Vev

So pleasing to hear a good end to this story!

The aircraft was flying from the Oaks to Pooncarie with two people on board. The family of the pilot raised the alarm on Friday afternoon when they had not heard from him.

http://www.abc.net.au/news/stories/2011/02/05/3130693.htm

Also, has anyone got any input as to the reasons for the modification - it was suggested that it may be due to a lack of rudder authority in certain situations. I'm battling to understand how an increase in the fixed fin area will address this, normally that is done to increase directional stability in one or more phases of flight or even to assist in spin recovery. I'm referring here only to the new ventral fin, I follow the flap modifications.

"fitting a larger ventral fin improves the aircraft’s directional stability – the pilot’s rudder inputs are fewer and smaller in all modes of flight".

When I spoke with them this week, they stated there was two reasons 1. Directional stability needed to be improved throughout the flight modes 2. Under server testing, during full power stalls, this modification assisted in spin recovery and provided better authority.

Cheers

Vev

I’m often amazed at the hostile reaction leveled at Jabiru when they are clearly trying to rectify an issue.

In my personal experience, they have always made every attempt to support any problem I have had… I have often received free or heavily discounted parts even though my aircraft is well out of its warrantee period…. I know many manufactures would simply send one to a call centre to chat with some dispassionate person on the other side of the planet.

I think we should be proud of what Jab have achieved as an Australian company and recognise their drive to keep on developing and improving.

It’s a small family company, not a global conglomerate, who do a fine job that deserves more support … they should be congratulated for listening and offering a solution.

Cheers

Vev

Talk about bases of fact ... when I spoke with Jab yesterday they informed me they will be paying for parts! You buy the parts on account and then you send back the old bits for a credit.

Cheers

Vev

Hi Nev,

I quite agree ... the idle system and choke do very little in terms of fuel contribution when the butterfly is open ... a mistake often made is to have the idle set too high and the choke system not work on start up as the throttle (butterfly) needs to be all but closed to create the pressure drop to work the choke and idle systems.

Again I agree ... float levels are important in terms of mixture control and they need to be checked to ensure they remain constant during routine servicing. The Bing has its subtle characteristic and understanding the different needle and seat compound combos and sizes is important to manage float levels.

Interesting observation on the FAA finding ... someone there obviously doesn't understand how a CV carby works!

Cheers

Vev

Nev,

I guess it has the potential to very marginally lean the mixture but it's small beer, it more about improving the atomisation of the fuel ... never the less it still needs to be done in conjunction with the recommended jetting as per the attached bulletin released in 2009 to increase the fuel mixture.

http://www.jabiru.net.au/Service%20Bulletins/Engine%20files/JSB018-2.pdf

This mod was shown to me when I did the engine course at Jab 6 months ago.

Cheers

Vev

Hi SP6,

No probs ... the answer is Yes and Yes

You can tell the emulsion tube as it has 4 holes at 2.5mm in the side of it ... you cant mistake it when you have it in your hand. Yes the air density sense port is the one, however be careful when you drill it as its a big hole.

Cheers

Vev

SP6,

For the 6 cyl only (doesn't work on the 4) ... drill the emulsion tube out from 2.5mm to 3mm and drill the air hole from the mouth of the carby using a 3/16. To further improve the EGT/CHT spread remove the manifold divider and replace it with a 12mm round. The carby mod came from the South Africans and has been tested but Jab in oz .. it works well.

Cheers

Vev

I am more than happy with the handling and performance of my J170... Being a manditory mod, what happens if I choose NOT to implement it?

Compliance – Implementation Schedule

 The changes detailed within this Bulletin are mandatory for all J170 aircraft. They must be carried out within the next 300 hours of flight or within 12 months of the date of issue of this Bulletin – whichever is the sooner.

Hi Donkey,

I wouldn't second guess a manufactures written safety directive unless I had something in writing saying you can .... I'm sure your insurance wouldn't hesitate to write you off .... I would also hate to think what sort of a defence you would put up in front of a court should a passenger get hurt or worse!

If you are in doubt about the benefits, give Jab a call.

Cheers

Vev

I should have also mention there is a new mod to reduce flap defection too .....

Cheers

Vev

This was posted on the Jab site regarding upgrades to rudder peddles and fitting a new ventral fin.

http://www.jabiru.net.au/Service%20Bulletins/Airframe%20Files/JSB029-1J170.pdf

Cheers

Vev

G'day Ross,

Yes I did fit the K liners and it all seems to work as advertised ... I have done 42 hrs on them so far and all is very good, in fact my oil consumption is almost nil now. However I did also replace the rings and gave the bores a light hone too.

I also changed the out the push rods and rockers for the new hollow type, which also allowed me to blank off the oil feed gallery and turned to old rocker chest oil feed "T" piece into a breather .. I think this also helps keep things cooler in the rocker chest owing to better drain back of oil to the sump.

Cheers

Vev

Jaba-who,

I think the best I can suggest is the parts manuals ... I think the 2200 parts book is possibly the best diagram, albeit not that clear.

Cheers

Vev

Hi DC10,

Sorry to hear about your latest engine experience but glad your dog was not with you to extend your misery.

Thanks for the feedback on the engine condition...

The service info, re checking the torque, came from Aug Jabachat and may take a while to find its way into a service bulletin.

