Engine failures

[Yenn]

There is much talk of engine failures on the forum but how bad is the problem and what are the causes. Could we have some information, such as what , where, when and if possible why.

 

Have you had an engine failure and if so please tell us about it. I find it unnerving to be using an engine which many people are saying has a bad failure rate and no real information to make my own assessment.

 

 

[rick-p]

I'm the same as you Ian.

 

I find it quite amazing when it comes to the engine failure topic because you don't seem to be able to get any real answers or direction, paricularly on the mechanical failure statistics ie cause and following result.

 

I have been in a situation of one engine failure, rotax 582, fortunately the PIC was a very experienced chappy.

 

He only has one arm and a hook for the other so Ian you now know who I am speaking of.

 

It was carby ice.

 

He didn't bat an eyelid and landed it in a paddock not very long or wide and in the middle a gully which he jumped the aircraft over.

 

No damage to anything even my thoughts about flying remained in tact and I continued on learning as I was doing at the time of the incident.

 

I know now that an engine failure is only a fatality waiting to happen if you let the risk increase and the situation to degrade to the point of no return.

 

In other words fly safe in the first place try to avoid, of course unless unavoidable due to the circumstances of the flight, the aircraft being at any time in a place, position or attitude that would not allow for a safe engine out landing, well as safe as one can make it anyway.

 

How many times has your car engine failed you whilst it's under load?

 

I think for me it's been once in more than 2 million kay's of driving.

 

Engines have broken on start up and shutting down but only once under load.

 

I had an ald HQ Holden used as a taxi in which we ran up over 500,000 kay's and it was still going strong when sold.

 

You will probably find that a lot of the engine failures that occur are due to finger mentality ie fiddler's not really knowing what they are doing but they still do it.

 

The hydraulic lifters now on Jab motors were probably only installed to take it out of the hands of the fiddler's.

 

What we all need to know are the real reasons for the engine failures on any motor's used in our aircaft and that info factually diseminated to the end users not spread by way of hype or gossip only.

 

When I was in the Philippines recently an Australian guy came to the flying club and on seeing that some Xairs at the club were fitted with Jab's he immediately started to tell all that Jabiru were no good.

 

He said that the company was broke and they were closing it down because of so many engine failures.

 

Well even the locals thought that that which was said was a crock as of the 3 or 4 jab engines they do have operating at the club none have ever failed.

 

Of course there is a very strict maintenance program adhered to but that should be par for the course shouldn't it?

 

Anyway those in the know who read Ian's and my post please give us some direction as to where all this information can be found on all type engine failures as in my case I have both Rotax and Jab motors.

 

You think about it if all you ever here or see is not substantiated by fact and evidence and you believe it then you are really only a mushroom.

 

I heard that Jab motors had dangerous harmonics at about 2200 rev's but I have never been able to substantiate it as fact or fiction.

 

Why I was interested is that matter was that my aircraft's economic cruise is around that rev reading and has probably done of it's 250hr life 200hrs at those rev's.

 

Anyway if we are going to use this forum for reporting on engines lets substantiate all that is posted that has specific relevance to engine maintenance and failures by giving the reader reference points so that the reader of the post can make their own mind up in the matter, being able to make an informed decision.

 

Regards,

 

Rick-p

 

 

[facthunter]

Engine Failure Data.

 

I can sympathise with you Ian, And there will be a sense of frustration in all this. I don't think you will find out what you seek as there is a lot of denial about, as to the extent of the problem and what the causes are. A lot of it is not reported. If a manufacturer had an open forum that got to the nitty-gritty, he would lose a lot of sales, even though,from a moral perception, he should not.

 

Rick-P. the holden engine you mention, is fine in a taxi,not so good in long high-speed trips in the hot inland, and pretty ordinary in cement mixers (which are now hydraulically driven). Some very rugged car engines that perform well in rallies, seem to throw bits out of the side, when used in aircraft. Very few engine applications have the engine operating at about 75 % power constantly, as is the case in aircraft.

 

In GA the only remaining piston engine manufacturer left is LYCOMING, with a major market share. I know that CONTINENTAL are there too but I don't know where all the parts are made & whether the whole engine is made in-house. LYCOMING. went through a terrible period for a while & I feel have come out of the worst. I'm getting into this area to try and point out that even with CERTIFIED engines. with all the extra quality control (and cost) having only one engine (and it being a piston engine) you can never be sure that it won't stop. The materials used are of a far higher quality than we can expect for the money we pay.

 

If there are persistent faults in the motors we use ( and I personally think there are) They should be capable of being ironed out , Hopefully by the manufacturer, Or as often happens, By an after-market process Form a users group ,(like TOSG) That might be the way, but beware the deniers. N...

