Boeing 737 Max again, it would be nice if the windows [door plugs] stayed in!

[Gyro]

... Also now I understand why the door plug didn't fall in previous flight at a higher altitude: the higher the altitude the better the door plug self-locks into the frame.

As long as the stop pins are sufficiently aligned during pressurization, for the conical pins to lock in, yes. If it climbs with them misaligned, so that the stop tab castings are just sitting on the edges then it could still let go at any altitude. Of course a door warning sensor would have picked up this condition straight away, but unfortunately they couldn't be bothered to fit these on the plug doors, even though the annunciators for these are still on the flight deck.

Yes, it is a clever design, It took me a while to work out how they work. Initially they just looked like bump stops to make the door sit flush. Whether it can be regarded as a true plug door seems still open to debate as the stop fittings (ok, there are 12 of them )are bolted on and the door isn't tapered in the frame. It also creates a lot of potential alignment and tolerance requirements that might have resulted in a bit of unauthorized bolt loosening during fitting, as I suggested in reply #135. Pure speculation on my part of course.

[floobydust]

There were two failures- The NTSB is puzzled over the second. The locking bolts (likely) not installed, and the door moved laterally.
My understanding is the door has to first move DOWN to get the top lock pins out, compressing the springs, and then it's UP and out. But I could be wrong.
The bottom bracket screws found loose on the United planes, I think are the second mech failure here. Once those screws fall out...

The door could have been bumped off the stop pins on a previous landing.
You'd think somebody would notice a door ajar or the rattling sounds.

[Dundarave]

My understanding is the door has to first move DOWN to get the top lock pins out, compressing the springs, and then it's UP and out. But I could be wrong.
The bottom bracket screws found loose on the United planes, I think are the second mech failure here. Once those screws fall out...

Here’s the latest video from the 737 expert that provides a thorough description of the plug attachment system. https://youtu.be/5FcyvFfHsjQ?si=0rryavmB2_SfNs1R

The brackets are on the plug, and the pins are on the aircraft door frame.

The springs, incredibly, act to push the door up and into the released position.  The installers have to push the door down against the springs in order to get the locking bolts in.

I speculate that since there doesn’t seem to be a handle/leverage point on the inside of the plug, when it came time to put the 4 locking bolts in, there was no ladder outside for someone to help push down the plug against the springs so the bolts could be inserted.

The installer doddled off to report it, the interior guys replaced the wall coverings, and the bolts never got installed.

The design, while clever, was a bit too clever in the use of the springs to aid plug removal when necessary.

Further, if the pins and bracket arrangement had been reversed, with the pins on the plug and the brackets on the door, then indeed the springs would have worked to push the pins into the brackets.  Perhaps this was the original design thinking, but something happened to cause the pin/bracket swap during manufacturing changes.

Apparently,  other doors in the aircraft normally have pins on the door and brackets on the door frame.  So perhaps a change that caused unintended consequences.  Below is the relevant image from the video that shows the arrangement of the plug "guide track" (what I've been calling the "bracket"), and the door frame pins.

[Gyro]

...
You'd think somebody would notice a door ajar or the rattling sounds.

Well it is a Boeing 

If there had been an unlucky passenger in the window seat, he might have (briefly?) noticed the window not matching the hole in the interior trim.

[SeanB]

Probably was close to shift change, so the installer went off, and the next shift, seeing door in place, did not check, but simply put the interior and seats back, as they probably had a long list of stuff to finish, because the plane was due to depart before end of the shift.

[SiliconWizard]

Ouch, bad times for Boeing.
https://www.reuters.com/world/us/atlas-air-says-cargo-aircraft-landed-miami-after-engine-malfunction-2024-01-19/

[vad]

Ouch, bad times for Boeing.
https://www.reuters.com/world/us/atlas-air-says-cargo-aircraft-landed-miami-after-engine-malfunction-2024-01-19/

Quote: “ Investigators will be looking at questions like the age of the engine and its maintenance record.”

Boeing does not manufacture engines.

[CatalinaWOW]

Ouch, bad times for Boeing.
https://www.reuters.com/world/us/atlas-air-says-cargo-aircraft-landed-miami-after-engine-malfunction-2024-01-19/

Quote: “ Investigators will be looking at questions like the age of the engine and its maintenance record.”

Boeing does not manufacture engines.

No they don't.  But they won't be able to dodge this one either, since one of the prominent subjects of the failure investigation will be on the apparent failure of the containment system (fist sized hole in the top of the engine nacelle).  At least part of that is on Boeing's watch.  And probably done before the bean counter debacle cited by several on this thread.

[bdunham7]

No they don't.  But they won't be able to dodge this one either, since one of the prominent subjects of the failure investigation will be on the apparent failure of the containment system (fist sized hole in the top of the engine nacelle).  At least part of that is on Boeing's watch.  And probably done before the bean counter debacle cited by several on this thread.

The system is not required to contain all possible failures.  There are some disassembly modes that would be impossible to protect against without making the plane too heavy to fly.

[pickle9000]

 The "engine fire" (to be determined) is one of many failures that happen every day on all aircraft. Not saying it
wasn't serious it was but the plane landed safely. Lots of redundancy. That is very different from the inept
things going on at the FCC and Boeing.

