Webby737;

You are correct about Sta 740 Bulkhead in the aft area of the Fwd Cargo compartment. We would actually cut a 14" x 18" access opening in the bulkhead web to gain access to the FWD Bottle Bolt Casting when they required replacement. Most of ours were being replaced due to Corrosion. Once the Job was finished we would install a doubler over the cutout with Hi-Loks. STA 950 was also the FWD Bulkhead in the Aft Cargo compartment.

Weren't they written off?

yes I'm sure they were...(see the smiley face)

Indeed, by simply looking at the part, it could be very difficult to distinguish between cast or forged as the means of construction. Other than if a forged part were appropriate for the application in the aircraft design, certainly as a pickle fork would be, it is unlikely in the extreme that a cast part would also exist for that application. Castings have very different applications than forgings, and greater factors of safety required for the design (meaning a heavier part). I am aware that in another aviation industry, counterfeit parts were cast to appear to be replacement parts where a forged part was the correct part. Such use would have been horribly unsafe, and that was the highlight of the presentation. I'm not that least suggesting that is a factor here, other than to draw attention to the fact that there is a vital difference between cast and forged in aircraft part construction, and it's important to be aware of the difference if you're working on the plane. The means of construction difference extends after installation to how the part could corrode, or otherwise have defects. We're dealing with that these days with Cessna 210 wing spar carry through forging inspection and defects.

One hour seems optimistic - every day I am reminded that there is a huge difference between theory and practice. Will it be clean enough inside there to see something as subtle as a crack?

Quite true,
I would assume that the area or at the very least the bolt heads/tails would be covered in sealant.

The one Hour time estimate was probably written by some engineer who has never actually performed the task.

My job as a Structure AMT is to verify the Correct Part Number AND the Correct Effectivity assigned to the Aircraft that I'm installing the part on. Also verifying the Part Number on the documents that come with the Part. The part number is already determined for me in Boeing Drawings- Boeing Illustrated Parts List - Engineering Documents- Ect.
I do not have to know whether the part is a forging -casting - extrusion- ext. That is the job of Boeing and my Engineering Dept to instruct me which part to use. My job is to follow their written Instructions.

Dopsonj : Thank you for posting the link to the pictures.

In my experience, the time quoted for an inspection is purely the time it takes to inspect. It doesn't include any work required to get access to the inspection area and restoring the aircraft to a flight condition, including any functional testing.

Costcutting Outsourcing Strikes Again Perhaps?
 

I recall an FO correcting me when I said that the leading edges of a BAC 1-11 wing were then 'taken to another location and annealed.' He explained the difference between annealing and normalizing.

Wasn't there mention earlier in the thread about the casting of Pickle Forks? I took the answers to mean, originally they were milled from the solid, but later cast with substantial oversize and then milled down to size. I know the metal cad be recovered, but the effects on the finished casting are serious science. I'm given to understand that even the way a hole is drilled is incredibly critical; the speed and sharpness of the tip being stipulated by the boffins.

Sorrly charlie -where did you get that " answer"

Its doubtful that that item was/is a casting

But why not check with a credible source ? ASK Boeing or the Vendor !

That photo is what should be hanging around the neck of the OEM's corporate leaders, it encapsulates where the problem within the fish comes from. When the penny drops, and that gets finally acknowledged, then perhaps the OEM can get back to being a global leader.


[The worker in this photo is working on a part that was a "CNC" manufactured part... which resulted in extended maintenance inspections due to the precision of the CNC manufacturing process. The court documents indicated no CNC capability existed. The OEM's QA people were the messengers that ended up sueing WITHOUT SUCCESS for dismissal for doing their damned job. Nothing was ever done to replace these parts as far as I am aware.

Speaking as a "boffin", I think it's doubtful too. FAR 25.621 specifies factors to be applied to cast parts, and they are pretty penalizing from the perspective of weight and inspection. Though I have approved designs incorporating cast parts, these parts were in very low stress applications, with low failure severity, and easily inspected. I have changed the production technique for several parts from "cast" to "forged" to improve the product and save weight. And yes, we specify some holes and surfaces pretty closely too. I have nothing to do with Boeings, though it is very unlikely that I would approve a cast part in that application.

Of course, once a part is approved as a part of the type design, as said, it is not the role of subsequent technicians to necessarily understand how the part is made, and to make their own determinations as to airworthiness, other than in accordance with approved techniques and standards. Just put the right part in the plane applying the correct technique.

We all have a role to play in the safe operation of aircraft. For some of us, it may be at the beginning, specifying the manufacturing techniques and standards of quality. For others, it's maintenance or operation of the aircraft. We all have our own "areas" in which detail is important, and misunderstanding must be prevented.

The first article I read on the pickle forks (sorry, can't find it now) said that originally, the part was cut from billet aluminum, creating a lot of waste. It also had to then be shipped to a subcontractor on California for 'normalization'. The new forks are forged, (not cast), and 'don't need to be normalized', or shipped to California. (I suspect that maybe they still do.)

Aha! From Waterpilot's comment (#10) above: "To increase materials efficiency, the main component of the pickle fork is now produced out of forged, restrike aluminum. Previously the part was produced from block aluminum, which generated a significant amount of scrap because the pickle fork component was cut and shaped from the block. The pickle fork forgings now arrive in the approximate shape of the component so less aluminum is scrapped. In addition, the type of aluminum previously used for the pickle fork required shipping to California for stress relieving and return back to Auburn for continued production. The current aluminum forgings do not require stress treatment."

This has been an educational and informative thread. Hopefully this is all resolved safely.

FAA orders airlines to inspect dozens of Boeing 737s for structural cracks

Boeing discovered cracks on a few of its planes undergoing maintenance in China

Thomson Reuters · Posted: Oct 03, 2019 9:41 AM ET Last Updated: an hour agoThe U.S. Federal Aviation Administration said on Wednesday that aircraft operators must inspect 165 Boeing 737 NG airliners for structural cracks within seven days after the issue was found on a small number of planes.

Boeing Co notified the FAA of the issue after it discovered cracks on an aircraft undergoing modifications in China. The FAA said subsequent inspections found similar cracks in a small number of additional planes. The FAA said planes with fewer flights will eventually get inspected.
The article says the The order covers a total of 1,911 U.S. registered planes. The inspections can be done visually and should require about an hour per airplane, the FAA said.
Complete story can be viewed at: https://www.cbc.ca/news/business/boeing-737-1.5307170