Rotax 912 TBO (15 years) and On Condition

[BirdDog]

OK Lads,

 

I have had it confirmed with RAA....

 

If all maintenance is carried out, as per the ROTAX requirements (rubber replacements etc etc) and is all documented, then the use for private use only is supported by RAA running "on condition" past the 15 years.  Of course, no hire, or flight school etc, which makes some sense.  But to rip out an engine from an aircraft with only 400 hours on it, when it has not given one lick of trouble, is mad, and gladly agreed to by RAA.  ? Happy days.

 

J

 

 

[facthunter]

Well the prime cause of that is the manufacturer. They are not "immature" in the aviation scene and would have their reasons.  Perhaps they wish to sell more new motors, but perhaps even saying that is a bit unfair. IF you have rules they must operate as rules or where are you?   Is it ok to be a bit on the wrong side of the road if you are not watching or the phone rings or it's dark or you are late for work?.  You CAN get permits to fly IF you think you have a case. The permit is for that flight only and may have specific conditions attached to it.  You usually can't carry passengers and it's only a non revenue ferry flight. This is separate from a  flight with an allowable deficiency (permitted unservicibility) where there is a list in the POH and subject to PIC approval and in specified conditions, Like anti icing U/s only in  good weather.  Nev

 

 

[jackc]

On 16/10/2019 at 8:45 AM, BirdDog said:

OK Lads,

 

I have had it confirmed with RAA....

 

If all maintenance is carried out, as per the ROTAX requirements (rubber replacements etc etc) and is all documented, then the use for private use only is supported by RAA running "on condition" past the 15 years.  Of course, no hire, or flight school etc, which makes some sense.  But to rip out an engine from an aircraft with only 400 hours on it, when it has not given one lick of trouble, is mad, and gladly agreed to by RAA.  ? Happy days.

 

J

 

 

I have just had my Rotax 912 80hp approved with 345 hours but is past 15 years calendar time, it received the the Rotax rubber upgrade and and passed LAME inspection.  Test flight was Christmas Eve,  all signed off and ready to go!

 

[Thruster88]

If you think about it every aircraft engine is running "on condition" regardless of how new it is. At every annual or each 100 hours the engine must pass compression checks,  have no excessive metal in filter, have acceptable oil consumption and make static RPM or rated power. Casa allow engines in VH-XXX aircraft to run on condition even in flying school and other air work and private ops because it has be proven over a very long time to be safe to do so.

[Garfly]

In this webinar,  Mike Busch [US A&P] explains why he's not a fan of the TBO concept:

 

 

He also has heaps of other interesting videos on maintenance issues here:

https://www.youtube.com/channel/UCc-IpamUhzvGsAfMzH2lIcA/videos

[skippydiesel]

In my, very limited understanding, manufacturers TBO only does two things:

• Signals to the prospective purchaser that the manufacturers has a level of confidence in their product ( a marketing tool)
• Provides a "base line" for legislators & commercial entities in the hope of limiting their liability.

 

There are so many variables in the service life of most aircraft (piston) engine's that the accurate prediction of its safe working hours is impossible, so the manufacturer comes up with something to satisfy the above.

 

2000hr TBO would seem to be the current industry standard. As we all know, this is a near meaningless figure, as some engines will make & exceed TBO, without any form of major surgery,  while  others will have all sorts of life prolonging interventions but somehow still make TBO - go figure.

[IBob]

There's another elephant in the room (or moose in the bar) here: the assumption that field maintenance personnel are all capable of maintaining and refurbishing machinery to the same standard as the plant that assembled the original item.

In the case of aircraft, where maintenance personnel seem to be held up as shining of examples of perfection, we may like to think this is the case. But in reality I doubt it very much.

All of which is to say it can be a really good idea not to set about fixing it if it aint broke.......in my view.......

 

[Garfly]

That's pretty much the point of this Savvy Aviation (Mike Busch)video:

 

 

[IBob]

I'd like to listen to it, Garfly, but I just don't think I can do 90 minutes at that pace.......(

[jackc]

1 hour ago, IBob said:

There's another elephant in the room (or moose in the bar) here: the assumption that field maintenance personnel are all capable of maintaining and refurbishing machinery to the same standard as the plant that assembled the original item.

