Australian Search and Rescue is considering the promotion of a
means of communication between rescue helicopters and personnel on
the ground.
The ATSB will monitor and publish any subsequent action on the
ATSB website.
The helicopter engine lost power at a critical stage of
flight.
The pilot was unable to conduct a successful autorotation
landing.
The impact damage to the right fuel cell bladder and extended
periods of ground running during the day's operations prevented the
investigation from determining an accurate fuel consumption. The
investigation determined that a landing on sloping ground should
have affected both the fuel quantity indicator and fuel low level
advisory light equally. An indicated fuel quantity of 100 lbs (86.9
lbs useable) and coincident illumination of the fuel low level
advisory light, both reported by the pilot, could not be
explained.
Technical examination of the helicopter's fuel indicating system
established that illumination of the fuel low level advisory light
coincided with 35 lbs (21.9 lbs useable) indicated on the fuel
quantity indicator. At the company flight planning fuel consumption
rate of 176 lbs per hour, 21.9 lbs of useable fuel would likely
have equated to a flight time of approximately 7 minutes. In that
case, a reported departure from Lake Nameless Hut at 1515 hours
would have likely resulted in engine fuel starvation at about 1522
hours.
Technical examination of the helicopter and engine revealed no
anomalies. Therefore, the helicopter was considered capable of
normal flight prior to the occurrence. The amount of fuel onboard
the helicopter, less than that expected by the pilot, likely
resulted in unporting of the fuel cell fuel supply hose, and engine
fuel starvation during the turn to land at Tom Whitely's Hut. Due
to impact rupture damage of the right main fuel cell, an accurate
fuel quantity remaining could not be measured.
The pilot reported that the autorotation landing was normal and
that contact with a wire rotated the aircraft through 180 degrees.
As there was no evidence of helicopter contact with the fence prior
to, or during the initial ground impact, the investigation
concluded that the fence did not contribute to the accident
sequence.
Ground impact marks indicated a relatively steep approach with
low forward ground speed. Examination of the Height Velocity
Diagram indicated that, at the pilot reported height of 200 ft
above ground level, and airspeed in autorotation of 65 kts, a
successful autorotation landing should have been possible. Impact
damage indicated that the autorotation landing was unsuccessful. It
was therefore likely that the pilot's estimate of height and
airspeed at the time the rotor speed decreased was less than
actual. In that case, the helicopter may have been at a height and
airspeed from which a successful autorotation landing would be
difficult to perform.
The pilot reported that he had minimal recent experience on the
Hughes 369E helicopter type and had practised autorotation landings
in an Augusta 119 Koala helicopter type during the previous week.
While it cannot be discounted, the investigation could find no
evidence to indicate that lack of type-specific recency, or
contradicting cross-type pilot handling, contributed to the
unsuccessful autorotation landing.
While the pilot reported asking the passengers to confirm the
security of their seat belts prior to take off for the occurrence
flight, the passengers reported that headsets were not worn during
that flight. The ambient cockpit and other noise as the passengers
boarded the engine-running helicopter may have prevented them from
hearing any direction from the pilot. The front seat passengers
were ejected forward of the helicopter during the impact sequence.
The front seat passengers' seat belts, shoulder harnesses and
attachment points exhibited no evidence of damage, or having been
forced by impact forces. Therefore, it was unlikely that the front
seat passengers were wearing seat belts at the time of impact.
In effect, the selection process employed to contract the
operator for the day's operation included an informal risk
assessment. Risk assessments represent a valuable safety tool. They
can range from an informal experiential and environmental audit,
similar to that conducted by the coordinator of the Western Tiers
operation, to an in-depth analysis of all hazards likely to affect
the operation of an aviation system. That analysis includes
consideration of the likelihood of an identified hazard to an
operation, and the possible consequence to the aviation system
resulting from that hazard occurring.
A more formal and inclusive risk assessment, conducted by all
participants in the Western Tiers operation, could have enhanced
the overall safety of that operation. Some of the risks to the
operation, and possible risk treatments that might have been
considered by the interacting participants in the operation
were:
Pilot experience. The pilot's reported unfamiliarity with the
area of operations and lack of recency in the Hughes 369E
helicopter type could have been mitigated by a more extensive
orientation and check flight and briefing procedure. That process
could also have included appraising the coordinator of the
operation of the pilot's background and lack of local
experience.
