Challenger Force lands
successfully after prop failure
Evidence of blade strike (left)
and the noted lack of clearance between hub halves (right).
The manufacturer states that after the blades are torqued
there should be some clearance between the hub halves for
effective clamping of the blades.
This propeller was damaged during flight from striking
something, as can be clearly seen at the indentation on the blade
(arrow). Whatever hit the propeller split sections off both
blades, making it impossible to provide thrust and sustain flight.
Fortunately, the pilot was able to make a successful forced
landing on a road without further damage to the aircraft.
An interesting point arises as a result of this incident.
According to the manufacturer, this propeller hub requires some
clearance between the hub halves after the blades have been
torqued in place.
The specified torque value is 75 in./lb, never
to exceed 100in./lb. There appears to be no clearance visible on
either side of this hub, so it can be concluded that either
incorrect torque has been applied or the hub has been modified.
Although this is not a factor in the broken blade, the fact that
the hub halves may be incorrectly installed or torqued could have
resulted in loss of a blade in flight.
GSC PROPELLER TBO LIFE 5 YEARS/500HOURS 19 September 2001
Attached is a document from Zenair on the matter of Overhaul Lives for GSC
ground adjustable hardwood propellers. This has been passed to the AUF by
a Zenair owner.
Note that it gives an overhaul life of 5 years or 500 hours whichever
occurs first and that the propellers must be forwarded to GSC at that time
for airworthiness inspection. The AUF is advising of this document and
recommends that the requirements be met.
However, the document is dated May 1999 and GSC has been approached to
determine whether the figures given remain current.
In the meantime, all operators are to be aware of the attached
requirements which retire the propellers from service for GSC determined
airworthiness treatment after 5 years or 500 hours whichever occurs first
R Hewitt-Cook
Technical Manager
Zenith Aircraft Company
Mexico Memorial Airport
Mexico, MO 65265-0650 USA
(573) 581-9000
The following was received from GSC Systems (on May 17, 1999),
manufacturer of the two and three blade wood ground adjustable propellers
used as the standard prop with Rotax engines supplied by Zenith Aircraft
Company.
TBO TIME
ATTENTION: All owners of the GSC ground adjustable hardwood propellers,
we, the manufacturer of the GSC propeller are imposing a TBO time on all
our wooden ground adjustable propellers of either 5 years or 500 hours,
whichever comes first.
We recommend that when this time has been reached, your propeller be
returned to our factory for airworthiness inspection. Please contact our
warehouse to get necessary information on shipping method required to
return goods to us.
GSC SYSTEMS
6255 OKANAGAN LANDING ROAD
VERNON, BC VIH IMS CANADA
(250) 549-3772 PH
(250) 549-3769 FAX
OPERATING TIPS
ATTENTION: THESE TIPS MUST BE READ BEFORE OPERATION YOUR GSC PROPELLER
Ensure that installation instructions are followed precisely and that prop
attachment bolts are not torqued more than 100 in/lbs and a visible gap
between hub halves is necessary.
1. An initial visual inspection for cracks, nicks or any missing finish on
the prop
and subsequent inspections before each flight are recommended.
2. On an annual basis or every 50 hours, inspect and check propeller
attaching
bolts for tightness as well check that tracking and pitch are being
maintained.
3. Do not use the propeller as a tow-bar to move your aircraft.
4. Avoid running-up in areas containing loose stones and gravel.
5. Place the propeller in a horizontal position when stored for lengthy
periods.
Propellers should be rotated periodically when parked.
6. If your wooden propeller is stored in the elements, it is advisable that
a
propeller sock be used. These socks should be a material that is both
waterproof not allowing rain to enter but breathable, not causing moisture
to
be trapped under the sock.
7. GSC Propellers - TBO To maintain a like-new appearance, your propeller
can be waxed periodically with an automotive wax. Clean prop first with a
mild soapy solution.
8. Assume that your propeller is non-airworthy after any kind of impact
until it
has been inspected by qualified personnel.
9. If your propeller begins to show any of the following damage, it should
be
retired from service:
A deep cut across the wood grain
A long, wide or deep crack parallel to the grain
A separated lamination
An appreciable warp (discovered by inspection or through rough operation
An appreciable portion of wood missing
Obvious damage or wear beyond economical repair
A de-lamination of the leading edge protection
10. We hope that you have had a chance to go over all these stops and we
encourage
you to follow these instructions sinfully as well as the assembly
instructions to get
the best service from your GSC Systems propeller.
VERY IMPORTANT: If you are planning on selling your GSC prop, please
insure that operating tips and installation instructions accompany the
prop. If
you are not the original owner of this prop, please contact the original
owner
and check to see if operating tips and installation instructions were
followed.
For more information:
GSC SYSTEMS
6255 OKANAGAN LANDING ROAD
VERNON, BC VIH IMS CANADA
(250) 549-3772 PH
(250) 549-3769 FAX
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