Another through Bolt gone

[J170 Owner]

i_like_planes - Take a Bex and have a lie down. This forum is not the place to vent your spleen or post vitriolic comments. It is no wonder so many I know never come back here.

 

 

[Head in the clouds]

I'm staggered at the quality of spelling and grammar I see on this forum...... Several LAME's have told me.....

I'm with you on that J170, staggered and horrified, shocked in fact.

 

By the way that LAME's in your quote above, shouldn't that be LAMEs without the apostrophe if its plural rather than possessive?

 

And I'm mystified by your signature tag - what does 'old fashoined' mean? It isn't a spelling error is it?

 

 

[J170 Owner]

I've flown them in 42 degrees but you have to climb at higher airspeeds. Nev

The maximum ambient operating temperature is 38 degrees C. Page 54 in the POH. So flying in 42 degrees only supports my argument that people are NOT treating the planes and engines as they should. Facthunter - please do NOT take this personally and start rocking my roof or whatever. I am a nice guy despite what a very few may think.

 

 

[fly_tornado]

designed to confuse the grammar nazis

 

 

[biggles]

Slightly concerned that Jabiru say climb out at 80kts, my CH701 does that at top speed, I have put large air ducts on in the hope of alleviating/ forestalling the overheating problem (Assuming I ever actually finish & fly it!)

Not sure about other aircraft Derek , its probably best to talk to Jabiru about your concerns , but you are on the right track with the large air ducts. The heated air 'extraction' is important also .( "it won't come in if it can't get out ") As a minimum , I would also be monitoring cyl's 3 and 4 CHT's , even better if you monitor all four .

 

Bob

 

 

[J170 Owner]

I'm with you on that J170, staggered and horrified, shocked in fact.By the way that LAME's in your quote above, shouldn't that be LAMEs without the apostrophe if its plural rather than possessive?

 

And I'm mystified by your signature tag - what does 'old fashoined' mean? It's not a spelling error is it?

I do not exclude myself - I scare myself after reading my own stuff. But I'm sure you can tell a typo from something like using their instead of there or they're. I shall correct my signature.

 

 

[facthunter]

J 170, I am saying that modifying your technique for the conditions helps the situation. I am aware of the book limit on temp. It may have a bit to do with the fibre glass getting hot, and most "P" charts don't go above that temperature. Don't worry about your roof . I'm not like that. I am also not an extreme jab knocker. Nev

 

 

[J170 Owner]

J 170, I am saying that modifying your technique for the conditions helps the situation. I am aware of the book limit on temp. It may have a bit to do with the fibre glass getting hot, and most "P" charts don't go above that heat. Don't worry about your roof . I'm not like that. I am also not an extreme jab knocker. Nev

Whew, that's a relief...

 

 

[facthunter]

derekliston. You may end up doing a better job of cooling it than the jabiru installation. You need a pressure drop across the cowl area and I would consider baffling the cylinders like most aircooled aero engines do. Nev

 

 

[motzartmerv]

Ok , everyone take a chill pIll.

 

planes is a passionate young bloke. J170 , I'm not picking on you but mate please dont dump a sly comment and then complain when people bite. I too know people who won't come on this site due to sLu digs just like yours..

 

Cheers

 

 

[Hongie]

The maximum ambient operating temperature is 38 degrees C. Page 54 in the POH. So flying in 42 degrees only supports my argument that people are NOT treating the planes and engines as they should. Facthunter - please do NOT take this personally and start rocking my roof or whatever. I am a nice guy despite what a very few may think.

I searched around on the web for a while looking for lycoming and continental engines ambient operating temp limits to compare, but came up empty handed. All that is usually mentioned in the bulletins and manuals I found is that the oil must be suitable for the ambient temperature, and the mixture adjusted in such a way as to make the engine run cooler (ie, richer not leaner)

 

It would be interesting to see a correlation of failure vs. ambient air temp on failed engines. I do realise that the ambient temp on the ground is different than in the air, but not all that different at pattern height.

 

The only conclusion i can come to, (edit: without seeing a failure vs airtemp graph) is if you live in the northern half of Australia, or indeed most of Australia, don't operate a jab after 8am or before 6pm.

 

Any LAMEs or l2-l4s want to comment?

