Old 19th Apr 2018, 20:25
  #267 (permalink)  
Join Date: Nov 2016
Location: Lakeside
Posts: 428
I would think that loss of a fan blade under these conditions would suggest a chaotic exit for the blade mass... I have no difficulty imagining the blade in any or all of several postures post separation from the disc. The dove tail (pine tree) would be susceptible to “rocking” in normal use, forward in Thrust, and backward in windmill. I doubt the dove tail failed evenly in an instant, it would be unlikely the joint let go evenly across its attachment joint. If the failure originated in the rear of the joint, the blade would immediately try to unpeel forward causing the tip to migrate well ahead of the fan’s plane, perhaps explaining the lack of evidence of major contact damage to the blades bracketing it?

Wouldn't the blade accelerate forward, rapidly, as a reaction to loss of attachment? (Newton #3)? Contacting the containing ring (likely it’s first point of contact) it would react violently to interruption of its linear escape, and likely start to wobble intensely? From the reasonably crisp remnants of the cowl, it looks like the blade lingered, radially, at least long enough to trim the honeycomb back to solid metal (Kevlar?).

It would be most interesting to see what remains of the disc pine tree? My conclusion is that the blade left the axis of the engine’s shaft rapidly, but retained some radial trail. How far forward of the engine’s inlet did it extend before traveling aft?
Concours77 is offline