Alaska Airlines 737-900 MAX loses a door in-flight out of PDX
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Is "nipped up" still a recognised term?
Bolts
THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
ALL STEPS TO BE CARRIED OUT AS SPECIFIED AND IN THE ORDER SPECIFIED
PLACE KEEPING TO BE USED AS FOLLOWS - circle step number at the start of each step and crosss slash the circled step number on completion
IF IN DOUBT STOP AND ASK
1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut, washer and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1/6 of a turn (one flat) or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion : Signature ………….Date:……….
8 SUPERVISOR HOLD POINT : Task confirmed completed Signature ………..Date………..
Last edited by Europa01; 27th Jan 2024 at 21:48. Reason: Fair comment by aeromech3 - changes + tweaks in italics
It is where I come from but how about:-
THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion
THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion
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It is where I come from but how about:-
THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion
THIS TASK TO BE COMPLETED IN ACCORDANCE WITH WORK INSTRUCTION: 707- xxxxxxxxxxx
1. Obtain locking bolt assembly part No. 707 - ****### consisting of bolt, castellated nut and split pin
2. Insert bolt through hole in guide track from outboard side
3. Check bolt head is full seated
4. Thread nut on to bolt by hand until the nut is seated on the inboard face of the guide track.
5. Note the positions of the bolt cross drilling and nut castellations and tighten the nut 1//6 of a turn or less until the split pin can be inserted
6. Make-off the split pin by spreading the tangs leaving one across the end of the bolt.
7. Record task completion
Jokes aside, do we actually know if Boeing specifies a tightening torque for this application?
There could be good reasons for torquing the bolts unrelated to their primary function .
Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
“Nut, Screws, Washer and Bolts”
Soo many questions…
Was expecting a clown joke or clowns remark when days ago someone fielded the question “Calhoun-Clon-Clown?“
Information that is coming out of Boeing/Spirit (not only now but also (years) before) is shockingly far away from the highest standards that I have seen for years in aerospace commercial new building. The width and depth of this @&#$ I have not even seen far less complex and far more forgiving industries, industries to which I regularly help translate and adapt aerospace standards (and test lessons learned in reverse). I sincerely hope that the general public will understand that this is certainly not normal. Have had to answer and try explain that multiple times already since AK 704 got unplugged.
This situation has far wider impact than a single event, wider than a single model, wider than Boeing/Spirit. In that sense the scope of the present NTSB investigation is far too limited. So hope they start another one in parallel. We should ask ourselves general but also personal questions, for example:
Do we have a global aerospace systemic problem ?
If the standards have sunk so low - and sunk so low especially after the unprecedented massive (also wide international) attention/scrutiny that Boeing and the MAX got after the two fatal crashes - questions could be:
For example, (FAA will become an investigation in itself), how could EASA have given the MAX a 100% clear and based on what?
For example, Who investigated What. With what we find now it seems like either information was suppressed or investigators fooled and/or incompetent?
These far below business practice standards are suggested to have been driven by corporate and management greed.
What has been done to diminish these drivers and by whom?
How is it possible that you can push a global giant to the brink and get away with 90+ million.
How is it possible to appoint a new CEO who has co-thrived for years on safety culture cutting.
What happened with the tough talk in US Congress after the crashes?
Has US Congress answered the question how much funding the FAA needs to become effective? Self-regulation is showning hard limits.
FAA managers In congressional hearings lacked engineering and certainly manufacturing knowledge and experience - did they recognise that themselves, how do they solve that?
Boeing has got away with this for years. This means that competitors had to compete with that for years. Has this introduced a systemic risk or systemic strength in these competing organisations? There must have been a significant impact.
My experience at the time Boeing had a better name was that we regularly put in a higher design and manufacturing standard than Boeing In multiple technical fields. That would be untenable with the present day standards to compete with.
Throw*794AL talked about ‘safety accepters and safety rejecters’. I wonder how people from each group go to work everyday? And what happens when they meet?
So many questions… !
(the aging workforce means it will get harder to develop and implement the proper (known) solutions … )
Information that is coming out of Boeing/Spirit (not only now but also (years) before) is shockingly far away from the highest standards that I have seen for years in aerospace commercial new building. The width and depth of this @&#$ I have not even seen far less complex and far more forgiving industries, industries to which I regularly help translate and adapt aerospace standards (and test lessons learned in reverse). I sincerely hope that the general public will understand that this is certainly not normal. Have had to answer and try explain that multiple times already since AK 704 got unplugged.
