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Simonini Mini2 Plus Engine Failure and emergency landing on Golf Course


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Hi guys,
Had an engine failure yesterday on the simonini mini2plus 200.

Landing was fun but thanks to my always trying to keep downwind bomout options within reach, i nailed a perfect high g/s feather duster on Monash Country Club 16th hole fairway...wind was north east coming off the ocean.

https://www.livetrack24.com/track/1645021

wasnt sure how much wind shadow effect there would be passing down through tree line (a 10-12 knot coastal seabreeze was blowing 2-3km east of me) so i let the trimmers out about 40mm to try and compensate for that frightful dead airzone below tree top height and it all worked out well. I paced out two lovely looking 10meter long worm burn marks on the fairway grass...a token of my appreciation for the temporary club membership...hehehe. Real feather chuffing stuff (shame there was not a soul in sight to witness my one decent landing in my ppg career). 🥴

It looks like the upper connecting rod roller bearing has failed and in turn the engine seized. its early in the strip down but its obvious she has also grabbed a piston on the cylinder wall as well clearly running lean through exhaust port at the time of failure. Im not suprised by that because i was on about 3/4 speed system climbing up into the hills to the west of the coastline at the time trying to get home before sunset.

I had only increased the low and high speed mixture settings on previous flight yesterday as we are coming into our cooler months here in Sydney, so its not mixture related even though engine did end up running hot...i believe thst was due to unfavourable port timing caused by bearing failing.

Whats really interesting is that as the bearing failed the engine did not produce any audible knocking noise like you get with an automotive engine...small engine small noise i suppose.

Will be at the very least a new piston/cylinder kit (although im suspecting a crank split to replace lower connecting rod bearing may also be needed as im certain pieces of the failed upper rod bearing will have gone through the bottom end (i cant feel anything but shiny pieces of metal fell out of the spark plug when i removed it and tapped it on a hard surface)

Engine has about 150 hours and has always been very reliable.
I had the head off a few weeks ago and cleaned out decompression port also checking the liner for any score marks, put a walbro kit in it carby, and replaced the electric starter and battery.

What sort of hours are you guys getting out of roller type upper connecting rod bearings?

Ive never had a little end fail before, big ends  on other engines yes...but not upper. Makes me think roller type little ends are a bad idea?

20200519_170856[1].jpg

20200519_211129[1].jpg

Edited by adamjedgar
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The primary cause of that failure was a lean mixture, the piston has severely overheated.

The little-end bearing was a secondary victim to that condition.

"I had only increased the low and high speed mixture settings on previous flight yesterday as we are coming into our cooler months"

Sure you didn`t lean it out by mistake?

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Nah 100% made it richer on both...added about 1/8 on low and half a turn on high.

The crank had the tiniest bit of play in it when i was putting prop on...if i had known it had roller little end bearing, i would never have taken off. I was convinced it was the big end a few flights back but when i lifted barrel there was not play in the big end...i ended up putting it down to a bit of 2 stroke piston slap. Compression, starting, idling, and power were all great prior to take off, but i dont think with 2 strokes that means much!

Here is a photo of spark plug the day before. Even thought its a coffee brown colour, i normally run a black colour. For it to be going brown when i had increased rich mixture i think says the excessive movement in little end and failed bearing was adding friction heat to the underside of piston and also affecting exhaust port timing making engine run lean.

The other side of piston and barrel are unaffected by this.

 

20200517_144112.jpg

Edited by adamjedgar
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2 hours ago, Hann__ said:

Yeah OK........never heard of port timing being affected by a worn little-end bearing!!!!

I think the thought is that the piston drops a little....?
I cant see this being the case as anything meaningful would also drop compression below detonation which I am assuming has happened looking at that piston.
 

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Yeah, in theory a knackered little end would perhaps give 1 or 2 `thou play before it made itself heard, but to affect the port timing to any significant degree it`d have to have 2 or 3mm or more, and with that amount of play the engine would be making a hell of a racket....

Also, would retarded port timing necessarily make it overheat to this extent..?

The little-end on my Moster can be heard, it`s probably been like that for 200+ hours - a lot of two strokes are prone to it.

When i was younger and a fledgling motor bicyclist i was obsessed with the bloody little end bearing noise on my `bikes - i`d change them regularly and they`d sound great for fifty miles then go back to rattling. It`s a 2T `characteristic`.

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10 hours ago, Hann__ said:

Yeah, in theory

I'm no expert (or fan) of two-strokes... they are too much "art" and not enough science to my uneducated eye :) 

 

10 hours ago, Hann__ said:

Also, would retarded port timing necessarily make it overheat to this extent..?

Now that I think... if there was 1mm of play, would there be enough inertia in the piston to go + 1mm in compression as well as -1mm in induction.......?
But like you say, it would be like a jack-hammer if it had anything more than a few thou.

My first thought was a batch of crappy or low octane fuel causing it to knock/detonate/diesel (or whatever folks call it)  when under stress/high temps.
I assume these motors run close enough to the limit that a drop in octane would see it go into self-destruct.

On ‎20‎/‎05‎/‎2020 at 06:39, Hann__ said:

Sure you didn`t lean it out by mistake?

That's the simple answer though :) 
 

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On ‎19‎/‎05‎/‎2020 at 22:22, adamjedgar said:

Had an engine failure yesterday on the simonini mini2plus 200.

