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Thread: ELT battery replacement

  1. #51

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    Just to add another element to the discussion on TBO, there was a famous research scientist or engineer in England over the war that found in bombers, that the planes that were inspected more often were LESS reliable and less ready for duty. Thus, LESS NOT MORE, maintenance was better; sort of it it is running good it is better to let well enough alone.
    I don't have his name now, nor more details. but I'd guess that one aspect of this was that if an engine was likely to have trouble it may do it early in its life, and once past a certain hours it is more likely to last longer if not disturbed.
    This is not just theory, at least in the case I am reffuring to, the research was accepted by the RAF.

  2. #52

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    Quote Originally Posted by Bill Greenwood View Post
    Just to add another element to the discussion on TBO, there was a famous research scientist or engineer in England over the war that found in bombers, that the planes that were inspected more often were LESS reliable and less ready for duty. Thus, LESS NOT MORE, maintenance was better; sort of it it is running good it is better to let well enough alone.
    I don't have his name now, nor more details. but I'd guess that one aspect of this was that if an engine was likely to have trouble it may do it early in its life, and once past a certain hours it is more likely to last longer if not disturbed.
    This is not just theory, at least in the case I am reffuring to, the research was accepted by the RAF.
    There is an old rule. " If it ain't broke, don't fix it until it is."

  3. #53
    Mike Busch's Avatar
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    Quote Originally Posted by Bill Greenwood View Post
    Just to add another element to the discussion on TBO, there was a famous research scientist or engineer in England over the war that found in bombers, that the planes that were inspected more often were LESS reliable and less ready for duty. Thus, LESS NOT MORE, maintenance was better; sort of it it is running good it is better to let well enough alone.
    I don't have his name now, nor more details. but I'd guess that one aspect of this was that if an engine was likely to have trouble it may do it early in its life, and once past a certain hours it is more likely to last longer if not disturbed.
    This is not just theory, at least in the case I am reffuring to, the research was accepted by the RAF.
    The scientist was named Conrad Hal (C. H.) Waddington, and the reason you know about him is that I wrote a column on the subject (titled "The Waddington Effect") in EAA Sport Aviation last year. Waddington's work was virtually unknown because it was classified until after his death in 1975. At that time, his diary was published in England, but it never sold many copies and has been out of print for a long, long time. There are still a handful of copies in stores that specialize in rare old books.

    What Waddington discovered in 1941 was independently rediscovered in the late 1960s by aeronautical engineer Stanley Nowlan and statistician Howard Heap at United Airlines. Their work was the foundation of what has become "Reliability-Centered Maintenance." Nowlan and Heap almost certainly were unaware of Waddington's work, because it remained classified until 1975.
    Michael D. Busch A&P/IA CFIA/I/ME
    President, Savvy Aviator, Inc.
    President, Savvy Aircraft Maintenance Management, Inc.
    2008 National Aviation Maintenance Technician of the Year

  4. #54
    OK. The battery part I get. Does my "Repairman Certificate" allow me to sign off the functional check? I assumed it did, but .... I've been wrong before.
    Follow on discussion item. My ELT is 10yrs old (121.5/243.0) type. Any one have thoughts about replacing it w/the 406? If so which brand name?

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