Jabiru Engine 2200 Mechanical Problem Reporting

[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

 

 

[Dieselten]

Hi Vev,

 

Re your questions:-

 

The barrels were never removed on this engine, nor were any studs replaced. There is nothing in the Jabiru maintenance schedule about torque-checking the through-bolts so they were never checked except visual checks for the Torque-seal paint and oil-seepage at the cylinder-crankcase junction on every daily inspection. No signs of oil-seepage were observed at the cylinder where the bolts failed earlier that morning. (Today, just for curiosity, I took a 7/16" crows-foot wrench, my Sidchrome torque-wrench, and tried to check the other through-bolts at 26ft-lbs. The wrench slipped neatly off the first nut, causing me to leave a fairly significant DNA sample by way of a scraping of my epidermis on the fins of the No. 1 cylinder. The blood-trail led from the aircraft, across the apron to the hangar and the First-Aid kit. With a couple of large dressings now applied to my wounds, for some odd reason I have ceased to have much further interest in checking the through-bolts on a dead engine. The only good thing that emerged from this is I didn't step in fresh dog-turd on my way to the first-aid kit!)

 

Getting back to thge narrative, the heads were overhauled at 500 hours based on anecdotal evidence from other Jabiru users at the airport. They had their 2200 engine heads off at approx 250 hours and saw evidence of exhaust-valve pitting, and they strongly advised I do the heads at 500 hours. Their engines were similar vintage to mine but with fewer hours.

 

This proved to be sound advice because the glacier bushes were transferring metal to the rocker-rods, and one exhaust valve was starting to cut away slightly. The inlet valves were re-cut, glacier bushes replaced, new rocker-rods fitted, new exhaust valves fitted, top end decarbonised and heads lightly and carefully lapped back to their respective cylinders. Cost in parts was very reasonable and the a/c was off-hire for only a couple of days.

 

No EGT is fitted to this aircraft. The oil temperatures and pressures, and CHT, at time of failure were all normal, and the failure mode was instantaneous. There had been no abnormal behaviour or indications throughout the flight up to the time of failure.

 

Hope this helps.

 

 

[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

 

 

[dazza 38]

With certified engines, you pay for a "Paper Trail ".On the components fitted to the engine.As in serial numbers are tracked, any unservicabilities, repairs, new components etc to the engine are noted.

 

 

[Thirsty]

This isn't really a mechanical issue but it was a 2.2 jab failure caused by pilot neglect I thought you guys might be interested in.

 

I'm working towards getting my L2 qual at my local flying school. I turned up this Tuesday and found the owner in the hangar with the engine in bits from one of his Jabs. Turned out a GA pilot hired the jab and took off on a 36 degree day and off he went. A short while later a call on the radio to say he was in a paddock with an engine that wasn't producing any power.

 

When asked what happened he said he was climbing out and at about 1500' he noticed the CHT was in the red. He pressed on at full power as he wanted to get to 2500'. Well needless to say the power dropped off and he landed in a paddock. He didn't think there was anything wrong with pushing on with the CHT in the red by a fair margin! One of the pistons was melted through with the other three looking pretty sad as well.

 

I wonder how many school aircraft are treated this way but don't fail straight away - then fail later on for "unknown" reasons.

 

Luckily this guy is going to help pay for the damage he caused so the owner is at least a little bit happier.

 

 

[fly_tornado]

too melt like that, that engine is severely overloaded. you would think in a hire plane you wouldn't over prop the engine to stop that happening

 

 

[Thirsty]

I don't think you can prop any plane to prevent gross negligence. Any engine asked to run flat out in 36 degree temps is going to get pretty hot - even your car engine I would think. Jabs are air cooled so the OAT has a large bearing on the engines temp especially in a low airspeed max power climb.

 

 

[Thirsty]

I haven't spoken to the pilot ( I don't know him) but I guess what I would have done is lower the nose if I saw the temp getting up there and let it recover some then maybe climb at a more sedate pace. The installation is totally standard Jab and I think the prop on that engine lets the engine rev to about 3100 or so. On a warm day like that maybe there wasn't much lift around and as the field is at 200' he was probably climbing for around 3 minutes. He could well have been hanging on the prop at 60 knots for all I know and he may also have taxiied for half an hour.

