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Update on Cracks in Whirlwind props

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  • Update on Cracks in Whirlwind props

    I sent photo's to the manufacturer and he assured me these are superficial in the paint. He has seen them before and what is happening is the nickel edge is wrapped around to the backside and to keep it from strobing they paint the flat black on most of it. The nickel is more rigid then the carbon fiber and try as they might they cannot keep the paint in that area from cracking. He also stated they would be checked out thoroughly when they get them. The only question I have is how am I supposed to tell the difference between a crack that needs attention and one that doesn't.


    I debated wether to mention this now or wait until our props were inspected, but since any inspection won't happen until the week after Thanksgiving I thought it was a good idea for anybody else using a W.W. prop to inspect before further flight. These cracks are on the backside and extend from the edge but not over the top to the front and they are on the hub end of the nickel plated edge. I cannot say for sure how long they have been there. We are sending both props back for grease leakage at the hub and noticed these cracks while getting them ready to ship. Both blades, both props. Another reason for posting, found them on two props, are there more? I'm only a member of the Bearhawk family and do not post on other sites, so only Bearhawks with W.W. props will likely see this post. if anybody knows of others with W.W. props tell them to check them over. These could be just superficial and not a problem, I just don't know and won't know until they are inspected and I will post anything I find out ASAP. I can't imagine any crack superficial or not would't be a problem but I'm not the expert, just the observer.
    Last edited by Flygirl1; 11-20-2017, 06:13 PM.

  • #2
    Thanks for sharing. Definitely looking forward to your prop shop’s reply. Stay safe!
    ​Christopher Owens, EAA #808438
    Project "Expedition"
    Bearhawk 4-Place Scratch Built, Plans #991
    Bearhawk Patrol Scratch Built, Plans #P313
    Germantown, Wisconsin, USA

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    • #3
      A whirlwind prop is a wood core??

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      • Flygirl1
        Flygirl1 commented
        Editing a comment
        No, it has a hollow foam core. I'm not sure if all composite props are hollow, but I know this one is.

    • #4
      Are any of the whirlwind props certified? Or only experimental?

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      • Flygirl1
        Flygirl1 commented
        Editing a comment
        I don't think any are certified.
        I'm hoping it's not as serious as it looks and that they stand behind it. I like the performance and the look of this prop.
        Last edited by Flygirl1; 11-20-2017, 04:31 PM.

    • #5
      Thank you for the heads up. I have Whirlwind prop on my RV7 that I will be inspecting closely today due to your report. Thanks again.

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      • Flygirl1
        Flygirl1 commented
        Editing a comment
        Your welcome, glad you were able to see my post and hope it's OK. How many hours on your prop?
        Last edited by Flygirl1; 11-20-2017, 04:32 PM.

    • #6
      I've updated the original post to reflect correspondence with Whirlwind Propeller. If after inspection anything changes, I'll update again.

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      • #7
        I see you've already learned that the WW props show those cracks but they are in the paint. It's a pretty common thing with lots of discussion in various forums.

        WW props are foam core. I wish someone would make an experimental wood core prop.
        I'm a Tapatalk user so I can't see your "comment"

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        • Flygirl1
          Flygirl1 commented
          Editing a comment
          MT has a natural composite blade compared with the foam core. Maybe thats the best you can do at this time?

      • #8
        Doesn't MT make their blades on a wood core? Sure that's what I had on my Glastar.
        Is WW going to pay shipping both ways?

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        • Flygirl1
          Flygirl1 commented
          Editing a comment
          Just looking at the MT web site to and they have a comparison chart that has what they are calling "natural composite" on one Side and foam core on the other. So far we re paying shipping both ways, $205 with insurance. Due to the low time and the grease leaking they agreed to prorate the shop fees. They will zero time the props also. As far as the cracks that remains to be seen depending on exactly what they are.

        • Flygirl1
          Flygirl1 commented
          Editing a comment
          Total cost to us for 1 prop is $582.73. That is $425.73 shipping and the rest was tear down and zero timed. We did have the choice to find a prop shop closer, saving some of the shipping costs, but considering the fact they were leaking grease from the beginning and the cracks in the paint, we thought W.W. should have a look, plus they prorated the shop cost to reflect the low time of 188 hours.
          Last edited by Flygirl1; 12-06-2017, 11:19 AM.

