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danielabernath

Well Known Member
prop.jpg
sensenich propeller
Airplane is only had 50 hours when I bought her from builder; Most recently RV12 has been sitting outside in the hot Florida sun for a year now (waiting for hanger space).
I'm told that Florida is terrible for airplanes outside because of the sun but also because we are only a few miles from the Gulf of Mexico and the salty air.
I am told that this tears apart/deteriorates rubber gaskets in dish washers and such.
I'll supply pictures later as I went to airplane this morning without camera.
My mechanic says maybe can be repair or maker may have to repair. Looks to be a clean separate of the two halfs at the leading edge tip. I can see the dove-tail construction which holds the two pieces together.
(PS, last week A&P man, two of them, did condition report on airplane. They both, as did I, ran our finger tips across leading and trailing edge of both propellers and it was just fine. It only got into the high 80s last week but prop and plane are in the sun)

prop4_zpswkw6kagb.jpg
 
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11046402_10203975107393771_8397005898623849518_n%5B1%5D.jpg



sensenich propeller another picture of propeller split. This would be very bad if flying when it did this. (extreme pull to the left)
 
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10426674_10203975156595001_9009142098726494201_n%5B1%5D.jpg

Please note, no damage of any kind to prop face. (I used my thumb to scrape off a yellow bug internals)

Also note that 2 weeks ago, 2 A&P men, and myself, inspected the props for annual condition report and found nothing wrong.
 
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prop4_zpswkw6kagb.jpg
rgmwa said:
(Sorry about auto focus) Pretty serious delamination judging by the photo. Have you contacted Sensenich?
Click to expand...
I saw the flaw (understatement) and it was on a Saturday. i sent them the picture and asked them to correct this serious issue. De-lamination eh? I can see inside of the guts of the prop and it appears that the prop is held together on the leading edge with a modest "dove tail" system. I took my thumb and fingers to test and close it. It takes much pressure to move and I couldn't close the gap all the way. It has warped outward.
This is very troubling as this appeared to just happen spontaneously with only 94.8 hours on the Hobbs and I flew over the Rockies with this. If it happened there, I'd be writing this from some graveyard.
 
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water and humidity

water and humidity have the most effect to reduce the strength of composites. pull test two samples, one dry and the other from a humidity chamber, the dry one will be significantly stronger. water is the enemy of composites.
 
Is this the leading or trailing edge we're looking at?

No matter, I believe Sensenich will want to see the prop right away. Several years ago I threw 4 inches off the tip of a Hartzell, and they were VERY interested in getting it back to the lab to check it out.

Catastrophic prop failure is a big deal.
 
That prop blade is toast and I seriously doubt even Sensenich could repair it but they'll definitely want it back to study why it's delaminating like that because these carbon fiber blades are not supposed to do that.
 
danielabernath said:
It is the leading edge.
Click to expand...

That sure looks like the trailing edge to me. The first two pictures appear to be taken from behind the prop, on the right side of the plane, looking straight down at the damaged blade. For a clockwise prop rotation (when viewed from behind) that would mean you're looking straight down at the trailing edge.

Doesn't the leading edge have a metal edge guard over it?

Skylor
 
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skylor said:
That sure looks like the trailing edge to me.
Click to expand...

That was my thought too, looking at the photos of the decal, and nose gear leg.

10426674_10203975156595001_9009142098726494201_n%5B1%5D.jpg


prop.jpg


But, does the Rotax turn in the same direction as a Lyc?? A photo from the rear would show the leading edge if it turns the other way............:rolleyes:
 
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prop5_zpsmjirkqjg.jpg
In focus and
another angle
(I could ask the mailman to leave letters and packages there at the airport for me)
If I got the leading edge confused with the trailing edge this will explain why I taxi and fly tail first.
 
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Mike S said:
That was my thought too, looking at the photos of the decal, and nose gear leg.

But, does the Rotax turn in the same direction as a Lyc?? A photo from the rear would show the leading edge if it turns the other way............
Click to expand...

Here's a picture of the factory aircraft that shows conventional (for US) propeller direction, and a leading edge guard on the blades. The original OP's damage is clearly to the trailing edge.

vans-rv12-for-dave-blog-medium.jpg


Skylor
 
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I would guess that the delamination is from warpage. I once built a kitchen table and wasn't real careful of managing the grain orientation of the various glued up pieces. In some environmental conditions (humidity related) the table is quite flat and in others, there is a significant bow to it. The key lesson was that I had a serious experience deficiency and a real understanding of the wood's movement patterns were necessary to accomplish a project like that. Glue is no deterrent to mother nature's desire to do what she planned.