 

I was saying that you can't make an aircraft foolproof simply by propping it some particular way and that the pilots of these hire aircraft need to have some mechanical sympathy.

 

I've flown this plane a few times on pretty warm days climbing to around 3000' and have not noticed any issues but then I tend to throttle back a bit and take it easy 'cause if it breaks I now have to fix it.

 

 

[Acky]

Thirsty, I was flying another aircraft just prior to the time of the engine failure your referring to. I had to split my climb up to get the altitude i needed without running into the red. I think i had a throttle back straight and level cruise to cool down at 1200', 2000', 2500', 3200' and finally levelled out at 4000'. I was in a J170, and climb at about 80kts on a warm day. It was about 30deg at 8am, and when i left at about 11:30, it was about 39deg.

 

It sounds like your pilot just expected too much of it!

 

 

[planedriver]

Sounds like the young accountant next door to me who was stuck in traffic on a hot day before Christmas, with temp in the red, and thought that if he closed the windows and put on the air-con, things would improve. He cooked the engine and soon found out that you also need deep pockets to repair a beamer.

 

Unfortunately he did'nt have a clue about mechanical things.

 

The danger with an aircraft, is that you may be the next poor sucker to fly the thing, when it's previously been flown by a clown and damage already caused.

 

 

[Thirsty]

Exactly - pretty scary when you think about it. Probably best not to think about it!

 

Funny about the car overheating - he did the exact opposite to what he should have. Assuming a normal heater setup he should have put the heater on and idled the engine faster. Of course in your car you can just pull over and all is well except your wallet of course.

 

 

[facthunter]

People are not "engine" aware these days. In the early days of motorcycling (and car operation) the spark was manually operated and on motor bikes the mixture was manually operated too. Add to this the fact that some engines had adjustable oil flow with total loss oil systems. You had to be engine "savvy" to operate these things at all.

 

With some of the "larger" radials, they can be a bit intimidating too. Just getting a P&W R-2000 to start-up without backfiring it, was a work requiring some finess. Since backfiring damaged the carburetter sometimes, you were supposed to do your best. Besides "good" pilots don"t backfire engines on start up. Some aircraft had "flight engineers" who really didn't let the pilots start "their" engines. Some efforts to start more conventional pistons that are fuel injected, (manual systems) produced "cooked" starters, flat batteries or grass fires.

 

HIGH head temps. The best thing to do is INCREASE climb speed. Reducing power at the same time, may not be ideal once the head temps are elevated. WHY?. Because the mixture is richer at full throttle. IF you pull back, the mixture is leaner and does not give the same margin of protection against detonation.

 

, so you may end up causing what you are trying to avoid. Nev

 

 

[Yenn]

If you really wanted to ruin an engine on climb, reducing power is one good way. When you reduce power you tend to go to a leaner mixture and that results in less cooling. The only way to to reduce CHT is to lower the nose and get better airflow, then you may be able to reduce power without detriment. The overheating was probably caused by too high a nose attitude.

 

 

[fly_tornado]

overheating is caused by overloading the engine.

 

 

[Acky]

Just to clarify, i had rising oil temp, not CHT as well.

 

I'd be interested to know what speed the guy was climbing at, but i doubt we will find out. I think i could have maintained my 80kt climb without getting into the red, but broke it up into chunks as a precaution. I don't want to be responsible for damaging an aircraft!

 

 

[Jabit]

I have not read all this discussion but have seen quite a bit. It should be clearly spelled out by the manufacturer if the head studs should be tightened either wet or dry. There can be a significant difference in the two. I also firmly believe the studs should be tapered thinner in the middle and thicker at the threads. We had this same issue with VW engines trying to pull too much power with too high compression. We did not work it out for a long time but it was all about the studs, temp and detonation on too low a fuel grade.

 

I also believe the desperation to reduce fuel consumption has been the cause of some of the valve problems. I love the self regulating carb but who knows what it is doing through all stages of the flight? I do not have EGT but I would like to add one and see what happens. We did increase jet sizes in our 230 after we had to give the valves some attention on 2 cylinders with low pressure at about 400 hrs. This was inexpensive and since then (650 hrs) we have had no problems.