      • #9
        Their larger props are foam core. The "11" that I owned is as follows:

        "2-blade variable pitch propeller with a hydraulically operated blade pitch change mechanism providing the operation mode “Constant Speed”.
        The hub is milled out of aluminum alloy, and the blade material is a laminated wood composite structure coated in fiberglas reinforced epoxy. The leading edge of the blades are equipped with an erosion protection device. "

        Thats the the reason I picked WW this time; all composite construction so I thought. Were you getting a lot of oil spray on the windshield? Freight from north of the border to return the prop would make it cost prohibitive for me. Mine was assembled around the time you guys got yours but my blades were put in a McCauley hub so I am keeping my fingers crossed on the leakage. I've seen new props spray for quite a while and then slow somewhat but almost all of them will leak a bit. Still half a year away from an engine start.

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        • Flygirl1
          Flygirl1 commented
          Editing a comment
          Yea, we both had oil spray on the window. There is also an area inside the spinner around the blades that was pretty deep in grease. Cleaned it up and in just a few hours one side of each prop was heavy in grease again. W.W. said it should not leak at all and what was happening was oil was getting in the grease area and diluting it. It didn't look diluted to me but maybe the oil part was soaked up into the spinner leaving the grease behind. If that's the case at some point it will stop leaking grease and just leak oil. So your at the 90% done, 90% to go stage? We didn't start the engines until a week or two before first flight. How exciting! That half a year is going to go fast! 🙂

      • #10
        I don't know much about composites but believe a crack is not what you would get with any fatigue. Delamination is what I would expect with any failure. Guys on the site that have forgotten more than I'll ever know about this subject could chime in.

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        • #11
          Originally posted by whee View Post
          WW props are foam core. I wish someone would make an experimental wood core prop.
          Catto and Prince, albeit they're fixed pitch.

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          • #12
            W.W. does not have our props yet, but I have been corresponding with them. FYI this is part of an e-mail I received this morning:


            Hi, Donna. Actual blade cracks (the carbon fiber itself) are very rare for our products. It has been my experience since we took over the constant speed side of the business in 2005 that if there is a weak spot in a blade design it gets flushed out through beta testing and never reaches the market. Your 210 props are established products with an outstanding history, so unless something extremely out of the ordinary comes up you will not have to worry about structural blade cracks. Because the carbon fiber is flexible but the surface paint and primer coats are rigid there are still some paint crack problem areas that we continue to fight. These are around the nickel, as you see with your blades, and often small cracks will radiate longitudinally from the area at the top of the blade ferrule. They usually only extend about 1/4" or so but they can be concerning for a customer until we have an exchange like this. A few years ago we found a "flexible" primer coat material to try to mitigate these possible problems. Using it has improved the paint crack possibility but I don't think we will ever be able to eliminate it completely because of the nature of the carbon fiber.

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            • jim.mclaughlin924
              jim.mclaughlin924 commented
              Editing a comment
              Any news about your props?

            • Flygirl1
              Flygirl1 commented
              Editing a comment
              No Jim. We received a phone call message that they received them on Tuesday and they were headed to the teardown department. Wouldn't you know it. Next week we are forecasted to have flying WX for several days in a row. Almost unheard of in these parts this time of year. So all you Oregonians can thank us for the great weather. ;-) How's the Tweety bird treating you? Still flying on that wonderful 0-235 it came with?

            • jim.mclaughlin924
              jim.mclaughlin924 commented
              Editing a comment
              Donna
              Hope you get a resolution soon. Tweety is fine, just finished an annual a month or so ago. Had one little fuel leak in a primer line that had to be resoldered,but everything else was fine. I flew on Sunday, went up along the front range for some sight seeing. I am looking forward to finishing my Patrol, but Tweety makes the wait a lot easier.
              Jim

          • #13
            Our props are on their way back and the report on the cracks are “no concern”. So I guess that means it was in the paint. I e-mailed a request to talk directly with somebody about just what to look for in a crack that is a “concern” and that hasn’t happened yet. I was informed that the cracks we had were investigated thoroughly though and trust that they are OK.

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            • #14
              I'm very happy to hear that your props are good to go! Shame that the paint cracked, but far better than the spectre of shucking a blade tip!

              Bill

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              • #15
                Originally posted by Flygirl1 View Post
                I e-mailed a request to talk directly with somebody about just what to look for in a crack that is a “concern”
                This would be my question as well, "Well when should I worry about this?" lol. If this is a known, and apparently expected, issue I would think they would mention it to owners or people considering purchasing their product.
                Dave B.
                Edmonds, WA
                4 Place Quick Build

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