Engine Troubleshoot

Background
I still having problem with my OS 50 Hyper engine for my Century Raven TR3707. It probably need proper engine tuning, or engine brake-in, or new parts, or total new engine will more cost effective for me.

I had the crank case ( now I know the correct term for what I previously call "engine block") replaced since mine was broken in my last crash about one month ago. I have reused back all the internals.

I am using 15% Nitro, so that should work fine with a normal engine.

I continue with the test flight and trouble shooting.

Wednesday 2009-01-28
I took a quick flight session to see if I can figure out the problem. Brought it to PHAF field II, started the engine. Take off and have hover, then let it running in idle.. Looks very good.

From Remote Control Helicopter - 2009

However I was not able to continue the testing because it started to rain.

Saturday 2009-01-31
Brought the Raven to PHAF field II again. It was at about 9.50am.

This time, the weather is good. I was alone, I need to be extra careful. I already had half of tank of fuel left from the previous test flight.

I started the engine, put into hover, engine runs ok.

From Remote Control Helicopter - 2009

Landed, put on idle, check engine temprature, it was quite hot, turn the High Speed Needle (HSN) richer 2 clicks.

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Then continue to do the hovering.

Just when the fuel about to finish, suddenly the engine died! Let it rest for about 15 minutes, while thinking very hard what I need to do.
Tried start the engine again, but starter not able to rotate the crank shaft. Using my hand I need to put lots of force to rotate it. I opened up the glow plug, flush the fuel inside. Now the the starter is able rotate it. Put the glow plug back and I able to start the engine. Soon just when I about to take-off, the engine died again!!

This time same symptoms, so I quickly open up glow plug, and tried to flush the fuel from the engine, however this time even with glow plug is out, the engine still very heavy and the starter not able to rotate it.

At the end of the session, I was wondering if I really should get a new fresh engine!!

From Remote Control Helicopter - 2009

Finding So Far
Current symptoms:
1. The engine is very easy to start
2. It runs ok (at low RPM), I able to hover my remote control chopper
3. After about half of the tank (or a bit more) the engine suddenly stopped
4. Very hard to rotate the crank shaft, seems like something is holding the piston or shaft
5. It let it cool for about 15 minutes it will able to start again.
6. This time it can run just for few minutes only.
7. Verified that not due to hydro-lock since, even when I open up the glow plug, the crank shaft still very hard to rotate.
8. Verified tuning won't able to resolve the issue.

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Engine Testing Continued

Sunday morning, about 10.am. I need to troubleshoot and test the engine. It was not stable, died suddenly while running / hovering.

Reached PHAF Field 2, lots of other fliers already around.

I started the Remote Control Helicopter Century Raven TR3703 engine. The engine started easily, no problem at all. I brought the chopper to the take off spot, started doing the ground flight check, all controls and engine response ok. Everything is ok!

From Remote Control Helicopter - 2009

Then I started to takeoff and hover. Yes, it can hover ok just like yesterday, keeping the heights below 2 feet. After few minutes, suddenly the engined died! I already prepared for that, slowly let it settle down on the ground.

hmm.. it still happening. From a friend flyer, he was suggesting to tune the engine richer, that is, the engine died could be due to engine to rich and fuel has build up inside the engine resulting hydrolock.

I took some time to watch and snap some photos of other filyers with their aircraft.

From Remote Control Helicopter - 2009

From Remote Control Helicopter - 2009

From Remote Control Helicopter - 2009

From Remote Control Helicopter - 2009

Then I decided to give that a try, tune the engine richer than started the engine again. Tuning the engine is very tricky, I may need some time to get it right. I need to remind my self to be patient.

Ok, again, the engine easily can be started. I take off and put in hover again. Still keeping below 2 feet, until the fuel finished, the engine is till ok!! Good!!


Looks like that is true, the engine died was due to engine too rich. Need to confirm this again in next session.

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The Engine Is Not Stable!

In the last post (earlier in the morning), I have tested the Raven TR3703 hover ok. Everything looks good, but engine.

At the end of the test flight session the engine suddenly died (Saturday morning)!

