Troubleshooting

	Troubleshooting
Back to Main Page	1. Noises 1. Engine - includes 'wah wah's' 2. Gyro/tail problems 3. Clutch 4. Radio Glitch 5. Vibration/Wobble 6. Blades out of track - includes the 'woof' 7. Flight characteristics 7. Mechnical problems 7. Crash Failures

Noises (R30/50)
Clicking noise and see tail stop spinning for a split second	1. Make sure the belt is not too loose. It can be right in the house then when you take it to the field during Winter the aluminum tail boom will shrink and make the belt loose enough that the teeth of the belt hit each other. 2. Turn the belt over. The teeth form a direction they want to go from the torque of the main gear pulling on them and if you ever take the belt off and put it back on the opposite direction then the teeth of the belt will not mesh correctly with the teeth of the main gear. 3. Make sure the pin that holds the tail gear to the tail shaft has not started to come out. 4. Change the belt. Don't bother trying to look at all the teeth for something to be wrong. I have and never did. You could have a stretched spot that is not enough to see but is enough to cause problems with gear mesh. And as mentioned in the 2nd step the flexibility/stiffness of the teeth under operating conditions could be bad and you can't see that.
Oscillating sound that comes and goes. Most present in a hover or in slow level flight. Goes away during full power climbout. Also the noise varies with rpm.	<under construction>... unfortunately I don't have the answer yet. I have encounted this three times (once on my own helicopter) and it seems to disappear on its own. Things I have tried on mine and my friend Jim's are to install a new auto hub, new belt, and new main gear. None effected the sound. If it happens again on mine of one of my buddys I will update my findings here. 12-17-2002
Wah Wah sound	This is an oscillating sound that is present when making a descent. You may also notice the tail kicking a little. See 'Got the wah wahs' in the Engine Troubleshooting section.
Rushing water type sound from the engine.	Bearing is bad (usually the rear bearing). When bad enough you will notice tuning problems. The low speed has to be kept very rich to prevent the engine from getting hot. In the case of a recent one I diagnosed, the OS 50 was so rich that the tail was kicking and causing the nose to drift right. When doing 0 degree descents the very rich setting was causing the wah-wah's.
Clattering - metal type knocking noise coming from engine area when the engine is idling.`	This is due to loose bolts on the clutch.
Clicking sound while starting and intermittent screeching sound while idling	Worn fit between the pinion bearing and the pinion gear. This normally should be a tight fit when the bearing is installed. If it is not then use some loctite to the pinion gear from rocking inside the inside race of the bearing. Tip submitted by David Trips

Engine Troubleshooting
Setting the needles lean/rich	See Engine Tuning section
Note:	I have fixed several Raptors that had a problem with the fuel mixture changing during flight just by changing out the fuel tubing. What happens is the stock tubing deteriorates quickly. An example of what happens is the clunk line (tubing inside the tank) can collapse from the exhaust pressure. Another thing is the tubing crystalizes and gets a crack that lets air into the line. If you have engine problems, changing the fuel tubing is an easy thing to try.
