Sensenich Propeller Split~Mystery continues~Sensenich good people

From: Charley Denny <charleyd@> To: 'Daniel Bernath' <[email protected]> Sent: Monday, April 6, 2015 5:18 PM Subject: RE: Sensenich Propeller~~my felt covers on your propellers

Daniel,



We haven’t determined the cause of the damage at this time however we will replace the blades.



Regards,



Charley Denny



Sensenich Propeller

2008 Wood Court

Plant City, FL. 33563

Sensy "Plank"

danielabernath said:

From: Charley Denny <[email protected]> To: 'Daniel Bernath' <[email protected]> Sent: Monday, April 6, 2015 5:18 PM Subject: RE: Sensenich Propeller~~my felt covers on your propellers

Daniel,

We haven’t determined the cause of the damage at this time however we will replace the blades.

Regards,

Charley Denny
Sensenich Propeller
2008 Wood Court
Plant City, FL. 33563

Click to expand...

Dan,
Which model Sensenich prop cracked, the certified brass leading edge version for Cub types or the "Plank" wood prop for experimental applications?
Both are manufactured in Plant City. What airplane was it on?

V/R
Smokey

PS:Yep, the Plant City folks rock, I lived nearby for 10 years and enjoyed several "tours"! I really like their new Composite GA prop. I saw it go from development (on air-boats) to fruition on airplanes.

It was an RV-12 prop according to a prior thread.

Out of all of the people with knowledge of aviation here you would think someone could opine about how the trailing edge of a composite prop could open up like a melon.
By the way, I whined to the Base Operations Manager at Page about how the wind and sun were tearing my beautiful RV 12 to pieces and she permitted the baby to be moved into a covered area. Also, it is in a space next to a wall so hopefully the high afternoon Florida winds won't tear into it any more as well.

It would have been much better had this new information continued the prior thread than starting a new one. Oh well. If you are reading this, here is the thread that it began on...

http://www.vansairforce.com/community/showthread.php?t=124185

Aha...

danielabernath said:

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Dan,
Opining can only take place when one is certain of what to opine about. Thanks to Bill H for the thread link to clear that up!
Since a picture is worth a thousand words, we can now establish which prop you have and the type RV (12) and identify the damage. I'm far from an expert on composites, but I have watched the process firsthand on the F16 and understand it's strengths and limitations. It appears in the photo that the trailing edge suffered delamination as mentioned in a previous thread. Composites can and will (as you now are acutely aware) come apart from the resin or sandwich mold. Unknown as to why, possibly the vacuum bagging process, temperature extremes, humidity (invented in Central FL) or poor QA.

The take-away is the data from your prop will help others with their Composite GA props longevity and Sensenich has made good on their product.
Win Win...


Good luck with your 12...
V/R
Smokey
www.iamanet.org

I didn't want to step on sensenich's toes here. They have to deal with physics just like the rest of us and they appear concerned about this.
I am troubled that (as I said before) that 2 A&P men inspected the plane and including the prop as part of an annual condition inspection.
The two mechanics gave it special attention as they wanted to check out the (natural) play of the prop as you giggle it fore and aft.
I also used my finger tips and inspected the two sides of each blade.
Then...I taxied it back to its sunshine assaulted open space at SW Ramp at KFMY. I went back 11 or so days later and the blade was split wide open with the split facing up.
Again, it is the trailing edge.
Again, Sensenich is making good on it (new blades are not here yet and the RV 12 looks silly with a pitot tube sticking out so far. I put a red flag on the end).

Quite a mystery as even the maker can't tell me what caused this. Sunshine? We all have sunshine here in Florida. I now have a hanger of sorts (wall at west end, open at north/south end and open to the south with other airplanes). No more sunshine on Sunsunich blades (when the new ones come).
I hope I have contributed to the Vans Air Force Community as I have gained some much by coming here.

When people point at the pitot on my RV12 and ask "What's this?" the answer is "22 caliber, 700 rounds."

Yes - keep a piece of tubing with a streamer on it! Sharp little gadget.

It surprises me that a composite propellor is painted (or left) black.

I had the opportunity to do flight tests in Mohave, CA on a composite aircraft engine nacelle. It was summertime, temperatures were in the 105-115F range - low humidity, but it was like walking around in a toaster oven. The nacelle was raw graphite epoxy.

The black nacelle surface got extremely hot in the sun, so much so that the roughly 10 ft diameter nacelle was growing circa 1/4" relative to a connecting round aluminum part. Neighboring white painted parts were much cooler to the touch. The black parts could not be touched without burning oneself.

If your black painted prop sits in the sun, it could get hot, thermally distort in shape every sunny day, then go back to it's original shape once cooled down. The resin system may or may not be able to tolerate the temperatures it sees just sitting in the sun. (Note - the blade temperatures while flying will be much cooler.)

This may not be the cause of the failure, but seems undesirable nonetheless. Any composite aircraft part should be painted white, IMHO.

-Paragon
Cincinnati, OH

The back side of the blades are always flat black to reduce glare for the pilot. It would seem that the design and construction would have to accommodate that.

Mystery not solved; what caused propeller to split sitting in Florida Sun.
Sensenich made good. Here are the two new replacements.
Airplane is now under a roof protected from direct rays of Sol.

Any update on the cause of this?

what's the history on these props?????

Paragon said:

It surprises me that a composite propellor is painted (or left) black...........The black parts could not be touched without burning oneself.
If your black painted prop sits in the sun, it could get hot, thermally distort in shape every sunny day, then go back to it's original shape once cooled down. The resin system may or may not be able to tolerate the temperatures it sees just sitting in the sun. This may not be the cause of the failure, but seems undesirable nonetheless. Any composite aircraft part should be painted white, IMHO.
-Paragon Cincinnati, OH

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agreed on all points, but Sensi has been making almost this exact blade for Florida airboats for 20 years +, from what I gather.
how can huge flat blades, in the sun a LOT, on the 'glades, survive that kind of use and abuse, ( 300 hp airboats) and not this?

I thought that was the reason to spend the money on the Sensi product, the track record of their composite blades.

I won't speculate, just one more strike against this type of structure.
I think I'll stick with aluminum....it just cracks and falls off!

what's the history on these props?????

Paragon said:

It surprises me that a composite propellor is painted (or left) black...........The black parts could not be touched without burning oneself.
If your black painted prop sits in the sun, it could get hot, thermally distort in shape every sunny day, then go back to it's original shape once cooled down. The resin system may or may not be able to tolerate the temperatures it sees just sitting in the sun. This may not be the cause of the failure, but seems undesirable nonetheless. Any composite aircraft part should be painted white, IMHO.
-Paragon Cincinnati, OH

Click to expand...

agreed on all points, but Sensi has been making almost this exact blade for Florida airboats for 20 years +, from what I gather.
how can huge flat blades, in the sun a LOT, on the 'glades, survive that kind of use and abuse, ( 300 hp airboats) and not this?
(a data point, in BC, we get 17 hours of sun at peak summer, versus the measly 13 in Florida!...and temps around 90-100 F.)

I thought that was the reason to spend the money on the Sensi product, the track record of their composite blades.

I won't speculate, just one more strike against this type of structure.
I think I'll stick with aluminum....it just cracks and falls off!