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

Re Nord-Lock washers.
Please excuse a stupid question, but how many of the Sensenich specific 85397-1 Nord-Lock washers are requred if I replace the hub front plate with a new D1 version hub cover half?
I want to get all parts I may need for the maintence organisation Iwill use before we start.
I am not the builder of my 12, so must use a licence shop for maintenance.

RJTJRT - To answer your question ... there are six bolts that sandwich the two prop blades between the prop hubs and each bolt uses a Nord-Lock washer.
 
Re Nord-Lock washers.
Please excuse a stupid question, but how many of the Sensenich specific 85397-1 Nord-Lock washers are requred if I replace the hub front plate with a new D1 version hub cover half?
I want to get all parts I may need for the maintence organisation Iwill use before we start.
I am not the builder of my 12, so must use a licence shop for maintenance.

John, check your PM's
 
Sure, I just did this. Call Sensenich and place order over the phone. They may give you a hard time about mismatching SN's and such but insist that they send you latest design hub. I received Rev "F" hub and set pitch manually with digital level per Van's instruction. I entered SN's for both halves of prop hub and both blades in my prop logbook stating compliance with latest SB and installed per Sensenich instructions. Now I feel good about integrity of prop.

I called Sensenich yesterday and tried to order an E or F hub, front half only. I stated that I was aware of the fact that I would be limited to protractor pitch setting only (no center hub or guide pins). I was told by Don Rowell, President, that I had two choices; either order a D1 hub for $195, or send in my complete prop and hub for blade modification and receive the E or F hub at a cost of $545.

So, how were you able to order the new style front half hub? Who did you talk to, what was your cost, and what argument did you use to get this done? I totally agree with you that this new design appears to be much more robust in the cracking areas, and this is the route that I would like to take...................Tom
 
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Tom

I spoke with Steve Boser, Plant City, FL. At that time he was handling the hub SB. I told him I was not going to install another front hub with large pitch change cylinder when Sensenich had a redesign available which eliminated the large central hole. I suspect my being vocal in this thread had something to do with them sending me an "F" front hub. When I called to place order he recognized my name from this forum thread and we spoke at length about the issue.

I realize they don't want to separate hubs matched by serial number, but from my end, I don't want to do in-flight product testing. Cracked prop hub, even with redundant design feature to prevent separation, is not to be taken lightly...
 
I called for an update last week and was told replacements would not become available until September. Are they now selling the replacements?
 
I called for an update last week and was told replacements would not become available until September. Are they now selling the replacements?

I guess they don't have stock at this time. They are accepting order forms, which is posted on there support site, and they will fill them in the order received with one exception. If you have a cracked hub, you go to the front of the line, but mid September is the date that I was given also. I think that is the start time for hub deliveries............Tom
 
My big issue is the same as Jim Striker had. That big hole in the middle of the front plate to accommodate a poor excuse for setting blade angle is likely a major contributor to the cracking. Instead of forcing us to take a modified D hub called a D1, why not sell us the new style F hub. I think that someone at Sensenich thought that was a good idea. Here is a direct quote from the service bulletin.

NOTE: Since the basic blade shank geometry has not changed, it is possible to use older blades with newer hubs if a protractor is used to set blade angles.

That has to be the best fix out there. Only 3 little holes in the F hub, compared to that useless enormous hole that the D1 has. We all use a much more accurate blade angle measuring device and there is no need to keep that useless pitch cylinder. The problem is that now they are trying to force us to pay $545, instead of $195, which will include replacement of a good rear hub half, and have our blades modified to accommodate another useless blade angle setting mechanism. Did I mention aircraft down time while we ship our entire prop back and forth and for them to rework our original blades?? We're still going to use the protractor method to come up with less than a ,1 degree of variance between blades. This could be so simple. Just sell us F hub front halves for $195. We'll take care of the blade angle settings. Done, and done...........Tom
 
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My big issue is the same as Jim Striker had. That big hole in the middle of the front plate to accommodate a poor excuse for setting blade angle is likely a major contributor to the cracking. Instead of forcing us to take a modified D hub called a D1, why not sell us the new style F hub. I think that someone at Sensenich thought that was a good idea. Here is a direct quote from the service bulletin.

NOTE: Since the basic blade shank geometry has not changed, it is possible to use older blades with newer hubs if a protractor is used to set blade angles.

That has to be the best fix out there. Only 3 little holes in the F hub, compared to that useless enormous hole that the D1 has. We all use a much more accurate blade angle measuring device and there is no need to keep that useless pitch cylinder. The problem is that now they are trying to force us to pay $545, instead of $195, which will include replacement of a good rear hub half, and have our blades modified to accommodate another useless blade angle setting mechanism. Did I mention aircraft down time while we ship our entire prop back and forth and for them to rework our original blades?? We're still going to use the protractor method to come up with less than a ,1 degree of variance between blades. This could be so simple. Just sell us F hub front halves for $195. We'll take care of the blade angle settings. Done, and done...........Tom

I agree.
Hope others post their opinions here, so Sensenich can see the logic for RV-12 community.
 