Tried to rotate the crank shaft using the starter shaft, it is very hard, lots of force needed to just rotate it a little bit. Bring it back home. Later in the afternoon (same day), I spent some time try to trouble shoot.

From Remote Control Helicopter - 2009

Opened up the glow plug, and tried to rotate the shaft again, still very hard. Then I opened the head (with the heat sink). Now it can be rotated much easier, and I able to rotate it using my starter. I noticed quite lots of fuel came out from the cylinder. This could be the reason – hydro-lock.

From Remote Control Helicopter - 2009

Then, I put them back, tried to start the engine, and it started ok. Just let it running for about 10 sec and shut the engine down, since I did this right in front of my house, under the roof, I don't want to disturb my family inside!

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Later, I bring the Raven to in front of my house gate. Started the engine, then after I confident that the engine is ok, I started to bring it to hover. Just after about 5 seconds of hovering the engine died!! This time the crank shaft begins to be heavy again. I still managed to start the engine again, but this time it run for few seconds only, then it died. Hmmm.. looks like the running time is shorter and shorter.

From Remote Control Helicopter - 2009

Ended the session with lots of thinking in my head, I may need to go and find a fresh new engine!!

I'll try again tomorrow (Sunday).

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Hover test ok!

After 3 weeks of the crash today I did first test flight on the TR3703 the Raven.

More fix details
From the last post, I have put back the part together, tested the engine is able to run fine.

I have put in the rotor head onto the main shaft and put the wooden blade which I used before during my earlier time of flying.

Tested the servo movement and blade pitch:
1. Tail pitch rod is not that smooth, I bought the lubricant for RM30 at a hobby shop, and now it is ok
2. I had broken tail pitch ball link at the rudder servo. Replaced that, it cost me RM6!
3. I had another broken ball link at the blade grip ball. Replaced that too, cost me about RM3.50

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Then I checked the blade pitch, I have it as +9 to -9, that should be sufficient for my normal flying.

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At the flying site

Ready to fly

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Ok, it was 8.40 am in the morning. When I reached the PHAF Field 2, Brother Nick already there with his Compass Electric Heli. He is still learning how to hover, I gave him some tips from my experience, well probably he already know all that, but no harm of telling it again :)

After that I took out my Raven from my car DAF9594. I already pour in full fuel in the tank ealier at home.

Started the engine with no problem.
Did ground check, to make sure control movements are all ok.
Cyclic checked,
Rudder Checked,
Gyro Checked.

Play with the throttle, to ensure that engine is stable enough. Then I remember I need to lower the throttle curve. This because I do not want to overstress the "new engine".

I need to be very carefull because this is the first time I am going to fly the Chopper since it was crashed and rebuild. The setup and profile may be a lot different than before.

Then, slowly I increased the throttle, compasating any possible drifiting with cyclic control on my right tumb. It took off slowly, drifting to the left side and back, a bit, not that much. Compasate it to stay and hover at the same spot. Checked the balde tracking, it looks good, no need any adjustment.

Continue the hover for a few minutes, with in 1.5m heights, I need to be prepared on any problem that my happen. Landed at the same spot, and leave the engine running.

Yes, it able to fly (hover) with no problen. Check the engine, looks like it quite hot, so turn the High Speed Needle reacher. Also I push the trim for forward cyclic a bit to counter for the 'drifting backward' behavior.

Did the hover flight again this time I tried to climb and decent, still within about 3 m heights.
Everything is just ok. Alhamdulillah.

Then I landed, tune the HSN a bit more to reacher. But, the engine died.

I have appointment at 9.30am, about 5 more minutes, need to finish up the fuel.
Started the engine again, did the HSN tuning and hover. After a about 1 minutes, suddently the engine died!

It tried to start the engine but, looks like the crank shaft is pretty tight. I can barely turn it with my hand, with a lot of force.

Oh.. anyway, times up. I packed all the stuffs, wil troubleshoot the engine later.

Test Result
1. All controls are ok.
2. A bit vibration at the tail, probably due to low rotor RPM
3. Engine - need to trouble shoot!

