Quote from sevenstrokeroll:
do we think it is safe to say that the high bypass fans /engines are more susceptible by their nature to sucking bigger birds?
More birds, yes; bigger birds, I'm not sure.
Another issue is what happens to the debris of the wretched bird(s) after impact with the fan or spinner. Small birds are unlikely to damage the fan blades themselves, but what you don't want is for debris to enter the core of the engine. Although the JT8D probably picks up fewer birds, the CFM56 (with its much higher bypass ratio) probably ejects a higher proportion of impacting birds (and resulting debris mass) through its C-ducts. Passage through a C-duct, by-passing the core, is unlikely to involve further damage, though it may need to be cleaned.
On a CFM-56 walk-round, finding evidence of blood or very slight damage to the leading edge of a fan blade, it was usually considered OK to dispatch the aircraft provided the point on the blade was well clear of the intake to the core. If there was any doubt, a boroscopic inspection had to be called for. (Personally, in any case, I always had a good look up the back end at the LP turbine.) The great thing about the A320 and B737 is that all of this can be done without the need for a stepladder...
(EDIT) PS, re ShyTorque's post
The Nimrod accident at Kinloss was shocking, not least to other Spey fliers (I was on the BAC1-11 then). The Spey, of course, has an even lower bypass ratio than the JT8D. In view of the enormous number of birds involved, I'm not suggesting the engine type was necessarily a factor. But some thought that the Spey was more vulnerable to bird-strike damage than most.
Last edited by Chris Scott; 6th Mar 2011 at 12:55.
Reason: PS added