Fuel reserve. The 10-minute fixed reserve authorised for
external load operations in the company Operations Manual likely
maximised flexibility and payload during such operations. However,
the operation in the Western Tiers involved the movement of
external loads and carriage of passengers in an at times
inhospitable area, by a pilot unfamiliar with that area. In that
case, modifiers to the company 10-minute fixed reserve may have
been pertinent, and the company charter minimum fuel requirements
been more relevant to the operation.
Flight following. The operation was conducted in an at times
inhospitable and remote area of north-western Tasmania. There was
scope for a more formal flight following procedure to decrease
rescue agency response time and optimise the safety of the
operation overall. Available flight following options included
formal employment of a monitored flight and details schedule by the
participants in the Western Tiers operation, regular radio contact
between the pilot and Air Traffic Services, or the nomination of a
SARTIME by the pilot.
The departure of the rescue helicopter from the accident site,
without landing, was reported by the survivors to have adversely
affected their morale, and confidence in their subsequent rescue.
They were not aware that the ground rescue party was enroute to
their location. A means of communication from the rescue helicopter
to personnel on the ground may have prevented that decline in
survivor morale and confidence.
pilot the sole occupant, departed Strahan aerodrome at 0815 hours
Eastern Standard Time (EST) for charter operations in the Western
Tiers area of north-western Tasmania. Multiple flights were
required from a base at Lake Mackenzie to a number of dispersed
mountain hut locations. The flights involved transport of varying
amounts of external loads and personnel, and included extensive
periods on the ground with the helicopter engine running.
At approximately 1500 hours the pilot conducted a flight with an
external load from Lake Mackenzie to Lake Nameless Hut. He then
landed to embark three passengers for transfer to another hut. Two
of the passengers occupied the remaining two front seats and the
third passenger occupied the cabin right rear seat. The pilot
reported that, while on the ground, the fuel low level advisory
light had momentarily illuminated, but that he attributed that
illumination to the distribution of fuel in the tank due to the
slope of the ground. At that time, he reported also noting 100 lbs
(86.9 lbs useable) of fuel indicated on the fuel quantity
indicator. At 1515 hours, the helicopter departed Lake Nameless Hut
for Tom Whitely's Hut, which was located approximately 5 km to the
north-east. A passenger reported that, during that flight, a
caution advisory light had illuminated. The investigation could not
confirm the identity of that light. Having overflown the hut
landing area, the pilot initiated a left descending turn to the
south prior to commencing an approach to land.
The pilot reported that at 1524 hours, as the helicopter
descended through about 200 ft above ground level (AGL), and at a
speed of 70 kts, the main rotor speed decreased and the engine auto
reignition advisory light illuminated. Assessing that the engine
had lost power, the pilot reported that he initiated an
autorotation to land. He stated that "...the aircraft landed
normally, although heavily". He reported that, after the initial
ground contact, the aircraft was "...suddenly rotated through 180
degrees". That rotation was reported by the pilot to be as a result
of entanglement with an unseen "...little wire or whatever hooked
the aircraft".
The helicopter was destroyed by impact forces. There was no
fire. The pilot and three passengers sustained serious
injuries.
Wreckage information
The helicopter impacted the ground heavily on the rear of the
right landing skid, collapsing it and separating the left landing
skid. The fuselage impact ground scar measured about 2 m in length.
The main rotor blades struck the ground and severed the tail boom.
The helicopter came to rest about 7 m and bearing 200 degrees
magnetic from the initial impact point, facing the direction from
which it had approached, and lying on a fence line. There were no
ground impact scars between the fuselage impact ground scar and the
helicopter's final position. The right side rear fuselage floor
area sustained severe impact damage and the right fuel cell bladder
was ruptured.
The forward section of the cockpit was destroyed during the
impact sequence. The two front seat passengers were ejected from
the helicopter, in the direction of flight. On-site inspection
found the pilot's and passengers' seat belts and attachment points
intact and that the pilot's shoulder harness was separated at the
harness-to-inertia reel strap buckle. There was no evidence that
the passengers' seat belt buckles had received damage due to impact
forces. The pilot and front seat passengers' seat structure was
deformed and wrinkled. Information from the helicopter manufacturer
indicated that a vertical impact force loading of the airframe in
excess of 10 g would have been required to deform the seat
structure in that manner.
The investigation determined that there was minimal rotation of
the tail rotor driveshaft at ground impact. That was confirmed by
the lack of any impact or rotary damage to the tail rotor blades.
The engine output driveshaft was separated at the driveshaft lobes
and displayed little or no rotation at the time of separation.
The external load long-line was found attached to the cargo
hook. There was no evidence that the long-line had snagged on the
ground, other obstacles or the helicopter prior to impact.