Part of the conversation I had with Sensenich was the cost of the new hub. I was told they were supplying the hub at below cost. You can buy entire new prop with blades, hub, and hardware for $1760. Front hub with six bolts and washers for $195? I don?t know. The ?D? hub is no longer sold for new applications, so this is really old stock or new production of an old design. At one point in the conversation I mentioned that the severity of the problem might have warranted replacement parts at no cost to the end user. Better to get good parts into the field and reduce exposure to product liability.
 
The D hub may be inferior to the new version, but we have only seen a handful of cracked prop hubs, and mine has about 780 Hours with no cracks. I won?t lose any sleep with a D-1 version.
 
I just can't imagine that the cost of manufacture of the F hub is any more costly than the cost of manufacture of the D1 hub. They will both fit the same rear hub and the blades, and apparently they are not just trying to get rid of old stock, otherwise current orders for the D1 hub would be filled. The only loss with an F hub and non retrofitted blades is the loss of the pitch cylinder, which I never use anyway.

I started out with an early hub. There was a recall on them, and I had to send in my early hub, which was gold in color. Then I received a C hub in exchange that is black. My understanding was that the older hubs did not have sufficient blade clamping action. There was no charge for that change. it just meant down time for the airplane. Since then the have continued to redesign the hub and now have an F hub that eliminates that huge hole that accommodated the pitch cylinder, and seems far superior. So now cracks are developing in the C, and D hubs, so, instead of offering us the choice to go with the new F hub, they offer us a discounted price on a beefed up D hub and call it a D1. Sorry, but I would like to be done with this issue, and I strongly believe that by merely replacing my old C hub front half with the new F hub front half, this problem will go away. I'm not asking for it to be FREE, I am happy to pay the $195. I'm just against sending in my prop, having airplane down time, paying additional shipping both ways for the entire prop, and paying $545 to get it done. I just want Sensenich to send me an F hub and I will be totally satisfied with total confidence in the prop. By the way, I wouldn't be the first to receive an F hub front half as a replacement directly from Sensenich..............Tom
 
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I just can't imagine that the cost of manufacture of the F hub is any more costly than the cost of manufacture of the D1 hub. They will both fit the same rear hub and the blades, and apparently they are not just trying to get rid of old stock, otherwise current orders for the D1 hub would be filled. The only loss with an F hub and non retrofitted blades is the loss of the pitch cylinder, which I never use anyway.

I started out with an early hub. There was a recall on them, and I had to send in my early hub, which was gold in color. Then I received a C hub in exchange that is black. My understanding was that the older hubs did not have sufficient blade clamping action. There was no charge for that change. it just meant down time for the airplane. Since then the have continued to redesign the hub and now have an F hub that eliminates that huge hole that accommodated the pitch cylinder, and seems far superior. So now cracks are developing in the C, and D hubs, so, instead of offering us the choice to go with the new F hub, they offer us a discounted price on a beefed up D hub and call it a D1. Sorry, but I would like to be done with this issue, and I strongly believe that by merely replacing my old C hub front half with the new F hub front half, this problem will go away. I'm not asking for it to be FREE, I am happy to pay the $195. I'm just against sending in my prop, having airplane down time, paying additional shipping both ways for the entire prop, and paying $545 to get it done. I just want Sensenich to send me an F hub and I will be totally satisfied with total confidence in the prop. By the way, I wouldn't be the first to receive an F hub front half as a replacement directly from Sensenich..............Tom

Don't forget that 150$ Dynamic Prop Balance some just did....agree stop with the D and go with the F with same back half if not a safety issue...
 
This can't be helping the operation!

FAA Revokes Certificate Of Sensenich Repair Station
https://www.avweb.com/eletter/archives/101/4138-full.html?ET=avweb:e4138:1937224a:&st=email#231418


The recent revocation of FAA repair station license does not apply to us in any way.

Sensenich Propeller Manufacturing (metal props) of Lititz, PA and Sensenich Wood Propeller (wood and composite props) of Plant City, FL have not been affiliated with Sensenich Propeller Service since 1995 when they had a management buyout.
Sensenich Propeller Service does not manufacture propellers, they perform maintenance and repair services only.

Our repair stations in Lititz and Plant City are fully compliant with FAA regulations and meet all government standards.

For more information, please refer to our press release:
http://www.sensenich.com/wp-content/uploads/2018/08/Notice-re-FAA-Order-of-August-2018-A6514345Rev1-002.pdf
 
I agree with Doug. Why send us a retrofit, modified "C" hub instead of the new design "F"?

