MaverickM11 From United States of America, joined Apr 2000, 16486 posts, RR: 48 Posted (8 years 8 months 4 weeks 20 hours ago) and read 2262 times:
Why have there been no retrofits of older engines (older PW4000s, CF6s, and RB211s for example) with fewer, wider chord engine fan blades? Most new engines as well as those in production currently have fewer, wider fan blades so it would seem like an easy retrofit. Has it been tried? Why has it not worked? Would it work?
Lufthansa From Christmas Island, joined May 1999, 3152 posts, RR: 10 Reply 3, posted (8 years 8 months 4 weeks 16 hours ago) and read 2169 times:
I don't think the actual fitting of it would be expensive, but I imagine certification would be very expensive and that probably wouldn't add up
on a cost benefit analysis. As for the fuel savings, well, you would still be stuck with the existing high-pressure turbines and most importantly the combustion chamber, which is where the real fuel savings would come from.
Any major changes here basically would be like a new engine.... and I really doubt that would pay. It would probably be simplier and possibly cheaper just to put new engines on the aircraft. Weight that up against just upgrading your aircraft to a new type, and I doubt it would be cost effective.
Expratt From United States of America, joined Mar 2000, 311 posts, RR: 0 Reply 4, posted (8 years 8 months 4 weeks 4 hours ago) and read 2100 times:
It would be a major redesign effort to swap an engine's regular fan blades for wide chord fan blades. In addition to certifying the new fan blades as well as the new fan hub, the fan containment system would have to be recertified and that would mean a blade out test. The blade out test is the last test of a cert program because when the blade is released even if it is contained, the engine is destroyed. And since the mass of the fan rotor would likely change, does the front bearing support and the front bearing have to be changed. Because the wide chord fan blades may turn at a different speed, the low pressure turbine rotor may have to be rematched to the fan. Then there are the usual gamut of certification tests like durability, operability, icing, etc, etc, etc. It would be a very big and expensive effort for a retrofit program that would be risky if the operators don't buy it.