In the case of aircraft, where maintenance personnel seem to be held up as shining of examples of perfection, we may like to think this is the case. But in reality I doubt it very much.

All of which is to say it can be a really good idea not to set about fixing it if it aint broke.......in my view.......

 

I have had enough crap jobs on cars by qualified tradesmen to understand that there could be the same possibilities hopefully rare, on aircraft.  This is WHY I do all my own car repairs including engine rebuilds and maintenance using factory manuals.

The  only time I used tradies, was when I was too sick from Cancer to do my own work.

 

[WaterWings]

29 minutes ago, IBob said:

I'd like to listen to it, Garfly, but I just don't think I can do 90 minutes at that pace.......(

All his videos are great but best listened to at x1.25 speed. Its nice to hear from someone who knows what they are talking about, thinks before they speak and chooses his words carefully but its not the most fluid style.

[Garfly]

On the other hand, this vid seems to show some tricky cylinder work being done well by WA LAME, Lew Peake:  (and only 18 mins long! 😉

 

 

 

Edited January 4, 2021 by Garfly

[WaterWings]

Is there an Australian Mike Busch? A  good communicator who knows the difference between an annual and a condition inspection? Maintenance and modifications allowed on certified vs experimental vs slsa vs elsa etc.

It seems odd that an experimental where you can change to a different carb/exhaust/turbo/big bore or cast your own pistons would think that they might be bound to an hour or calendar limit.

Similarly how do you hope to operate “on condition” in an slsa that can’t change even tire size, prop brand or a single instrument without written factory approval?

Its a shame that there has to be such conjecture and not a straightforward explanation from Raaus or elsewhere.

[skippydiesel]

Seems like all the examples/videos about trying to keep LyCons in the air?😆 Could be this is the sort of intervention they routinely need to make TBO😝

[Thruster88]

10 hours ago, skippydiesel said:

Seems like all the examples/videos about trying to keep LyCons in the air?😆 Could be this is the sort of intervention they routinely need to make TBO😝

Have owned a lyc for 24 years and worked for a couple years at a maintenance organisation looking after LyCons almost exclusively it is not routine for an intervention to be performed. The need for intervention is nearly always found at the shop, not by pilots. The Rotax with its nikasil cylinders and liquid cooling is a fabulous engine also.

[Garfly]

 

 

 

[Garfly]

... and another 4 min. teardown.  😉

 

 

While this chap takes 7 minutes to put one back together:

 

 

Edited January 15, 2021 by Garfly

[Garfly]

 I found this detailed (40 mins) movie about servicing the 912 gearbox interesting and worth sitting through.

 

 

[Garfly]

... and, since too many 912 videos are never enough, this one shows how carb vent tubes can, in the wrong place, cause rough running.  

 

 

Edited January 18, 2021 by Garfly

[IBob]

I may have this wrong, but:

 

I'm pretty sure his problems started with his assumption those are drain tubes (and he's still thinking that and calling them drain tubes).
My understanding is they are nothing of the sort:

They should be connected to wherever the carb is drawing it's air from, their function being to ensure that the float chamber is at the same pressure as the incoming air. (So, for instance, if you have an airbox with a filter, they are connected to the airbox but after the filter.)

Put them anywhere else and you'll get exactly the sort of behaviour he's talking about, as the float chamber is then running at a pressure higher or lower than the carb air, resulting in rich or lean mixture.

 

Feel free to straighten me out if I haven't got this right.

 

[jackc]

I will have to check my drain? Tubes.  Don’t have an air box, only a pancake filter on each carby.

 

[Garfly]

He calls them 'drain tubes' when he speaks but 'vent tubes' on the title of his video.

[jackc]

Exploded view of carby.....

[skippydiesel]

Garfly - not only does he mis name the vent tubes I suspect the exhaust/muffler system he is running (doesn't look like ball & sockets system) is prone to all sorts of stress cracking.

[IBob]

FWIW, I believe it is the pressure on those vent lines that is lowered when a fuel leaning system is added to this engine...and that is done by introducing a small amount of vacuum taken from the balance pipe after the carbs (but before the engine).