Engine won't start - no pop sound from trying to ignite	1. Glow plug extension not making contact. I have helped many with this. _a. bad connection at the glow plug end. The most common fix is to replace this end with a standard alligator clip. The TTR3803 glow plug externsion has been the most trouble free then the others I have used. The only problem I have had is that I had to re-crimp the r/c car body pin they use. Click <here> for remote extension fixes. _b. broke wire. I've only help one person with a broke wire. _c. too much fuel/oil on the driver end or too much fuel/oil in the glow plug driver. _d. too much paint on the bolt holding the glow plug plate on. The does not allow ground contact. _e. if the glow plug extension is the type that uses an r/c car body pin then the pin could be touching the heat sink of the engine. 2. Battery in glow plug driver needs to be recharged. 3. Glow plug bad. 4. Flooded. Take the glow plug out and see if it's wet. If not, then the Low/High speed needles are closed too much or something is wrong with the fuel system and it can't get fuel to the engine. If it is wet, then put the glow plug driver on it to dry it out, then pull the full line loose from the carb and spin the engine over to get rid of the excess fuel in the engine. Put the glow plug back in and try again. Also see my page on the unflooding procedure. 5. 1st time to start engine or just changed the needle settings _a. Must not be getting fuel to carb. Rotate the throttle lever fully clockwise then turn the low speed needle fully clockwise. Don't tighten it, just turn clockwise until you feel it stop. Next rotate the throttle arm open (counter clockwise) an 1/8 turn (about idle position). Next get a clean piece of fuel tubing and hook it up to the carb. Blow through the line while turning the low speed needle counter-clockwise. When you feel the air blow through the line, then you are close enough it should crank. To set the needles right, read Engine Tuning 6. If you are using the Thunder Tiger glow plug extension and the helicopter will not crank using it but will when you connect direct to the glow plug then you may have a problem with the ground connection. I have seen more then once where the painted black engine bolts did not conduct. For these I used a metal brush on my dremel to remove the paint from the bolt to fix the problem.
Engine won't start - can hear some pop sound from trying to ignite	1. Battery in glow plug driver needs to be recharged. 2. Starter spinning too slow 3. Glow plug bad
Engine won't start - fuel flowing backwards	If you can see fuel flow to the carb then back to the tank as you try to crank the engine and the engine cycles through starting for a split second and dies, then the engine is too hot.
Engine won't idle	Engine decreases rpm after you remove the glow plug driver. 1. Glow plug bad 2. idle mixture too rich (don't use the glow plug driver to set it, use proper technique to set mixtures) 3. clutch dragging too much. With the engine not running, rotate the clutch bell. If you have resistance, then the clutch shoes have sprung out or broke. Otherwise, the gap size maybe too small and the clutch is engaging at too low of an rpm.
Dies in transition from idle to hover	First, to begin with if everything was fine before and with no adjustment changes you now have this problem, then the first suspect is a bad glow plug. If the plug is good and/or this is a new setup then this is probably just a mixture setting problem. This happens when the high speed and low speed needles are adjusted too far off from each other. A common cause is when someone has the high speed needle set too rich to compensate for the too lean low end needle. When you are hovering, you are using the low speed needle setting, not the high speed. The low speed is a ratio of the high speed, so if you are hovering and the heli leans out, then when you richen the high speed (main needle), you are also richening the low speed. So this kinda accomplishes the task, but not really. Not if you do aerobatics. This also produces the bad effect of the 'rich spot' between idle and mid throttle. As the engine is at idle and is ...lets use lean for this example... then as the throttle is increased, it eventually gets to the transition area where the high speed starts to effect it. If the high speed is too rich, then the fuel flow sees a sudden increase. Too much increase in fuel as compared to air, and it will put the fire out :) Note: This symptom can be caused by a bad glow plug. If the glow plug can't get hot enough, this makes the engine overall run rich. The low and high maybe effected differently and cause one end to be a lot more rich then the other and therefore cause the engine to die during the throttle transition. Note2: I did have the rich spot at 1/3 throttle for the first 4-6 gallons on my TT36. That was before I knew how to adjust an engine correctly, so I can't say this would have eliminated the problem totally, but it should help. The rich spot did fade away. I have not had a rich spot in a very long time and I use the original low speed needle. It has no problem transitioning from low to high.
