Thread: Canadian Helicopter Crash report

This was a very interesting read.

https://tsb.gc.ca/eng/rapports-repor.../a21w0045.html

From the findings:

“The investigation determined that the pin was manufactured from 316 stainless steel instead of tempered H11 tool steel as designed. Because 316 stainless steel has approximately ⅓ the tensile strength of H11 tool steel, the pin was unable to withstand the forces applied to it during normal operations. As a result, the pin failed in a shear mode approximately 21.4 hours of time in service after being installed in the rotor head assembly.

At the time the pins were being manufactured, FMC stored the raw material by diameter or profile, not by material composition. As a result, when a worker collected material to complete the assigned job, it was up to that individual to ensure that the correct specification of material (e.g., carbon steel, aluminum, titanium, 316 stainless steel, H11 tool steel) was selected.

After the initial machining operation, the 343 pieces produced were sent to Bodycote Thermal Processing (Bodycote) for heat treatment (operation 070). While completing the heat treatment, the company performed a hardness check on several of the pins to ensure that the process was completed satisfactorily, and that those parts met the required specification. It was during this step of the process that Bodycote discovered several pieces that did not meet the hardness specification and determined that they were of a different material.
Bodycote contacted FMC quality personnel by e-mail to notify them of the discrepancy in material in some of the parts.

Senior quality control management within FMC did not communicate the observations made by the heat treatment provider in the e-mail exchange with the quality control inspector. As a result, the inspector was not aware that they should anticipate and would have to deal with incoming non-conforming parts.”

Very poor processes at the Fore Machine Company (FMC).

Interesting also that FMC closed up shop a few months later. I wonder if the owners are now living somewhere they can't be extradited from....

For anyone interested in aviation/helicopter safety, while visiting family in NZ last month I happened to watch a documentary on the recently released coronial inquest into the unusually high crash rates of Robinson helicopters in NZ. Very interesting.

Steve