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C-130H dynamic balancing


pavane88
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Hello. C-130H mechanics! 

I have a question about C-130H prop' dynamic balancing.

We are currently using the VXP equipment

C-130H prop' balancing data collection is HSGI and 7000 in-lbs

We performed a check both of which exceeded the limit(within 0.2 ips)

However, reducing ips of 7000 in- lbs increases ips of HSGI

Is it normal for HSGI's ips to go too high when ips is reduced to 7000 in-lbs?

Can it be corrected inversely? If so, which section should IPS be based on?

 

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i havent used the balancer yet so cant answer your question directly. however, a couple years ago we got a

newly overhauled prop in the test cell. Everything was fine up to NGI. As throttle was advanced and blade angle

increased, the prop noise and RGB vibration increased. Above 1000° TIT the noise was like someone or

something beating on your chest - unpleasant, almost painful. RGB vibration was topping at 1.4 to 1.6 mils.

 

We went through the prop records and everything seemed to be in order. We then did a loose blade and 

tracking check, which also checked good. While standing a distance away from the engine looking at

the prop, we thought there was an optical illusion. It seemed that the #2 and #4 blades were narrower

than #1 and #3. On measuring the width at various points from the tip to +- halfway in, we found the #2

and #4 blades around 2 inches narrower than the others. 

 

These 2 blades had a couple thousand hours on and had been reworked several times, while the other 2 were

new. Essentially there were 2 blades working their asses off, and 2 just along for the ride. My thoughts are

the noise and vibration were being generated by the 2 working blades being at a higher than efficient 

angle and probably very close to stalling.

 

Just something to think about .....

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