MaverickM11
Topic Author
Posts: 15326
Joined: Thu Apr 06, 2000 1:59 pm

Why No Wide Chord Fan Blade Retrofit?

Mon Mar 14, 2005 12:00 pm

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?
E pur si muove -Galileo
 
777wt
Posts: 828
Joined: Wed Jan 19, 2005 7:45 am

RE: Why No Wide Chord Fan Blade Retrofit?

Mon Mar 14, 2005 2:21 pm

An redesign of the engine and it'd be costly to do so.
Also certification and testing process is another thing too.
 
MaverickM11
Topic Author
Posts: 15326
Joined: Thu Apr 06, 2000 1:59 pm

RE: Why No Wide Chord Fan Blade Retrofit?

Mon Mar 14, 2005 3:13 pm

True, but I'd think it'd be relatively easy to replace multiple, narrow engine fan blades with more efficient, wider blades and retain the same air flow fundamentals?
E pur si muove -Galileo
 
Lufthansa
Posts: 2303
Joined: Thu May 20, 1999 6:04 am

RE: Why No Wide Chord Fan Blade Retrofit?

Mon Mar 14, 2005 3:31 pm

Maverick,

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
Posts: 306
Joined: Wed Mar 08, 2000 6:15 am

RE: Why No Wide Chord Fan Blade Retrofit?

Tue Mar 15, 2005 3:22 am

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.