Originally Posted by
turboshafts
From the report:
Components rejected, in operation or during overhaul, were inspected in accordance with the Continued Airworthiness programme. Those which were considered to show new or unusual failure modes were then routed by the manufacturer to its materials laboratory for further analysis. However, the laboratory did not have the capacity to carry out an investigation of every component rejected during gearbox overhaul. When the Continued Airworthiness programme for the AS332 L2 was initiated it was determined, based on previous operational history, design calculations and the maintenance programme requirements, that damage to the planet gear outer race would not adversely affect the continued airworthiness of the helicopter. Therefore, planet gears which had been rejected for spalling were not routinely routed to the laboratory for additional investigation.
I think that was more of a capacity problem, rather than not of interest.
It is disturbing though, that they did not take action to investigate every one of them.
But the failure risk experienced on the L2 was assessed on the 225 by means of
decreasing the TBO.
Sorry I don't follow you. I'm referring to the given running time and the TBO.
So 1080 to 2000 hours is 900 hours. It ran 300 hours until failure from last
modification, inspection and repair, whatever that means. According to the certification testing, it could have some spalling at 2000 hours that would not lead to catastrophic failure.
Turbo shaft
Sorry, I got the wrong end of the stick about your comment on the running time, please accept my apologies.
Re the two types of planet gear, the 2nd stage planet gears are produced by two manufacturers, and they have done since the L2 was certified. Obviously the outer dimensions of the gear are identical as are the method and dimensions of the location to the second stage planet carrier. I don't know what the differences are in terms of raceway profiles, bearing roller design etc. You can also "mix and match" gears from each manufacturer within the module so you could end up with different manufacturers gears in the same epicyclic stage / module