/closing of the plug. No worksheets to cover the work. Possibly the techs just put it back the way they found it. That's not the way to do airplanes.
The "graffiti" on the window may have been put there so nobody thought the window was an open hole and banged their head or damaged the window (speculation). Also it does serve as evidence that all the photos are of the same door (or window at least).
An interesting sentence from the report shows that they measure seal flushness in inches not mm (to address an earlier comment about the metric system):
During the build process, one quality notification (QN NW0002407062) was noted indicating the seal flushness was out of tolerance by 0.01 inches.
Lift Assist Spring Force
Looking at the photos and estimating the spring parameters:
10 coils
.125 inch diameter music wire
1.6 inch OD
Gives a fully compressed load of over 50 lbf per spring and a rate of about 10 pounds per inch; that would leave 70-80 pounds of lift at the time the fingers cleared.
17-7 stainless is a few percent decrease in force and rate.
If the wire diameter is 0.09 inch, then it drops to 40 pounds fully compressed for the pair and 2.5 pounds per inch, so 35 pounds to clear the fingers.
C'mon NTSB, these are day 1, did the parts conform questions/answers.
Maybe the door seals are just that sticky?
They have the previous 16 flights. Was the last one with a big slam on the landing? Something popped that door up and if it wasn't the springs, what was it?
10 coils
.125 inch diameter music wire
1.6 inch OD
Gives a fully compressed load of over 50 lbf per spring and a rate of about 10 pounds per inch; that would leave 70-80 pounds of lift at the time the fingers cleared.
17-7 stainless is a few percent decrease in force and rate.
If the wire diameter is 0.09 inch, then it drops to 40 pounds fully compressed for the pair and 2.5 pounds per inch, so 35 pounds to clear the fingers.
C'mon NTSB, these are day 1, did the parts conform questions/answers.
Maybe the door seals are just that sticky?
They have the previous 16 flights. Was the last one with a big slam on the landing? Something popped that door up and if it wasn't the springs, what was it?
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The report's main conclusion:
Overall, the observed damage patterns and absence of contact damage or deformation around holes associated with the vertical movement arrestor bolts and upper guide track bolts in the upper guide fittings, hinge fittings, and recovered aft lower hinge guide fitting indicate that the four bolts that prevent upward movement of the MED plug were missing before the MED plug moved upward off the stop pads.
Page 14 of 19 DCA24MA063
This information is preliminary and subject to change.
Overall, the observed damage patterns and absence of contact damage or deformation around holes associated with the vertical movement arrestor bolts and upper guide track bolts in the upper guide fittings, hinge fittings, and recovered aft lower hinge guide fitting indicate that the four bolts that prevent upward movement of the MED plug were missing before the MED plug moved upward off the stop pads.
Page 14 of 19 DCA24MA063
This information is preliminary and subject to change.
Documents and photos show that to perform the replacement of the damaged rivets, access
to the rivets required opening the left MED plug (see figure 15). To open the MED plug, the two
vertical movement arrestor bolts and two upper guide track bolts had to be removed.
to the rivets required opening the left MED plug (see figure 15). To open the MED plug, the two
vertical movement arrestor bolts and two upper guide track bolts had to be removed.
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The group will also be looking at ... Spirit AeroSystems’ ongoing development of its voluntary SMS program.
NTSB Prelim questions
On page 15of19 figure 14 … it looks like the upper right hand track bolt in the guide is much closer to the guide right hand edge than in other pictures …
or is it the shadow of the bolt?
adding …
Figure 16 shows the corresponding hole … so it is indeed close to the edge … so if correct then the roller into the guide distance/depth is quite small (is that what one of the posters a long time ago referred to? … the Boeing description of the required depth was not immediately clear to me at the time without a proper drawing… ).
also interesting to see figure 15 which shows the door opened much further than 15 degrees, so not using the steel cable (strap assy), … not immediately clear if it was supported on the outside or just supported by the hinges with maybe something preventing it from going the full 90…?… is there a kind of support visible through the window behind the ‘ funny face ‘ …?
and interesting to see the apparent difference in circular contact surface (not the top tear damage) of the pads, from white below to full black higher up … a difference also referred to by earlier posters.
Also interesting on page 18 … seal QN and FFF check… but still not clear to me if a new seal is required if you open the plug by 15 degrees … or as in this case by say 60-90 degrees…?
or is it the shadow of the bolt?
adding …
Figure 16 shows the corresponding hole … so it is indeed close to the edge … so if correct then the roller into the guide distance/depth is quite small (is that what one of the posters a long time ago referred to? … the Boeing description of the required depth was not immediately clear to me at the time without a proper drawing… ).
also interesting to see figure 15 which shows the door opened much further than 15 degrees, so not using the steel cable (strap assy), … not immediately clear if it was supported on the outside or just supported by the hinges with maybe something preventing it from going the full 90…?… is there a kind of support visible through the window behind the ‘ funny face ‘ …?
and interesting to see the apparent difference in circular contact surface (not the top tear damage) of the pads, from white below to full black higher up … a difference also referred to by earlier posters.
