The Squirrel helicopter was being used to carry an underslung
load of operating fireworks during the Perth Australia Day
fireworks display. The helicopter's flight path followed the Swan
River, remaining clear of spectators. After the fireworks were
ignited, some projectiles from the fireworks appeared to pass
through or close to the left side of the helicopter's main rotor
disc. The helicopter was not damaged.
The helicopter operator had approached the local District Office
of the Civil Aviation Safety Authority (CASA) for an approval to
conduct the display. The operator was of the understanding that the
fireworks were non-projectile and advised this to the local CASA
officers. Although the company fitting the fireworks had advised
the event promoter that the fireworks included eight-shot Roman
Candles, eight-shot Crosette Candles, Flares and Silver Fountains,
the event promoter, the local CASA officers, and the operator
expected a cascading type display with nothing ejecting from the
helicopter's underslung load.
Because it was the first display of its type in Australia, the
local CASA officers sought advice from CASA officers in Canberra.
Although the Canberra based officers advised against approving the
display, the local CASA officers considered that because the
fireworks were non-projectile, the display could be conducted
safely if the operator met certain guidelines. The helicopter
operator was also required to demonstrate that the rig, on which
the fireworks were mounted, could be safely flown as an underslung
load. The local officers reported that CASA officers in Canberra
advised that because the fireworks were being flown as an
underslung load, they were not regarded as dangerous goods.
The rig on which the fireworks were mounted, was a large
circular metal frame attached to the helicopter by web-type slings.
When flown, the rig demonstrated good flying qualities and the
local CASA officers reported that the mechanisms securing the
fireworks to the rig appeared sound. However, the assessment flight
was done without the fireworks attached or a test firing of the
fireworks. A Flying Operations Inspector from the local CASA
district office granted conditional approval for the flight. The
conditions included requirements to remain a minimum distance of
300 m from the shoreline and that the display was not to be flown
over any person or boat.
The helicopter lifted the load from a pad near the Swan River
and while it was flying along the river, the fireworks were ignited
electrically from a control box operated by a pyro-technician
sitting in the cabin. The pilot reported that he was surprised when
the first fireworks ignited, that they were red flares that ejected
from the rig. However, they operated without incident. The
cascading-type fireworks also operated without incident but when
the Roman Candles fired, some of the shots fired upwards towards
the helicopter. The pilot reported that he had felt the rig moving
in response to the igniting fireworks but this movement did not
affect the controllability of the helicopter. He was unaware that
any of the shots had come close to the helicopter until the copilot
later reported that some had appeared to do so.
After the helicopter landed, it was found that eight rounds of
the Roman Candles had dislodged during the flight and fallen from
the rig. The recoil generated by the shots ejecting from the rounds
appeared to have caused the rounds to move up and out of the
securing straps. As the rounds fell from the rig, they tumbled and
the shots continued, some of which passed close to the helicopter.
The company that fitted the fireworks reported that the strength of
the recoil generated by the Roman Candle had been
underestimated.
During the investigation, it became apparent that there were
differing opinions as to whether an underslung load was considered
to be part of the helicopter with respect to dangerous goods
requirements. CASA subsequently informed the investigation that
anything attached to an aircraft is considered to be part of the
aircraft and that dangerous goods carried as an underslung load
must be treated no differently from dangerous goods carried inside
the aircraft. CASA also advised that dangerous goods carried
differently to that which is required by the Civil Aviation
Regulations must be subject to written permission issued by
CASA.
There was a misunderstanding among the pyro-technicians, event
organiser, helicopter operator and local CASA officers in relation
to the types of firework being carried by, and fired from, the
helicopter. As a result, the approval given by CASA for the display
was based on incorrect information. The mechanisms that secured the
Roman Candle rounds to the rig did not prevent the rounds from
dislodging from the airframe and were therefore inadequate for the
purpose.