[Andy Chee]

The "engine fire" (to be determined) is one of many failures that happen every day on all aircraft.

Apparently a chunk of the engine let go and punched a "softball-sized" hole through the top of the engine.

Punching a hole through anything does NOT happen every day on all aircraft!

[PartialDischarge]

Boeing cannot be blamed for this engine failure, but I still don't trust 100% the software solution to the MCAS fiasco which downed 2 new airplanes. Being software I just can't trust that airplane anymore.

[pickle9000]

The "engine fire" (to be determined) is one of many failures that happen every day on all aircraft.

Apparently a chunk of the engine let go and punched a "softball-sized" hole through the top of the engine.

Punching a hole through anything does NOT happen every day on all aircraft!

A hole is bad, no question but the engineering behind the engines is phenomenal. The cowling contains
Kevlar but its not perfect. Have a look at this:

[SeanB]

Last one is a 747 cargo, with GE engines. Basically an airframe made in the 1990's, and one that has literally millions of flight hours and landing cycles for the type. Nothing new about it, and the same for the GE engine. Yes it shed turbine blades, but they got contained and left out the back, not through the cabin, and the engine was safely shut down, with the other 3 still providing more than enough power.

[tom66]

Alaska Airlines CEO: We found 'many' loose bolts on our Max 9 planes following near-disaster

https://www.nbcnews.com/business/business-news/alaska-airlines-found-more-loose-bolts-boeing-737-max-9-ceo-says-rcna135316

Just reported.

[floobydust]

"... {Boeing} announced a one-day work pause at its Renton factory for employees to learn and focus on quality assurance."
"It is the first of many “Quality Stand Down” days Boeing will host over the next few weeks at its factories." 

I think most of us here have tightened important bolts- you know the kind with washers, maybe cotter pins, using a torque wrench. It's actually not that difficult after reading a manufacturer's instructions. Surely Spirit and Boeing have 3D exploded view drawings on-line as well to help assemblers, assuming that is the problem. Or is it?


"These troubles are heavily the result of the company’s Jack Welch acolytes and General Electric-style management, weak board of directors, union busting, and exchanging Boeing’s history of engineering excellence for McDonnell Douglas’ “bean counters.” Regular readers know I have written about this often."

"In 2001, a top Boeing aerospace engineer John Hart-Smith presented an internal paper before top executives warning of excessive reliance on outsourcing — a paper that was lauded by his peers within the company but ignored by management. Behind all this was one driving force: to keep the stock price up and reap high executive compensation."

"The Boeing Problem won’t be resolved until real consequences are visited personally on the top executives and the directors. A return to the culture of engineering excellence and reduction of subcontracting may be too much to ask from a company so invested in this business model. But it needs to happen, or more deadly incidents will occur.
“Given what has happened with the two fatal crashes and this incident, the financial targets have to take a back seat for Boeing and its supply chain”...
source: Seattle Times

Meanwhile the executives sit and circlejerk in the boardroom I guess.

[Andy Chee]

I think most of us here have tightened important bolts- you know the kind with washers, maybe cotter pins, using a torque wrench. It's actually not that difficult after reading a manufacturer's instructions. Surely Spirit and Boeing have 3D exploded view drawings on-line as well to help assemblers, assuming that is the problem. Or is it?

Having never worked on an aircraft assembly line, I presume all the tools (particularly torque wrenches) are provided to the workers?  They haven't gone down the private housing construction route, where builders bring their own tools to the worksite??

[pickle9000]

I think most of us here have tightened important bolts- you know the kind with washers, maybe cotter pins, using a torque wrench. It's actually not that difficult after reading a manufacturer's instructions. Surely Spirit and Boeing have 3D exploded view drawings on-line as well to help assemblers, assuming that is the problem. Or is it?

Having never worked on an aircraft assembly line, I presume all the tools (particularly torque wrenches) are provided to the workers?  They haven't gone down the private housing construction route, where builders bring their own tools to the worksite??

Order of operation, fastener, tools everything is normally on a checklist. Tools are supposed to be checked in
and out as well so things are not left inside an assembly.

[MT]

Seams Boing have all sorts of problems!

[tggzzz]

I remember when Boeing used to over-engineer their aircraft...

[MT]

Renton factory assembly culture; At the end of his online post, the whistleblower asks “So, where are the bolts?” then offers a guess:
“Probably sitting forgotten and unlabeled … on a work-in-progress bench. Unless someone already tossed them in the scrap bin to tidy up.”

https://www.seattletimes.com/business/boeing-aerospace/boeing-not-spirit-mis-installed-piece-that-blew-off-alaska-max-9-jet/

[Gyro]

“The reason the door blew off is stated in black and white in Boeing’s own records,” the whistleblower wrote. “It is also very, very stupid and speaks volumes about the quality culture at certain portions of the business.”

The self-described Boeing insider said company records show four bolts that prevent the door plug from sliding up off the door frame stop pads that take the pressurization loads in flight, “were not installed when Boeing delivered the airplane.” the whistleblower stated. “Our own records reflect this.”

I wonder if those records still exist!

[SeanB]

Probably got signed and stamped with the seal of some long dead QC person, who also stamped a few thousand documents as well.

[SiliconWizard]

Is this self-sabotage?

[MT]