 

 

[rick-p]

Facthunter nothing is ever certain in this life but we can if we work on it balance the probabilities in our favour.

 

It's fact and cold hard evidence that we are after not unsubstantiated rumours.

 

Thats the frustration a lot of us face.

 

We all know basically what engines can and can't do and what they have to do in the different applications for which they were designed for that is the various types of motors we have, from cars to boats to planes.

 

But what we are really after is to crunch the numbers and assess the probability factors of a failure and reduce that probability by using the knowledge of the cause these failures to rectify each individual cause of a failure.

 

This is so whether it's an engineering problem or a finger mentality problem.

 

We want honesty from both the manufacturer and end user otherwise the problem will continue.

 

Your idea about forming a group like TOSG is great but unfortunately we are dealing with people and the effort required to get something like that going is beyond a mere mortals patience and strength.

 

You can always fly low and slow and then you haven't got far to go when the fan up front stops turning.

 

Regards,

 

Rick

 

 

[Guest Andys@coffs]

Hi Guys

 

had 3 seizures in a 582 in quick succession when relatively new to the sport. The 2nd seize occurred during run in after rebuild of #1, the 3rd after run in on first climb out after rebuild #2. Ultimately all 3 were related to the fact that the engine was lean. It wasn't until I put in a 582 EMS with new probes all round that it became clear that the engine was lean, and EGT was too high. moving the jet needle 1 position higher (so that the point of the needle was closer to the top of the carby) on the circlip lowered the EGT by 70 degrees Celsius and put it back into the normal range. The EMS also, by virtue of the very hi brightness warning LED that I added to the alarm circuit, showed that during normal operations in the max heat of Summer in Adelaide it is very easy to exceed max EGT on normal climb out.

 

A very expensive lesson that ultimately the "professional" repairer should have been up on. Once again a lesson to me on the relatively small (when compared to a 4 stroke) operating margins that a 2 stroke needs. That said I still have the 582 and trust it more now that I understand the what and why of what occurred.

 

That said, anyone who is well aware of how to operate a 582 will find it a robust and reliable engine

 

For me, the 3 consecutive seizes took an engine early in its useful life and rapidly moved towards the latter with oversized pistons rings and rebores etc. A very expensive lesson, more so than the cost of a new engine.

 

Andy.

 

P.S when the first seize occurred I was halfway down my crosswind leg. Even though I knew about turn backs on EFATO before I even started to really think about what need to be done I had already instinctively turned 90degrees back towards the runway. I ended up landing downwind (which was about 20kts) across the cross strip, and then into the wheat field. No damage, but a touchdown in a trike at about 120km/hr relative to the ground) the only thing going faster was my pucker valve. The point here is that I too was one of the crowd that said Id never turn back on EFATO yet I did, and did it unconsciously. I was lucky that I only had a 90degree turn to do, and that the wind was strong enough to have not allowed me to get far from the field and sure pushed me back there in a hurry. So I'm more cautious to judge others who do turn back, and I always now brief to myself what I 'll do on EFATo as I now know you don't have time to think it through when it happens. I was in a 55kt cruise machine, in a 120kt plus machine I doubt I would have survived.

 

I also didn't report it. Don't ask me why, I don't know. (this was about 5yrs ago)

 

 

[Yenn]

I won't ask why but I can hazard a guess. I have reported a couple of engine failures to AUF as it then was, in the hope that others could steer clear of the same problems

 

If we don't report we cannot expect RAAus to know of the faults and therefore they cannot see any trends developing. It was only by a strict regime of reporting that the old aircraft piston engines had such an enviable record of safe operation.

 

Now we are getting some reporting here and if it continues we may be able to make an assessment in the future, so keep up the good work with news of real incidents, not gossip.

 

 

[facthunter]

Engine reliability.

 

Andy. The main jet affects the mixture on the slide carburettors at the full open position & nearly full open, the needle works the middle, and the slide cutout, ( opening at the front )affects idle to about 1/4 open. The bigger the cutout, the leaner the mixture If an idle mixture screw (threaded,tapered needle, downstream of the slide),is available ,(fitted), obviously it affects the idle as well. With the seperate mixing chamber chokes, they only function when the throttle is closed.

 

Nothing will kill a two stroke quicker than a lean mixture on wide-open throttle as you can testify, usually with a hole melted through the crown of the piston, or the edge near the exhaust port. These engines get a bad name when they don't always deserve it. If they are in good condition and tuned properly their reliablity can approach that of a good four stroke. They must be set up rich from about 3/4 throttle to control temps,& the EGT reading is a must have in the specified range.

 

Rick-P could we start the ball rolling wih a Private Message to a willing co-ordinator to see what information would be forthcoming? Nev

 

 

[Dieselten]

Vote of confidence for the "Blue-Top" 582, a terrific engine provided you keep the maintenance up to it and beware any elevated EGT.

