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Thread: Cabin Heat Muff Chaffing

  1. #1
    Senior Member jmorrical's Avatar
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    Default Cabin Heat Muff Chaffing

    Working the engine area to complete the first condition inspection. Noticed the #1 and #3 intake manifold (Induction tubes) has been chaffed by contact with the cabin heat muffs. While it's hard to get accurate measurement I would say the chaff is about .015 to .02 inches of the tube taken off in an area of less than 1/2 inch. Here this photo is with muffs removed.

    IMG_9189.jpg

    Should I replace the intake manifold (induction tubes)? Or be satisfied with some reshaping of the muffs to prevent future contact and putting it on the watch list.

    IMG_9190.jpg

    IMG_9191.jpg

    IMG_9194.jpg

    Sharpie mark showing edge of the area where either the induction tubes or the muffs need to be shaped to prevent chaffing.
    Last edited by jmorrical; 10-08-2024 at 02:11 PM.
    Jim Morrical

  2. #2
    Senior Member Andy's Avatar
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    Default Re: Cabin Heat Muff Chaffing

    "Should I replace the manifold? Or be satisfied with some reshaping of the muffs to prevent future contact and putting it on the watch list."

    I think you would need the nominal wall thickness and a better estimate of the erosion to make an informed choice.

    If the damaged area fails you will have one cylinder running very lean and the engine damage may cost far more than a new intake tube.







  3. #3
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    Default Re: Cabin Heat Muff Chaffing

    Agree with Andy. Find out the wall thickness and make your risk tolerance decision.

    In regards to the muffs, I recall that I had to shape a depression/concave area on 1 or 2 of the muffs to prevent contact.

    Congrats on the first condition inspection and good eye!
    Dan Arnold
    KEUL

  4. #4
    Senior Member jmorrical's Avatar
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    Default Re: Cabin Heat Muff Chaffing

    A $700 lesson learned. I'm replacing the #1 and #3 induction tubes.

    I just thought this fit was the way it was. Didn't expect movement between the muffs and tubes. My inexperience set me up.

    Wish there had been a Note or Caution in the Firewall Forward Manual bringing attention to this potential problem and suggesting shaping the muffs somehow to avoid contact. Or better yet couldn't the muffs have been built to address or prevent this hot spot...this chaffing.

    This photo and others in my EX(1) Fire Wall Forward Manual are not representative of my installation. They show good clearance between muffs and tubes. My muffs were right up hard against the induction tubes.

    Screen Shot 2024-08-17 at 5.56.27 PM.png
    Last edited by jmorrical; 09-05-2024 at 05:13 PM.
    Jim Morrical

  5. #5
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    Default Re: Cabin Heat Muff Chaffing

    Ouch! Good news is you found that down here not up there. Or on short approach to your favorite "no go around" strip.
    Dan Arnold
    KEUL

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    Default Re: Cabin Heat Muff Chaffing

    Better to catch it here than on a tricky approach.

  7. #7
    Senior Member jmorrical's Avatar
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    Default Re: Cabin Heat Muff Chaffing

    An update. Waiting on parts.

    When I took the induction tubes off I could see there is really very little chaffing. What I thought was chaffing was deformation of the softer aluminum tube just conforming to the contact with the stainless steal muffs. I could not have know that without seeing inside the tubes.

    All in all I am glad to be replacing tubes so there is no question about them in the future.

    IMG_9216.jpg

    IMG_9217.jpg

    Here you can see the bump inside where the muff pressed on the tube. It's deformed just a bit. Actually I know now the exterior of the tube has very little chaffing.
    Last edited by jmorrical; 10-12-2024 at 08:21 PM.
    Jim Morrical

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    Default Re: Cabin Heat Muff Chaffing

    Agree. Thanks for the update. It's too hot to fly here anyways. Might as well do maintenance.
    Dan Arnold
    KEUL

  9. #9
    Senior Member jmorrical's Avatar
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    Default Re: Cabin Heat Muff Chaffing

    This is not too important, but it might help others with this experience. Had several ideas including asking a muffler shop for help. I just couldn't bend the stainless steal by hand. In the end here's how I shaped the muffs for clearance I needed from the induction tubes.

    I was able to hammer shape them. Several four inch diameter circles were cut with a four inch hole saw I had in the tool box. Then I used a rasp to shape a depression in what I would call a wood buck. With the wood buck and a couple other wood circles inside the muff for extra support the hose clamps held it all together. This made the muff rigid enough for hammer shaping. It took a couple tries to get the shape I needed for clearance but it worked.

    I'm ready for parts tomorrow to finish the Condition Inspection.

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    Last edited by jmorrical; 10-08-2024 at 02:14 PM.
    Jim Morrical

  10. #10
    Senior Member jmorrical's Avatar
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    Default Re: Cabin Heat Muff Chaffing

    When you reassemble all this USE CAUTION. Do not over tighten the induction tube coupler hose clamps. The coupler with hose clamps connects the induction tube to the sump induction tube. The tubes are very thin walled aluminum. First go at it I must have overtightened the clamps and crimped one of my new tube!

    You can see specific instructions for this in Service Bulletin CK-SB006 Rev A Engine Inductions Hose Replacement Dtd. October 16, 2015

    It says:
    "...centering the coupler over the two tubes. Use the 1” mark as a guide. Secure in place with clamps, torque to 10-14 in-lbs."

    Screen Shot 2024-09-05 at 11.46.51 AM.png


    Screenshot 2024-09-09 at 1.36.38 PM.png
    Last edited by jmorrical; 09-09-2024 at 11:49 AM.
    Jim Morrical

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