Bell Helicopter Co 206B (III), VH-AZH, collision with water, Bendora Dam NSW, 13 January 2003

The pilot was qualified and authorised and had recent experience
for the operation.

The helicopter had sufficient fuel of the correct type on board
for the flight. Rotational damage to the main rotor system and
engine was consistent with engine operation at the time of
impact.

The helicopter was at high all up weight and operating close to
maximum predicted performance in an area with reported variable
winds. While those conditions would have increased the risk of
encountering LTE, the pilot was highly experienced in long-line and
water-bombing operations and had been operating in the area of
Bendora Dam for most of the day. That experience should have
mitigated the risk that LTE was a factor in this occurrence.

Although of a non-standard construction, the occurrence bucket
was assessed as being capable of normal operation, and was able to
be carried by the helicopter at its post-accident assessed
capacity. There was no evidence that it contributed to the
accident.

While the manufacturer of the 'Bambi Bucket' warns of the
possibility of dynamic rollover when conducting water-bombing
operations, the use of a 24m long-line by the pilot, and vertical
water pick-up would have diminished the likelihood for that to have
occurred in this occurrence.

The investigation could not confirm the position of the cargo
hook release circuit breaker prior to the accident. Had the circuit
breaker been in the open-circuit position the rapid release of the
bucket by the pilot, such as in an emergency situation requiring
jettison of the load, would not have been possible.

The nature of the helicopter's impact with the water, and the
resulting damage sustained by the pilot's helmet, reinforced the
protective benefits of the use of flightcrew helmets.

It is possible that, during the water pick-up, the pilot may
have been at a distance from the shoreline from which, had an
engine failure occurred, the helicopter would not have been able to
reach land. In that case, the provisions of CAO 20.11 would have
applied, requiring the pilot to wear a PFD. That would have greatly
eased the difficulty experienced by the helicopter crewman and
others performing the rescue and, potentially, lessened the
severity of the pilot's injuries.

Given the absence of pilot recollection and witness reports of
the accident, and the lack of detailed indications of operation of
the helicopter at impact, the reason(s) for the accident could not
be established.

While recognising that, in this accident, the pilot was rendered
unconscious and therefore unable to exit the helicopter without
assistance, the ATSB draws attention to the benefits of HUET.
Studies have shown that escape from helicopters involved in water
accidents can take longer than the average time that a person can
hold their breath. HUET has been shown to decrease exit times from
an immersed helicopter, and increase the likelihood of a successful
exit by an uninjured occupant. The provision of HUET to pilots,
aircrew and passengers regularly operating over significant
expanses of water would maximise the possibility for the successful
exit of occupants from an immersed helicopter.

The Bell Helicopter Company, JetRanger III helicopter was
engaged in water-bombing in support of fire fighting operations in
the vicinity of Bendora Dam, about 37 km southwest of Canberra. A
Bell 412 helicopter, with a pilot and crewman on board, was
conducting water-bombing operations in conjunction with the
JetRanger. An Aerospatiale A350 Squirrel helicopter had recently
returned to the area of operations and was conducting a survey of
the Bendora fire zone.

The pilots of the two water-bombing helicopters had seen each
other as they passed on opposite legs of a racetrack pattern
between the fire and the dam. As the Bell 412 returned to the dam
for water pick-up, the pilot noted the absence of the JetRanger
during that pattern. At about 1238 Eastern Standard Time, the Bell
412 pilot unsuccessfully attempted to contact the JetRanger pilot
on the radio. A short time later, the pilot of the Bell 412 noticed
the upturned fuselage of the JetRanger in the water. He immediately
broadcast a PAN call, and contacted the Squirrel pilot to advise
that the JetRanger was in the water.

The Bell 412 pilot released his water bucket on the shore of the
dam and established a hover close to the upturned helicopter. The
crewman entered the water and freed the unconscious pilot from the
wreckage. The Squirrel arrived at the dam and landed on the
shoreline and two of the occupants entered the water to assist the
crewman, who was experiencing difficulty keeping the pilot afloat
during the rescue. Once on the shore, the pilot was resuscitated
before being transported to a Canberra hospital. There were no
known witnesses to the accident.