Engine starts but the main rotor does not turn and the tail spins constantly, even at idle. / I tried to lift into a hover, but the main rotor won't spin and the tail is very sensitive.	The engine started backwards. Kill it and start again. If you have repeated problems of it starting backwards, then here are a few things that can cause that: 1. Low speed needle set very rich - try a hotter glow plug 2. New engine - have to put up with it until it's good and broke-in 3. Clutch dragging - the added resistance increases the chance of it reversing during the compression stroke
Head Speed is very fast before the helicopter lifts off but after lift off the head speed drops way below normal.	This describes a very lean condition on the low half and a very rich top end. 1. Change the glow plug 2. Change the clunk line (inside the tank) <Here's how> 3. Clean the carburetor <Here's how>
Engine leans out even with mixture settings rich	If your engine is leaning out severely and no amount of tuning will stop it then an often overlooked cause is from a loose fan. Sometimes when you try to crank the helicopter and it is fuel locked then this can slightly unscrew the prop nut and fan. When this happens it allows some in/out play in the crankshaft. Then while the engine is running, the connecting rod pin grinds against the back plate. With the engine spinning 10,000+ times per minute this quickly builds up heat from the friction and overheats the engine. The above fix is the most common but I did get an email from someone that was having the same problem and it turned out to be that his muffler was full of carbon buildup. He tried two engines before figuring out the muffler was clogged. (Thanks Ian for the info)
RPM's increase significantly just as the fuel runs out	This is normal for any gas helicopter. What happens is as the fuel level becomes lower then the top of the hole in the clunk, the carb is now pulling in some air along with what is left of the fuel. When you mix more air with the fuel this is a lean ratio. Really you should stop the helicopter before it runs out of fuel so it does not go through the lean condition. Although it only last a few seconds it is still not good for an engine to experience a lean condition.
Info on checking a glow plug
Got the wah-wahs	I have some possible cures listed below but first I wanted to share my experience with this. In all but two cases I have fixed the wah-wahs by leaning the low speed, as opposed to the common tactic if richening it. As an example, at one of the fun flys I was at I overheard a friend of mine telling someone he needed to richen the low speed because when the carb goes into the low speed side it is deprived of fuel. I spoke up and agreed that that can sometimes be the case but that I have also seen the wah-wahs from being too rich. Basically it is a problem with a bad transition from the high speed side to the low speed side. I explained it could go either way but I figure it is too rich because the guy said it had been fine until that weekend. The humidity was high so that means less oxygen per given volume of air which means the fuel/air ratio is rich. The guy did lean the low speed a 1/4 turn and my friend was a little skeptical. The guy went out and flew and it was ok for a couple of minutes then did the wah-wah again. I went out on the flight line to help him out. I ended up leaning the low speed another half turn and leaned the high speed nearly a half turn. This solved the problem. My friend that told the guy he needed to richen the low speed noticed the helicopter was running good and came out to see how we fixed it. The guy told him we leaned the heck out of it :) Note: The above could easily have been a bad glow plug. If in doubt change the plug before you mess with your needle settings. In general if all is fine then the next time your start the helicopter the engine is way off adjustment then it is most likely the glow plug. === Other known fixes: Take out any up/down slop in the main gear, dry the oil from the auto hub bearings, and using a constant tail drive. === Constant tail drive === The wa-waas can be cured by using a driven tail when all else fails to totally remove the issue. Because the tail rotor cannot free wheel when the problem starts it damps it out. The problem is aggravated when the freewheel grabs, then lets go causing the engine hunting to get worse especially when you consider what the tail has to do through the gyro the compensate. -- This tip contributed by Stephen Bell, thanks Stephen :) === Up/Down slop in the main gear === Add shims under top c-clip of auto hub to remove any up/down play in the main gear AND in the main shaft. <Click here> for more info. Note: No up/down play in the main shaft is just as important as no up/down play in the main gear. A guy I talked with by email eliminated his wah-wahs by removing the 3/32" play in the main shaft. At the same time he did an experiment that with his Hirobo Shuttle. He was able to reproduce the wah-wahs in that helicopter by making an 1/8" play in the main shaft. Another thing that can cause the wah-wahs is flying at an rpm that puts the engine right in between the high and low speed transition of the carburetor. As an example a buddy of mine was having the wah-wahs bad in flight mode 1. He richened the low speed needle but that didn't help at all. I looked at the problem and found his 1/4 and 3/4 points were at 78% but his 1/2 point was at 42%. I increased the mid point and that fixed the problem. What happens is the engine 'hangs-on-the-pipe'. Once his engine got up to a certain rpm the Weston muffler (with some pipe characteristics) would try to govern the rpm. So as he would back off on the throttle the carb was not feeding as much fuel but the muffler was still keeping the engine at the same speed. So same speed but less fuel means lean condition.

