And down goes another jab.

[Gentreau]

Just been looking at the Jabiru website and I noticed a couple of claims that strike me as possibly innaccurate.

 

At 60kg installed weight it is the lightest 4-cylinder 4-stroke aircraft engine of this output manufactured in the world.

Actually, I think the D-Motor holds that particular record at 48kg installed (http://d-motor1.vpweb.be/Price---product-specifications.html)

 

Surprisingly it is the same weight as the Rotax 582.

Not according to Rotax (29.1kg) http://www.flyrotax.com/enginesImpressum/product-rangeImpressum/carburetedImpressum/582-65hpImpressum/engine-data-performance.aspx

 

 

[Keenaviator]

How many Jabiru engines are there in service? Probably 7000 or more. My point is that this is the first time I have heard of an induction manifold coming loose on a Jab. Clearly something was missed during re assembly after the bulk strip like loctite and correct torque setting. Not good and whoever signed it out at Jabiru will be getting a rocket no doubt!

 

Gentreau, you can safety wire cap-head screws - take a look at the exhaust manifold screws on any 2 stroke Rotax.

 

Cheers, Laurie

 

 

[Gentreau]

Ok, having never seen these screws, I was imagining something rounded and un-drillable (maybe that would be called button-head screws).

 

If they are of the same style as the 582 exhaust bolts then they could be drilled and wired.

 

Have to say though, it does sound strange for them all to go walkabout at the same time.....

 

Looking forward to hearing the conclusion from MozartMerv when has all the details.

 

 

[cscotthendry]

Bloody hell, I do not remove the cowl and check my engine as part of the daily inspection.

Gold! That, and "running a spanner over me nuts"

 

 

[facthunter]

Poor assembly will kill any mechanism. The RR engine in the A-380 blew up as the result of an elbow in the internal oiling system being bored off centre. This is a quality control failure not a design fault.

 

Daily inspections won't find internal faults. Your awareness of whether the engine "feels" right vibration etc comes into play there. Check for signs of dark metal stain near cylinder base etc indicating fretting and things like that Some people say "it has been doing that for a while. it must be OK... WRONG!!!!. Untorqued bolts, missing gaskets, etc shouldn't be acceptable on a lawnmower let alone a PLANE. If thats's what it is like on the outside, what is it like on the inside? If an engine isn't running smoothly investigate it. Monitor your fuel usage rate It can indicate something changing. ( In any case you need to for flight planning purposes, be aware of your ACTUAL fuel usage) Nev

 

 

[Sapphire]

Poor assembly will kill any mechanism. The RR engine in the A-380 blew up as the result of an elbow in the internal oiling system being bored off centre. This is a quality control failure not a design fault.Answer:

 

Don't they check these parts before assembly. Though I remember as a kid working in a machine shop in Los Angeles producing a quantity of parts for a big landing gear. I was drilling holes using a jig and one of the holes came out too large due to swarf. Show it to the boss and he said "that's ok, as long as there arn't too many" A random check by the customer would allow a certain percentage of u/s parts. Sorry to the pilot if your plane got that part.

[facthunter]

People in any safety conscious industry get "blaise' about it and need a shake-up every now and then. I't can't happen to me syndrome. Nev

 

 

[Doug Evans]

The instructor said it was difficult to start. But ran normally otherwise on this flight.

that to me would be a warning that some thing not right hard to start would be a problem happening {WARNING }

 

 

[sain]

*snip* self edited due to excessive prattishness. apologies to all.

 

There was a thread a year or so back about jabs being hard to start in cold weather. It can get pretty chilly this time of year down in Nowra, so for me I would have been expecting it to be hard to start.

 

Mind you, I have exactly 0 hours behind a jab engine and that issue may well have been resolved. I really don't know squat.

 

 

[facthunter]

It pretty well has, by opening the jets out in the carburetter "choke " mechanism and keeping the throttle closed. I don't know how many jabs are operated on mogas but the mogas needs more fuel to start cold. Nev

 

 

[motzartmerv]

No this aircraft was in goondiwindi. But it gets bloody cold up there too.

 

 

[cheyenne]

At the 25 or 20 hr services the lame should be checking all exhaust bolts and screw clamps as a general inspection during maintaince, this would have picked up a loose or missing bolt.