The JetRanger helicopter was substantially damaged in the
accident. Examination of the helicopter indicated impact with the
water in a slightly right side down, nose-low attitude. Damage to
the main and tail rotor systems indicated that both rotors had been
under power when the helicopter impacted the water. Rotational
damage to the engine compressor and turbine assemblies confirmed
engine operation on impact with the water. Advice from the engine
manufacturer indicated that the engine was probably producing above
flight idle power at that time. There was no evidence of any
pre-impact engine or other aircraft abnormality that would have
contributed to the development of the occurrence.

A main rotor blade impacted the pilot's upper doorframe, and the
right upper overhead window. There was also impact damage evident
on the pilot's helmet, consistent with the helmet being struck
either by the door frame structure or a main rotor blade.

An estimated 135 L (107 kg) of fuel was on board the helicopter
at the time of the occurrence, which was sufficient for the planned
flight. A sample of that fuel was sent to a laboratory in
Melbourne, Victoria, for analysis. That analysis confirmed that the
fuel was free from contamination and of the correct type. Along
with a number of other helicopters, the JetRanger had been
refuelling from a mobile tanker. None of the pilots of those
helicopters reported any fuel-related problems during the day's
operation.

The occurrence bucket attached to the JetRanger was placarded as
a `Bambi Bucket' model 1012. The company operations manual did not
list the 455 L capacity, 1012 model bucket for use and instead
described the 545 L capacity, 1214 model bucket for use by company
aircraft when conducting water-bombing operations. The bucket
manufacturer left the choice of bucket for use when fire-bombing
with the operator. However, the bucket manufacturer did not suggest
either of the 1012 or 1214 buckets for use with the JetRanger.
Instead, the manufacturer recommended use of the 410 L capacity,
9011 model bucket.

The bucket was attached to the JetRanger's cargo hook by a 24 m
steel cable. Electrical wiring was fixed to the cable to allow
operation of the water release mechanism by the pilot and, when
required, to enable the addition of fire retardant foam. The cargo
hook unit included a manual and electrical release, to enable
pilot-activated release of the bucket and cable. The helicopter's
cargo hook electrical release circuit breaker was found in the
open-circuit position. As part of the investigation, the circuit
breaker was reset and the cargo hook release was tested
electrically and manually. While it could not be determined whether
the as-found position of the circuit breaker resulted from pilot
selection or the accident, both release mechanisms operated
normally during subsequent testing.

An internal `cinching strap' controlled the volume of an
`as-manufactured' `Bambi Bucket' via a series of metal `D' rings
positioned along the length of the strap. That allowed selection of
70%, 80% or 90% of bucket capacity. Nylon webbing loops stitched to
the inside of the collapsible synthetic bucket positioned the strap
inside the bucket. The bucket strap fitted to the occurrence bucket
was non-standard and did not include any `D' rings. Instead, the
strap had been tied off with a knot. That was contrary to the
bucket manufacturer's Repair Assessment Manual¹ that stated
that it was not an acceptable practice to tie knots on the strap.
The manufacturer cautioned that such actions may result in a false
indication of the actual maximum volume of water in the bucket.
Following consultation with the bucket manufacturer, it was
determined that the bucket was of a non-standard construction.

Examination of the occurrence bucket revealed that several of
the nylon webbing loops had been torn from the inside of the
bucket. The investigation was unable to determine when the webbing
loops failed. The bucket's capacity was 420 L measured in the
as-found condition. During that test it was noted that the
`cinching' strap exerted no influence on the bucket's volume due to
the torn webbing loops. Post accident testing of the bucket's
electric water release mechanism was carried out utilising the
helicopter's electrical system. That test revealed that the
bucket's mechanism operated normally.

