The 777 losing a fan blade inflight

[Speedbird744]

I have heard from a source that if one of the 777's twin engines were to throw a fan blade inflight the engine would become unbalanced and produce vibrations that could cause a loss of stability. Is this true and has the 777 been tested for this?
Thanks

[HPSOV]

This is true of any engine, from the 115hp piston in a C152, to the huge things under the wings of 777's. If you lose a blade the spinning mass becomes husgely unbalanced, if you continue to let the engine run it is most likely it will tear itself off the airframe. So a shutdown is the only option.

[Dave Incognito]

I’ve seen footage of Pratt & Whitney testing their 777 engines (PW4000 I think) in which they detonate one of the fan blades to test the engine’s containment casing (sorry, don’t know the technical terms).

It really makes a mess of the engine, but none of the debris punctured through the sides of the casing. The video didn’t mention whether or not vibration was being measured, but I am sure that would have been taken into account.

Here is a link to the P & W Engine Testing (http://www.pratt-whitney.com/3b/html/features_engine.html) section of their web page which briefly describes the various tests inflicted upon each of their engine designs.

Have a good one, Dave.

[N380UA]

In theory and on the day of certification of a power plant you will have 100% containment of the engine nacelle. Meaning nothing will penetrate. However as the entire engine ages, penetration is possible.
As to vibration after having thrown a fan blade, or anything else for that matter, would generate an engine vib above 2.0 on the indicator, requiring an engine shut down.

Most 777 are operated with the GE90, on which the first stage compressor blades are full composite.
:eek: