ANALYSIS OF ACCIDENT TO SIKORSKY S-76C++ HELICOPTER-25 MAY 2017

The helicopter S-76C ++ was involved
in an accident on 25th May 2017 during the flight. It was a VIP Flight from a
Helipad at an elevation of 2000 Ft. There were four passengers and two crew
members onboard the helicopter at the time of accident. Both the pilots were
well experienced and duly qualified to operate the subject flight.

The helipad was prepared in an open
ground measuring 118.6 M X 110 M where, an area measuring 75 M X 75M was
barricaded for the helipad. There were obstructions all around the helipad.

The requirements for Touchdown and
Lift-off Area (TLOF), Final Approach and Take-off area (FATO) and Safety Area
as per CARs was available at the Helipad. However the adequate length of
take-off climb surface of 8% slope was not available because of obstructions.

The helicopter landed at the helipad
at 1105 Hrs. The temperature at the time of departure (Approx. 1200 Hrs.) was
around 40 degrees with visibility fair and variable winds of 3 to 5 knots from
northerly direction.

The maximum AUW permitted for flight
at Mean Sea Level 2000 feet and at Temperature of 40 degrees as per Flight
Manual is 10400 Lbs. The All up weight (AUW) for the flight calculated by the
crew was 10891 Lbs. as against the actual Wt. of 11183 Lbs calculated by the
Inquiry Team.

The required rejected take-off
distance, for the maximum permissible take-off weight permitted at Critical
Decision Point (CDP) of 45Kts comes out to be 1250 feet approx. as per the
performance data available in the flight manual. This rejected take-off
distance was not available at the temporary landing ground.

From the above it can be inferred
that the landing area was not suitable to carry out safe operations in Category
A as well as Category B due to inadequate take-off climb slope caused by close
proximity of obstructions around the Helipad.

After the helicopter picked up and
came to hover, the Captain turned heading towards Northerly direction, and
thereafter hovered out of ground effect to proceed for the take-off. The PIC
had stated that after few seconds into hover when the helicopter was around the
edge of the helipad, co-pilot called out rotor RPM 102%.

This was acknowledged by PIC and he
continued to apply power to gain height and also moved forward to cross the
obstacle (High tension wires) for take-off. The helicopter did not gain height
even after the application of extra power. During this time the helicopter had
crossed the barricaded area and was engulfed by the dust which was kicked up
due to strong rotor downwash caused by the main rotor, this further obscured
the vision of the crew.

As the helicopter was transiting in the
process of take-off with max collective, the co-pilot called out, close
proximity of cables and rotor RPM drop at 93%. The helicopter started sinking
instead of climbing to cross over the obstacles.

The PIC immediately called for
raising the undercarriage to avoid entanglement with high tension cables.
However, in the process, the helicopter belly hit the high tension cables and
helicopter lost the yaw control and turned right. Subsequently, the main rotor
blades hit through a tree and also the roof of a truck and sheared off. The 5
tail rotor blades also hit the roof of a hut and sheared off. Thereafter the
helicopter crash landed and settled on the ground between truck and a hut.

The PIC had earlier operated flight
from the same landing area in December 2016, and the temperatures were much
lower and could manage the take-off with low power requirements.

It was evident from the media video coverage
that, as the helicopter hovered out of ground effect to proceed for take-off,
it got engulfed in dust which reduced visibility of the PIC.

