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the feathering shaft on a Belt CP
This information applies to both the Belt
CP V1 and V2, but be warned, the two use different size feathering
shafts and different methods for tightening them. Both will be
covered in this article.
If you have damaged a
feathering shaft, remember to also check the mainshaft, as it may well
also be bent.
REMOVING THE DAMAGED
First thing is to remove both main blades,
making sure you do not loose the little Nylock nuts from under the
blades when you remove the fitting bolts.
Belt CP V1
The V1 uses nylock nuts to lock the main
blade holders onto the feathering shaft. These are 5.5mm so because they
are buried down inside the blade grip, you need TWO box spanners that
will fit inside there, which means they need to be fairly thin walled.
put a box spanner on the nuts at either end, and undo by turning them
anticlockwise. They should undo relatively easily.
Belt CP V2
The V2 uses metric Cap Screws to lock the
main blade holders onto the feathering shaft. Because these are buried
down inside the blade grip, you really need TWO metric hex drivers
rather than normal allen keys. Put one in each cap bolt at either end,
and undo by turning them anticlockwise. They should undo
relatively easily, however, they may also have been thread locked
in. If they will not move, use a soldering iron to heat the cap
bolt head and try again. This will usually allow you to undo them.
Once the bolt/nuts are off, pull just one
blade grip off carefully. Make sure you don't loose the small
washer that fits under the bolt/nut. Once the blade grip is off,
remove the various shims and washers, NOTING THEIR ORDER AND THE
DIRECTION AS WELL as one has a small flange (V1 only I believe) that
MUST be fitted the correct way around. In that washers case, the
small flange that sticks outwards MUST go against the INNER BEARING
ITSELF to avoid any binding.
Lay the parts out carefully, and in the
order they came of the feathering shaft.
If the rubber dampers are still in the main
head casting, remove them as well and inspect them for cuts or
Now pull the entire feathering shaft out,
complete with blade holder or whatever is still on the other end, and
disassemble and lay out as per the first side.
If the feathering shaft is too badly bent
to be pulled out, you may have to resort to cutting it off close the
head with a hacksaw so that it can be removed.
REFITTING THE NEW
Basically this is a simple reversal of the
above procedures, but care needs to be taken to get the thrust bearings,
shims and washers in the correct position and direction, and to get the
blade grips pinched on to the new shaft with the right level of
tightness. Also check the rubber 'O' ring dampers for any cuts or
softness. If there are any, always replace them as they are
crucial to goof flying and accurate tracking.
Check the blade grips carefully, as they
can be cracked in a crash, especially on the arm where the connecting
ball fits. If in doubt - REPLACE THEM
The thrust bearings can be difficult, so
care is needed, plus you will need something like a vernier caliper that
can measure the inner hole diameter, as the two
outer parts of these three part bearings have DIFFERENT SIZED INNER
HOLES. The one with the LARGER DIAMETER INNER HOLE MUST BE ON THE INSIDE.
Belt CP V1
Because the V1 uses the nylock nuts to lock
the main blade holders onto the feathering shaft, you have to use some
care and finesse to get the tension on them just right, as both ends
need to be tightened up at the distance along the thread. A trick
I use is to prelock one nylock nut on to the end of the new shaft, and I
then thread lock it so that it is unlikely to move when I tighten the
other one, with about 4 threads of the feathering shaft showing out of
Then assemble the other side, and pull that
nylock nut down until it is about the same distance on to the feathering
shaft. If you get this right, you will find that it should also be
showing around 4 threads sticking out of the top of the nylock nut. Now
continue tightening carefully until the blade grips start to bind
slightly when turned on the shaft, and once that point is reached,
loosen the nut until the grips are just nice and free to rotate.
Belt CP V2
Because the V2 uses the Cap headed bolts to
lock the main blade holders onto the feathering shaft, rather than the
nylock nuts used on the V1, it is very simple to get the tension on them
just right, as both ends normally need to be tightened all the way up to
the end of the shaft. It is a good idea with these to use a very
small amount of thread lock on each bolt to ensure they cannot vibrate
Finally check that the blade grips to
ensure they are nice and free to rotate, and that there is minimal
"teeter" which means up and down movement of the blade grips.
Belt CP V1 exploded parts diagram
(CLICK IMAGE FOR FULL DETAILED GRAPHIC IN A NEW WINDOW)