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OldAg84
24th Aug 2001, 17:49
Just yesterday I was out and about working. My travels took me to the Greensboro airport. I noted 7 L-1011's of various apparent heritages. On my way out I drove past 4 which were parked at one corner of the airfield. The four, with IAG markings looked to be in pretty good shape, although one was missing a few cowlings and engine covers. Now for the question- close up on one of the A/C the 1 and 3 engines were windmilling. At least one was making a consisting clinking sound, fairly loud and inconsistent. Can, over time, engines be damaged this way? Thanks in advance.

Hwel
25th Aug 2001, 02:01
The clinking noise is caused by the turbines.Under normal operating conditions The attachments between the turbine blades and shaft are very hot and is spinning very fast so an expansion gap is left. This causes the individual blades to be "loose" when cold and turning very slowly. Thus the clinking noise is when each bade reaches the top of the circle it drops down towards the shaft, and at the bottom of the circle it drops away from the shaft.
In general it wont do any harm to the engine over short periods of time. However stored aircraft would more normally have covers fitted, both to stop windmilling and prevent animal infestation, sand or dirt.
Hope that helps.

gas path
25th Aug 2001, 19:55
That sound is the fan blade part span shrouds (clappers) contacting each other as the fan rotates. the shrouds are there to control the spanwise airflow as the engine turns and also to damp out vibrations. They also limit the amount of movement of the blade in the hub.
part span shrouds (http://rcl.eng.ohio-state.edu/cmml/research_viby3.jpg)

OldAg84
27th Aug 2001, 17:38
Upon explanation- makes perfect sense.

I was surprised that none of the engines were covered- I got the feeling none of the A/C were going to be moved anytime soon.

Thanks.

stator vane
27th Aug 2001, 20:55
could also be the sound of money dropping out of someone's pocket into that airplane! :D

Shemptol
6th Nov 2001, 09:08
Can You Say Capton Wiring?

411A
7th Nov 2001, 07:59
...that would be Kapton....and there is not much in the L10, for those that are interested...

Dagger Dirk
9th Nov 2001, 23:28
...that would be Kapton....and there is not much in the L10, for those that are interested...
Enough to do this:
see story atthis link (http://www.iasa.com.au/panorama.html#SV163)
http://www.iasa.com.au/images/RiyadhL1011a.jpg
http://www.iasa.com.au/images/RiyadhL1011.jpg