An old wire and timber post fence was located in the vicinity of
the accident site. The fence was about 1 m high and aligned about
050/230 degrees magnetic. The fence was laterally displaced about
3.5 m from the initial impact point. The fence posts and wire
exhibited no evidence of having been contacted prior to, or during
the helicopter's initial ground impact.
Testing of components
Analysis of the helicopter fuel system determined that a common
fuel-sending unit activated the fuel quantity indicator and fuel
low level advisory light. The fuel-sending unit, fuel quantity
indicator and fuel low level warning system were removed from the
helicopter and tested. Testing indicated that those components were
serviceable in accordance with the manufacturer's maintenance
manual. The fuel low level advisory light illuminated at 35 lbs
fuel indicated on the fuel quantity indicator, in accordance with
the manufacturer's maintenance manual. Testing, disassembly and
inspection of the engine fuel pump, fuel control unit, fuel nozzle,
bleed valve and power turbine governor, revealed no anomalies.
Meteorological information
The Bureau of Meteorology Area Forecast, valid at the time of
the accident, indicated Visual Meteorological Conditions with
moderate southerly winds. The pilot and passengers reported bright,
sunny conditions and a light and variable southerly wind.
Personnel information
The pilot in command held an Air Transport Pilot (Helicopter)
Licence, a Command Multi-Engine Instrument Rating and was endorsed
on the Hughes 369E helicopter type. At the time of the occurrence,
the pilot had accumulated a total of 3,565 flying hours, including
74.0 hours on type. He had flown 34 hours in the previous 90 days,
of which 5 hours was on type. He was reported to be fit and well
rested prior to the flight.
On the afternoon prior to the occurrence, the pilot completed a
0.5 hour proficiency check flight with the company Chief Pilot, in
accordance with the company Operations Manual and CAO 20.11
appendix 4. It was reported that the check flight did not include
external load or autorotation sequences. The pilot reported that he
had significant prior external load experience, conducted in
several helicopter types. He was unsure when he last practised an
autorotation in the Hughes 369E. He reported, however, that he had
completed autorotation and other emergency training in an Augusta
119 Koala helicopter about one week prior to the occurrence, and in
a Bell 205 helicopter about one month prior to the occurrence.
Helicopter information
The maintenance release was current and there were no
outstanding maintenance requirements. A routine 100-hourly engine
inspection was carried out on 25 May 2002. Post-accident technical
examination of the engine and wreckage indicated that the
helicopter was capable of normal operation prior to the
occurrence.
The gross weight of the helicopter at the time of impact was
estimated to be within the authorised maximum operating and Height
Velocity Diagram weight limits. The longitudinal and lateral
centres of gravity were estimated to be within published flight
manual limits. Helicopter performance was estimated to be
sufficient for both in and out-of-ground effect flight.
Fuel planning/loading
The company Operations Manual stated a flight planning fuel
consumption rate of 100 L (176 lbs) per hour for the Hughes 369
type. Charter helicopter fuel planning was required to include the
provision of 20 minutes fixed and 15 per cent variable reserve.
However, a reduction to a 10-minute fixed reserve was authorised
for helicopter external load operations. That amounted to 42.4 lbs
(29.3 lbs useable) indicated on the fuel quantity indicator at the
company planning fuel consumption rate.
The pilot reported that the company Chief Pilot suggested a
planning fuel consumption rate of 200 lbs per hour and that 100 lbs
(86.9 lbs useable) indicated on the helicopter fuel quantity
indicator equated to about 15 to 20 minutes flying time. He stated
that, throughout the day's operations, he maintained a fuel log
indicating an average fuel consumption of approximately 200 lbs per
hour. The ground search and rescue party reported that, on arrival
at the accident site, they collected paper and other loose items in
the immediate vicinity of the wreckage. Those papers and items were
secured in a large bag left at the accident site. The pilot's log
was not recovered from that bag of items.
The pilot reported that a total of 280 L of fuel was added to
the helicopter during the day using the operator's drum fuel stock
and hand rotary fuel pump located at Lake Mackenzie. That amount of
fuel was based on the pilot's understanding that approximately 280
turns of the rotary pump were made during the day's refuels and
that pump output was 1 L per turn. He reported that he visually
checked the fuel quality after each refuel. Post-accident
examination of the remaining company drum fuel stock confirmed that
it was JetA1 and did not reveal any contamination. Post-accident
testing of the hand rotary pump used to refuel the helicopter
determined an actual pump output of 0.7 L per turn.