This situation has far wider impact than a single event, wider than a single model, wider than Boeing/Spirit. In that sense the scope of the present NTSB investigation is far too limited. So hope they start another one in parallel. We should ask ourselves general but also personal questions, for example:
Do we have a global aerospace systemic problem ?
If the standards have sunk so low - and sunk so low especially after the unprecedented massive (also wide international) attention/scrutiny that Boeing and the MAX got after the two fatal crashes - questions could be:
For example, (FAA will become an investigation in itself), how could EASA have given the MAX a 100% clear and based on what?
For example, Who investigated What. With what we find now it seems like either information was suppressed or investigators fooled and/or incompetent?
These far below business practice standards are suggested to have been driven by corporate and management greed.
What has been done to diminish these drivers and by whom?
How is it possible that you can push a global giant to the brink and get away with 90+ million.
How is it possible to appoint a new CEO who has co-thrived for years on safety culture cutting.
What happened with the tough talk in US Congress after the crashes?
Has US Congress answered the question how much funding the FAA needs to become effective? Self-regulation is showning hard limits.
FAA managers In congressional hearings lacked engineering and certainly manufacturing knowledge and experience - did they recognise that themselves, how do they solve that?
Boeing has got away with this for years. This means that competitors had to compete with that for years. Has this introduced a systemic risk or systemic strength in these competing organisations? There must have been a significant impact.
My experience at the time Boeing had a better name was that we regularly put in a higher design and manufacturing standard than Boeing In multiple technical fields. That would be untenable with the present day standards to compete with.
Throw*794AL talked about ‘safety accepters and safety rejecters’. I wonder how people from each group go to work everyday? And what happens when they meet?
So many questions… !
(the aging workforce means it will get harder to develop and implement the proper (known) solutions … )
Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
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The issue with quality culture I've been mulling over (after the discussion about the "removal" vs "opening" classification) is comfort and familiarity. I am not an aerospace engineer or mechanic, but I'm interested in how processes work (by analogy with those that I follow).
If I am asked to perform an activity such as removing a few bolts do I have a mental model of how they are going to be replaced? If I'm removing these bolts as part of a written-up subtask I might just trust (or indeed know) that the higher-level task that demands their removal will also ensure their replacement. If I have bought into a quality and safety culture shouldn't it feel uncomfortable to be unbolting something outside of a process that I trust/expect to restore it?
I think it should be easy to distinguish in process terms between opening a standard passenger door using the handle (as flight crew would do) and opening a door by removing bolts with a tool?
If I am asked to perform an activity such as removing a few bolts do I have a mental model of how they are going to be replaced? If I'm removing these bolts as part of a written-up subtask I might just trust (or indeed know) that the higher-level task that demands their removal will also ensure their replacement. If I have bought into a quality and safety culture shouldn't it feel uncomfortable to be unbolting something outside of a process that I trust/expect to restore it?
I think it should be easy to distinguish in process terms between opening a standard passenger door using the handle (as flight crew would do) and opening a door by removing bolts with a tool?
Last edited by Goth; 27th Jan 2024 at 12:31. Reason: typo
Here's another nut and bolt SNAFU by the manufacturer
Report 2020-014.pdf (aaiu.ie)
Report 2020-014.pdf (aaiu.ie)
I am starting to wonder how the NTSB and other accident investigators today perceive causes in design and manufacturing.
If you want to understand what preceded this at this point in time you would probably have to rely on a whistleblower and a class action law suit. That’s weird.
My copy of CAIP's from 1971 (updated for some years and costs) which I studied and loaned out to promising mechanics for their preparation for Licensing exams, states clearly this is the minimum standard.
In regards to locking nuts BL/3-13 applies.
I respect the IAA, they kept the Licensed Engineer status for a long time and the the report AAIF 2020-014 pdf can hardly make a recommendation to adhere to basic standards.
My take on that incident is that the pin had some interference fit and though the nut was fitted as evidence by the tang washer inner face (hardly floating) remember that 271inlbf is hardly a grunt on a 1foot spanner, but that the cotter pin might well have passed through the nut slots, and the pre-drilled hole in the pin is not possible, my blunt side cutters are testament to the difficulty of removing split pins when even one leg is slightly bent; the correct diameter split pin was never there.
Not relevant to B737-9 incident where visual check was easy but same conclusion: the split pins were never there.
In regards to locking nuts BL/3-13 applies.
I respect the IAA, they kept the Licensed Engineer status for a long time and the the report AAIF 2020-014 pdf can hardly make a recommendation to adhere to basic standards.
