Tips about Helicopter Maintenance
Today I would like to share some experience about RC helicopter maintenance. We all know the importance of keeping the heli always in good condition so the heli won't crash due to mechanical problem. Just people may overlook some worn parts which may not be visible such as bearings that will become a serious problem eventually. For example, a worn bearing will induce high frequency vibration, that will wear the shaft or other metal support parts further. What I'm trying to point out here is the improper maintenance (or not doing maintenance), not only the improper assembly, will cause serious crash. Therefore, it is highly recommended to check (even disassemble) those moving parts periodically, and replace the worn parts especially bearings before they could become an issue. It is definitely nothing but good.
Now I will share with you which parts I always check and replace most frequently. The first item is the bearing (actually those bearings). It is always suggested to use a brand-new, high-quality genuine bearing which is much more durable. Even with a high-quality bearing, probably it will be worn easily than you may expect. For example, the one shown in the picture below that taken off from the main grip, has just been used for 350-400 flights (and never crash). It must be replaced with a new one under this condition.
As the bearing is placed symmetric (two blades per one main rotor, one bearing was installed per each blade grip), the bearing from the other grip should be replaced at the same time.
The bearing I chose is from Singapore (SKF/EZO).
A drop of Loctite threadlocking is still required to secure the feathering shaft screw though this will make it harder to disassemble and check the bearing later. Anyway, it will be easier to remove the screw by heating up the screw for 1~2 minutes.
Normally the thrust bearings are more durable. We only need to refill the bearing grease during the maintenance.
The main grip bearings of both helicopters have replaced with new ones. I also found one of the linkage ball was worn. This may wear the plastic ball link soon eventually. Thus I replaced this linkage ball as well.
The maintenance of main rotor head of heli #1 is done. And I always spread a thin layer of antirust oil afterward. Even the steel screw won't rust.
The antirust oil is also applicable to outside of the motor.
Now let's look at the tail gear box. Any little wornout happened in the tail will cause vibration that become is a serious problem for tail performance, even cause a crash due to tail failure.
The tail gear box become dusty easily. It is suggested to disassemble this portion and clean up all the parts from time to time.
Don’t be rush! Make sure you clean up every part completely.
These parts were replaced with new ones. Just they seem still work. Thus I keep them as spare for emergent use in the field.
Assemble the new parts accordingly. Don't forget to apply Loctite threadlocking.
I spread a thin layer of CLP to all metal parts and screws. Then use a dry cloth to wipe any residue of CLP. Now all the bearings have been replaced with brand new ones, and both helis look shining. You may also check the 2nd bearing base of main shaft (for heli such as GAUI X7 and Align 700E), and change the bearing if you see need.
Here I have a tip to make those bearings more durable. You may get the Scorpion Motor Bearing Lubrication Kit. And apply the oil to all bearings using the needle point applicator every 3~5 days of flying. This will double the life cycle of bearings.
Using a soft brush to clean the main gear. And do not apply extra lubricant here.
Both helicopters look great after proper maintenance.
You will notice the test flight is much quiet than before.
In summary, here I show the pictures for some common bearings to be check.
(main shaft bearing, main grip bearing, tail drive gear bearing, tail box bearing, motor bearing)
Last but not least, you shall also check the connectors between power cable and battery, said every 200~300 flights.
You may need to replace the power connectors if you see them get loose or wear. Otherwise, power failure could happen unexpected during the flight, and cause crash if you do not know (or have no chance) to perform auto-rotation.
You may also check the battery side.
I always keep some spare connectors.
New connectors make you feel safely.
Regarding the battery, if you realize you are not going to use the battery for a while for some reasons, you may charge/discharge the battery to 3.8-3.85V per cell for safe storage until you are ready to use the battery again. Do not leave your LiPo packs sitting around on a full charge for more than a couple days. The battery life and performance will be affected significantly by the way the battery is charged, discharged and maintained.
Hope my sharing is helpful to you. Enjoy and fly safely!
Article Source: 5iMX.com