Gary

Sensenich beefed up the original "big hole" hub cover style in the trouble area so that they would still be compatible with revision D and older hubs, thus allowing use of the original pitch cylinder for setting blade angle.
Of course, you can always use a protractor if you want and not use the pitch cylinder.

Our hub vendor has a 3-4 month lead time, so Sensenich geared up production of revision "D1" replacements in-house, with deliveries planned to begin in early September.

While revision "E" and later hub covers will fit on older hubs, the blade pitch pins won't line up, so you have to use a protractor for setting blade angles.

We can supply revision "F" hub covers upon customer request, but note that these will not be available until later in the Fall after delivery of all current orders for revision "D1" covers.
Sensenich plans to begin in-house production of revision "F" hubs in the mid to late 4th quarter of 2018.

steve from Sensenich
 
Sensenich beefed up the original "big hole" hub cover style in the trouble area so that they would still be compatible with revision D and older hubs, thus allowing use of the original pitch cylinder for setting blade angle.
Of course, you can always use a protractor if you want and not use the pitch cylinder.

Our hub vendor has a 3-4 month lead time, so Sensenich geared up production of revision "D1" replacements in-house, with deliveries planned to begin in early September.

While revision "E" and later hub covers will fit on older hubs, the blade pitch pins won't line up, so you have to use a protractor for setting blade angles.

We can supply revision "F" hub covers upon customer request, but note that these will not be available until later in the Fall after delivery of all current orders for revision "D1" covers.
Sensenich plans to begin in-house production of revision "F" hubs in the mid to late 4th quarter of 2018.

steve from Sensenich

Re F Hub covers availability, Thanks Steve.
Could you come back to us in future, when the F hub covers become available?
John
 
Sensenich beefed up the original "big hole" hub cover style in the trouble area so that they would still be compatible with revision D and older hubs, thus allowing use of the original pitch cylinder for setting blade angle.
Of course, you can always use a protractor if you want and not use the pitch cylinder.

Our hub vendor has a 3-4 month lead time, so Sensenich geared up production of revision "D1" replacements in-house, with deliveries planned to begin in early September.

While revision "E" and later hub covers will fit on older hubs, the blade pitch pins won't line up, so you have to use a protractor for setting blade angles.

We can supply revision "F" hub covers upon customer request, but note that these will not be available until later in the Fall after delivery of all current orders for revision "D1" covers.
Sensenich plans to begin in-house production of revision "F" hubs in the mid to late 4th quarter of 2018.

steve from Sensenich

Wow!! I am ecstatically excited to hear that the "F" hub will be offered. Since I have no cracks now, I am good with waiting for an "F" hub. This is the best news of the day. Your logic does make sense in offering the D1 hub, and many will opt for it in order to retain the pitch cylinder functionality. I am glad to hear that you are offering us a choice. Thanks..................Tom
 
Re F Hub covers availability, Thanks Steve.
Could you come back to us in future, when the F hub covers become available?
John

Will do.
"D1" covers will start shipping early September.
"F" covers hopefully will start shipping in November or early December.

If customers want to switch their hub cover order over to revision "F":
-let us know ASAP so we can update the order in our system
-shipment won't be till later this Fall (as above)
-you will have to use a protractor to set blade angles (since the hubs subject to the service bulletin have a non-compatible pitch system).


steve from sensenich.
 
Sensinich informs me that the ?d? hub is the correct
replacement for the original. I was under the impression there were only three small holes in the new one. Actually it looks very much like the original. Anyone else have same reaction?
Dick Seiders
 
Just read last few pages to get caught up (duh).
I am fine with the d1. I have no cracks
on the original. The F sounds like overkill to me.
Dick Seiders
.
 
Right after I sent my double-cracked original hub cover to Sensenich they sent me (and I paid for) the newer "D1" hub cover. The D1 cover looks somewhat the same as the original cover but is thicker in cross-section near the perimeter of the big round pitch adjustment hole. The Sensenich engineer assured me that the D1 cover was much stronger than the original and was more than adequate to the task. I guess we'll see if that proves true.

It is my understanding that the three-hole hub cover is an optional alternative offered by Sensenich but its availability may be delayed by production issues. The use of a three-hole cover on an older one-big-hole cover means that you lose the auto-adjustment capability (not a big deal in my view) or you have to send the whole prop back to Sensenich for a pitch-adjuster mod. Lots of info on this in previous posts. Also, read Sensenich's FAQ and SB.
 
Just read last few pages to get caught up (duh).
I am fine with the d1. I have no cracks
on the original. The F sounds like overkill to me.
Dick Seiders
.

