The Great Ongoing Aviation Thread (general and other)

Miscellaneous and Personal Stuff I Must Share
5243

You also need to make the checklist.

Procedures to gain access to the area in question need to be identified (in this case I expect they’re existing, but some parts of planes are very tricky to get to and may need more specific instructions than “literally remove everything til you get there”).

Parts to replace loose bolts need to be available and shipped, assuming they aren’t standard bin parts, or even if they are the OEM often pays for kit parts in a case like this.

You probably wouldn’t want to reinstall the existing ones, because if they were improperly installed then they were likely improperly loaded, and their performance may be degraded.

But then you also need procedures to check the lugs, bushings, flanges, skins, whatever else the improper loading of the attachments over X airframe cycles may have also improperly loaded. Some parts aren’t easy to inspect and need specialized procedures; you can’t just say “do an eddy current inspection”, you need to provide the calibration and methodology instructions for it. These instructions may not exist, so specialists have to author them, get them checked, and get them approved, in this case almost certainly by the FAA instead of internally. It may be easier to scrap and replace certain parts in some cases because otherwise your damage tolerance assessment of the improper loading may show that the uncertainty means you have to inspect it again every year forever instead of every 4 or 8 years or whatever was originally designed (speaking very generally about repairs and subsequent mandatory inspections). So if it’s cheaper to say “replace this machined bracket”, then you gotta get those in stock and distributed to the fleet, and all with intense scrutiny on the manufacturing and quality control of those parts.

All these decisions have to be compiled and documented and approved by the FAA (not just each procedure, not just each part design, but the whole damn thing to show it actually resolves the problem and mitigates all risks).

Then the work gets done, inspected, signed off, reassembled, signed off, functionally and operationally tested, signed off and then, probably, the plane can return to service.

If all goes well.

Continuing airworthiness and the airworthiness directive process is one hell of a subject matter. Nothing is as simple as “just tighten loose bolts!”

5244

I agree with the responses to what I said but the process has to be empirical and not a which hunt. This isn’t something that gets added to the bottom of the FAA’s “to do” list. And they can’t declare Boeing a toxic unknown and start doling out 100 hr D-checks.

5245

If the user of a smart tool decides to purposely cheat it, then they are basically a criminal. Whole other problem solving chain.

5246

Even a “simple” condition with a straightforward solution can take months or years of progressive action to resolve, depending on the number of affected aircraft, their age, the compliance demonstrations, in some cases the foreign validation. The time it takes is a function of severity but also feasibility and definitely affected by regulator oversight and level of involvement.

Guaranteed there’s a lot of parallel work going on behind the scenes, but it all has to add up to an actual solution. You can’t just assume it was “loose bolts because they weren’t tightened” because it may actually have been “bolts that came loose due to vibration” (hypothetically).

You have to find the root cause and resolve it. Sometimes these things happen over the course of years; I’ve seen an airworthiness directive with five updates and multiple steps before a final design was obtained and approved.

From what I’ve gathered, a draft inspection program was submitted and is undergoing review and correction. It may be an interim inspection to get planes operating again, with follow on AD actions to be published in a few months. This is an incredibly complex issue - doors always are (and IMHO this is a door no matter what you call it) and the depths of quality failures needs to be understood.

5247

Nuts/bolts coming loose are an easy fix if they backed out. They go to a safety wire set up and they re-certify the door. I have to believe they know by now why that door departed the airplane. I don’t see it as a function of rushing the investigation as much as a “throw more bodies at it” issue to get it properly resolved.

5248

Did you miss everything else I wrote?

“They recertify the door” will require much, much more than installing 4 bolts. It will need the static and dynamic stress analyses, it will need the hazard assessment review, it will need the inspection and maintenance process review, etc. It is not a trivial and quick task and it will be reviewed with a fine toothed comb by the FAA, and likely also by other validated countries (just as the other countries reserved the right to review and validate the MCAS fix). More people don’t help, when what’s needed is comprehensive aircraft level understanding.

And that’s just the engineering. Boeing’s manufacturing certificate is also a problem (as design and manufacturing are separate legal processes in this industry).

I actually speak from experience; airworthiness procedures and aircraft certification are my job functions and I’ve been involved in plenty of continuing airworthiness and airworthiness directive related projects. You don’t rush this.