It could be an error when selecting the boards in the initial layup.

Larry
 
There is no wood in these propeller blades. They are molded within a hollow female mold. The finished part is hollow inside, except for the knob portion At hub shank.

I have never seen this happen with one of these blades.
If it were mine, I would be looking very closely for any (it may be very slight) indication of a location where a large point load got applied. Most likely right near the tip.
 
rvbuilder2002 said:
There is no wood in these propeller blades. They are molded within a hollow female mold. The finished part is hollow inside, except for the knob portion At hub shank.

I have never seen this happen with one of these blades.
If it were mine, I would be looking very closely for any (it may be very slight) indication of a location where a large point load got applied. Most likely right near the tip.
Click to expand...

Could you explain that please?
 
rvbuilder2002 said:
Look for any indication (even light scuff marks) that anything push against it.
Click to expand...

I think he means something hit it, a car, 4 wheeler, another airplane, a tug. Something hit the end of the prop, and this cause the shear fracture of the bonded propellor.

Example: Take two yard sticks and hold them together. Then bend them and notice how as they bend, then ends displace from each other. This is due to shear displacement along where they are touching. No think that they are bonded, and they will become as one. Trying to bend will create a shearing force along that bond plane. If that bond strength is weaker than the yardstick material, then if bent to failure, the bond will break (shear) due to that shear force and separate the two yardsitck again. This is what has apparently happened to your prop.

If this prop is constructed like the Whirlwind, with a bladder expanding inside the prepreg material and then it is baked within a die, then it is odd that a clean shear plane fracture like this would develop. If that truly is the case, then the prop company would be interested in getting this prop back.
 
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BillL said:
I think he means something hit it, a car, 4 wheeler, another airplane, a tug. Something hit the end of the prop, and this cause the shear fracture of the bonded propellor.

Example: Take two yard sticks and hold them together. Then bend them and notice how as they bend, then ends displace from each other. This is due to shear displacement along where they are touching. No think that they are bonded, and they will become as one. Trying to bend will create a shearing force along that bond plane. If that bond strength is weaker than the yardstick material, then if bent to failure, the bond will break (shear) due to that shear force and separate the two yardsitck again. This is what has apparently happened to your prop.

If this prop is constructed like the Whirlwind, with a bladder expanding inside the prepreg material and then it is baked within a die, then it is odd that a clean shear plane fracture like this would develop. If that truly is the case, then it might be a poor original bond and likely a propellor defect yielding this failure from an external "bump" at a tip.
Click to expand...

Pretty much Bill.

I am not suggesting there is no defect in the blade. There is no way to tell from a couple of photos.
What I am suggesting is that I am doubtful that there is a defect that did not show up in 50 + hrs of flying, but that would suddenly allow this to happen just from the propeller sitting out in the sun.
But I have been wrong before, and probably will be many more times in the future. This may be one of them.
Hopefully a clear cause can be determined after careful inspection of the blade.
 
I looked all over it and it is as smooth a babies fanny. Nothing. I used my finger nail to scrape off the guts of a yellow bug, then used my hand to wipe it and find nothing on it whatsoever. Nothing. Not a nick, blemish-nothing but a dead bug's guts.
 
BillL said:
I think he means something hit it, a car, 4 wheeler, another airplane, a tug. Something hit the end of the prop, and this cause the shear fracture of the bonded propellor.

Example: Take two yard sticks and hold them together. Then bend them and notice how as they bend, then ends displace from each other. This is due to shear displacement along where they are touching. No think that they are bonded, and they will become as one. Trying to bend will create a shearing force along that bond plane. If that bond strength is weaker than the yardstick material, then if bent to failure, the bond will break (shear) due to that shear force and separate the two yardsitck again. This is what has apparently happened to your prop.

If this prop is constructed like the Whirlwind, with a bladder expanding inside the prepreg material and then it is baked within a die, then it is odd that a clean shear plane fracture like this would develop. If that truly is the case, then the prop company would be interested in getting this prop back.
Click to expand...

I'm going to the airplane again tomorrow for some tip pictures but it is attached at the tip. Here is a picture that gets near the tip. I didn't see separation at the tip so I didn't bother to get a picture. It is intact at the tip.
prop5_zpsmjirkqjg.jpg


March 17, 2015 I taxi to SE ramp at KFMY. It is inspected (propeller) by 2 a&p men and myself for annual condition report.
March 17, 2015 I taxi back to space 43.
March 28, 2015 I look at plane tied down and see that the propeller is split.
That is all there is to it.
 
