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  #131  
Old 09-29-2018, 05:35 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, 07:00 PM
Piper J3's Avatar
Piper J3 Piper J3 is online now
 
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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 2007
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 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 09-29-2018 at 07:03 PM.
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  #133  
Old 09-29-2018, 07:13 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, 07:20 PM
rvbuilder2002 rvbuilder2002 is offline
 
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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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  #135  
Old 09-29-2018, 07:54 PM
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Piper J3 Piper J3 is online now
 
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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 2007
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 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #136  
Old 10-01-2018, 12:42 AM
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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  #137  
Old 10-27-2018, 08:50 AM
AirHound AirHound is offline
 
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Default Repitching after hub cover change

Anyone adjust to other than the book 71.4? I don’t display MP but on takeoff and climb-out will get a high alert. I’m turning 5000-5200 with 71.4+-.1. High MP alert goes away at initial cruise.

Should I adjust to something less like 71.2 to reduce MP on take off? I’m usually midrange loaded.
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  #138  
Old 10-27-2018, 10:17 AM
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Quote:
Originally Posted by AirHound View Post
Anyone adjust to other than the book 71.4?
Yes, I have set a friend’s prop pitch on a Synergy-built RV-12 and also pitch on my E-LSA RV-12. Neither is set to exact 71.4.

If I recall… the Synergy is more pitch and mine is less pitch. Both planes fly identical in climb and cruise.

The key is to set pitch for 5200 RPM at ~1000 FPM initial climb. This should give 133mph/115kts cruise at 5400 RPM.

Above figures are from my experience with temp around 70F and field evaluation - 1000MSL.
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Jim Stricker
Hinckley, Ohio
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
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 406

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #139  
Old 10-31-2018, 11:33 PM
pilotyoung pilotyoung is offline
 
Join Date: Jan 2018
Location: Birmingham, AL
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Default Prop Static RPM

I complied with the SB on the prop today for the second time. After inspecting the front hub and finding no cracks, I put it back together and set the prop angles. When I was finished, bolts torqued, etc. one side was 71.3 and the other was 71.4. After putting the prop spinner on, I warmed the engine up and did a static RPM test. I got 4,900 rpm. I then did a test flight and in level flight could get over 5500 rpm.

As a newbie, my question is should I leave it the way it is or reset it to a slightly smaller angle to get a static rpm of 5,000?

Thanks.

John
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  #140  
Old 11-01-2018, 06:03 AM
hook hook is offline
 
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Quote:
Originally Posted by pilotyoung View Post

As a newbie, my question is should I leave it the way it is or reset it to a slightly smaller angle to get a static rpm of 5,000?

Thanks.

John

My opinion: if you're happy with it, leave it.

Ours are set for a slightly higher angle (relative to the canopy rail... and also backwards from how I'm used to thinking about prop pitch) so that we get better take-off and climb performance but worse cruise speed.
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