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HelicopterThunder TigerRAPTOR 50 › Engine Busted - what went wrong?
08-07-2007 02:46 PM  10 years agoPost 1
mazon

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Hi guys ,my tt50 engine just busted, posting what happened to get some opinions as to what may cause it.

History:
TT50 engine been through 16 gallons on CP15%.The last time i opened up the engine was 6 gallons ago to change bearings. Engine was performing fine. Engine was tuned to hold back plate for 3~4s, hardly any lean runs. Normal curve headspeed ard 1650. idle up curve ard 1950.

What happened just before today:
Last sunday, i took out the engine to install a gov. So took the chance to change the bearings. since i was at it i thought might as well do some cleaning up. The piston had some carbon residue on top and a ring of slight brownish patch around just below the ring. Are these signs of lean?

The cylinder sleeve has some black patches at the exhaust ports.

So i use scotch bite n clean away the residues on both the piston n cylinder. took out the con rod n clean the inside of the piston also.

Changed both the bearings and assemble back,everything looks ok. turn the crank shaft by hand it was normal, no signs of binding.

Here's some pics of when i change the bearings.

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08-07-2007 02:48 PM  10 years agoPost 2
mazon

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Today:
First flight - richen the engine abit as bearings are new. Flight was mostly hovering and slow figure 8 using only normal curves to let it run in abit.
Felt it was smoother then before i change the bearings. back plate temp was cool .So i thought all was good.

2nd flight - started with normal curve , flew around landed n tested back plate, temp ok. then switch to idle 1. headspeed higher. responsive and quite good power, so i thought great the bearing change works.
Then i test the rev max on idle 2. i set the limit too low so proceed to land n increase the limit.

I throttle up again on my normal curve, while hovering at eye level,can hear the engine start to get higher pitch like leaning out. then followed by metal sounds then engine cut...

i thought it was the fan came loose. When i came back, realized the con rod broke n the engine case got 2 holes!!

Damages:
-con rod broke, piston sides broke, engine case broken with 2 holes

-cyclinder looks ok.the rest of the engine looks ok except for scratches inside the casing.

Need experts' opinions...
Anyone else have this happen before? what could have caused it? Kindly share ur experiences so that wont repeat this again.

sad...

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08-07-2007 04:44 PM  10 years agoPost 3
Stealth

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Rio de Janeiro -​Brazil

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It seems you've done everything right. It sound like a mechanical failure (con rod broke in flight), nothing you could do about it anyway.

Maybe a more careful inspection next time on critical parts when you disasemble your engine.

Trex250, 600ESP 4025-630 CC85HV 12S, E325 Cobra X9303 2.4

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08-07-2007 05:18 PM  10 years agoPost 4
SC Raptorman

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South Carolina

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Did you make sure you put the rod in the right direction ?

Oh what a feeling 3D Flying can be
Magnum Fuels

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08-07-2007 05:31 PM  10 years agoPost 5
Qrrambero

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San Francisco / Bay​Area

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Too Lean.. This mistake is made by many. You want a little more power, you see lot of smoke coming out and close the needle one or two clicks and here are the consequence.
Sorry, I have been there. Remember is better to fly with a little less power and you will have the engine for a long time or more power and you engine will last few months or weeks.

Ae

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08-07-2007 05:38 PM  10 years agoPost 6
Raffy

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Chicago, Illinois

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Now it's your chance to get that OS50Hyper you have always wanted.
The last time I had a similar situation like that is when the fan nut came off my engine. Engine screamed like hell and internally blew to pieces.

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08-08-2007 07:33 AM  10 years agoPost 7
w.pasman

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Netherlands

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Your backplate was cool so I don't believe you were running lean overall.

There might have got some dirt in the carb, causing engine to lean out suddenly in your last flight. But that sounds pretty unlikely to me.

Were you running too high RPM?

Another possibility is that your needle settings were unbalanced, so that the high end was lean while the low end was rich. I had this problem with my previous OS50, midrange had to be set very rich in order to get the top end right...

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08-08-2007 03:08 PM  10 years agoPost 8
SkateFreak

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Cambs UK

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i hate to say it but i would go with mechanical failure...
If you were running excessively lean you would have far more signs from the engine and i've never come across a con rod failure from the lean running.
Am also very surprised at the damage to the engine case!

I would look to the con rod, maybe installed backwards, maybe just a failure of the part... either way it looks like its beaten the heck out of your engine

Pick up a hyper
Have been running mine on the rich side for 2+ reasons, still good power and excellent condition

-Jvr

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08-08-2007 06:06 PM  10 years agoPost 9
MJWS

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Airdrie, AB - Canada

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Doesn't look like you fried it to me. Looks like something got damaged or incorrectly installed during dissasembly / assembly. This is a pretty rare failure mode and doesn't seem like a coincidence that it happened right after it got torn down and rebuilt. Maybe a snap ring, keeper on the wrist pin or something gave up the ghost or wasn't seated properly. It ran until something had a chance to move.

I had a motor spit a wrist pin (from the factory) once. Completely gutted the motor, but didn't make such a nice hole.

The clue for me is:
took out the con rod n clean the inside of the piston also
Maybe it just broke. But even in WOT crashes screaming on the ground at 25K they don't often punch through the crankcase.

Mike

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08-10-2007 11:55 AM  10 years agoPost 10
mazon

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Thanks guys for your insights.

Piston was not stuck on the sleeve, con rod broke at the top just below the piston, was still connected to the shaft , could not have flip over enough to punch hole in the case. Maybe the holes were due to the broken fragments.

Luckily the engine failed while hovering so autorotated down n heli is ok.

I know its simple to just get an OS but this TT50 is not that bad, has been quite reliable and managed to start almost every time. on top of that the fuel consumption is great.i thought it can at least last me til inverted hover, but who knows it decided to go for early retirement before i'm even half way there.

I read somewhere in the engine manual that tt has warranty, so i contacted my LHS and told him abt the engine. He asked me to bring it down for him to take a look.

He examined the engine and commented that it did not have any signs of lean or over heating. its maybe due to too high rpm.

He advised me not to run high rpm and use higher nitro/lub content fuel. He then offered to replace the damage parts with half an engine for FREE, so practically i got back a new engine except the heat sink and carb. And he will be sending the busted engine back to TT for further analysis.

Kudos to my LHS for the fast response n service.

The engine was only 5 months old, still not very sure what caused it. I m very sure i assembled back the engine correctly and didnt ran it lean, was shocked at the holes in the casing as well. I have asked around , and some flyers said it may be due to cleaning of the piston, cylinder,etc with scotch bite, which may destroyed the smooth running surfaces...

Will be using back the replacement and has started to break-in the new engine...

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08-10-2007 04:32 PM  10 years agoPost 11
w.pasman

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Netherlands

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Congrats, nice to have a cooperative LHS!

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08-10-2007 07:44 PM  10 years agoPost 12
airdodger

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Johnston USA

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You don't want to touch the piston with anything it is matched to the liner and you don't want to change any clearances. The brown is oil burning from being too hot. It is hard to tell with the pictures but looks like the rod was installed wrong side to the crank, unless you have a chamfer on both sides.

Chris

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