 

Main cause of elevated EGT is lean mixtures (self-evident) but what causes sudden lean mixture? Number one candidate is a partial-blockage of a main-jet. Cure is to land, pop off the float-bowl(s), pull the engine through several times by the hand-starter to flush the main jets clear, then re-attach float-bowl(s), start, ground-run and if all is well, test-fly. 90% of times the problem is solved.

 

Main problem with the Blue-Tops seems to be alternators failing and jamming the engine. Steel caps on the ignition coils can come adrift and jam between stator and rotor and cause what appears to be a siezed engine. As the engine has to be torn down to replace the alternator, it is a good time to "zero-time" the engine with a full rebuild anyway.

 

Have over 1000 hours on Blue-Tops, haven't had a failure yet. But I am always expecting one, on each takeoff, climb, cruise, descent and landing and plan accordingly.

 

 

[bushpilot]

Dieselten - I found your observation re the 582 leaning problem really helpful. Do you know if the same issue (& remedy) applies to 2-strokes - like the 503?

 

Is the procedure u recommend, after seeing higher than normal EGTs, something that should be done regularly as a preventive thing - regardless of EGT issues? i.e. to clear the build up of obstructive particles in the main-jet, or is this a non-occurence; i.e. any partial blockage happens in an instant - rather than build up..?

 

Cheers

 

Chris

 

 

[Dieselten]

Chris,

 

the partial main-jet blockage is a rapid-onset phenomenon, and it can occur with the 503 as well as the 582. The remedy is same in both cases.

 

Bear in mind the EGT gauge is a very sensitive DC voltmeter basically, and only a few millivilots gets to it from the EGT senders, which are just thermocouples. I measured 13millivolts DC on my 582 (@4000RPM) on a probe which I suspected had failed. The problem turned out to be a slight increase in contact resistance where the sender-wired plugged into the terminals on the rear of the EGT gauge itself.

 

The fix for this is to remove the gauge from the panel (loosen off the nuts that hold the clamp under the panel) and just bring the gauge forwards on the end of its cables so you can see the sender-wires attached to the terminals, and remove, then re-insert each terminal one by one, spraying a little "Electrolube" or similar contact-cleaning compound onto the connectors in the process. This usually fixes the resistance problem.

 

The other potential trouble area is where the connectors on the ends of the probe-leads connect into the wiring that goes to your instrument-panel. Any increase in resistance here can result in highly erroneous readings, almost always a low EGT. So if you see a major imbalance in EGT between cylinders, first flush the jets clear, and if the imbalance persists, check the connectors at the rear of the gague and any connectors in the wiring-harness. Chances are your problem is here rather than an actual engine problem per se.

 

 

[Sean]

Typical EGT & CHT values

 

Hi

 

Just bought an aircraft with a Rotax 447.

 

Can you tell me what are some typical values for EGT & CHT.

 

Thanks.

 

Sean.

 

 

[eastmeg2]

Hi Sean,

 

The 582 specs are: EGT maximum 1250 F, coolant tempt between 130 to 180 F.

 

But then the 447 is air cooled, I suggest you download Rotax's PDF documentation from their website.

 

Rgds,

 

Glen

 

 

[Sean]

Thanks Glen & Harwis.

 

Glen, I couldn't find the PDF on Rotax's site?

 

Sean.

 

 

[eastmeg2]

Sean,

 

Try this site.

 

http://www.rotax-aircraft-engines.com/a_engine_503_447.htm

 

Rgds,

 

Glen

 

 

[farri]

farri on Engine Failures.

 

Hi Everyone,

 

I always taught everyone that any engine can fail for a lot of reasons and sooner or later it probably will and if it did all that realy mattered at the time was to get back on the ground saftely.

 

The bottom line is that a single engined aircraft should be flown within gliding distance of a safe place to land at all times,this saved me enough times to have been worth it.

 

Now I know that a lot of pilots don`t like this as it limits where they can go, but thems the breakes, I`m Affraid,so it`s up to everyone to place their own value on their lives and the cost to others.

 

 

[Sean]

Found it, thanks Glen.

 

 

[jetboy]

For your stats: Rotax 503 SCSI on Bantam failure during climbout @ 950' shook rattled & prop stopped. Low compression traced to failure of little end conrod needle rollers portions of which were found in various places, and a broken ring. These were the early caged rollers design. Aircraft had previously sat around for a couple of years before I bought it and I had 3.5 hours on it at the time. I expect there would have been pitting on the rollers due to lack of regular running. I consider the 503 the most reliable of the Rotax 2 strokes especially the dual ignition (went on to loose a coil in flight 40 hrs later but those early coils were recommended changeout @ 300 hrs / 3yrs)

 

Ralph