More fixing needed
Still I have few items need to be fixed/replace before I can do the "learn new skill flying". They are:
1. Good blade, at least similar to before, the 600mm Hurricane Carbon Fiber enforced blade
2. Currently I have 2 broken servo casing, holding to the frame only with 3 screws instead of 4 (1 side got 1 screw holder broken).
3. Engine - what is the problem here?

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Fixing The Raven

I had the engine fixed (I think). Cikgu Vanan has swapped the broken block with a replacement. After putting back all the internals, crank shaft, sleeve, and piston, looks like this is going to work and I'll be saving 600-150 = RM450 with this solution.

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He also helped to take out and replaced the bent main shaft and damaged clutch bell gear and counter gear.

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Total parts so far is about RM300, and that is including the engine! Looks like that is all what I need, other than the expensive blade.
Here are the list:
- Engine: change the block only, using old pistons, carborator etc
- Both Sides of metal lower frame: Cikgu Vanan has knocked it straight in 5 minutes!
- Tail boom: use new one, old one only with minor damage at one of the end only, I'll keep, will know it straight for use later
- Flybar: straighten it back for reuse
- Spindler bar: replaced with new
- Couter Gear: changed new
- Clutch bell gear: replaced
- Skids: Replaced
- Blade: will use my old wooden blade for now ( replacement for this is real expensive $$)

Last night I spend till 3 am to put the new spinder bar and skids.

From Remote Control Helicopter - My Journey

From Remote Control Helicopter - My Journey

This morning I put parts together, skids fuel tank and engine into the lower frame. Then the muffler. The manual file I downloaded is very useful. Put in Swashplate onto the main shaft. Put the upper frame into the lower frame. Put the tail boom.





So now the Raven have almost everything except for the rotor head including the main rotor blades assembly and the flybar.

At about 1300, I decided want to try to start up the engine. Put in some fuel, the same one taken out after the crash. Then carefully while have a steel holding the skid I tried to start the engine up. However seems not working, just to realize that I have fully closed the HSN (High Speed Needle). Open it up of 1.5 turn, then it started ok!

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Still have to check is the tail rotor pitch link.

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Damage Assessment

Had a very bad crash last Sunday, 4^th Jan 2009.

The problem could be due to:

1. Broken pressure tube (connected to the muffler)
   
2. Clutch issue, broken or something, releasing the blades from the engine
   

Here are the damaged found:

Engine	OS .50
Lower frame	HI3112
Counter drive gear/clutch bell gear	HI3040
Skids	HI3122A
Tail pitch ball link	HI3152A
Funky Blade	CN2412
Main shaft	HW3053A
Vertical tail fin	HI3067Y
Tail boom	HW3062A
Flybar	HW3173A

Skids and lower frame

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Engine

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Tail fin and tail pitch ball link

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Main Shaft and Flybar

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Lesson learn..
1. After few move, should stop & check before continue to fly.
2. Need to train for autoratation during inverted.
3. Fly higher for new tricks!
4. Don't panic. probably I can minimize the damage or avoid the crash if have fast and correct reaction.

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Did 3 loops today!

Today, from the morning I have set my mind to try the loop maneuver.

Metal Fan Bearing Problem

I had my bearing problem fixed earlier. Alhamdulillah, lucky me that Cikgu V able to fix that easily by putting some bearing lubrication oil and some gentle knock.

Also, he has managed to get a starter shaft machined to fit this new metal fan. So this problem will not occur again, I hope.

Flying Time

I already able to do it confidently in Real Flight simulator, so there is nothing much to worry.

Reached Putra Heights Aircraft Field at about 9.15am. Today we are using old place, which have much bigger space.

I had about half tank of fuel already filled in. So I started the Raven engine. Starting the engine is much easier, the engine started right away.

Utilize the remaining fuel for in-flight check while hovering and a quick figure 8.

After that, landed the Raven, and fill up the tank. This is from new gallons, 5^th gallons for this Raven.

From Remote Control Helicopter - My Journey

Flew the Raven again do some figure 8, and practice stall turns as well. Now I am more confident in executing the normal 180 degree stall turns.

I had to confine my flying space to let other flyer flew their airplane.

Landed the Raven, with the confident I have, I am ok, and the Raven is ok, so I should continue with loop or even inverted hover!