Gyro/tail Troubleshooting
NOTE: The number one problem I run into with poor gyro performance is due to resistance in the tail control system. This can be from misaligned tail rod guides and or no oil on the tail pitch slider. Disconnect the link from the tail servo and feel how much force you have to use to work the tail. It needs to be very low resistance. If it does not slide with very little resistance then you need to find where the problem is. To do this split the areas in half. You already have the link to the tail servo off so now take the other end of the control rod off. If you still have the resistance then the problem is in the tail guides. However if the tail control rod slides freely then the problem is in the tail section. To split this area up, push the two pins out of the tail pitch arm (this is item 13 in <my manual> ). This will tell you if the problem is in the blade grip area or the pitch slider/lever area. This technique of splitting the problem area will help you pinpoint the problem.
NOTE: I have found a lot of poor gyro performance problems are due to poor mechnical setups. Heading hold gyros are great, however if you don't know any better then they can fool you into thinking everything is ok. By this I mean that in heading hold the gyro will tell the servo to move to whatever location it takes to keep the tail in place. This is what it is suppose to do, however if you did not mechanically center the servo and linkage then you will run out travel in times you need it. You will notice the tail gives up and let go. To set it right, the gyro must be placed in non-heading hold mode and you set the linkage to achieve 4.5mm as shown <here> with the servo arm centered up.
Tail lets go	1. The battery voltage could be too low. The tail is the first thing that stops responding with low voltage. 2. If you have radio problems then some gyros like the gy401/502/601 will reset and at that time it will store a new center location. If the rudder stick in not in the center at the time then the helicopter will rotate later when the stick is placed in center. 3. Two of my flying buddy's both had problems with the tail not holding during certain times. One would let go just in a simple descent. I found the problem due to the 9253 servo. Both of theirs had developed resistance. Normally when you rotate the servo arm it feels very smooth and rotates easily on this servo. I found that the problem was in the motor. It appeared that the motor had dried grease inside. This is the first time I have seen this problem with these servos and since it happened on two of them it might be something to check if you experience a gyro problem. Another possible cause is not having full travel. This caused by not setting the gyro to non-heading hold and mechanically adjusting the linkage so the tail is centered as shown <here>. 4. Check for a broke pin in the tail gear.
Tail Wags	This generally means the gyro gain is too high. If you are setting up a new helicopter and you notice you have to turn the gain below 60% then you should move the ball on the rudder servo arm in one hole toward the center. If this is a new problem and everything was working fine before then most likely the head speed has increased. Either due to changing fuel, changing needle settings, or some other problem with the engine. Another thing to look for is if the foam tape holding the gyro is disentegrating. Another possible cause could be missing teeth on the drive belt (caused from a previous crash).
Helicopter spins extremely fast as soon as it gets light on the skids.	Click <here>
Tail is kicking, sometimes 90 degrees	1. First make sure the tail blades are on the right direction and spinning the right way. Check <here>. It is easy to get the belt twisted the wrong direction when you install it. And yes, I have seen the blades installed wrong on more then one occasion :) 2. Are you using a 6V battery (5 cell pack)? Some gyros and or servos do not operate on a non-regulated 5 cell battery. The instructions may say it operates from 4.8V to 6.0V, but you have to keep in mind that a 5 cell pack will be nearly 7 volts on a full charge. 3. Check for a missing tooth in the main gear or the belt. <R30/50> 4. If the problem is the belt but you can't see anything wrong with it, then turn the belt upside down. The teeth of the belt tend to form in a certain direction after some use.<R30/50> 5. Check for a broke roll pin the the red tail gear. If the newer type then check that the solid pin is still secured with the set screw.<R30/50> 6. If you have a Telebee gyro then check to see if the circuit boards inside are vibrating. Look for white dust. Wrap one layer of electrical tape around the edges of the board and re-install. 7. If the nose goes right then you have a radio problem. Check for notchy top and bottom main shaft bearings as well as a bad pinion gear bearing and top start shaft bearing.