The JetRanger pilot held a current Commercial Pilot (Helicopter)
License and a valid medical certificate. He had a total of 6,713
hours total flying experience, with in excess of 2,917 hours on
type. He was appropriately endorsed for, and very experienced in,
fire fighting and long-line operations. The pilot was reported to
be medically fit for the flight.

The pilot sustained traumatic head injuries and was submerged
for an undetermined period. During subsequent interviews he was
unable to recall any details of the accident.

The all up weight for the helicopter, including the 420 L of
water carried in the non-standard 1012 model bucket, was estimated
to be about 3,309 lbs. The maximum take off all up weight for the
ambient conditions was estimated to be about 3,320 lbs.

The helicopter's centre of gravity was estimated to have been
within limits.

The Bureau of Meteorology forecast for the Bendora Dam area
indicated an east-northeasterly wind at a speed of 15 kts. Other
helicopter pilots operating in the area on the day reported winds
that varied in direction and strength. Visibility was reported as
`good', with some smoke in the area. The investigation was unable
to determine the actual wind direction and speed at the time of the
accident.

Federal Aviation Administration Advisory Circular AC90-95
described the conditions under which a loss of tail rotor
effectiveness (LTE) can occur. Included among those conditions
were: high all up weight; out of ground effect hover; low forward
airspeed; high power settings; and a wind direction from the left
or rear of the helicopter. LTE can result in a loss of control.

The `Bambi Bucket' Manufacturer's Operator's
Manual² warned pilots
not to execute 90 degree pedal turns when the helicopter was close
to the water and towing the bucket. That warning highlighted the
danger of the bucket suspension lines becoming caught on the rear
of a landing gear skid, resulting in a dynamic rollover when
lifting the bucket. Federal Aviation Administration Advisory
Circular AC 90-87 indicated that dynamic rollover normally occurred
during slope landings and take-offs, with some degree of bank angle
or side drift, with one skid in contact with the ground. In that
case, the in-contact skid acted as a pivot point. If an excessive
roll rate was permitted to develop around that pivot point, a
critical bank angle could be reached where roll could not be
corrected, even with full lateral cyclic. The helicopter would then
roll over onto its side.

Other water-bombing pilots reported that, on previous sorties,
the JetRanger pilot had been lowering the bucket vertically into
the water to fill from an out of ground effect (OGE) hover, and
then lifting it clear vertically before transitioning to forward
flight. Underwater photographs of the helicopter showed that the
bucket cable was not positioned over the rear of the skid assembly.
Examination of the helicopter's landing gear skids did not reveal
any damage from the bucket cable.

There was no system in place to track the fitment and
maintenance of the company's cargo hooks.

Civil Aviation Order (CAO), 20.11, 5.1.1(a), stated that:

`Aircraft shall be equipped with one life jacket for each
occupant when the aircraft is over water at a distance from
land:

(a) in the case of a single engine aircraft - greater that that
which would allow the aircraft to reach land with the engine
inoperative...'

Para 5.1.7 of the CAO stated, in part:

`Where life jackets are required to be carried in accordance
with subparagraph 5.1.1(a) each occupant shall wear a life jacket
during flight over water...'

The pilot was reported to have been conducting his water
pick-ups from close to the shoreline of the dam. The pilot was not
wearing a personal flotation device (PFD) at the time of the
accident.

A Flight Safety Foundation report - External Loads, Powerplant
Problems And Obstacles Challenge Pilots During Aerial Fire Fighting
Operations, based on USA accident reports from 1974 to 1998, stated
in part:

`Research has shown that the average person, when immersed in
cold water, can hold [their] breath for 17.2 seconds, plus or minus
3.7 seconds. Studies of water accidents involving military
helicopters and civilian helicopters, however, show that successful
underwater escape requires 40 seconds to 60 seconds'.

Helicopter underwater escape training (HUET) teaches pilots,
other aircrew and passengers an instinctive escape procedure
providing them with an improved chance of survival in the event of
a helicopter ditching into water. The pilot reported that he had
not undertaken HUET.