My take on that incident is that the pin had some interference fit and though the nut was fitted as evidence by the tang washer inner face (hardly floating) remember that 271inlbf is hardly a grunt on a 1foot spanner, but that the cotter pin might well have passed through the nut slots, and the pre-drilled hole in the pin is not possible, my blunt side cutters are testament to the difficulty of removing split pins when even one leg is slightly bent; the correct diameter split pin was never there.
Not relevant to B737-9 incident where visual check was easy but same conclusion: the split pins were never there.
Last edited by aeromech3; 28th Jan 2024 at 02:05.
Sorry: I won't quote the other posts I am referring to - this thread is going the way of the AF447 one with hundreds of pages to read!
According to throwawayboeingN704AL comments section at leehamnews.com, the aircraft fuselage assembly airplane #8789 (to become N704AL) had issues with rivets, and the "the mid-cabin port side semi-plug type emergency exit door plug" pressure seal. The replacement seal was (presumably for expediency purposes) borrowed from another fuselage assembly #8799 (to become N705AL).
Question 1: Was the LHS door plug also urgently borrowed from another fuselage assembly (N705AL), possibly with the four retention bolts with castellated nut and split pin assemblies not yet fitted on that replacement assembly?
Question 2: Would four new retention bolts with castellated nut and split pin assemblies be fitted if the door plug needed to be removed (CMES)/opened (SAT) for any reason, before it left the factory or after, such as during scheduled maintenance, or would just the split pin be replaced?
Question 3: What of that 'other' aircraft assembly the pressure seal was borrowed from (N705AL) - who has that airframe right now, and has it been inspected with a little more thoroughness than all the others? What of the paperwork of the other airframe? Was that consistent with the story from throwawayboeingN704AL about SAT and CMES entries for that airframe as well?
Question 4: How do you align the door plug with the fuselage? Is appears to be a two person job, with one on the inside loosening the bolts on the top roller bracket and bottom spring loaded guides, and then moving the door in conjunction with the person outside until the two line up properly with the door seal before tightening them up on each side? That would involve the four roller guide bolts being a two step process: First to have the bolts holding the (slotted hole) roller guides in place loosely so the final bracket location can be adjusted within the slotted bolt holes, and then the final torque being applied to lock them into place permanently. I'm assuming the four retention bolts with castellated nut and split pin assemblies were missing, but the bolts that keep the roller guides in place are the ones that are loose on this airframe and have been discovered loose on other airframes, aren't they? Is this omitted second tightening step the smoking gun that defines the entire issue? A missing page in the manual maybe that defines this tightening step and insertion of the retention bolts, or the person that performs these steps is missing on the production line?
Question 5: Re post 1191 (fdr)
The four retention bolts with castellated nut and split pin assemblies that were missing do not have to be torqued to any major tightness. The function is to prevent the pin assembly from moving past them, and the stresses on the bolt are at right angles to the bolt. The nut is just there to prevent it from sliding out of the hole it is in, and the split pin is just to ensure the nut doesn't loosen. Being snug tight or very tight is not going to make that much of a difference as the bolts stop the door plug pins from sliding up-and-down within the roller guide brackets - only that it is there as an interference to prevent free up-and-down movement. This is consistent with the story the opposite right hand side door plug assemblies requiring tightening by Boeing. Are my assumptions valid?
Re post #1428 (Europa01)
QA Inspection procedure:
Outside:
Ensure even gap between door and frame, and seal and door plus assembly is flush with airframe.
Inside:
Confirm all four retention bolts are fitted, nuts are tightened so no thread is visible between nut and bracket and verify bolt does not have free play, and place daub of colored thread locker paint over split pin to confirm inspection. Repeat for other side of door plug.
Ensure all four bolts for each roller guide are torqued to specification.
Question 6: On the airframe N704AL, are all the doors (regular ones that open and close), and door plugs assemblies (that are semi-permanently closed) showing colored thread locker QA inspection paint? Both sides? How about the other airframe the door seal was borrowed from (N705AL)? How about all other airframes that have been inspected to date? Is the QA inspection paint daub present on each and every one (I'd love to see the FAA spreadsheet with the inspection ticks and crosses and look for any patterns)? Are the loose bolts that have been found on other airframes showing signs of QA daubing, indicating that at some stage they have been installed and QA inspected?
Question 7: Why aren't the NTSB looking for the missing door pressure seal as well? Surely any deformation imprints or tears in the flexible material on that would tell a story to clarify which angle the door plug departed the airframe?