 

Adrian

 

 

[Thruster87]

So Motz are you telling us that it was returned from a factory bulk strip with no gasket installed under the inlet manifold, or is it meant to be a metal-to-metal face seal? Only back in the air 40 hrs - small wonder you're a trifle pee-ed. Like Alice in Wonderland, this gets "curiouser and curiouser". cheers

You will find that there is no gasket as the 2 halves of the plenum are joined together using Loctite 515 cheers

[dazza 38]

Hi Andy, It was great to read that nobody was hurt. Cheers to the instructor.

 

 

[jetjr]

Cheyenne and Thruster are correct, there is no gasket and these bolts should have been checked at 25hr service (arguably the most important service in an engines life)

 

There isnt one bolt here but 5 or more?? Ill bet they didnt all fall out in 15 hrs flight time.

 

No daily check will see these, only visible from below and removing lower cowl is a significant job

 

Id also expect that engine would have been running lean well before the manifold "fell off". Full EGT monitoring would pick this problem up if someone was watching. Even a tiny pin hole leak at these O rings makes them run very hot. Possibly look for damaged valves and other heat related damage to heads.

 

It is very good no one was hurt.

 

 

[motzartmerv]

You will find that there is no gasket as the 2 halves of the plenum are joined together using Loctite 515 cheers

Well that odd as they sent the gasket today;)

 

 

[motzartmerv]

Egt monitoring requires an egt gauge. Which is not fitted in this acft.

 

 

[motzartmerv]

I'm just trying to get the boys up there to send me the MR. Issued from the factory when it came back. Something's not jelling.

 

 

[facthunter]

Air leaks ocurr in carb to manifold and manifold to head joints. Also the inlet valve guides may do the same thing. Your highest manifold vaccuum is when the throttle is closed and the volume of air flow is least. ie at IDLE. If you engine does not idle well ( evenly) and start well, have it investigated. Once you give the engine full throttle the manifold vaccuum( depression ) is less, and less air leaks in. At high flow rates the effect is less although you don't want air leaks at all. Just as a little aside if you have a complete failure of a supercharged engine caused by the induction system you can sometimes keep going by equalising the MP with atmospheric pressure, so there is no gas leak in or out. That principle may make what I am saying a bit clearer.. Nev

 

 

[jetjr]

"Well that odd as they sent the gasket today;)" - maybe youll get an empty envelope?

 

See page 127 of overhaul manual, clearly shows Loctite and O rings being used and no gasket, also shows offending bolts, there are 5 on a 4 cyl.

 

The upper induction pipes have all been fitted to the cylinder head during sub-assembly and by now it will be obvious if any have been fitted to the wrong head.

 

 The two halves of the plenum chamber are fitted together as shown, using Loctite 515 sealant between the halves.

 

 Once assembled by hand the plenum chamber can be fitted to the engine.

 

 Insert new O rings into the plenum chamber as shown. In this application the O rings must be installed dry – sealant will be added later.

 

BUT there is a new long square type induction which could be different. Unless its a near brand new engine its unlikely to be fitted, only been out for 6 months or so and expensive to upgrade.

 

I stand by my soapbox comments that with known Jabiru problems, full EGT and CHT monitoring should be mandatory.

 

 

[Aldo]

Well that odd as they sent the gasket today;)

Motz

 

Where the inlet manifold connects to the head they have or at least they are supposed to have gaskets, stripped my 3300 yesterday for a top. Where they come out of the air box there is no gasket.

 

 

[motzartmerv]

Yea ok. Just spoke to th instructor, they received the gasket today, which is for the connection to the head, and there are 2 bolts.

 

I wish I was actually there so I could have a look for myself..

 

 

[Sapphire]

When I work on an engine and remove gaskets I always rejoin with a high temp sealant. [red] Ok for exhaust. Avail Super Cheap about $20-25 for big tube that fits into a chalking gun

 

 

[eightyknots]

It and other Jab engine developments took and takes place as a result of "feedback" from pilots who have had engine failures. They call that "tombstone technology". Though that happens to various degrees elsewere. Qantas nearly lost an A380 and wing cracking is becoming an issue. You have to look at how much testing is done before the product is is unleashed to the public and how much of a guinnea pig the public have to be.

Tombstone Technology:

 

 

[facthunter]

What is "Tombstone Technology" meant to mean.? If you owned a jabiru you would give up. Honestly, they have some problems but you have got to wonder how much of it is bad workmanship and maintenance, There is a lot of good stuff on Jabaru's website. have all those instructions and bits of advice been carried out with all the engines out there? I reckon I'm pretty neutral on this one, but you will never get anywhere unless you make sure that you deal in facts. A lot of this condemnation is by people who don't operate them or own them. I am not sure that the engines Motz has been dealing with have had the right thing done with them either. Nev