Operational information
The helicopter flight manual stated that the fuel low level
advisory light illuminated when approximately 35 lbs of fuel (21.9
lbs useable) remained in the fuel tank. The manual further stated
that illumination of the fuel low level advisory light required the
pilot to 'land as soon as possible', which was defined as:
Execute a power-on approach and landing to the nearest safe
landing area that does not further jeopardise the aircraft or
occupants.
A warning was included in the flight manual that, with the fuel
low level advisory light illuminated:
Sideslips may cause fuel starvation and result in unexpected
power loss or engine failure.
The flight manual also contained a Height Velocity Diagram that
represented combinations of altitude and airspeed from which "a
successful autorotation landing would be difficult to perform".
Those figures were calculated at mean sea level, over a smooth hard
surface and on a standard day (15 degrees C temperature, 1013.2 mb
atmospheric pressure). The manual mandated adjustment to the
helicopter gross weight limits, as a function of density altitude,
in order for the Height Velocity Diagram to remain applicable. The
pilot reported that he entered autorotation from a descending left
turn at approximately 200 ft AGL. While the speed of the helicopter
as the pilot rolled out of the turn could not be accurately
determined, the pilot reported that he established 65 kts in the
autorotation descent.
Organisational information
The Civil Aviation Safety Authority (CASA) had conducted regular
surveillance audits of the company since issuing the company with
an Air Operator's Certificate. The last on-site audit was conducted
on 6 July 2001 and a remote audit was conducted on 30 January 2002.
Those audits did not indicate any safety deficiencies.
The Civil Aviation Safety Authority approved company Operations
Manual directed that "...all operating personnel associated
directly with..." the company were to observe the "...instructions,
procedures and information contained in..." the manual. The Manual
also directed that "...all company personnel associated with
piloting and flight line management..." must sign the signature
sheet in the master copy of the Operations Manual "...as evidence
of having read, understood and agreed to apply the procedures and
data contained in it". The occurrence pilot was employed by the
operator on a "standard day" contract, and was therefore required
to comply with the provisions of the Operations Manual, but was not
required to sign the master copy of the Manual.
The coordinator for the Western Tiers operation reported that
there was no formal contract in place with the operator for the
day's operations and no formal audit of prospective helicopter
support organisations by the charter client. It was reported that
the operator was contracted for the day based on extensive previous
experience operating with the charter client and the statewide
experience of its pilots. The occurrence pilot had not previously
flown in the Western Tiers area of Tasmania.
Survival information
The pilot reported that a flight operations brief was conducted
with personnel present at Lake Mackenzie prior to commencement of
the day's operations. That brief included operating around the
Hughes 369E helicopter and the operation of the aircraft doors and
safety belts. The pilot also reported that, prior to takeoff for
the occurrence flight, he had asked the passengers to confirm their
seat belts were secure. Passengers reported that they were not
wearing headsets during that flight.
Flight notification details for the flight were not submitted to
Airservices Australia, nor was there any requirement to do so.
There was no formal flight-following process undertaken by the
operation. The pilot reported that radio communications with Air
Traffic Services (ATS) had not been possible. The pilot reported
making a Mayday broadcast on the forestry service channel following
the reported engine power loss. That broadcast was not reported as
having been received by any station.
Prior to being noted overdue, the pilot had departed Lake
Mackenzie for Lake Nameless with an external load and was to return
to Lake Mackenzie. At about 1600 hours, the helicopter was reported
overdue to the operator by the coordinator of the Western Tiers
operation. The operator then alerted Melbourne ATS of the overdue
helicopter. At 1652 hours, ATS alerted Australian Search and Rescue
(AusSAR). The pilot reported manually activating the Emergency
Locator Transmitter (ELT) shortly after 1700 hours. AusSAR directed
an aircraft to the area to conduct a beacon search at 1715 hours.
That aircraft flight crew made the initial detection of the ELT
signal on 121.5 MHz at 1720 hours. The ELT signal was first
detected by the COSPAS/SARSAT satellite constellation at 1756
hours.
At about 1900 hours, a rescue helicopter from Hobart located the
wreckage and survivors. A number of attempts were made to land at
the accident site. Low cloud and fog prevented the landing and the
rescue helicopter departed for Launceston airport to refuel. The
survivors reported that departure of the helicopter resulted in a
marked decrease in their morale.
The ground search and rescue party arrived at the accident site
at 2338 hours. The four survivors required treatment for varying
degrees of hypothermia and spinal and other injuries. They were
transported from the site by rescue helicopter and arrived at
Launceston General Hospital by 0516 hours on 29 May 2002.