You had to decrease the gain value because the tail started wagging.	1. Your head speed has increased, possibly a lean engine or from changes you made to the throttle curve. 2. The helicopter is out of balance. Vibration is the cause of low gain settings. Check the blades, check for bent main shaft, spindle shaft, tail shaft, out of balance tail blades, etc. Also the start coupler could have become crooked the last time you started the heli. 3. I found that a sticky clutch caused me to have to turn down my gain by 20%. Check the engine/start shaft alignment and look for a broke shoe. 4. If you have a Telebee gyro then check to see if the circuit boards inside are vibrating. Look for signs of white dust.
HH doesn't hold good	1. The RPM's should be 1850 to 1950 for 3D flight on a 30 size, and 1750 to 1850 for a 50 or larger. It's also important that your engine is running good. If your engine loads up a lot then you won't be able to keep a consistent RPM. Remember that if your main rotor speed drops 300 rpm, then your tail will drop over 600 rpm. 2. Tail blades too short. For the Raptor 30/50 85mm blades are as long as you can use without risk of hitting the main blades. So to improve performance use blades that don't flex and have a wide cord, like the NHP 85mm carbon tail blades.
Tail was fine but then started behaving weird and would let go	That is a standard reaction to a low receiver battery. The tail is usually the first to show signs of low power.

Clutch Troubleshooting

See Clutch Repair section

Radio Glitch

1. Bearings - The common cause is notchy top and bottom main shaft bearings that have been damaged in a crash. The pinion gear bearing is also a high suspect as well as the bearing inside the clutch bell and the top start shaft bearing.
<R30v1>2. The screws that hold the tail boom support rods to the horizontal fin are just a little long. Use a dremel cut-off wheel to take off the last 1/16"-1/8" from the screw. This will keep it from making metal to metal contact with the tail boom. The v2's use a much thicker end on the rods and do not need to be cut down.
3. Make sure you don't have the antenna wire beside a servo wire or the servo.
4. Look for any metal to metal vibration, from something loose or even something broke, like the right tail boom support rod. If it cracks, it could be causing the interference.
5. If you run an antenna wire parallel with a metal object like the tailboom or the support rods, then they will absorb RF and cause range problems.
6. The tail rotor control rod coupler could be vibrating against the tail boom.
7. Have you recently added anything to the heli just before the glitchs began? A friend crashed while learning and decided to make a bigger landing gear. He made one out of metal. Although everything was secure and not vibrating, it cause him RF problems. Maybe because of reflecting or absorbing the signal.
8. Another possibility is that if your struts have worn through on the bottom like mine, then the skids might be loose enough to vibrate against the set screws.
9. An intermittant on/off switch. The contacts inside get carbon buildup and make a 'dirty' connection. Some devices like the Gem 2000 are designed to detect this.
10. The battery pack maybe bad. The connections from one cell to the other, and the plug wire that solders to the cells can break if exposed to a lot of vibration or hard hit from a crash.
11. Look at your antenna wire, if there are any hard bends, the wire might be broke inside. Use fuel tubing to help prevent this.
12. If you can't find any problem with the helicopter, then you need to send the radio and receiver in to a service center. They can check to see if the frequency has drifted and do a vibration test for intermittant connections inside the receiver.
13. If you have a Gem2000 then unplug it. I know of two cases in which this device was defective and causing the servos to jerk.
14. The antenna in your radio could be loose. The antenna can be removed by unscrewing it and sometimes it will become loose on its on over time.
15. For belt driven tails, the belt can develop a high static voltage that can cause the radio to glitch when the voltage arc's. Grounding the tail boom to the engine can help prevent the problem. (Tip contributed by Dave Tilton).
