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  #131  
Old 09-29-2018, 04:35 PM
RFSchaller RFSchaller is offline
 
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Location: Phoenix, AZ
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My replacement arrived yesterday, and as luck would have it there was a nick in the edge of the central hole. I sent them a picture and Sensenich is exchanging it for another replacement. They seem like good folks to deal with. In the phone discussion the engineer told me they increased the thickness at the edge of the central hole and no longer make the degree marks go all the way to the edge of the hole. He said there have been about three failures of the 1200 hubs they originally fabricated.
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  #132  
Old 09-29-2018, 06:00 PM
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Piper J3 Piper J3 is offline
 
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"About three failures of the 1200 hubs" is absolutely unacceptable for a part that is critical for safety of flight. Shipping a part with a nick in the edge of the central hole is unacceptable - period.

Almost all manufacturers use Six Sigma quality control. Six Sigma measures the capability of a process to perform defect-free work. Six Sigma means a failure rate of 3.4 parts per million or 99.9997% perfect. This is the defect rate in the field which includes design, fabrication, shipping, and installation.

3/1200 broken prop hubs is complete show stopper.

Would you fly in a helicopter with parts that had 3/1200 failure rate?

Sorry for the rant...
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 397

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 09-29-2018 at 06:03 PM.
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  #133  
Old 09-29-2018, 06:13 PM
AirHound AirHound is offline
 
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B Hub no cracks, F Hub easier pitch adjustments
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  #134  
Old 09-29-2018, 06:20 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by Piper J3 View Post
"About three failures of the 1200 hubs" is absolutely unacceptable for a part that is critical for safety of flight. Shipping a part with a nick in the edge of the central hole is unacceptable - period.

Almost all manufacturers use Six Sigma quality control. Six Sigma measures the capability of a process to perform defect-free work. Six Sigma means a failure rate of 3.4 parts per million or 99.9997% perfect. This is the defect rate in the field which includes design, fabrication, shipping, and installation.

3/1200 broken prop hubs is complete show stopper.

Would you fly in a helicopter with parts that had 3/1200 failure rate?

Sorry for the rant...
If Sensenich had just ignored the issue I think Ranting would have been warranted.... but they didn't do that......
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Scott McDaniels
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  #135  
Old 09-29-2018, 06:54 PM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
If Sensenich had just ignored the issue I think Ranting would have been warranted.... but they didn't do that......
I agree. However, if they are charging for replacement hub they should issue the latest design - "F".
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 397

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #136  
Old 09-30-2018, 11:42 PM
RFSchaller RFSchaller is offline
 
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Jim,

Six Sigma sounds great in a management sales pitch, but I was involved in a $105M project replacing power plant steam turbines. The well established manufacturer (who shall remain nameless) managed to drill a bolt hole on the shaft coupling 2 off center - 6 months after they mixed up orders and shipped the wrong turbine rotor to another client. When we got the feel good six sigma presentation I told them they needed to get the next 10,000 perfect to get back on the statistical curve.

Rich
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