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  1. #1
    New Member Buritonian's Avatar
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    Rotax 912 - what is high hours?

    Hi All,

    I'm in the market for a used flexwing (under £10k) and keen on something with a 912 engine. If an engine has been well maintained should I worry what hours it has - is their a number of hours at which a 912 is done for? The number of hours varies wildly on those advertised on afors and I'm no longer sure its a good measure of a good or bad deal.


  2. #2
    Airfield Ops dickymint's Avatar
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    Depending on the engine serial nr, you have Rotax TBO of 1200-1500hrs for the earlier engines (pre 2008 I think), the later engines I'm sure have a TBO of 2000hrs, I'm sure someone more knowledgeable will confirm this


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    New Member Buritonian's Avatar
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    And on reaching a TBO milestone, is the overhaul a must or are the components inspected and only replaced if worn?
    Not looking to cut corners but to make an informed purchase.


  4. #4
    Co-Pilot D-Flyer's Avatar
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    Happy to be shot down by others with greater knowledge, but my understanding is if itís in a certified aircraft (like a Sport Cruiser registered as group A), then an overhaul is mandatory, whereas on the microlight fleet, itís by inspection, so a well looked after engine can be used well past the 2000 hrs recommended by Rotax. I believe Iíve seen some engines advertised as having done well into the 3000 hr territory, and Iím sure others will know of higher numbers.


  5. #5
    Captain andy dixon's Avatar
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    Iíve pulled many 912 and 912s engines to bits for a 1,500 and 2,000 hour overhaul, and to be honest every one was a waste of my time and a waste of the customers money.
    The highest hours 912s Iíve done was 5,100 hours,(the cam shaft was replaced at 3,600 as it was noisy) a couple of sprag bearings in its life. When I stripped it I just measured everything and changed all the oil seals. Engine now on 6,100 hours.
    Engine currently doing flexwing pleasure flights out of Clarkfield airbase in the Philippines
    disclaimer....as per 2010 European libel act....these are my thoughts only and may not represent the thoughts or actions of any person /company/group/manufacturer named in this article/Internet posting


  6. #6
    New Member Buritonian's Avatar
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    Thank you very much chaps - I thought as much. A worthwhile discussion as since 912ís can last so long, in the future the likes of me starting out on a budget will likely be looking at market full of high hours 912ís (instead of 2 stroke options)


  7. #7
    Co-Pilot Wexfordair's Avatar
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    I think I remember one of the guys on here talking about running a eurostar for around 5000 hours without going near it with a spanner. Mines got 1850hrs and running like a clock. I do carb sync and regular compression checks. The gearbox I think is meant to be inspected every 600hrs but again it's never had a problem and that inspection has been pushed out as well, but it is a standard 912 and the "s" gearbox might get harsher treatment and need a more regular looking at.
    this may sound agricultural but when you get used to your own engine you tend to know if its not running right or sounds a bit different and it usually tends to be the ancillaries like exhaust, carbs, and cooling systems that give more trouble than the engine itself.
    A 1000hr school flexwing engine may often be a better buy than a ten year old 150hr engine because any bugs will have been weeded out and they like regular use
    Last edited by Wexfordair; 06-01-19 at 12:13 PM.


  8. #8
    Captain andy dixon's Avatar
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    When I stripped my own engine 912 at 1,500 hours TBO,obviously I measured absolutely everything right down to the "stretch" on the bolts. I compared all the measurements to Rotax tolerances manual, on average the engine was less than 20% worn based on the MAXIMUM sizes in the manual.
    Bear in mind the components may not have been at the maximum size when they were new. The pistons looked like they had done 500 miles in a car engine.....not a mark on them.

    As Wexford says it’s exhausts that give up first, carb bits get worn, but do keep up with the gearbox services.
    And yes at least a school engine never gets stood long enough for rust to appear on them vital internal parts of your engine.
    disclaimer....as per 2010 European libel act....these are my thoughts only and may not represent the thoughts or actions of any person /company/group/manufacturer named in this article/Internet posting


  9. #9
    Wannabe Pilot Jinx's Avatar
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    I recently sold my quantum 912 with about 2200 hours on it. Ran absolutely perfectly, started first time every time. Compression felt good when turning the prop by hand during cold preflight checking (this is perception, try a few and see if they feel different, some are tighter than others). The only thing I replaced other than regular servicing was the radiator cap in the 300+ hours I put on it last year.


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