16. Do you have the antenna wire tied in a knot? This will cut down on the range.
17. <Raptor 30v2/50v2> On my helicopter I had a radio problem that started a couple of months ago and slowly got worse. It would show up as a wobble just like you would get at a slow head speed. This would happen at a certain rpm around 1800. Eventually it got to the point that the problem would show up three or more times during a flight. The problem turned out to be the start shaft. Some of the black oxide coating on the start shaft had worn off where the clutch bell bearing and top start shaft bearing sit. This changing conduction points was the problem. In radio issues no conduction or a constant conduction are fine, however a changing conduction creates problems. What I did was to use a dremel to grind away the black oxide coating from these areas.
18. At idle the servos were going nuts. I was thinking bearings or antenna routing but the problem turned out to be my remote glow adapter wires were touching the wire leads of my throttle servo. I put a couple wire ties on the remote glow adapter wires and my RAPTOR is fling great again! - Tip contributed by Ralph StClair

Vibration
on spool up	1. If say one blade is straight out and the other is just a little off, then there will be an off balance until there is enough rpm to pull them centered. 2. If the blades don't have equal tightness, then one will lead/lag more then the other until they get up to speed. 3. If the blades are too loose that will cause it too.
when landing	Just after you touch down and as you lower the throttle stick, the helicopter shakes bad until the blades spin down enough. Problem is noticed when on a hard surface and does not show up much when on grass. 1. The 25% throttle position is too high. 2. The 25% pitch setting is too low. 3. The engine is not tuned right, the low speed needle is too lean. 4. If the blades are too loose that will cause it too.
horizontal fin/ up/down tail	The up/down vibration of this fin suggest the source of the vibration is from the tail if the frequency is very high (in the 8Khz range. If it is in the 1.5Khz range then it is from the rotor head.. 1. Main blades not in track. 2. Main blades not balenced. 3. Tail blades not balenced 4. Bent tail rotor shaft. 5. Bent or cracked blade grip 6. Bent pitch arm on slider 7. Worn/loose belt 8. Worn output or input shaft pulley. 9. Bent main shaft
Tail fin side to side vibration	The static tracking of the tail blades is bad. This is often due to a bent tail hub. If you have the older tail hub that came on the R30v1 then the long set screws that go into the hub could be bent. To check the static tracking place the tail blades at zero degrees pitch and rotate one blade so that it is pointed forward. Measure the distance the tip of the tail blade is from the tail boom. Now rotate the other blade forward and measure again. They need to be the same to be correct.
using training sticks	The rpm you are running is in the resonate frequency of the training sticks. 1. Try a higher or lower throttle setting. 2. Change the angle of the traning sticks. 3. Cut off an inch or two to change the resonate frequency of the sticks. 4. If using the Roto-pod then make sure the center bolt is loose enough to allow the platform to rotate.
fuel foaming	This is usually a sign of a vibration related to the engine area. This is because fuel foaming is caused by a frequency higher then what the rotor generates. 1. If the engine is running bad, then it will produce a lot of extra vibration. 2. Check the runout of the engine crankshaft. 3. Use a high point balancer on the fan/hub 4. Check for a bent start shaft. 5. Check if the start shaft coupler rotates straight.
whole heli shakes / Wobble	1. R30/50 Check for a loose bolt(s) (Page 11, Step 11, Item 1) that go into the flybar see saw hub. 2. Blades are too tight. Adjust the tightness of the blade bolt just tight enough so that if you hold the helicopter on the side with the blades stretched out and parallel to the ground then give the helicopter a bump the blades will not move. 3. Check the grease on the rubber dampeners. You can do this by taking one blade off then rotating the nut/bolt on the end of the spindle shaft clockwise. If it rotates easily then it is lubed well and that is not the problem. 4. Check the tightness of the links on the head. You should be able to twist the links with very little resistance. If they are hard to twist then take the link off and resize it. Also check the tightness of the bolt through the mixing arms (both the ones on the see saw hub and the mixing hub). With the links off they should rotate easily.
