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How on earth do you prove that it’s to the same specs without paperwork underpinning that? What do you think “fake” means in this context? That the part is rea
by NamTaf 3y ago
How on earth do you prove that it’s to the same specs without paperwork underpinning that?
What do you think “fake” means in this context? That the part is really a Loony Toons sketch of the real thing, stickytaped to the surrounding engine? No, it means it’s essentially an outwardly identical part without the appropriate QA/QC processes undertaken to certify it as genuine and to spec.
This may for example include destructive and nondestructive testing of parts, or it might include tracking the manufacturing process parameters to ensure correct outputs. For example, a cast component has sufficiently low levels of porosity, inclusions, etc. that might in time lead to premature failure. Or it might mean that there wasn’t sufficient record of the brew of the metal going into the casting or the casting process itself to confirm the part has the requisite material properties. In all but the most dire circumstances, it’s nearly impossible to verify whether any of that was done correctly just by looking at the part; for all intents and purposes, it’ll look identical to a real part.
In the case that the OP references regarding Virgin Australia [1], the parts were a low-presssure turbine blade and a high-pressure turbine nozzle seal. Both of them would fall into situations similar to the above. If cast, the turbine blade would need to prove what I outlined, amongst much more. If machined from billet, it’ll still need proof the ingot itself was manufactured correctly which mirrors a lot of the above. In the case of the seal, there’s similar processes to prove that the non-metallic material is to spec so that a Challenger-style failure doesn’t occur, except within expected operating parameters.
The link I provided regarding Virgin Australia gives much more detail about the core issue at play. This isn’t a situation where manufacturer B is stamping its parts as made by manufacturer A. It’s where manufacturer B says it can make a part compliant with the specifications, same as manufacturer A, but then does not have the required documentary evidence that it meets those specifications.
1: https://www.smh.com.au/business/companies/two-virgin-aircraft-pulled-from-flying-due-to-unauthorised-engine-parts-20230918-p5e5ka.html https://www.smh.com.au/business/companies/two-virgin-aircraf...
- sokoloff 3y agoSharing this not to defend forged paperwork, but because I find it fascinating and think others may as well. In the 60s and 70s, there was a lot of crossover between automotive and piston aircraft parts. In particular, Cessna used the same voltage regulator as Ford. Ford used millions of these and Cessna tens of thousands. They were all made on the exact same production line and all got a Ford part number. Relying on statistical process control, Ford demanded a certain percentage of their parts get extra, manual QC inspection. Cessna demanded 100% inspection of their parts. Solution: make all the parts on the same line, divert enough for the greater of (Cessna production plus spares) or (Ford’s SPC needs), QC that amount and stamp those inspected parts with a Cessna number (in addition to the Ford part number). Ford and Cessna can each get parts cheaper than if they were handled separately. Now, the question comes up: if there are no QC failures detected, are the Ford-only parts as safe as the Ford-or-Cessna parts coming off the line?
- notahacker 3y agoAnother question is whether parts that failed Cessna certification found their way into the Ford aftermarket parts supply chain...
- hef19898 3y agoMoat likely, which isn't a problem per se, as those Ford parts don't fly. If those Ford parts found their way into the Cessna spare parts supply chain, that would be a problem. And it most certainly happened at on point in time.
- sokoloff 3y agoI can virtually guarantee that Ford parts have flown on Cessnas over the years (because some aircraft owners are notoriously cheap). They absolutely fly entirely successfully (and legally) on E-AB aircraft (experimental-amateur built) using the same engine/alternator that Cessna uses.
- hef19898 3y agoE-ABs aren't real aircraft so! ;-)
- DiogenesKynikos 3y agoThank you for the detailed explanation. Anyone who has spent time in less developed countries knows what a difference strong government regulations on the market make. People in Western Europe, the US and other developed areas tend to take for granted that the food they buy in the grocery store is what it says on the package. That doesn't just happen by itself, and it's not a safe assumption everywhere.