Jenki

Contributing Member
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About Jenki

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  • Gender Male
  • Location Slovakia (Europe)
  • Interests flying, off-road

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Jenki's Activity

  1. Jenki added a post in a topic Grass strip help....bumpy.   

    Our operations have to be performed to keep grass cover to grow and not to destroy lawn. This is the reason we are using mulch-laying machine.
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  2. Jenki added a post in a topic Memorial flight 100th anniversary of independence   

    One more video from the same occasion - more professional and longer as well.
    The most interesting is the mixture of professions among pilots flying - from real astronaut to farmer, all flying light aircraft. Old C-172 (160HP) was a camera-ship.
    And we are planning to repeat flight this year again / just at beginning of May 2019
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  3. Jenki added a post in a topic Grass strip help....bumpy.   

    What about mulch-laying machine? We are using such machine very often to keep grass part in proper conditions ...
    We even don't use mower very often, just this kind of machine. And quality of grass part is getting better in time.

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  4. Jenki added a post in a topic Snowplay   

    Really beautiful
    Country, flights and video as well. Simply excellent
    All your videos are interesting and let say "good work and processing" but this one is really top, sort of professional piece.
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  5. Jenki added a topic in Avid fox flyers pics and vids   

    Memorial flight 100th anniversary of independence
    Formation flight to visit friends in Italy on the occasion of 100 anniversary of state Czecho-Slovakia and gen. M.R. Stefanik - founder of state.
    M.R. Stefanik was Slovak pilot, French general, notable politician and founder of Czecho-Slovak Legion in Italy during first World war.
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    • 84 views
  6. Jenki added a topic in Avid fox flyers pics and vids   

    Windy day Slovakia mountains
    February this year was a little more friendly regarding weather so why not to enjoy sunny and windy day ...
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    • 56 views
  7. Jenki added a post in a topic Wind   

    Well, if I am speaking about wind speed troubles or limits, it is always matter of T/O or landing, close to ground.
    In the case  of cross-country i.e. across Europe from Slovakia to Italy or Croatia, we are often flying in levels of favorable tailwind 40-50 knots, we are even planning such trips considering wind speed. My Stylus was able to fly 100-110 knots ground speed with 80 knots indicated (Rotax 80 HP). But such conditions are very rare in the winter, even day is very short and conditions are very unstable here usually. Turbulence and wind gusting can be very big troublemaker here as well. But country is beautiful from Stylus... as you can see


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  8. Jenki added a post in a topic Wind   

    For me, 20-23 mph steady wind, no gusting is probably the maximum doable, if I really need to fly - if I am speaking about Stylus - Avid like plane, empty weight is about 750 lbs, MTOW 1250 lbs.
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  9. Jenki added a post in a topic Rotax 912 Oil Change Interval?   