Just had a quick rummage... it seems Simonini recommend no less than 98 octane and folks who struggle to get 98 octane have been getting by with 95 octane.
It might be worth a ponder if you have been using 87 :( 

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sorry i havent replied in a few days guys...busy.

What i have found consistently interesting with this motor is that from new, it has always rejected fuel out through the intake...the air filter is the standard simonini mini2plus one and its always wet...even on the day it siezed.

I am thinking that perhaps i might also get a replacement set of reed valves....i dunno i cant figure out why the engine is rejecting fuel through intake, unless the Nirvana "Tuned Exhaust" is in reality not so tuned?

 

another photo added here, although you guys have already seen the worst of it i think. You can clearly see how the needle roller bearing has completely collapsed on the connecting rod.

A complete engine rebuild incl bottom end unfortunately. About Euro 400 in parts at this stage. Thats almost $700 AUD...costly mistake. what really sucks is that i also have the Japenese DLE 200 twin on another paramotor. I havent touched the mixture on that engine since i bought it 5 years ago...i have run 6 month old fuel in it...left it sit in the shed with old fuel in it...i get it out, prime, hit the starter with choke on for a handleful of revolutions until she pops, turn off choke, and voila...it fires up everytime and never misses a beat!

Clearly Japanese stuff is by far the way to go even compared with European engines. No surprise really considering how many 2 stroke engines are built in Japan for Honda, Suzuki, Yamaha etc.

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20200527_140437 (Large).jpg

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Hi, to detonate that much something is way off. If your mixture is close then it could be a CDI fault, ive seen this quite a few times over the years developing 2t mx engines. Also do you know if the flywheel is on a taper or a woodruff key?  Cheers

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On 20/05/2020 at 13:54, Hann__ said:

Yeah OK........never heard of port timing being affected by a worn little-end bearing!!!!

No it wouldnt happen. The exhaust side of the piston is always the side to get damaged simply because its the hottest. 

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On 20/05/2020 at 16:14, Blackburn Mark said:

I think the thought is that the piston drops a little....?
I cant see this being the case as anything meaningful would also drop compression below detonation which I am assuming has happened looking at that piston.
 

This is nothing to do with play in any bearings

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  • 2 weeks later...
On 20/05/2020 at 07:22, adamjedgar said:

so i let the trimmers out about 40mm to try and compensate for that frightful dead airzone below tree top height and it all worked out well.

 

Being a newbie pilot, i questioned my instructor on this tactic.

 

He said it was not wrong to do it, and most people wouldnt have the smarts to think about that on landing. (consideration also for different wing trimmer types).

 

Do you think the trimmer out landing would have given you more stability if infact there was some rotor?

 

cheers

 

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This is how i imagine it.

The more forward speed you generate (head wind) the less of an effect any rotor (side/up/down wind) would play on the wing (i imaging a speed boat cutting through waves, fluid dynamics and all that good stuff ), plus increasing internal air pressure of the wing making it a bit more "solid" yet "flexible" with the reflex wings.

there's plenty of other factors that would go into stability of the wing. The rotor acting like mini gusts on multiple areas of the wing, top surface mainly as wings get stability from pilot weight below it, not wind "weight" pushing above it causing poor control or a collapse. The less time spent in that the better. The wing quickly transitioning from one force to another spells trouble.

Would i have put my trims out ?

I would like to think i would but i bet i would of had to much to think about before thinking "trim adjustment specific to random landing spot with dead zone/rotor".

The pilot has had the time and experience to add those little extras on for added safety. 

Best thing to do when starting out is don't use such areas as bail out zones. You want as little as possible that you have to think about when in these situations. At lest till experience dictates otherwise.

 

 

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I have been really focusing on trimmer out landings for inland flying over the last few months. You dont have to let them out much.

The object of the exercise is to replicate what GA aircraft pilots do. Its all about groundspeed. You see when one has a 10 knot headwind, and comes down near the ground, that headwind may suddenly dissappear for whatever reason (obstacles, themic activity, wind gust cycles etc). You should always try to land with a ground speed that matches your wings minimum flying speed at your weight range.

This is more important inland than on the coast i think. However the rule of thumb is to always let out trimmers when landing in wind. How much only comes from practise...but at least 25% i think. Also you never want to descend down through tree height slow on brakes. You are going to go through wind shadow so faster is important...otherwise you become a brick.

So for me, when i had to deal with this emergency landing i had the following thoughts

1. Golf course 

2. How strong is the wind...(golf courses always have flags to look at)

3. How much trimmer out will i need

4. Which fairway is going to be the flattest (this is actually really difficult to pick...golf course fairways are really hard to ascertain  the flattness of from even low altitude...they are full of little humps and drains that may be only a foot high/deep but can be catestrophic when landing)

5. Out of the flattest looking fairways, which one is most direct into wind

6. Out of the most direct into wind, which one is nearest to rescue and people seeing me in the event i crash.

 

There were practially no golfers on the course at the time so i wasnt worried about hitting anyone of a golf ball hitting me.

 

I endedup picking the fairway closest to to road because i knew the slope of the road well and guessed that was my best knowledge of the slope of the golf course fairway options available to me. Im glad i did to, onece i was on the ground i realised some of the other choices would have been awful ones. Also by coming in faster, i was able to alter my glide angle during flare to match the changing slope of the fairway. This is really important.

Edited by adamjedgar
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