 

 

[Dieselten]

Having shown the close-up photos of the broken through-bolt in-situ to several learned and experienced people associated with steel-making and structural engineering (in plentiful supply in my location), the verdict is a unanimous one - FATIGUE.

 

The question is why did a pair of through-bolts let go at 675 hours when they are supposed to do 1000 hours before being worked on as part of the top-end overhaul? If we had been experimenting with this engine and making adjustments to it then I could perhaps understand. But this engine was maintained by the book and "a good runner" in every respect with never a hint of trouble, no high temps or low pressures at all. In short, this engine ran perfectly until a sudden and inexplicable failure.

 

Trying to torque-check these bolts, especially on the underside of the engine, is not easy. No special tool seems to exist (such as the cylinder base-nut wrenches for Lycomings and Continentals), and it appears we are left to take it on faith they will not loosen in 1000 hours. In the absence of any signs of crankcase fretting, one has to assume they were tight until the moment of failure. Either that or there is an issue with metallurgy, design, assembly or all three.

 

So I am at the head-scratching phase of the investigation. Meanwhile I have an AOG, an engine somewhere between here and Bundaberg (and hopefully not under three feet of mud) and no seeming solution in sight except the expense of another engine.

 

I had expected better.

 

 

[biggles]

Diesel....

 

I'm sure all Jab owners are watching , with more than a passing interest , to see how this issue is resolved. Like yours until the failure , mine also operates without fault , starts instantaneously irrespective of time since last use , with normal pressures and temps . Runs extremly cool (around 250 F) at cruise with CHT's monitoring both back cylinders . It (#A 2787 ) has been in service since March 2009 and has done 190 hours . It is the hydraulic lifter model , fine finned heads with the old external rocker lubrication system . The aircraft is flown and maintained solely by myself and uses Avgas exclusively.

 

Bob

 

 

[Steve Donald]

I wonder if Jabiru will ever value their customers and get this issue eliminated? Might just take a class action to get them to sit up and take notice. None of us want to see Jab in receivership we just want these potentially great Aussie engines do the 1,000 hours TBO that they are advertised to do.

Hiya Guy's, yep it is all a bit much i think Jab are now saying at any overhaul or necessary repair time, to upgrade to the new engine specs, which acknowledges a weak point, I would have thought an offer from the company would offer the conversion for engines sold over the last 3 years many only have 200 or so hrs, or at the least at cost only, b4 a catastrophic failure of the engine occurs which as we know can lead to various outcomes, i am not sure of the cost involved with doing the full conversion completely to the new specs, but hell it would be nice to have it done for that added piece of mind especially when you have your kids in the passenger seat, it does make a bit of a mockery out of the pre flight check, when you take off knowing there are these low hr failures, i do wish something can be done b4 lives are lost.

 

 

[Dieselten]

Engine now at Jabiru's engine shop. Waiting for results of tear-down. May I respectfully suggest anyone who experiences such a failure please return the engine to Jabiru...only by examining lots of such cases will their technicians be able to isolate the cause(s) and come up with a fix. We all want these engines to make their 1000hr Top End times.

 

 

[ieadave]

Engine now at Jabiru's engine shop. Waiting for results of tear-down. May I respectfully suggest anyone who experiences such a failure please return the engine to Jabiru...only by examining lots of such cases will their technicians be able to isolate the cause(s) and come up with a fix. We all want these engines to make their 1000hr Top End times.

Any news or update yet??

 

 

[jetjr]

Reco 6 cyl are still being sent out with reused through bolts, if they meet spec they go back in.

 

 

[Yenn]

I checked the info sheet that came with my 2200 Jab engine, bought 200+

 

hours ago, factory rebuilt to zero time. It has the original through bolts. Hopefully they were better quality back in those days. The rebuild was 2005.

 

 

[Dieselten]

Engine may be coming back next week. Have had AOG for 9 weeks so far. Will be my own engine zero-timed. We'll see how long it lasts.

 

 

[pudestcon]

Aircraft on ground?? just guessing Don ... damn acronyms.David

AOG leads to LAS

 

Pud