Can feel it when idling	The clutch and/or fan is out of balance. If you are using the stock fan then it is relatively light weight compared to the clutch. This is how I align the clutch <here>.

Blades out of track
standard first time setup	Use the blade that you did not use to set the pitch with. If you did not use a pitch gauge or do not remember which blade it was, then it depends on how you want to affect the head speed. If you want more head speed, lower the high blade, if you want less head speed, raise the low blade. If you want to maintain the head speed, you have to raise the low blade and lower the high blade by the same amount.
going out of track in flight	1. The flybar control arms (the 90 degree arms against the see saw hub) are loose due to the set screw threads stripped or the set screw was not on the flat spots on the flybar. If the threads are stripped just take the inside metal hub out then rotate it 180 degrees and re-insert it for a new set of threads. 2. Covering loose. If it's the heat shrink type covering, then reheat it to shrink it. 3. Bad blades, a)one flexes more then the other. b)the chordwise CG is too far to the back. Hang the blade from the bolt hole, it should hang straight down. 4. Spindle shaft bent. This will cause out of tracking problems as the shaft rotates. To check it take one blade off and turn the nut on the end of the spindle shaft while you watch the tip of the other blade. If it moves then the shaft is bent. 5. Thrust bearings installed backwards - <click here>. 6. Thrust bearings are damaged, look for missing or loose balls in the cage. 7. Your rpm is too fast. Keep it under 2000. For me, 1850-1900 is a good speed for 3D flying, 1600 for normal flight mode. Too high of an rpm causes the thrust bearings to become notchy. 8. Lube the rubber dampeners in the rotor head using dielectric grease. This is 100% silicon that can be found at an automotive parts store. I have found this to be the most common problem. 9. Check the bolts in the top of the head that go into the see saw hub (the thing the flybar goes through) R30/50. 10. Head block may have become oval shaped where the top of the main shaft is. This can happen from a crash. See if you can rock the head side to side and see the main shaft move inside it. Also make sure it's not something simple like the head block bolt being loose. Do not over tighten this bolt as this could cause it to snap in flight. 11. Dan Kitching has a good idea to stop the woof n' poof that some have experienced on the 30's R30/50. Even if you don't have this problem, it's still an easy and cheap way to make a tighter control system. He glues the sleeves on the screws for each pivot point using epoxy. He used to have a diagram showing this but since then his website has gone down. 12. Lube the pivot pin in the center of the head block and also the rubber head dampeners. 13. Check static tracking. Raj Patel has a good webpage about this. 14. Loose fit of the bearings in the blade grips <here> R30/50. 15. I have heard of a Raptor 50 (600mm blades) being cured by using the upgraded metal pitch arm MPV0012 R30/50. The idea is that the pitch arm was twisting. Another idea is some pilots with the Sceadu helicopters have fixed their 'woof' problem by removing the brass inserts in the rubber grommets of the collective servo. This is probably changing the resounce frequency and is the reason it works. 16. Some have reported a sloppy swashplate was the cause 17. 0 Delta mod 18. Flipping the head to change to negative delta R30/50 Note: I have never had to do this to any of the Raptors I have fixed. There are thousands of Raptors flying with the stock setup that do not have a problem, so the design is fine and should not need to be modified. If you do flip the grip you should be aware that you will loose some cyclic authority and may need to install some faster paddles depending on your preference. Also it is just a band-aid fix as it does not fix the real problem. 19. Some have found tightening the blade grips so the blades can't pivot out as easily solved it. 20. Check for loose elevator A-arms. This is what I found on one of my friends Raptors. 21. Screw that holds the ball on the blade grip could be bent. Tip provided by 'Raffy' on the RunRyder forum.
Blades only out of track on one side	The flybar paddles are not aligned. Go to <this> page for info on figuring out what is wrong.

