The Cessna 185 (C185) aircraft had returned and landed at the
departure aerodrome after completing a charter flight of
approximately 90 minutes duration. The pilot reported that
following a normal landing and after the tail wheel had been
lowered to the runway, the aircraft nose commenced to yaw to the
right. The pilot estimated that the aircraft was travelling at
about 20 kts and despite applying full rudder and the use of
differential braking it was not possible to regain directional
control and the aircraft ground-looped. The left main gear-leg
collapsed and the outboard portion of the left wing was
substantially damaged when it struck the surface of the runway. The
propeller also was damaged on contact with the runway. The pilot
and three passengers were not injured and vacated the aircraft
without assistance.
The pilot had been endorsed on the aircraft approximately one
week before the accident. Although he had significant experience
operating other tail-wheel equipped aircraft, he had logged only 18
hours on the C185. The majority of that experience had been
accumulated while ferrying the aircraft from Moorabbin to
Broome.
Following the accident, archived data from the Broome automatic
weather station was retrieved from the Bureau of Meteorology. The
data indicated that at the time of the accident a southerly wind
was blowing with wind gusts recorded up to 11 kts. Analysis of the
data indicated that the pilot could have encountered a right
crosswind of up to 10 kts during the landing. That was within the
aircraft manufacturer's demonstrated crosswind limit of 15 kts.
The aircraft centre of gravity was calculated to have been
within published limits. However, it was close to the aft limit,
thereby making directional control more difficult in the gusting
crosswind conditions.
The weather conditions prevailing at the time of the accident
would have made the aircraft more difficult to control, especially
during the later stages of the landing roll as the aircraft slowed
down and the rudder became less effective. Directional control at
lower speeds becomes increasingly dependent on tail-wheel steering
and the use of differential braking. The directional instability
would have been further exacerbated with any sudden increase in
crosswind component due to the gusty crosswind conditions.