Looping

The last time or actually the first time I tried the loop was at Puchong Putra Prima (http://rotormax.blogspot.com/2008/11/first-loop-try.html) where I ended almost crash! Since then I have been checking the Raven, did lots of thinking and practicing in simulator.

Filled up the tank again and waited for the field to be clear. I don't want to have any complication when trying new maneuver.

Then, when the time came, I took off, did few stall turns.

Then I setup for my first loop.

I flew at a level flight about 100 feet above the ground from my left to right. Then I started to climb, keeping constant elevator the Raven climb and start to invert just before it is inverted I pull more negative pitch to have the feeling of negative pitch lift force. Yes, I can confirm that it is adequate for inverted hover. Then, continue to dive to level again and completed the loop. Yes it works!!

The second time I tried, with the same setup, from left to right, climb, inverted, dive, level to complete the loop, this time at a lower altitude, because I did not give enough negative lift before the dive.

Then I tried inverted hover. At quite same altitude (yes I need them to prepare for any mistake), let the Raven fly away with tail in, then start to climb and invert. I stay there for about 3 seconds and dive back. Yes, I was able to invert hover the Raven!

Ok still have about half tank of fuel, so I decided to have another loop.

Same setup, from left to right, climb, invert, suddenly

• I hear the engine running at very high pitch
  
• Oh what happened, is it come from my Raven or somewhere else?
  
• Oh why Raven not really responding to my input, I need to initiate autorotation, but I am currently inverted!!
  
• Yes, it must have come from my Raven, how do I reduce the engine speed??
  
• I need to start dive and level it for autorotation
  
• Yes it is diving, but o-o not enough height!
  
• Boom, and silent, no engine sound anymore, it already crashed!
  

This is exactly where I found it after the crash.

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;

And the damage looks very bad!

From Remote Control Helicopter - My Journey

Main suspect – Pressure tube to the muffler broken. See the above photo.

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With New Metal Fan

New Metal Fan

I have managed to get the replacement for the broken fan. It is a shiny CNC metal fan!!

However, the metal fan will not work with the original motor starter shaft. It has a one way roller bearing at the center, suitable for its own 6mm starter shaft.

First thing I need to figure out is how to have the starter set. Even if I bought the special 6mm starter shaft, there is no way that I can use that with my current starter motor.

To resolve the problem, I manage to get a workshop to grind the original starter shaft into the 6mm cylinder shaft. Tip of the original shaft had to be cut because the guy had over-grind the end part.

From Remote Control Helicopter - My Journey

For the new metal fan to work, I also need to remove the existing
auto-release starter shaft on the Raven. I was able to install the new metal fan and remove the existing starter shaft and their bearing with out any problem.

Before..

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After..

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Hard damper

While I purchasing the metal fan, Fendi (on of the 3d guru for RC Helicopter) was there and giving me advice to also change the damper. Damper is the most important thing for any 3D maneuver. I believe that hard damper will make sure faster and sharper response for any inputs.

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Putting in this dampers is not that easy, it took me about 1 hour just to do that alone.

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Time to fly

In the morning of new year 1st Jan 2009, time to try out this new metal fan.
Reached Putra Heights Aircraft Field 2 at about 8.30 am.

Filled up the fuel and ready to start the engine. The custom made shaft did not fix tightly enough at the tip but putting bit more in does take the grip.
I manage to start the engine!!

And taxi out slowly from the shades where I have my equipments.

Hover and in-flight check, landed for engine idle check..

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Fly the Raven, normal circuit with figure 8. Landing time, I hover and slowly 'taxi' the Raven to the original takeoff site, it is quite challenging and I need to put extra focus not stray and hit any near by trees.

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At 9.30am I went back for breakfast with my family.

11.30am came back to the flying field, filled up the tank and tried to start the engine.

!! This time the new fan is not able to grip the shaft any more. Trying to put some masking tape did not help. Suspecting that the shaft has worn, I packed and went back.

Troubleshoot
At home I took out the upper frame part (as usual when I need to access the fan/engine). Trying with other 6mm shaft revealed that the roller bearing at center of the metal fan has stuck/damaged, and it is not shaft problem.

Well at least, I was able to fly for 1 tank on 1st Jan 2009!

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