CFMI Eats FOD
 

A question to B738 Drivers or others knowledgeable about CFMI engines:

I was waiting behind a 738 at a runway hold and saw the #1 engine ingest a plastic bag (shopping carrier bag). Small pieces were quickly spewed out the back. I advised the crew, who thanked me and then proceeded with their take-off. Would ingesting a plastic bag be cause for concern on the CFMI or is that a non-event?

I don't know the procedures in this case but I know the CFM56-5 and -7 (A320 and 737NG) are extremely rugged and reliable engines.

Even better the Snecma and GE expected them to be.

The maintenance intervals keep getting stretched to the dislike of the engine maintenance shops..

CFMI : a shining success story of US - French cooperation

http://www.aerospace-technology.com/...E-CFM56-11.jpg

Forget about the ruggedness, that's a subjective word at best in its use about judgements in this case.

AS long as yu saw it come out, probably no big deal as it must have passed through the fan discharge. About the only concern is a tempoary blockgage if it gets stuck on some stator vanes in the core. I assume that the crew really didn't even see a bobble on their instruments.

With a plastic bag being light weight and rather flimsy, how would a piece stuck to a stator vane show up on the engine indications?

P.S. It did appear to have passed through the fan discharge.

Doubt it would cause any physical damage, however it reminds me of a problem on a 757 I think many many years ago, constant hot starts and unable to make full power. After many component changes traced the fault to a sensor covered/blocked by a piece of melted plastic (preumably a bag).

I agree, and IDG air/oil cooler can be blocked too - causing high temp./disconnect...Turnback from taxi, engine shutdown and quick visual inspection can solve this situation- but with delay...

I reckon the guy in the pic is in breach of a few H&S laws there!

I did the same thing many moons ago, the boss said put a hard hat on in case it drops off the crane, my reply was why bother!! ;)

The 757, if I remember correctly does have a probe at the back of the engine as it uses EPR to set thrust and needs a probe in each end of the engine to measure the difference in inlet/outlet pressure. The CFM56 only has one small probe in the inlet as it uses N1 to set thrust, so the chances are a bag would have just wistled through and nobody was the wiser, especially as the bypass is 5:1 so a lot of air going around the core.
As with all these things, who really knows for sure but for pure airmanship, better go back to stand and have it checked out by an Engineer.If the engine developed a fault on takeoff on account of it, it would be hard to justify in court!

Al.

Laughed at that one, very funny.:ok:

Speaking of longevity of the CFM-56 engines, am I correct in my memory that I've read somewhere that a CFM-56 engine is responsible for operating the highest number of hours without being removed for attention? I can't remember the exact figure, so I won't guess, but it was astonishing, even to a layperson :)

Some interesting facts and figures on the CFM website for those interested http://www.cfm56.com/index.php

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:ok:
Halfway down this page:
http://www.b737.org.uk/737classic.htm

I knew I'd seen it somewhere! :ok: