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  #1  
Old 07-10-2018, 06:42 PM
DHeal DHeal is offline
 
Join Date: Sep 2006
Location: Windsor, California
Posts: 693
Default FYI: New SB 18-07-05 on RV-12 Sensenich Props

FYI: New SB 18-07-05 on RV-12 Sensenich Props

http://www.vansaircraft.com/pdf/serv...sb18-07-05.pdf
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David Heal - Windsor, CA (near Santa Rosa)
EAA #23982 - EAA Technical Counselor and Flight Advisor; CFI - A&I
RV-12 E-LSA #120496 (SV w/ AP and ADS-B) - N124DH flying since March 2014 - 650+ hours (as of July 2018)!
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  #2  
Old 07-10-2018, 09:02 PM
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DaleB DaleB is offline
 
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Location: Omaha, NE (KMLE)
Posts: 1,845
Default

How nice of them to release that the day after we pulled the spinner off to start our condition inspection.
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RV-12 # 222 N980KM "Screamin' Canary" (bought flying)
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  #3  
Old 07-11-2018, 07:18 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 923
Default

This SB is a visual inspection of the front prop hub. Unfortunately, on the RV-12 there is a Front Spinner Plate blocking the view necessary to inspect the front prop hub. To remove the Front Spinner Plate all six bolts that hold the front prop hub must be removed. Blade pitch angle will need to be re-established when front prop hub is reassembled and re-torqued. This is a lot of work for a repetitive inspection every 50 hours of flight. I fly ~ 150 hours/year so I will have to do this inspection three times annually.

At some point Sensenisch redesigned the front hub to eliminate the pitch cylinder. Perhaps the large hole in the aluminum hub reduced strength and now cracks are developing along the thinnest edge at 90° to the axis? Maybe this becomes a problem because of the way the Rotax 912 stops so suddenly when you shut it down.

The new design front prop hub eliminates the large hole and instead has three smaller holes along the central axis of the hub. See drawing below. Special pins are inserted in the two outer holes to rough in the blade pitch angle. Once set, the pins are removed. No more large pitch cylinder and corresponding large hole in front prop hub.

So I’m wondering if Sensenich will offer the new front prop hub as a one-time fix for this service bulletin. Perhaps discount price, or free replacement, like they did for SB11-04-15 where 2A0R5 revision B Hubs were replaced free because a small percentage of hubs were prone to prop blade pitch loss.

It will be real nice if I don’t have to disassemble my prop three times/year…


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Jim Stricker
Hinckley, Ohio
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 366

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Special Thanks to EJ Trucks
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  #4  
Old 07-11-2018, 07:25 PM
n233va n233va is offline
 
Join Date: Jul 2014
Location: Prescott, AZ
Posts: 25
Default HUB FAILURE

Reference this SB and Sensenich Service Bulletin. I was the single failure on a Rotax 912ULS in a 2013 RV12 SLSA. Happened on 6/19/1018 while returning to Prescott, AZ. Was flying at 11,500 at 5300 RPM when a sudden significant harmonic vibration occurred. Not sure what it was but suspected the Prop. Safely returned to Prescott. Upon examination, a crack was observed in the front hub. The crack started at the first pitch setting mark and propagated around the hub. After removing the six bolts, the hub fell off in TWO pieces.

I strongly recommend that anyone who has a Sensenich Prop with the nylon plug for setting pitch, closely follow Sensenich’s SB and inspect their prop ASAP. Had I shed a blade, probably would not be writing this.

Hopefully these links to the photos will work. If not, PM me and I'll sent the pictures of the broken hub.

https://www.dropbox.com/s/r9y0zdwzlo..._0148.jpg?dl=0
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  #5  
Old 07-11-2018, 07:30 PM
n233va n233va is offline
 
Join Date: Jul 2014
Location: Prescott, AZ
Posts: 25
Default Correction

Date of occurrence was 6/19/2018.
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  #6  
Old 07-11-2018, 08:04 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Holy S..t!!! n233va - I'm going to insert your picture in this post. That be the case, this should be listed as a Safety Alert by Vans just like the SA for Incomplete Welds on Flaperon Torque Arms and not a Service Bulletin. Holy S..t!!!

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Jim Stricker
Hinckley, Ohio
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 366

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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  #7  
Old 07-11-2018, 09:17 PM
AirHound AirHound is offline
 
Join Date: Oct 2006
Location: OFallon IL now, everywhere before
Posts: 198
Default

Quote:
Originally Posted by Piper J3 View Post
Holy S..t!!! n233va - I'm going to insert your picture in this post. That be the case, this should be listed as a Safety Alert by Vans just like the SA for Incomplete Welds on Flaperon Torque Arms and not a Service Bulletin. Holy S..t!!!

Jim,
Are there different prop options for an RV12? I don’t know what they would be. Maybe Cato?

Doug
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  #8  
Old 07-11-2018, 09:24 PM
Piper J3's Avatar
Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 923
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There's nothing wrong with the Sensenich 2-Blade Ground Adjustable Prop.

I just need assurance that hub isn't going to break.

And what I mean by assurance is not having to look every 50 hours to see if hub is broken...
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Jim Stricker
Hinckley, Ohio
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 366

LSRM-A Certificate 2016
Special Thanks to EJ Trucks

Last edited by Piper J3 : 07-11-2018 at 09:46 PM.
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  #9  
Old 07-11-2018, 09:29 PM
RFSchaller RFSchaller is offline
 
Join Date: Oct 2010
Location: Phoenix, AZ
Posts: 2,243
Default

How many hours were on the failed hub? Was there any evidence of a manufacturing flaw? I have a Rev C prop so I am very interested in this.
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  #10  
Old 07-12-2018, 02:16 AM
jdelpeso jdelpeso is offline
 
Join Date: Mar 2006
Posts: 34
Default

Hi Bob
Just wondering if you performed a dynamic prop
balance
Mine was 2 grams out of balance in the tip
and had to be repaired
Jose del Peso 120633
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