Airplane Engine Clicking Noise?

[Mxfan]

Whilst boarding a flight recently, I noticed a clicking sound coming from the aircrafts engine as I climbed the stairs to board the plane. The ground crew where preparing the plane as normal so I assumed this was a common noise to them as id never heard it before. When the plane took off the sound from the engine didn't sound normal to me and a few of the passengers kind of looked at each other in alarm. I know the plane wouldn't of taken off if there was an issue but I was just wondering if anyone knew what the cause or reason for this noise would be?

[RATTER15]

They were probably getting the starting handle ready!

[RATTER15]

This noise? Media URL: http://forums.jetcareers.com/threads/jet-engine-clicking-while-windmilling-on-ground.135894/
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[RATTER15]

Or this Media URL: http://forums.jetcareers.com/threads/jet-engine-clicking-while-windmilling-on-ground.135894/ Description:
Description:

[Hypognosis]

@Ratter

paste links direct into the message box. Whatever you tried, it's broken.
1.
http://forums.jetcareers.com/threads/jet-engine-clicking-while-windmilling-on-ground.135894/

2.
http://forums.jetcareers.com/threads/jet-engine-clicking-while-windmilling-on-ground.135894/

[Hypognosis]

Oops. Copied same link twice.

This link is from further down the page and is educational (despite years of enthusiasm about aviation, I never knew this one!)

http://youtu.be/phludDUfakg

[ivor4781]

wind milling is correct the blades are very slight loose to compensate for expansion,you can hear this on every jet if its windy when its stood,

[Mxfan]

Thanks guys, it's really interesting to know. There's another video in the link Media URL: http://youtu.be/6ZVaeP1fE6w
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