Ivoprop
- Ivo prop - Ivo propeller
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1-800-FOR-PROP |
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Service
Bulletin #4 Jul-9-98 Subject:
Ivoprop Magnum & Direct Drive Engines or 2:1 Reductions Purpose: To
detect blade movement inside the hub due to improper installation
and, or harmonic resonance between prop and power plant. To prevent
further flight if this situation is detected and develops in unsafe
condition (Aluminium bushings inside the blades becoming loose, breaking
bolts, blades etc..) Introduction:
Above mentioned combinations produce high level of torsional pulses during
their firing cycle which several times exceeds their nominal torque and
also torque reversal pulses. If the prop is mounted loose and, or gets in
a harmonic resonance with the engine the blades could move inside the hub
back and forth in a plane of prop rotation. What
to do: Prior to the next flight or airboat ride accomplish the following: Get torque
wench and check its calibration by hanging a known weight on its arm and
multiplying the weight in pounds by arm in feet. This reading should be as
close as possible to actual recommended torque on Y2 " bolts (we
tried several torque wrenches and most of them were off by a lot). Mark
the prop position in relation to the crankshaft. There are 2 positions to
mount 3-blade prop and 3 positions to mount the 2-blade prop. This makes a
great difference in how the prop and engine vibrate together and each
position creates totally new situation. It is impossible to determine
which position is best for your particular prop engine airframe
combination without actual testing it on it. Torque
the 1/2" bolts to new torque value of 65 ft. X lbs. Run
the engine momentarily on the ground through the full RPM range. Check
the torque on 1/2" bolts and if you are not using lock nuts safety
wire the bolts. Cut
the strips of stainless steel tape about 2 "long and 3/8 " wide
(tape supplied with this S B. Clean
the area around gap between blades or gap between blades and blade blocks
by rubbing it with clean napkin soaked with ME. K solvent. Apply
stainless steel tape across the gap next and parallel to mold parting
line. Use a round object to press the tape on the surface. Follow
this inspection schedule to check if tape is broken: After
short ground run up through full RPM range on the ground and then first
15minutes, 30minutes, I
hour, 2hours, 4hours and then every preflight inspection. Also follow this
schedule from the beginning if the prop has been reinstalled in a
different position in relation to the crankshaft. If
tape breaks or cracks remove the tape, clean the surface with M E. K and
apply new tape and start the inspection schedule from the beginning. ff
tape breaks again remove the prop from the service and contact IVOPROP
Corp. Request
to dealers: please forward this S.B. and stainless steel tape to your
customers who are subject to this S. B. Keep the record of addresses of
your customers to which this service bulletin applies. Make sure that any
prop being sold to the above-mentioned combinations is accompanied with
this Service Bulletin Compliance.-.
Mandatory Note: Do not use prop in 2-blade configuration without blade blocks (missing pieces of pie, which fill out the big gaps between the blades. POPULAR
WAYS HOW TO MOUNT PROP LOOSE Not
torquing the bolts Do not rely on feel, Get torque wench and calibrate
it by yourself. Torque on 1/2 " bolts are 65ft. X Lbs. (not 65 inch X
Lbs.) Bottoming
the thread of the mounting bolts into the driving lugs or lock nuts.
Use extra washers if the bolts are too long. Not
having driving lugs pushed all the way into the flange. Inserting
spinner composite backing plate anywhere between what bolts are
supposed to compress together, these fibreglass or composite backing
plates compress with a heat and pressure and you loose torque on the
bolts. Using
wrong hardware Another
example - if your 2 1/4 " diameter center boss is too long or the radius
at its base to big to accept our hardware.
Knurled
Plates Instructions Magnum Model The knurled plates shall be installed so that knurling finish on each plate is in contact with the blades. The
knurled pattern is 60 degrees symmetrical so if you reinstall the blades
between crush plates later in different position the imprint on the blades
should match the knurled pattern. However (because the manufacturing tolerances) to get the best match number the blades and plates and always put the blades back in the same place. Torque
the mounting bolts to 65ft x lb. dry (no oil or lubricant on the
thread) and run the prop momentarily through full RPM range. Re-torque the
bolts. Repeat
the above procedure until the torque stays the same. Install
the service bulletin stainless steel tape and follow the inspection
schedule from service bulletin. Any time you inspect the tape check the
torque on the bolts during the first four hours. After that check torque
every ten hours.
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IVOPROP
CORP |
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1-800-FOR-PROP |