I thought it was interesting the info made mention of the economy tuning kit being fitted for part of its life may cause a bolt failure .... it's basically an admission that the previous factory jetting may cause a future failure even if the recommended jets are fitted. I presume Jab are recognising that through bolt fatigue from detonation caused by lean jetting is a problem .. it makes me wonder if there should have been a recall on all engines to address this issue rather than provide a procedure to check bolt tension as a precursor to a failure? Although having said that I wonder how many failure there has been, albeit cold comfort if it's your engine.

Cheers

Vev

It really is unacceptable that the through bolts should fail ... I have heard (unconfirmed by Jab) they are working on an improved system, which I'm sure will be well received by many.

Attached is a maintenance quote from Jab to manage through bolts.

"Occasionally a high-hour engine will suffer a failure of a crankcase through-bolt or crack a cylinder base. The cause of these issues can be detonation (such as if the engine operated with early versions of the economy tuning kit for part of its life) or uneven positioning of cylinder base nut to thread/shank. In some cases crankcase fretting will occur as a secondary effect of these same factors.

While fretting is rare there is a simple check which allows the problem to be detected early: By checking the tension of the nuts on the bottom crankcase through bolts (the ones easier to access) at a setting of 28lb.ft. These bolts are tensioned at 30lb.ft during engine assem- bly, so if there is any movement in these nuts at 28lb.ft some form of bolt or case damage is likely. Jabiru should be consulted if this is found. Note that

increasing the bolt torque beyond 30lb.ft will damage the through bolt, so torque wrenches must be accurately cali- brated before carrying out this test. We recommend that this test be carried out as a precaution during the last 200 hours before the engine is due for a top- end overhaul. In addition, if the engine is extremely hard to turn after a through-bolt has been replaced, this is a likely in- dicator of crankcase fretting and Jabiru should be consulted".

In addition to this procedure when checking or torquing new bolts, one should check both ends of the bolt as just doing one end isn't sufficient.

Cheers

Vev

Hi Dieselten,

Glad no one was hurt.

The engine hardly sounds like it was under any stress when it failed ... as you suggest, not a time you would expect to see detonation.

Couple of questions on the failure if you don't mind?

Were the barrels every off this engine or the studs removed? Was the torque ever checked on the through bolts and was there any movement? What was wrong with the heads when they were reco'd? Does this engine have a EGT, if so, does it ever run >1250 deg F?

Cheers

Vev

Hi Bob,

I got exactly the same response from Rod Birrell yesterday ... he said CASA had informed the RAA that 600kg would be through by Christmas, just didn't say which one!

Cheers

Vev

Hi Ian,

Yes this is excellent stuff in terms of RF and good to see you have made this commitment.

However, I think we need a fundamental philosophical change in the way weather is reported and taught to meet CAR 120 requirements. The code system is outdated, cumbersome and exposes infrequent users to risk thought misinterpretation of the data.

As I have said before, this is one of those left over processes that belongs to the flat earth society and not 21st century airmanship.... we have better communication systems available why not use it officially!

Cheers

Vev

Does anyone know if this has been discussed at Board level as yet? Without doubt it is the one part of NavEx training that most students struggle with; and so unnecessary given that as soon as they have passed the tests many are going to be using any available PLM website or PLM software, as they dont intend to get licenced for higher levels of aviation.

Birrell said whilst it is in the Ops Managers basket of things to do, he suggested if this is something the members want a few letters of support would be useful to get things moving along a little faster.

So guys, if you want to take a few minutes to send Rod Birrell an email ( [email protected] ) and let him know in the interest of safety you support the adoption of a plain language weather report, I'm sure this will lift the profile and speed of implementation.

Cheers

Vev

Cheers Doug .... very nice.

Vev

Hi Pud,

Yes you can strip ethanol out out of fuels ... however you will deplete the octane of the fuel which will cause significant performance problems (detonation etc), not to mention you will end up with a waste disposal issue and an economic loss of 10% of your purchase price. Apart from all of that, it's also dangerous to mess around with such volatile products, which is never a good idea.

I think one is better off avoiding using ethanol blend fuels whenever possible ... if you have a choice, use unblended fresh fuels every time.

Cheers

Vev

G'day Jack T,

Strewth cobber, to learn the lingo will be a mongrel for a septic ... you will sound like a galah for a while but you'll be apples in the end. To give you the drum, head past the black stump and do some jackaroo yakka .. no raw prawns out there mate and you'll pick up dinkum stuff.

Hooroo

Vev

In my view, ethanol fuels is really all about meeting political agendas ... I think there are very few positive characteristics about ethanol and wont use it in any of my toys.

I say ... Alcohol is best mixed with drinks and not mixed with flying.

Cheers

Vev

Hi Jack,

You are spot on in terms of fuel consumption increase using E10, although it should be more like a 5% change ... the energy value of ethanol is close to half of mogas and therefore you need to burn almost twice as much to get the same energy value.

The actual octane rating on the pumps in Australia is measured differently to the US. Aust report the RON number and the US uses what is called the AKI (Anti-knock index) which is the average of the RON & MON (R+M)/2.... in reality AKI 93 in Florida is the same as RON 98 in Australia. You will find that 98 is available from just about all the major oil companies.

Cheers

Vev