 

 

[jetboy]

Slightly concerned that Jabiru say climb out at 80kts, my CH701 does that at top speed, I have put large air ducts on in the hope of alleviating/ forestalling the overheating problem (Assuming I ever actually finish & fly it!)

I have the 701SP airframe and J2200 with the factory "low speed" larger air ducts. - I dont know if they are still available

 

With a large exit area it makes the required cylinder pressure differentials at 1.3 VS and runs all day with relatively cool CHTs

 

But if youre expecting to ever see 80 kts you must be contemplating a 3300 up front

 

Ralph

 

 

[Thirsty]

The temp limit is related to the airframe not the engine. FYI the earlier jabs don't have these limits!

 

 

[sain]

Time to pipe down on the "stop jab-bashing" comments guys. Motz has had 3 jab engine failures in the last 12 months (i think and I can't be stuffed going back to check). Re-read what he said but pretend they were rotax engines (or lycoming or whatever makes you happy). Is it reasonable for him to express that hes worried about sending students up in them? Is it reasonable for him to express that hes worried about kids being up in them. Is it reasonable for him to say he doesn't want to run a school with them anymore? Is it reasonable for him to say that he wishes the engine manufacturer would examine the problem more closely and do more to help identify and correct the problem? Take the fact that the engines are from Jabiru out of the equation and is anything he has said really objectionable?

 

If you still think its jab bashing - Would you buy another car from the same manufacturer if you'd had 3 of their engines bite the dust inside of 12 months during routine driving?

 

You guys are just making it so people won't want to report failures or incidents that they have. please quit it.

 

 

[derekliston]

I have the 701SP airframe and J2200 with the factory "low speed" larger air ducts. - I dont know if they are still availableWith a large exit area it makes the required cylinder pressure differentials at 1.3 VS and runs all day with relatively cool CHTs

 

But if youre expecting to ever see 80 kts you must be contemplating a 3300 up front

 

Ralph

No mate, only the four cylinder and that was just an off the cuff speed but I'm sure it will do 80 in a vertical dive!!! Thanks though, you have made me a bit less worried, I will monitor all four CHTs and EGTs.

 

 

[vk3awa]

Apologies J170 Owner.....you did post a question.

 

As we all know, Jabiru have had many variants in the evolution of their engines. With some of these variants sometimes a change in long term reliability occurs. As an example, the change from solid lifters to hydraulics utilising the existing 330 degrees cam, in hindsight, may not have been a great move. It probably caused many problems, some of which are still being suffered today....ie broken through-bolt perhaps. Over time, the hydraulic lifter production engine has been changed by the factory to address issues and try to get some long term reliability back into their engines. As some of the older engines time expire, for whatever reason, my belief is we should see an improvement in reliability with perhaps the possibility of seeing 1000 hour TBO's without major issues being the norm.

 

I'm a long time Jabiru builder/owner/pilot/L2 (I am still flying my 3300 taildragger Jabiru I started building in 2001) I am certainly a fan but have a fair insight into some of the engine's limitations/shortcomings. (depending on variant)

 

The piston circlip issue you mention is another story.

 

73's VK3AWA

 

 

[Gentreau]

........ The only conclusion i can come to, (edit: without seeing a failure vs airtemp graph) is if you live in the northern half of Australia, or indeed most of Australia, don't operate a jab after 8am or before 6pm............

So an Australian company produces an aircraft for sale in Australia which must not be operated in temperatures above 38C ??

 

.

 

 

[Sapphire]

I am not a fan of valve lifters- they have made otherwise good engines expensive and unreliable. As far as I know, their only advantage is quiet operation. My last a/c had straight through exhaust-what an overkill.

 

 

[Keenaviator]

Apologies J170 Owner.....you did post a question.As we all know, Jabiru have had many variants in the evolution of their engines. With some of these variants sometimes a change in long term reliability occurs. As an example, the change from solid lifters to hydraulics utilising the existing 330 degrees cam, in hindsight, may not have been a great move. It probably caused many problems, some of which are still being suffered today....ie broken through-bolt perhaps. Over time, the hydraulic lifter production engine has been changed by the factory to address issues and try to get some long term reliability back into their engines. As some of the older engines time expire, for whatever reason, my belief is we should see an improvement in reliability with perhaps the possibility of seeing 1000 hour TBO's without major issues being the norm.