    To be precise, there are no exact numbers in SI-912-016 regarding hours or deadlines. So far 25 hours interval I have never heard  - but could be possible in some cases. To be sure that I am keeping exact information, please find following text from SI-912-016 below:
    3) Lubricant
    3.1) General
    Foreign particles formed during combustion are suspended in the motor oil. Together with oil components that are not sufficiently resistant to heat, these foreign particles can cause parts such as pistons, piston rings, exhaust valves, etc., to seize and lead to problems.
    On turbocharged engines, failing to ensure an adequate cool-down period prior to shut-off may lead to particle deposits and cause damage to bearings and seals. Hard oil residues can obstruct parts of the oil system and lead to damage.
    - In addition to insufficient cool-down periods, the use of unsuitable oils and not obeying oil change intervals can especially cause such damage.
    - Long-term operation with an engine that is too cold and/or operating too long with an overly rich fuel mixture can cause water and fuel contamination in the oil, reducing its lubrication capacity.
    - Furthermore, long down times with oil that contains water and contaminants can cause corrosion damage, especially on the bearings, with serious consequential damage.
    The criteria for correct motor oil selection are:
    - Correct oil viscosity for cold starts and sufficient oil pressure at high temperatures.
    - Good gear wear protection.
    - Avoidance of clutch slipping due to use of additives.
    - Insufficient oil flow capability causes too much volume to remain in the engine, leading to low oil level in the external oil tank. This can only be detected during testing with an oil level indicator installed on the oil tank.
    - Ability to withstand combustion products containing lead, which enter the oil during AVGAS operation.
    - High oil temperature durability. This is especially important for the turbo engine due to the risk of oil carbon buildup on the bearing and sealing seats of the turbocharger. The oil carbon buildup (coking) can also flake off and block/restrict the oil return passage
    Conclusions
    - If possible, operate the listed engine types using unleaded or low-lead fuel. (AVGAS 100 LL is not considered low leaded in this context.)
    - Use the recommended motor oils tested and released by BRP-Rotax according to section 3.2 of this SI.
    - Use only oil which is classified by ROTAX® standard (RON)!
    - Due to high stresses in the reduction gears, oils with gear additives such as AeroShell Oil Sport Plus 4 are highly recommended.
    - Because of the incorporated friction clutch, oils with friction modifier additives are unsuitable because this could result in clutch slipping during standard operation.
    - Avoid oils strictly specified for use in Diesel engines. These may not be suitable due to insufficient high temperature properties and additives that may affect the operation of the slipper clutch in the gear box.
    - On turbocharged engines, always conduct a cool-down run before shutting down in accordance with the relevant Operators Manual.
    - Pay special attention to engine operation tips (see section 6).
    3.2) Operation with unleaded and low-lead fuel (less than 0.1 g/liter lead content)
    Motor oils tested and released from BRP-Rotax (for use with unleaded fuel or MOGAS), which we recommend for use with our ROTAX® engine types 912 i, 915 i, 912 and 914 Series:
    Brand               Description                                                    Specification      Viscosity
    SHELL®               AeroShell Oil Sport Plus 4 1) 2) 3)            RON 424*         SAE 10 W-40
    1) according to RON 424
    2) with new formulation
    3) in red bottle
    * Specification RON 424: The ROTAX® Norm 424 (RON 424) is a BRP-Rotax internal standard, which is only available on special request via the ROTAX® Authorized Distributor and will not be disclosed to third parties without prior consent.
    NOTE: The previous formulation of AeroShell Oil Sport Plus 4 can still be used until its expiration date.
    NOTE: The coefficient of viscosity indicates the tendency of oil to flow but it is not necessarily a quality code. Country specific deviations of the viscosity are possible.
    3.3) Operation with leaded AVGAS fuels
    Perform maintenance checks according to the latest Maintenance Manual.
    More frequent oil changes will assure timely removal of residues and oil sludge thus avoiding increased wear or operating troubles.
    Motor oils tested and released by BRP-Rotax (for use with leaded AVGAS), which we recommend for use with our ROTAX® engine types 912 i, 915 i, 912 and 914 Series:
    Brand              Description                                                       Specification   Viscosity
    SHELL®               AeroShell Oil Sport Plus 4 1) 2) 3)             RON 424*        SAE 10 W-40
    1) according to RON 424
    2) with new formulation
    3) in red bottle
    * Specification RON 424: The ROTAX® Norm 424 (RON 424) is a BRP-Rotax internal standard, which is only available on special request via the ROTAX® Authorized Distributor and will not be disclosed to third parties without prior consent.
    NOTE: The previous formulation of AeroShell Oil Sport Plus 4 can still be used until its expiration date.
    NOTE: The coefficient of viscosity indicates the tendency of oil to flow but it is not necessarily a quality code. Country specific deviations of the viscosity are possible.
    .
    6) General engine operation requirements and operating tips
    1. Keep the motor oil temperature below 120 °C (250 °F) over most of the operating period.
    2. Always insure that the oil type used is adequate for climatic conditions and peak engine operating temperatures. If operational oil temperatures exceed 120 °C (250 °F), use of a mineral or petroleum based oil is not recommended.
    3. For turbocharged engines ensure an adequate running cool-down period to prevent deposits by coking of oil.
    4. When operating with unleaded fuels or MOGAS and when engine oil temperatures often exceed 120 °C (250 °F) use of a high quality full synthetic oil is recommended.
    5. To avoid formation of condensation water in the motor oil, the oil temperature must rise at least once every operational day to at least 100 °C (212 °F).
    6. Avoid extended use of carburetor air pre-heating when safe and reasonable.
    7. Depending on the type of fuel used, operating conditions, and the demands of the engine mission profile it may be necessary to increase the frequency of oil changes to avoid the excessive build up of lead and other residues in the engine oil. Always adjust the engine oil change intervals to avoid excessive build up of sludge in the engine oil.
    Excessive engine vibration, particularly at low idle speeds, can impair the carburetor fuel metering system leading to a too rich mixture condition. This rich mixture condition can further lead to rough engine operation and excessive carbon and lead deposits.
    NOTICE
    Do not use oil additives and observe the operating limits as per the relevant Operators Manual.
    I hope this will help to avoid any misunderstandings.
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  10. Jenki added a post in a topic Rotax 912 Oil Change Interval?   

    Just for information, Maintenance Manual Rotax 912, just for sure I asked certified service for clarification:
    Unleaded fuel (MOGAS) 100 hours
    Leaded fuel (more then 30% of operations) 50 hours
    Maybe it is not really clear from manual, but they told me as I wrote above

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  11. Jenki added a post in a topic Rotax 912 Oil Change Interval?   

    100 hours interval if runing MOGAS fuel (unleaded) - oil and filter change.
    200 hours interval  - oil, filter and spark plugs change
    5 years interval - rubber parts and hoses change, fuel pump change
     
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  12. Jenki added a post in a topic Silvester Fly in Slovakia   

    You know, Guinness Book of World Records
    But this group is flying for years aerobatic formation on gliders L-13 Blanik, all-metal doubles eaters , for now they are four-ship, full aerobatic program. No professionals, just very experienced pilots, some of them are members of formation flying together more then 30-35 years.
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  13. Jenki added a post in a topic Silvester Fly in Slovakia   

    Z-37 is real STOL, even at MTOW requires less than 200 meters/600 feet for T/O and landing. Prop clearance is about 20" and visibility from cockpit excellent due to unusual very long main gear.. No runway necessary. We have plenty of them here, many for sale as crop dusting is no more required ...and nearly 800 aircraft built till the end of 1987.
    And yes, very similar concept and design, not very common for aerial topdressing aircraft.
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  14. Jenki added a post in a topic Silvester Fly in Slovakia   

    Here you are
    In this case  aerotow is turboprop version Z-137 T
    We have standard piston version rebuild for passengers but doing aerotow as well, just no more then 2-3 gliders ...
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  15. Jenki added a post in a topic Silvester Fly in Slovakia   

    Oh no,
    this one is LET Z-37 Čmelák (English: "Bumblebee") - an agricultural aircraft which was manufactured in Czechoslovakia 1965 -1987. It is powered by Avia M462RF air-cooled 9-cylinder radial engine (supercharged), 235 kW (315 hp) - CS engine based on Soviet Ivchenko radial engine. About 740 built with piston engine built.
    Another 51 turboprop aircraft built (version Z-37 and Z-137T TurboCmelak) with Czechoslovak turboprop Walter M-601Z. We have still many of them flying here, turbo version very often for towing gliders as well. We have some record here, 9 gliders Blanik aero-towed by TurboCmelak Z137T.

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