Flight characteristics
The tail 'kicks' during spool-up.	1. The spring pin (page 12 (14)HMU2-12B) R30/50 has come out and is catching the inside of the tail case. This happened with a friend of mine. He asked me about the tail catching during spool up about four months ago. I told him that either his belt was loose or had a stretched spot and the teeth were hitting each other inside the tail boom. Last weekend I checked his belt tension and it was very loose. We tightened it up and that seemed to fix it until he lost tail control during a flight and crashed. What happened is when the belt was tightened, that caused the red pulley to hold the pin a little tighter and pulled the pulley further away from the back part of the tail case where the pin had visibly been grinding on. That's why it seemed to fix it, but it instead gave it just enough extra room for the broke pin to come out of the tail shaft. The inside of the tail case had held the pin in for many months. You could see where the pin was grinding the case out. So if you see your tail rotor catching during spool up, stop and take the tail case apart so you can examine the pin. 2. Belt has a stretched spot either from factory or caused by a crash. I had a bad one from the factory on my Raptor #2.
Pitchy in FFF, rolls/flips too slow	1. Check the CG <here> 2. Blade troubleshooting
Nose dips down in forward flight	Check the CG <here>
Oscillating wah-wah type sound during descents, helicopter shakes	1. richen the low speed needle, read Engine Tuning How-to 2. clutch is gripping too much, maybe about to break 3. shoes are dragging on the fan hub. 4. another possible problem is the engine/start shaft alignment. I don't know if this will difinitely cause the problem, but I highly recommend checking it. Any extra vibration in this area can cause problems. 5. Resonant frequency due to frame flexing. 6. up/down play in main gear 7. use constant tail drive or slipper clutch to add loading R30/50 8. Autohub is causing the problem, try removing all oil from it. 9. Possibly caused by loose fitting pinion bearing R30/50
When I try to lift off, the helicopter spins around really fast!	Click <here>

Mechnical Problems
Knocking sound when moving the elevator arm back and forth	R30/50 This is caused by the front section of the elevator control arm (pg 8, step 6, item 15) is hitting against a corner of the frame spacer that is behind the top start shaft bearing (pg 6, step 3, part BK0059). You can fix this by rotating the frame space so a flat side is toward the elevator control arm instead of a corner.
Belt ate the bottom flange of the front left pulley	R30/50 When you install the tail boom you need to hold up on the boom and tighten the four bolts up front then the two in the horizontal fin. If you don't then the boom will be at a slight down angle which causes the belt to ride on the bottom flange instead if riding between the flanges.
Main shaft bolt broke	The main problem is that most people overtighten these two bolts. The top and bottom bolts are the only things holding the entire head to the body of the helicopter. So most people react by overtightening these in anticipation of preventing the head from coming off. Unfortunately this actually increases the chance of failure. By tightening this bolt too much you have both a force stretching the bolt as well as side force from the two edges of the main shaft. This in combination will snap the bolt. In addition another side effect has to do with the bottom bolt. Too tight will warp the autorotation hub sleeve and not allow it to work well. === The new v2's have long shanked bolts to help with the problem but some are also shearing these so replace them after every 8 cases of fuel in the R-50. We also glue the head block on. People doing milder flying will have no issues and others are actually drilling the freewheel and rotor hub along with the mast to use a slightly thicker bolt. - tip contributed by Stephen Bell

Crash Failures
Chopped the tail boom off while flying	This is most often due to the blades being too loose in the grips. I see loose blades all the time. You should be able to hold the helicopter on its side and the blades should stay in place even with a slight bump. If you are performing a maneuver and lose a lot of head speed then with loose blades they could easily pivot. When they do this they can easily reach the tailboom.
Crash after repair	After repair from a previous crash you are hovering or otherwise not doing any high load maneuvers then suddenly the helicopter crashes. This most likely happened because of a link failure from the previous crash. It is important to check all of the links. If you can pull one off without much pressure then it needs to be replaced.