Also interesting on page 18 … seal QN and FFF check… but still not clear to me if a new seal is required if you open the plug by 15 degrees … or as in this case by say 60-90 degrees…?
Last edited by A0283; 6th Feb 2024 at 23:10.
About the only thing I see new in the report is the images of the damage caused as the stops bypassed and the guide fittings tore out. It was obvious to most that the plug could not have departed if the stop bolts had been fitted.
I suppose we'll have to wait a year to find out what f'd up process allowed the aircraft to enter service without the stop bolts fitted.
I suppose we'll have to wait a year to find out what f'd up process allowed the aircraft to enter service without the stop bolts fitted.
You can add this to your collection of "dumb things rich people say":
https://www.nbcnews.com/news/rcna136416
An event like this must not happen on an airplane that leaves our factory. We simply must do better for our customers and their passengers.
-Dave Calhoun
-Dave Calhoun
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Interestingly on a photo in the report a Boeing technician is holding the partially stripped door seal into the camera, which may be too long to fit without buckling. The report mentions a non-conformity considered tolerable at Spirit regarding the seal. This further corrobates the story of the wistleblower about the process failure, avoiding an official entry about the opening of the plug as a shortcut.
Rivets sit quite close to fuselage`s outer skin.
G Forces
Quite right DaveReidUK...
Originally Posted by Europa01
Now we can see that the lift assist force is not enough to lift the door/plug even depressurised.
Well, more accurately, under 1g conditions it isn't enough ...
So an additional 0.2 G, as is likely going over Runway Centre Line Lights, or mild turbulence at 16.000 ft, would be all that is required.
Originally Posted by Europa01
Now we can see that the lift assist force is not enough to lift the door/plug even depressurised.
Well, more accurately, under 1g conditions it isn't enough ...
So an additional 0.2 G, as is likely going over Runway Centre Line Lights, or mild turbulence at 16.000 ft, would be all that is required.
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Rivet axis are facing in longitudinal direction of fuselage according to Fig 14. of prelim report. Not visible from air side of fuselage.
Amazing that a NCR about the rivets was filed at Boeing the very day after arrival at Renton.
If QC guys at Boing weren't already in the loop, I tip my hat.
Rivet axis are facing in longitudinal direction of fuselage according to Fig 14. of prelim report. Not visible from air side of fuselage.
Amazing that a NCR about the rivets was filed at Boeing the very day after arrival at Renton.
If QC guys at Boing weren't already in the loop, I tip my hat.
Amazing that a NCR about the rivets was filed at Boeing the very day after arrival at Renton.
If QC guys at Boing weren't already in the loop, I tip my hat.
Then with the interior almost closed up, the rivets are replaced, door is in place, inspector has blinders on as they only inspect what they are supposed to.
I wonder who spotted the rivet problem at the outset.
I mentioned earlier that the engineering response should be to mark the door with written instructions to remove and replace the fasteners and a QR code to give part number and process and QA/QC signoff and that no hardware removal happens without scanning the door QR code to log the action automatically to QC.
Quite right DaveReidUK...
Originally Posted by Europa01
Now we can see that the lift assist force is not enough to lift the door/plug even depressurised.
Well, more accurately, under 1g conditions it isn't enough ...
So an additional 0.2 G, as is likely going over Runway Centre Line Lights, or mild turbulence at 16.000 ft, would be all that is required.
Originally Posted by Europa01
Now we can see that the lift assist force is not enough to lift the door/plug even depressurised.
Well, more accurately, under 1g conditions it isn't enough ...
So an additional 0.2 G, as is likely going over Runway Centre Line Lights, or mild turbulence at 16.000 ft, would be all that is required.
The damage to the stops is what happens if the door moves up far enough that it cannot come back down because of the step between the hardened contact and the rest of the bracket. That would leave a small gap at the bottom or top of the door that might let the pressurized air leak out until the pressure controller dumped enough to pop it into full contact. This is another feature I was hoping for in the report - the exact configuration of the door seals.
I mentioned earlier that the engineering response should be to mark the door with written instructions to remove and replace the fasteners and a QR code to give part number and process and QA/QC signoff and that no hardware removal happens without scanning the door QR code to log the action automatically to QC.
Turns out this is exactly how Boeing builds airplanes. Procure faulty or unfinished stuff, put it mostly together, see if it flies.
T-7 was one of the brighter spots in Boeing's defense business, as the Air Force has been looking to replace the ancient but incredibly capable T-38 for decades (many pilots flying planes older than their fathers...), and this was the first aircraft to measure up to that task.
https://www.defensenews.com/air/2024...-faulty-parts/
Interesting that the preliminary report gives details of when the door plug was shipped from Spirit Malaysia and when it arrived in Wichita but doesn't mention that the door plug that was actually installed in the accident aircraft and found in Bob Sauer's back yard was destined for a different airframe, evidenced by the L/N in the photo in post 629. It may be an irrelevance or a red herring but the devil is almost always in the details....and while it wasn't the proximate cause of the incident (bolts) when the team charged with looking at quality systems and traceability evaluate the various QMS's employed at Boeing and Spirit, the reason for that could be a useful finding.
Without the help of lift assist springs ...