If "F" hub is overkill I'm sure Van's and Sensenich would continue to offer original design with large pitch change cylinder. The "F" hub is the latest design that incorporates gage pins to set rough prop pitch and eliminates the large central hole.

I don't think you can have "overkill" when it comes to safety...
 
You are miss reading my statement. Absolute assurance against failure of a component is not possible. Sensinich engineer I spoke with stated the d1 hub design is 90 % less likely to fail than original design. That sounds like a significant improvement to me. The F hub is coming later, and requires some additional changes that may create new issues, not to mention cost and downtime. It?ll likely be fine as well. You get the information and make your choices.
Dick Seiders
 
I don't think I misread. 90% safety improvement is not nearly good enough for me. If Vans and Sensenich are using the "F" hub on all new installations that's where I want to be. I now have a "B" rear hub and "F" front hub with no worries about catastrophic inflight failure.
 
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.
 
"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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"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......
 
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
 
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.
 
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.
 
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
 
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.
 
Sounds like you did a good job. Dont mess with success! After you fly for a while at various flight conditions if you want to change it you always can, say at the next CI.
 
About the white Delrin pitch cylinder

"Of course, you can always use a protractor if you want and not use the pitch cylinder."

This may be obvious, but it wasn't to me and I did not see it in print anywhere: if you do decide, as I did, to use the suggested replacement hub (D-1?) and do not replace the white Delrin cylinder (which I did not) you have to make sure that the blades are seated as far out as possible when you tighten the new hub. I failed to do so and was surprised when my spinner would no longer fit. It acted as if the blades had become fatter, which led to me wondering if they were being pulled in further and presenting a wider part of the prop to the spinner.

I contacted Sensenich and quickly received an answer: I could put the cylinder back in to ensure proper blade positioning, or make sure that the blades are as far out as possible.

I'm putting the cylinder back in. YMMV.
 
FAQ

Right after I sent my double-cracked original hub cover to Sensenich they sent me (and I paid for) the newer "D1" hub cover. The D1 cover looks somewhat the same as the original cover but is thicker in cross-section near the perimeter of the big round pitch adjustment hole. The Sensenich engineer assured me that the D1 cover was much stronger than the original and was more than adequate to the task. I guess we'll see if that proves true.

It is my understanding that the three-hole hub cover is an optional alternative offered by Sensenich but its availability may be delayed by production issues. The use of a three-hole cover on an older one-big-hole cover means that you lose the auto-adjustment capability (not a big deal in my view) or you have to send the whole prop back to Sensenich for a pitch-adjuster mod. Lots of info on this in previous posts. Also, read Sensenich's FAQ and SB.

"Of course, you can always use a protractor if you want and not use the pitch cylinder."

This may be obvious, but it wasn't to me and I did not see it in print anywhere: if you do decide, as I did, to use the suggested replacement hub (D-1?) and do not replace the white Delrin cylinder (which I did not) you have to make sure that the blades are seated as far out as possible when you tighten the new hub. I failed to do so and was surprised when my spinner would no longer fit. It acted as if the blades had become fatter, which led to me wondering if they were being pulled in further and presenting a wider part of the prop to the spinner.

I contacted Sensenich and quickly received an answer: I could put the cylinder back in to ensure proper blade positioning, or make sure that the blades are as far out as possible.

I'm putting the cylinder back in. YMMV.

The FAQ (http://www.sensenich.com/wp-content/uploads/2018/07/FAQ-for-SB2016-06-revB.pdf) provides great information. Am I correct in thinking that Sensenich will sell us just the front cover half ?E? or ?F?? If so what?s the cost?
 
Am I correct in thinking that Sensenich will sell us just the front cover half ?E? or ?F?? If so what?s the cost?

I ordered only front half of Rev ?F? Hub Cover with mounting bolts and hardware in July, 2018 for $195. Sensenich says this is discount price but I think they would have provided it for free based on severity of the SB...
 
The FAQ (http://www.sensenich.com/wp-content/uploads/2018/07/FAQ-for-SB2016-06-revB.pdf) provides great information. Am I correct in thinking that Sensenich will sell us just the front cover half ?E? or ?F?? If so what?s the cost?

Scott,
This is a link to a post (post 119) from Sensenich about this in another thread.

http://www.vansairforce.com/community/showthread.php?p=1284274#post1284274

http://www.vansairforce.com/community/showpost.php?p=1284274&postcount=119

John
 
I measured 0.16 inch thickness of the old BR hub at the center weakest point.
The new D1 hub measures 0.27 inch at the same location.
So the D1 hub is more than a tenth of an inch thicker than the old hub at the
the stressed area of concern. In addition, the embossed-pitch-setting hash
marks on the new D1 do not extend to the edge of the large hole like they do on the old hub.
I am confident that the new D1 hub is MUCH stronger than the old BR hub.
 
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