I referenced shaft seizure a couple pages back, "lock". The bearing "race" is supplied oil by a pump. The pump is dumb, so the oil needs be regulated by scavenge through vaned galleries (manifold). If the "vane restrictors" (the installed regulators of oil flow) become clogged (coking, carbon), the bearing "box" is pressurized with oil, and the seal fails, supplying oil to "where it shouldn't be" (Joyce). It ignites, causing heat and utter failure of the oil seal. Now the bearing is metal to metal, supplying friction heat to the heat of combustion, and the shaft slows in its fixed mount as its bearings grind to a halt. If the timing of the failures is sufficient, the Shaft locks, the wheel scrubs off its splines, overspeeds, and separates from the engine in pieces whose shape shows not Blade (related) failure, but hub failure, the part of the Wheel that is the strongest, witness the perpendicular fractures of the disc.
v-aero
The AD is not serial specific because every engine is supposed to be "identical". Each engine has a rigorous "provenance" to include which bloke did what, and what he ate for breakfast that morning. lomapaseo would know best, but an AD is not issued across the fleet to scrap an anomalous and single power plant. The Onus is on the manufacturer to demonstrate that the failure is a one-off, if not, hence the "Model" AD. The AD here has listed exactly the powerplants to be subjected to accelerated inspections and/or Strip. "And for good measure, all the rest" is a litigable and overbroad (even punitive) ruling. imo
bear
Last edited by bearfoil; 12th Nov 2010 at 16:20.