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Thread: O-320 Oil Cooler Baffle STC

  1. #71
    mmoyle's Avatar
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    Default O-320 Oil Cooler Baffle STC

    Marv and I are making a new set of baffles for his narrow deck 160 hp. The 200 hour old oil cooler had cracked.. reinforced with 0.032” stainless and made 4 spacers to evenly load the flanges on the oil cooler.. bit heavier than needed as the bolt should have been number three not four.. machined all four to the same length ...within a thousand and a half..


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    Last edited by mmoyle; 07-04-2018 at 12:56 AM.

  2. #72
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    Default Re: O-320 Oil Cooler Baffle STC

    That beats me using 3/16 hard aluminium tubing with washers. Nice!
    "You can only tie the record for flying low."

  3. #73
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    Default Re: O-320 Oil Cooler Baffle STC

    What is the thermal coefficient of the aluminum radiator vs the steel standoffs so carefully machined? In other words, at highest potential operating temperatures, will the radiator grow more than the sell clamps securing it will safely allow?

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  4. #74
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    Default O-320 Oil Cooler Baffle STC

    Ha! One reason...well two. Wanted to transfer the load so to speak. Wanted larger surface area when the assembly was put under compression. This transmitted more potential bending force to the stainless plate...and somebody..is somehow....this eliminated any concerns. Maybe...a re-do.....vibration isolation mounts....I joke. If we had ordered AN3 bolts...would have done the same thing, used the same 4130 3/4” round stock and smaller diameter 4130 tubing and larger OD washers at the bolt heads.


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    Last edited by mmoyle; 07-04-2018 at 04:15 PM.

  5. #75
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    Default Re: O-320 Oil Cooler Baffle STC

    Quote Originally Posted by Stephen View Post
    That beats me using 3/16 hard aluminium tubing with washers. Nice!


    Yours and mine save weight. Marks look nicer.



  6. #76
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    Default Re: O-320 Oil Cooler Baffle STC

    I take it Marv's ws not done per the Stewarts STC? Prior field approval?

  7. #77
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    Default Re: O-320 Oil Cooler Baffle STC

    Nope...nada.. looked through all the log books and the FAA CD for the aircraft. Stewart’s STC calls for a .040” thick aluminum doubler...I duplicated Airforms Inc’s PMA’d baffle reinforcements using stainless. Waiting on a call from the A/I.


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    Default Re: O-320 Oil Cooler Baffle STC

    Quote Originally Posted by mmoyle View Post
    Marv and I are making a new set of baffles for his narrow deck 160 hp. The 200 hour old oil cooler had cracked.. reinforced with 0.032” stainless and made 4 spacers to evenly load the flanges on the oil cooler.. bit heavier than needed as the bolt should have been number three not four.. machined all four to the same length ...within a thousand and a half..


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    Bit of explanation......was going to just patch up the old baffles and work up a new set when I got home. When I got the plane, the baffles were cracked where the oil cooler was mounted as no doubler was installed. I made a .040 doubler, as I understand is called for in the Stewart STC, and installed it, with sign off by the AI. But the baffles were in such bad shape that they did not hold the doubler, which resulted in the oil cooler cracking. Ordered a new cooler and realized that we were going to have to rebuild the baffles or it would happen again. We duplicated the old baffles, but fit the new pieces a lot better, and used the Air Forms cooler mounting as a pattern for the oil cooler installation to prevent future fatigue cracking of the oil cooler ears.


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