Parts to Monitor
last updated 11-23-2004

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Most common parts to check
Ball links To check a link pull on it and see if it comes off. If it comes off with light pressure or you see side to side slop of it on the ball then it is time to replace it.

The links that wear out most often are the ones close to the ground. This would be the one at the back of the tail control rod and the ones on the throttle link. Note: If you put a new link on and it is still loose then what happened is dirt got embedded into the old link and it wore down the ball. You have to change both the ball and the link when this happens.
Fuel line inside tank One of the number one causes of engine tuning problems is from detoriated clunk line. At the end of a flight the tank is full of hot exhaust gases that break down the silicon fuel tubing. This makes the line soft and soggy. It can also crystalize.
A-arm rods Check the metal rod at the bottom of the A-arms. If the holes in the A-arms are tight it can cause the rod to eventually work its way out.
Rubberbands One is on the radio tray helping to hold the receiver and battery in place and the other one to check is holding the antenna wire at the back.

Less common parts to check
Ball Links screws It has not happened to me but a few times, but sometimes when looking for slop in the control system I have found the screw(s) that hold the balls on are loose just enough that the ball moves on it.
Check pitch arm The two screws that hold the pitch arm on can back out sometimes and cause side to side slop.
Check clutch If you have the engine out and you notice the edge on the back side of the shoes are not parallel to the straight edge of the hub then the clutch liner got too thin and now you have to change both the liner and the clutch. Ideally you should check the gap between the liner and the clutch shoes and when the gap is more then 0.010" per side then replace the liner before the clutch is damaged. If you do not have feeler gauges then take the start shaft out and the clutch off. Place the clutch in the bell and push it to one side against the liner. Next see if a business card will squeeze between the clutch and the liner. If it fits loosely then replace the liner. Read this.
Muffler bolt If you bought a Raptor 30 and are using the stock two or three piece muffler then the long bolt that goes through from front end to back will become loose from time to time. It's best if you tighten the bolt immediately after a flight, while everything is still warm.
Muffler bolts The bolts that hold the muffler on have spring washers which lose their spring when they get hot. This makes the muffler vibrate loose, resulting in a very lean engine which can quit if you keep flying. (submitted by Gary Benade, thanks Gary :)
Carb nuts
and bolts		 1. The nut that holds the main needle on the carburetor could be loose from the factory.
2. Also check the nut that holds the throttle lever arm on.
3. And the bolt that holds the barrel in. It is the one that goes in at an angle.
Dirt in plastic links If you find a loose link and find the plastic link still snaps on another ball fine, then suspect dirt in the plastic link. This grinds on the metal ball. Change both the link and the ball.
Tail blade grips Check for slop in the tail blade grips on the tail hub. If it is very loose that is a sign that the nuts or set screw going into the hub has backed out. If it is just a little slop that could just be the fit of the blade grips on the bearings. If that is the case you can sand a little off the inside of one grip and that will allow it to squeeze closer to the bearings.
Rotor head double link A flying buddy had an in-air boom strike that we believe to be caused by the double link on the rotor head breaking, so check yours for fractures caused by a previous crash and make sure they fit on the ball good. If you can easily pull them off then you need to replace it.
Locknut loose on the
main shaft		 As part of your pre-flight check, make sure the bolt and locknut on the bottom of the main shaft is secure. Note: do not overtighten or this will cause the autorotation hub not to work. (tip came from Bob Cardone, thanks Bob)
Bolt through auto hub I found this bolt was broke in 3 places on a crashed Raptor of a friend on mine. I helped him put the crashed Raptor back together then we flew a tank through it and while fueling up again, we found the head of this bolt was gone. A section of threads and another section of threads with the nut on it was all that was left. This very easily could have caused another crash. So after a crash or hard landing check this bolt. Also make sure the bolt is not tightened too much. This will help cause the bolt to break.
Start shaft bearing block After 534 flights Raptor #1 had worn out the start shaft bottom bearing block. My guess is the bearing got too much dirt in it and eventually locked up causing the bearing to rotate in the bearing block. It melted the frame and covered the bearing with a coat of plastic.
Gyro tape I regularly check this by slightly pushing on the gyro to see if the tape tries to separate. I typically have to replace the tape that came with my Futaba gy401 gyro about every 500 flights using 15% nitro fuel. If you fly 30% then it will greatly shorten the lifespan of the tape.