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Christopher Murphy said:
I have a brand new GA prop sitting in the box waiting to go on the airplane (0320 rv4) I will be calling sensenich tomorro for sure
cm
Click to expand...

I wouldn't be too terribly, unnecessarily worried about the O-320 GA prop. It's built quite a bit beefier than the RV-12 Rotax version. I've been running mine for almost 2 years now, and it's been a flawless performer.
 
waited..

After reading some of the posts here, it makes me think the prop may have been damaged.

I fly low level aerobatics at airshows with my rv4 so I need confidence that the prop wont fly apart! I have been watching your posts about the prop
cm
 
The chit-chat back and forth here on this prop is meaningless.

It needs to be removed from the aircraft and returned to the manufacturer for a determination as to what happened.

That information would be most useful.
 
Inspected by two A&P men and myself. Then, I taxi from fuel area back (southeast ram) through south ramp to southwest ramp past all the airplanes parked on south ramp then onto D for a few feet and then to space 43 Southwest ramp.
Any contact with anything except the yellow bug is unlikely. It sits about 4 spaces away from any other airplane at space 43.
1621.jpg
 
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From: Charley Denny <[email protected]>
To: [email protected]
Sent: Monday, March 30, 2015 9:49 AM
Subject: Sensenich Propeller

Hello Mr. Bernath,

I am sorry that you are having a problem with your propeller. Can you send the blades to us for evaluation?

Regards,

Charley Denny

Sensenich Propeller
2008 Wood Court
Plant City, FL. 33563
813-752-3711 Phone
813-752-2818 fax

From: Do Not Reply [mailto:[email protected] ]
Sent: Saturday, March 28, 2015 2:26 PM
To: [email protected]
Subject: Info Request by Daniel A. Bernath, Lawyer, March 28, 2015, 2:25 pm

Information Request Received
Sensenich.com - Contact Form
March 28, 2015, 2:25 pm
first_name

Daniel A. Bernath, Lawyer
email

[email protected]
message

I have a propeller of yours on my Vans RV 12 Light Sport and it has split along the leading edge. It was put on about 2 years ago by the builder. Interestingly, I had the airplanee inspected by two A&P men about a week before and they examined the aircraft and especially the propeller (they wondered why there was some play in the mount) and they found no defect. Then, the leading edge has split open. 503 367 4204 239 288 6034
 
Gus Funnell
Today at 10:33 AM

To

me

You need to contact the prop manufacturer: Sensenich. They are the
ones who make and repair the propellers used on the RV-12.

(813) 752-3711

[email protected]

The serial number is 29748C and it was delivered to Wes in 2011, so I
believe it is out of the Sensenich warranty period.

The picuture does not show much detail; I'd see if you can get a
higher res version to send to Sensenich, so they can really see what
is going on.

Vans
 
From: Charley Denny <[email protected]>
To: 'Daniel Bernath' <[email protected]>
Sent: Monday, March 30, 2015 12:05 PM
Subject: RE: Sensenich Propeller

Mr. Bernath,



The first thing that we need to do is inspect the blades to determine the cause of the problem and go from there. I can have UPS pick them up at our expense as soon as you have them boxed and ready to go.



Regards,



Charley Denny



Sensenich Propeller

2008 Wood Court

Plant City, FL. 33563

813-752-3711 Phone

813-752-2818 fax
 
history of Sensi composite props?

I am not speculating here, wise to wait for the report from Sensenich.
my comment is that I think that Sensi has thousands of these out on airboats, so we are talking constant sun, salt, and **** going thru them. That sounds like the real torture test, not sitting on a ramp in the sun.
will be interesting to hear the results.
 
It is not logical that it was hit by a rock or some other hazard as it was always isolated in a part of the field where no obstructions and no other airplanes nearby. This odd edge could be as the two parts pulled apart and some of the material went on one half and the other material went on the other half.[/COLOR]
d9937ed4-6da7-4e1c-8cc2-56b2f636755a_zpsctgciwyc.jpg

I took more pictures.
I see what looks like an indent, blunt, little on the forward part of the separated half. (the silver is just a reflector so the auto focus will not focus on the ground).
I talked to Sensenohn and they say that I must send them both to them in Plant City.
I wonder how that a bump would appear on the edge that is trailing. "I don't know." said he.
"Maybe hanger rash." (It sits outside until I get a hanger).
 
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Brop blade

was purchased December2015. Airplane is in Ohio, always hangared. 15 minutes later and it would be sitting in a very muddy field halfway between Dayton and Richmond.

Wayne 120341
 
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