Analysis by Aviation Safety
Management Society of India

The pilots failed to carry out proper risk assessment before Take Off
which is essential particularly when flying VIP’s.
The Helipad was unsuitable since it did not provide for adequate distance
to clear the obstructions.
The knowledge of the Pilots about the adverse effects on the performance
of the Helicopter in high temperature conditions appears to be inadequate. The
Density Altitude of the Helipad with an elevation of 2000 Ft and surface
Temperature of 40 Degrees was almost 5480 Ft which increased the power
requirement for Take Off thus reducing the reserve of power as well as reduced
the all up weight which could be lifted by the helicopter.
There was an error in calculation of the All Up weight by the pilot.
Actual All Up weight was found to be 11183 Lbs. whereas the Pilot had
calculated the Weight as 10891 Lbs. The calculation of the pilot was almost 300
Lbs. less than the actual. In high temperature and calm wind conditions, the
reserve of power further reduced.
The lack of knowledge on the part of the pilots about the rules,
regulations and procedures related to Performance Class 1, CAT “A” Operations is
quite evident.
The pilots lacked Situational
awareness about the surface conditions which were dusty, in the immediate
vicinity of the helipad and high tension cables and other obstructions in the
takeoff path.
The Captain gives the impression of being over confident, unprofessional
, complacent and bit casual in calculations of all up weight of the helicopter,
power available, power required, reserve of power and technique of taking off,
climb and obstacle clearance from
restricted areas with obstructions in close vicinity.
The Pilot should have gone to the beginning of the helipad to make use of
the full length of the helipad rather than taking off from the center of the
helipad.
The action on the part of the pilot
to gain height in hover before initiating take off further reduced the reserve
of power for takeoff.
While moving forward for takeoff, the
helicopter was engulfed in dust bowl which must have made the pilot uncomfortable
during critical phase of transition. Possibly in panic due to the approaching
HT cables, the pilot raised collective to cross the obstruction. However, since
the helicopter speed was below transition, application of more power resulted
in the rotor RPM dropping and coning angle of the blades increasing. This
resulted in helicopter striking the cables in front and crash land.
The District administration failed to prepare the helipad as per the
guidelines and the helipad area had loose dust which led to the dust rising due
to rotor downwash. The takeoff time was around noon, temperature was in the
region of 40 degree C. Even if the water was sprinkled to prevent dust from
rising, the direct hot sun with 40 degree temperature was enough to dry up the
wet sand. The sprinkling of the water should have been done just 10 mts before
the arrival of the VIP.
It also appears that the pilots were
not aware of the handling characteristics of their Helicopter while operating
near its max limits and also they failed to appreciate the power, weight ratio
and the height of the obstruction which they were supposed to cross.
The Pilots although well experienced
and qualified did not factor high all up weight, elevation of the helipad, high
density altitude, dusty helipad and high obstructions.
The Pilots had landed at the same Helipad about a year back in the month
of Dec when temperature are low and hence the density altitude is low. In
addition, the Pilots had landed on this helipad just an hour before the time of
accident .During the approach, pilots should have assessed the Helipad
environments and general performance of the Helicopter. May be the operation at
the helipad a year back and landing of the Helicopter an hour before the time
of accident gave the pilots a false sense of complacency.
Lessons Learnt:-

For every flight it is essential to plan and carry out good
preparations related to the flight, particularly for VIP flights under marginal
conditions.
Make sure that you are fully situationally aware and have
good knowledge about your Helicopter, its performance, limitations, Systems,
Emergencies and operating procedures.
In depth knowledge of the terrain, obstructions around the
Helipad, Surface conditions of and around the helipad, weather and
environmental conditions, is essential.
Correct technique of Take Off, Approach and landing from
Helipads particularly restricted, dusty Helipads (As far as possible, Dusty Helipads
should not be accepted) should be known to the Pilots.
Make sure that the water is sprinkled just half an hour
before the arrival of VIP so that no dust gets kicked up due to rotor down wash
during takeoff or landing.
Professional Risk
assessment, comprehensive Pre Flight Briefing, Good CRM, Knowledge of Rules,
Regulations and Procedures, high standards of Knowledge and Skill Levels,
remaining alert and Situationally Aware particularly during critical phases of
the flight and avoidance of overconfidence and complacency, are essential for Safety
of Aviation Operations.
Never be complacent, overconfident and do not indulge in
show off or eagerness to impress VIP.
High temperature conditions obtained during summer months will
lead to high Density Altitude, high requirement of power, less reserve of
Power, reduced load carrying ability and maneuverability, longer takeoff and
landing runs due to higher TAS and Ground speed.
Pilots must be careful in
calculating the Density Altitude, Reserve of Power and load carrying capacity.
The Load and Trim Sheet
must be accurately prepared keeping in mind Power Available, Power Required,
all up Weight and CG Limits. No casual attitude should be displayed.
Please do not accept any additional load beyond capacity
even if the request comes directly from VIP. Have courage of conviction and
inform the VIP politely that you are placing the safety of VIP on highest
priority and hence cannot accommodate the additional load.
Even if you have made a
mistake in calculating max all up weight and you realize it after pick up to
hover, do not hesitate to sit down and offload. It is better to sit down,
reduce weight and face little embarrassment then to crash land attempting to
take off with additional load. If you have made a mistake, do not aggravate the
situation by attempting to take off (Under false belief and misplaced hope that
you will be able to take off) in order to save little embarrassment.