5249

For any door on which they find loose or missing hardware there will need to be a plan to evaluate the surrounding structure for damage caused by the loose bolts.

e.g. aways upthread we had some pix of a UAL airplane where the bolts had apparently worn the holes in the bracket they penetrated into an oblong shape. How much hole deformation is acceptable? How do you measure deformed holes? What parts need replacing if the holes are now out of re-use tolerance? How do you replace that part since it wasn’t designed for in-the-field replacement? What tooling is needed to ensure the new bracket is properly aligned? etc.

Once the bolts had become loos and allowed the dummy door to shift a bit before it eventually parted the airplane, all the load calculations on the rest of the door structure were invalidated. Were the 8 places the stop pads on the dummy door mate with the stop pads on the doorway possibly or probably overstressed? Should they be inspected? using what tools and procedures?

None of that is left to the judgment of some A&P with some safety wire, a wrench, and riveting tools. All of that is decided by a team of engineers after proper analysis and is written into the repair plans.

5250

I know it’s unrelated to the Boeing “door story,” but it’s probably not a headline the company wants to see regardless. No news is good news, after all.

5251

Good find. Thank you.

The word “Boeing” in that headline is all about SEO optimization and clicks. And is part of what might become a real problem.

All of USAF’s long- and medium-haul VIP transports are Boeings. Except for a couple of bizjets.

5252

I swear to God, the FAA has to start handing out some lifetime-flying bans. This is getting 'way out of hand: https://www.cnn.com/travel/japan-plane-american-passenger-bite-intl-hnk/index.html

5253

Not basically. If they sign off on something being done, knowing they didn’t do it, it’s fraud. For us, it’s inspection measurements. The quality manager at my current facility had to drive that point home VERY strongly in a town hall.

I’m still struggling how a CMM report went “missing” in the turbine case. Does aviation manufacturing not do document reviews before shipping?

Don’t need to ban someone if they’re serving prison time.

5254

Even most murderers get out of prison eventually. People need to know that they will never, ever be allowed up in an airplane again.

5255

Alternatively, airlines could announce that passengers forcing a delay through bad behaviour will be sued for costs.

Any idea what it costs to force a jet to make an unscheduled landing because someone threw a hissy fit on the plane? Tens of thousands of dollars would be a start.

5256

I looked to see if Blinkin’s plane was a MAX. Apparently not. It’s one of the older 737’s.

5257

That depends on whether the bolts were improperly installed. New door, new bolts, inspect the frame and back in business after the process is certified.

They’ve inspected 40 of the planes so far and that process will be reviewed for recommendations on the process going forward. Right now every structural engineer they can lay their hands on is involved in this.

5258

Ok, if you say so. Good job on your next repair or modification approval application, I’m sure it’ll go great.

5259

It’s what is happening now. They’ve already inspected about 25% of the planes. They will review what they found and decide how they want to proceed going forward. Could be simple, could be a clusterfuck.

If the door in question was improperly installed then they can separate out the planes that had faulty door installations from the ones that were properly assembled.

5260

It’s a clusterfuck.

You’re welcome to take incredibly complex situations, regulations, and processes and simply them to short, meaningless statements for convenience but it’s not particularly interesting or informative.

Those of us with an understanding of what’s happening - and those with the intellectual curiosity to learn about it - will carry on with more nuanced discussion.

As it stands, there’s no terminating action to this AD and no officially published set of procedures. Some operators have their own delegated individuals employed or contracted who have the skills to put together inspection plans for their individual aircraft and get them approved by the FAA, plans which likely include very conservative assessments and frequent re-inspections as long as it gets the planes back in the air in the short term. Others will choose to wait for a more formal plan, approved by Boeing and the FAA, which may be more in-depth but with longer mandatory re-inspection intervals. I am certain that whatever is happening now will not be the final action taken on this issue for the fleet.

A couple of years ago I had a customer where we were able to get regulatory approval for something for the short term, provided a component was fully replaced with a new one at very short intervals (approximately twice a year for that customers operations). This was very expensive, but the alternative was grounding the plane for 9-12 months while a new design to correct a problem was developed, tested, approved, had parts made and delivered, and installed. The maintenance intervals are now on the order of 2-3 years without part replacement being necessary. This whole thing was subject to an airworthiness directive.

Nothing is simple in this industry.

5261

Yet another Boeing door problem - somewhat humorous.

"The passenger was eventually rescued when engineers broke down the door after the aircraft landed in Bengaluru around 3:42 a.m. local time. The airline released a statement which reads, “SpiceJet regrets and apologizes for the inconvenience caused to the passenger. The passenger is being provided a full refund.”

5262

The refund is nice. As long as the passenger isn’t required in exchange to return his deposit(s).