There's a hint in the report that the selection of the wrong metal may have been more than a storage issue. The company hadn't ordered enough H11 steel to make 350 pins, there was only enough to make 320. Did someone decide 316 Stainless was 'good enough'?

More startling to me was the way the manufacturer (a subcontractor) dropped the ball when the pins came back from heat treatment, another subcontractor. The heat treat companies spot tests had detected that some pins weren't all properly hardened, so they tested them all, told FMC there was a problem, marked the failures with a yellow stripe, and returned the good and bad pins in separate boxes.

Unfortunately no-one told FMC's overworked QA Inspector there was a problem, he didn't read the paperwork, and then – because he was overloaded – the hardness tests were done by unqualified production staff whilst he did the dimensional checks.

It's very common to find accidents are the result of several small errors. Having a Slack Alice or persons contemptuous of H&S on the team doesn't help, but it's extremely difficult for good people following a routine to stay alert. And it's daft for management to expect unqualified staff will realise they're doing the job badly!

The pins could be made on a mini-lathe…

Dave

Edited By SillyOldDuffer on 27/10/2022 09:23:13

Surprised?

I am reading my way through old MEs, and repeatedly the use of Silfos in making boilers comes up. Why is this any different?

I would also mention the foolish method of making the boiler with just a seam joint between barrel and throatplate, not fully flanged. Again and again this is declared as a safe method of making a joint, possibly 8" long and at 100psi, daft.

A while ago, the cockpit window on one aircraft failed due to someone deciding that BA screws were a good enough fit.

Regards Ian.

At least with proper traceability they will be able to find all the suspect components and replace them. The paperwork is expensive, but you can see why it's needed.

Have a look for a book (freely available in pdf form) called 'Truth, lies and O-rings' for the ultimate expression of this.

Remind me never to send anything to the Foster Heat Treatment Company Ltd LLC Inc. The idea is something that would be good to write into a procedure for critical parts, but in the absence of that procedure no business would do this on their own initiative to a customer's parts.

I dread to think how many people have died over the years because of a failed O ring.

DC31k

I'd always understood that when dealing with aerospace components it was a general rule to positively mark any sub-standard (or fraudulent) components discovered in a manner than prevented them being inadvertently used should they re-enter the supply chain. Obviously the parts have to be passed back to the purchaser so and investigation into what went wrong can be mounted.

Presumably the heat treatment people would have known these were aerospace parts and would have dealt with them appropriately. Bottom line is the results indicated that something had gone seriously wrong and that there was no way the stainless steel parts could have been up for any job that the correct, tool steel ones, needed to be specified for.

Robert

I don't think the procedures actually covered wrong material. Sub standard or incorrectly treated material certainly. But flat out drawing the wrong bar from stock no.

Something of a "no one could be that stupid" issue. However stored, drawing the right material for a job is so fundamental to any metal working shops business that it almost has to be assumed that the firm will have ways of getting it right. Ultimately you can't specify everything.

Seems that a more robust approach would have been for the bar supplier to have permanently marked the relevant type, batch and certificate number on the bars. Then FMC could have been required to use only marked material from the same batch or at least having equivalent certificates. Given that 8 bars f new materils were insufficient to make the number of parts ordered its an odds on bet that FMC had a bar in stock which they planned to draw out and use to make up the numbers. Objectively fairly shady but something that could have been gotten away with if the right bar were pulled.

Bottom line is that FMC corporate culture wasn't really up to aerospace demancds.

Clive

Edited By Clive Foster on 27/10/2022 19:27:29

As part of a set of wax die moulds for RR I was the bench person involved in finishing them for delivery. The largest produced a cone like piece about 12 inch diamiter and 8 inch long with a section of about 1/4 inch thickness the tool was a cube shape with a cone machined in one end and a side plate with a smaller cone to make the part thickness. The side plate was held in place by 4 swing bolts 1/2 inch UNC and about 6 inch long with nuts made to fit. The swing bolts were made from high tensile steel I think EN 16 T but the apprentice making them used wrong thread firstly and helped himself to some EN 1A to remake them without telling anyone. The result was the die opened under pressure with molten wax spraying out the first time it was used. The operator was slightly burnt and there was an investigation when the steel was found to be incorrect but the faulty parts made with wrong thread were found.

David