Question 8: Where does one purchase a set of Specialist Bolts for British Industry alluded to in post 1416? I need a set for my workshop, to go with my left handed tools!
According to throwawayboeingN704AL comments section at leehamnews.com, the aircraft fuselage assembly airplane #8789 (to become N704AL) had issues with rivets, and the "the mid-cabin port side semi-plug type emergency exit door plug" pressure seal. The replacement seal was (presumably for expediency purposes) borrowed from another fuselage assembly #8799 (to become N705AL).
Question 1: Was the LHS door plug also urgently borrowed from another fuselage assembly (N705AL), possibly with the four retention bolts with castellated nut and split pin assemblies not yet fitted on that replacement assembly?
Question 2: Would four new retention bolts with castellated nut and split pin assemblies be fitted if the door plug needed to be removed (CMES)/opened (SAT) for any reason, before it left the factory or after, such as during scheduled maintenance, or would just the split pin be replaced?
Question 3: What of that 'other' aircraft assembly the pressure seal was borrowed from (N705AL) - who has that airframe right now, and has it been inspected with a little more thoroughness than all the others? What of the paperwork of the other airframe? Was that consistent with the story from throwawayboeingN704AL about SAT and CMES entries for that airframe as well?
Question 4: How do you align the door plug with the fuselage? Is appears to be a two person job, with one on the inside loosening the bolts on the top roller bracket and bottom spring loaded guides, and then moving the door in conjunction with the person outside until the two line up properly with the door seal before tightening them up on each side? That would involve the four roller guide bolts being a two step process: First to have the bolts holding the (slotted hole) roller guides in place loosely so the final bracket location can be adjusted within the slotted bolt holes, and then the final torque being applied to lock them into place permanently. I'm assuming the four retention bolts with castellated nut and split pin assemblies were missing, but the bolts that keep the roller guides in place are the ones that are loose on this airframe and have been discovered loose on other airframes, aren't they? Is this omitted second tightening step the smoking gun that defines the entire issue? A missing page in the manual maybe that defines this tightening step and insertion of the retention bolts, or the person that performs these steps is missing on the production line?
Question 5: Re post 1191 (fdr)
The four retention bolts with castellated nut and split pin assemblies that were missing do not have to be torqued to any major tightness. The function is to prevent the pin assembly from moving past them, and the stresses on the bolt are at right angles to the bolt. The nut is just there to prevent it from sliding out of the hole it is in, and the split pin is just to ensure the nut doesn't loosen. Being snug tight or very tight is not going to make that much of a difference as the bolts stop the door plug pins from sliding up-and-down within the roller guide brackets - only that it is there as an interference to prevent free up-and-down movement. This is consistent with the story the opposite right hand side door plug assemblies requiring tightening by Boeing. Are my assumptions valid?
Re post #1428 (Europa01)
QA Inspection procedure:
Outside:
Ensure even gap between door and frame, and seal and door plus assembly is flush with airframe.
Inside:
Confirm all four retention bolts are fitted, nuts are tightened so no thread is visible between nut and bracket and verify bolt does not have free play, and place daub of colored thread locker paint over split pin to confirm inspection. Repeat for other side of door plug.
Ensure all four bolts for each roller guide are torqued to specification.
Question 6: On the airframe N704AL, are all the doors (regular ones that open and close), and door plugs assemblies (that are semi-permanently closed) showing colored thread locker QA inspection paint? Both sides? How about the other airframe the door seal was borrowed from (N705AL)? How about all other airframes that have been inspected to date? Is the QA inspection paint daub present on each and every one (I'd love to see the FAA spreadsheet with the inspection ticks and crosses and look for any patterns)? Are the loose bolts that have been found on other airframes showing signs of QA daubing, indicating that at some stage they have been installed and QA inspected?
Question 7: Why aren't the NTSB looking for the missing door pressure seal as well? Surely any deformation imprints or tears in the flexible material on that would tell a story to clarify which angle the door plug departed the airframe?
Question 8: Where does one purchase a set of Specialist Bolts for British Industry alluded to in post 1416? I need a set for my workshop, to go with my left handed tools!
Last edited by Thirsty; 27th Jan 2024 at 17:06.
Nuts and Bolts
Calling out Europa01 and 639.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Never had a task card that stated "thread nut on bolt by hand" this is just too basic and though over thorough, excludes mention of the washer.
In my training days this was graphically demonstrated by a poster of a somewhat sexual picture of a bolt entering a nut (without washer/condom).
Otherwise a reasonable attempt at a task write up.
Last edited by Europa01; 27th Jan 2024 at 21:28.