September - October - The Recreational Aircraft Association

Safety
Propeller Safety / Gary Wolf
Another non certified in-flight
adjustable prop failure, this time on an
O-360. It appears that the crack started
from one of the internally-drilled holes
for the blade retainer. In this case the
engine mounts broke immediately, but
fortunately the engine stayed within
the cowling. The damages to the plane
and floats will approach $50K. RAA
prevailed upon this low-production
manufacturer to recall all of his props,
and he has done so. There were only
two examples of this prop in Canada.
The manufacturer has also agreed to
remove the O-360 as a recommended
installation. We have sent photos and
a cautionary note to the TSB and to
MD-RA. Since there is no more risk to
Canadians and the manufacturer is
acting responsibly, we are not naming
him at this time.
A Hartzell or other certified constant
speed prop costs only a few thousand
dollars more than a non-certified prop,
and the Hartzell comes with thousand
of hours of testing. Many of the noncertified
prop manufacturers do their
testing on the customer. In this case
it was a false economy - this pilot will
miss the entire flying season while he
rebuilds his airframe and dismantles
his engine for inspection.
Top: The rebuild of the airframe begins here.
Above: the prop hub.
September - October 2007 Recreational Flyer 35