 

I'm a long time Jabiru builder/owner/pilot/L2 (I am still flying my 3300 taildragger Jabiru I started building in 2001) I am certainly a fan but have a fair insight into some of the engine's limitations/shortcomings. (depending on variant)

 

The piston circlip issue you mention is another story.

 

73's VK3AWA

Well said Daryl. Good to see you popping up on this forum!

 

 

[Keenaviator]

I am not a fan of valve lifters- they have made otherwise good engines expensive and unreliable. As far as I know, their only advantage is quiet operation. My last a/c had straight through exhaust-what an overkill.

Huh?

 

 

[derekliston]

I was a LAME at Archerfield for nearly ten years and one of the schools there operated a Jabiru. I reckon I saw it return from xcountries almost as often on the back of a truck as in the air and in fact that school used to tell it's pilots to fly both directions through the lane on the same side of Mt Cootha because there was nowhere for a forced landing on the other side!! Having said that, the Jabiru must be the most successful Australian designed and built airframe and engine by a very big margin and as I stated earlier I am putting one in my CH701, I want the weight saving and the cost saving over the Rotax. Just have to monitor very carefully.

 

 

[Ultralights]

ok, i saw this today on a recently overhauled Jabiru engine, to put it mildly, its absolutely disgusting.. on a certified engine? this type of Jabiru workmanship goes against all engineering principles when it comes to fasteners. common engineering principles is. on any fastener, the nut MUST have a minimum of 2 threads exposed past the top of the nut/collar/whatever hold it. max is 4.

 

if any engineer in the military, or the airline industry, or any of my staff at did this, they would not be an engineer for long...

 

but jabiru? this is acceptable..

 

i normally keep my mouth shut on Jabiru engine quality, but after seeing this, i am truly shocked. and as a aircraft structural engineer worked on B747/767/707/727/737, Airbus A330, Kiowa and Squrrel airframes, i have not once seen bolts like this. not even on the most insignificant tertiary structure, let alone on the only bolts holding your crankcase and cylinder barrels together.

 

 

No LAME should ever sign this off....

 

dont get me started on the little corrosion issue with said structural fasteners.. obviously used hight temp resistant parts...

 

 

[Keenaviator]

ok, i saw this today on a recently overhauled Jabiru engine, to put it mildly, its absolutely disgusting.. on a certified engine? this type of Jabiru workmanship goes against all engineering principles when it comes to fasteners. common engineering principles is. on any fastener, the nut MUST have a minimum of 2 threads exposed past the top of the nut/collar/whatever hold it. max is 4.if any engineer in the military, or the airline industry, or any of my staff at did this, they would not be an engineer for long...

 

but jabiru? this is acceptable..

 

i normally keep my mouth shut on Jabiru engine quality, but after seeing this, i am truly shocked. and as a aircraft structural engineer worked on B747/767/707/727/737, Airbus A330, Kiowa and Squrrel airframes, i have not once seen bolts like this. not even on the most insignificant tertiary structure, let alone on the only bolts holding your crankcase and cylinder barrels together.

The 12 sided nuts you are looking at is the initial AD where the original reduced head nuts were replaced with these. Even though there is no lounger the required 1.5 threads showing through the grip length of these new nuts is greater than the original - by about 1.5 threads. The second part of the AD to be completed at top overhaul time was to replace the through bolts and studs with new longer ones that allowed the correct 1.5 threads to protrude.

Unfortunately there is more to the problem than nuts or bolts/ studs - the source of the problem relates possibly to hydraulic lifters.

 

It would be interesting to hear from someone who has converted their late model hydraulic lifter engine back to solids as to whether there have been subsequent through bolt issues....

 

 

[Hongie]

I am not a fan of valve lifters- they have made otherwise good engines expensive and unreliable. As far as I know, their only advantage is quiet operation. My last a/c had straight through exhaust-what an overkill.

What do you mean sapphire?

 

 

[Sapphire]

What do you mean sapphire?

Compered to mechanical tappets, hydraulic valve lifters are unreliable and expensive. Even when working as designed they can fail at high revs. Dirtly oil makes them fail, as well as normal wear. Mechanical tappets are adjustable for as many engine lives as you want. Hydraulic valve lifters have silent operation but over the roar of an a/c engine you wouldn't know the difference. Bad choice if you want to move the valves reliably.