Jet engine clicking while windmilling on ground

zmiller4 said:
You also hear clicking from the CF34's with the continuous ignition on (or during a stall test), but it's more of a click and less of a rattle like the loose blades produce.
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That's what first came to mind when I read the thread title. That rhythmic clicking ("tick tick tick") is from the electric igniter in the combustion section of the jet engine arcing, correct? Not unlike what you hear when starting a gas stove?
 
inigo88 said:
That's what first came to mind when I read the thread title. That rhythmic clicking ("tick tick tick") is from the electric igniter in the combustion section of the jet engine arcing, correct? Not unlike what you hear when starting a gas stove?
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That's affirm, when the ignition is turned on.
 
scooter2525 said:
I know this has been covered before, but I can't find it under searching. While a jet is sitting on the ground shut down, I'll hear a consistent clicking. What is that?
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I was told that it is the fan shaft bearings as they rub together un-lubricated.
 
TFaudree_ERAU said:
Or the "company mechanic checking the oil while you're in the cockpit getting the clearance". White guys CAN jump.
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Have you seen the size of a spark that those things make? It was demonstrated during one of my A&P classes, and I will just say that if I hear those firing I will do my best not to touch anything that might be remotly connected electrically. I don't blame someone for jumping.
 
N18040 said:
Have you seen the size of a spark that those things make? It was demonstrated during one of my A&P classes, and I will just say that if I hear those firing I will do my best not to touch anything that might be remotly connected electrically. I don't blame someone for jumping.
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Isn't the engine grounded to the airframe, thus the spark being completely harmless?
 
TFaudree_ERAU said:
Isn't the engine grounded to the airframe, thus the spark being completely harmless?
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I've definitely felt the shock from a lawn mower ignition system in ways that I "shouldn't" have been able too, and turbine igniters definitely have a little more power than a push mower does. Thanks, but I'll stay clear.
 
I don't know about other motors but on the f404 the noise is from the tree fittings being loose when the engine isn't warm (since they expand to their normal size at regular operating temps). The fan blades are def not clinking against the intake walls....that would be bad juju
 
BobDDuck said:
Bad stuff starts happening when the blades rub against the interior of the engine cowling.

I just finally got an answer from a Bombardier Tech Pilot last month about the loud popping noise we hear on the CRJ every once in a while during climb out is. Turns out it's the wing attachment bolts shifting slightly. That's comforting.
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So that's what that sound is! Thanks for the share. Not a trip goes by in the 200 where I don't hear that pop. They told us it was normal, but no one I spoke with knew what it was. Just finished 4 days in a CRJ700. All were pop/click free.
 
Lee D said:
So that's what that sound is! Thanks for the share. Not a trip goes by in the 200 where I don't hear that pop. They told us it was normal, but no one I spoke with knew what it was. Just finished 4 days in a CRJ700. All were pop/click free.
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A number of SKW airplanes used to have a service letter from Bombardier explaining the noise in the can...it was an interesting read.
 
I tried to get a service letter for it but I could only get the verbal explanation from the tech pilot. I'd love to see the actual letter.
 
N18040 said:
I've definitely felt the shock from a lawn mower ignition system in ways that I "shouldn't" have been able too, and turbine igniters definitely have a little more power than a push mower does. Thanks, but I'll stay clear.
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Yeah good habit for sure... The igniter spark is definitely enough to keel you!
 
If the plane is equipped with counter-rotating blades it will eliminate the problem, along with less yaw in single engine scenarios.
 
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