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  • Re: Roger Lee 912uls

    by » 3 months ago


    Roger

    On this discussion I will agree that we disagree.  The FAA is dead wrong on this one and I have a lot of evidence to counter the anecdotal claims of users.  The 100 hour was never intended by Rotax to be an on condition check.  That is the FAA interpretation.  Trust me i know that there are many failures of components that are run beyond the TBO limits.  (crankshafts for one) 

    One can not measure piston and ring wear, cylinder wear, valve wear and the list goes on of items not covered in a 100 annual.  I will not comment more on this subject as I have high blood pressure and have to be careful these days.  

    Cheers


  • Re: Roger Lee 912uls

    by » 3 months ago


    High blood pressure we both have. LOL Plus I just had a left hip replacement two weeks ago. Getting old is a PITA. I'm still in physical therapy for another month.

    We agree on some items. The only reason I sided with the FAA was they are the ones I (and others) have to answer to if something happens or I have to go to court. You don't have to answer to an aircraft Mfg or Rotax. It's the FAA with the power to hold your feet to the fire. Plus since the insurance companies said they'd follow what the FAA said then that helps too.

    Nothing in our debate stops anyone from doing the TBO overhaul or a new engine. It's just a choice.

    I would still like to know if you think all Rotax engines should be grounded prior to 2008 which would put anything early out of TBO????

    I have some Losartan for you if need be. LOL (It's what I take)

    p.s.

    No need for high BP meds these are just fun conversations.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Roger Lee 912uls

    by » 3 months ago


    Roger if we are talking about the 15 year TBO (calendar time) call out that is a different issue.  The time is due to seal degridations, age, and corrosion issues with bearings and other iron parts.  Ignition parts, like the high tension cables and spark plug ends as well as the well known hoses that should be replaced.  In addition full carb overhaul for the very same reasons.  This is important especially on low hour engines with high calendar time.  The only way many parts can be checked is with a full teardown inspection.  Additionally with the older crankcases you need to address any made before mid 2006 when the case design was upgraded.  i normally recommend a full short block for those engines so you can get a 2000 hour TBO as the old case is only 1500 tops.  

    The issue with high hour engines is different.  In those cases we have to  look at cycles and given the nature of small aircraft, with limited log book entries and the like, the type of use such as training or cross country, one can predict the outcome and should plan to replace rather than fly it to failure.  There is no doubt that flight school engines have a much higher stress level than normal pleasure flights.  Flying all day at altitude and cross country is pretty tame compared to touch and go flights all day long.  

    As an example there used to be a large group of glider (hang glider) tow planes used in some areas.  These consistently would crack the crankcases on the old design blocks at 600 to 900 hours.  Full throttle from sea level to 2500, drop the glider and dive back to the field for another pickup up to 50 times a day.  Early CT aircraft as you may recall had the same issue when imported into the USA.  High pitch to go fast that overloads the engine and same effect, it would crack the cases.  These were the motivators to the crankcase change in 2006.  Most everyone had no issue but you will note on the older blocks the inspection for crack is still part of an annual.  The other part of that story is most of the ones that failed had crankcase fretting internally for the very same reason.  Don't read more into it that that however as an 80 hp with fixed pitch set correctly most likely will never have any of those issues.  

    So to answer the question, if it is over the time in calendar months you cant predict it is OK with just an annual in my view. 

    Cheers


  • Re: Roger Lee 912uls

    by » one month ago


    Howdy RW,

    I agree that years time is different than flight time and yes some types of flying are harder on planes than others. i.e. training aircraft with student pilots taking off and landing and running the engines rpm up and down all day. I agree too that too many owners / mechanics don't have a handle on prop rpm settings and the stress that over pitch can do especially like you said the older engines with the other crankcase. I had 3 planes in past years with fretting issues, but they all failed early on. I haven't had any fretting customers with the newer case. No matter what we agree on and I do believe in good maint. that someone has to explain all those engines that are older than 2008 and before and all the 3K - 4K hour engines that are doing just fine. Sometimes regardless of what we are told or the few failures along the way massive owner use and longevity may show we need to adjust our views.

    Cheers are good, but I'll give you a hug next time I see you. 😇

    Hope all is going well.


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


  • Re: Roger Lee 912uls

    by » one month ago


    Just some food for thought. 

    Before your 2008 timeline we need to look at what type of aircraft were being used.  Lightweight Rans and Kitfox running fixed pitch are not at all the same as what we commonly see used in the past 10 to 15 years.  Aircraft fly mostly faster, higher and with a huge variety of props.  In addition let us not discount changes in the dailly fuel supply, automotive, it has dramatically be changed due to demand and blending of far more "fuel aromatics" in the fuels.  Rotax did a lot of evaluation to allow 10% Ethanol and for the most part that has not been an issue in any long term use.  I would also argue that for  the bulk of aircraft were not used as trainers, this really did not become a big deal until Sport aircraft, LSA, rules started.  At that point we still used a lot of 2 strokes also. The 912 100 HP engines did not start serial production until 1999, the widespread use really began about 2001 to 2003.  At that time we saw the shift from all users to go for the higher power and high production numbers would be seen up to about 2007.  Dramatic changes in aircraft design were in the early years of Sport LSA aircraft driven by the promise of nice aircraft that were factory built and to standards.  

    i believe that the anecdotal evidence supports the fact that aircraft, how we learned to fly them, significantly changed from those days.  The high use hours of an old tube and fabric aircraft is not the same for the most part as the new glass and metal planes,  I doubt very much is the older aircraft flew as many hours as most of today's.  Yes I grant you that there are exceptions however an old Kitfox 3 with a 912 or even 912ULS most likely never flew as much as you did with your Flight Design CT.  

    Obviously this is my opinion and I am old and feel entitled to have it. 

    Cheers


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