Message text written by INTERNET:kevin@eastyorkshire.co.uk
>Please can anyone advise what the pitch should be at both ends of travel
on
my prop.<
I used to have an NSI prop and, although this was with a Rotax 912S with
non tapered blades (64" diameter), the setting up procedure is very
similar.
You only have adjustment of pitch at the low pitch end using an aluminium
spacer. The high pitch end is determined by the position of the peg when
the cuffs are installed at the factory. As I had been incorrectly supplied
with a prop designed for a slower aircraft using a Rotax 912 the max pitch
was initially limited to 24.5 degrees. The blades had to be returned to the
factory to have them reset which then gave a max pitch of 30 degrees. It is
important to check with a test flight that a go around can be safely flown
at max pitch in case the pitch motor fails in that position. I my case we
achieved a ROC of 300fpm which was considered adequate.
The choice of spacer for the low pitch end is chosen so that the engine
will not overspeed during take-off and initial climb up to about 80kts.
With the NSI this is an awkward procedure requiring a selection of spacers
of different thicknesses. I found that a spacer of 16.5mm thick gave a
minimum blade angle of about 19 degrees keeping the rpm within the 5800
limit up to 80kts. Unfortunately this took 3 attempts and the prop has to
be removed and fully disassembled every time the spacer needed changing. By
the third time I had got it down to a 2hr job. Great care has to be
exercised when splitting and reassembling the hub to avoid damaging the
sleeved wires supplying the pitch motor. This is an area where the
Airmaster is much better. The pitch stops can be adjusted without removing
the prop and even individual blades can be removed without removing the
hub.
Regards
Nigel Charles
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