Page 16 - Forum-2021-JanToMarch

It is highly probable that there were no When the CP lever was moved up to the
abnormalities in the helicopter’s engines from same position as at the time of climbing, and
the time of takeoff until transition to level the right hand was extended to the ITT trim
flight. As the engine had been operating when switch, almost the same composition as in
the helicopter crashed, it is highly probable the image of video camera (-4 minutes and 5
that the MRB had been rotating at constant seconds) was reproduced.
rpm until the helicopter collided with trees.
It is highly probable that the helicopter was 2) View from the cockpit
conducting engine data checks enroute from The inspection was conducted after parking
takeoff. When the helicopter commenced the same type of helicopter with a magnetic
turning right above the mountains, it is prob- heading of 150 degrees, the same heading as
able that engine checks had been completed. at the time of accident. It was conducted at
It is highly probable that the mechanic was about 13:40 on April 10, 2018; however, the
conducting engine checks, concentrating on pilot’s face was not exposed to direct sun-
the flight instruments, and hardly watched shine. The pilot’s view was not blocked, and
outside. And it is somewhat likely that his it was possible for him to recognize visually
attention was focused on addressing the en- the obstacles lying ahead in keeping the
gine data check records even after the engine piloting posture, when either only glancing at
checks were completed, but this could not be the instruments without moving his head or
specified. facing the instruments and looking at them.
Since the engine check was finished 2 min- However, when the body was bent forward
utes before the collision with trees, it was diffi- and the head was lowered a little, the glare
cult to link the relationship with the collision.
shield blocked the forward view (the horizon).
Therefore, it seems that when the obstacles
Lesson 5: Analysis of human voices requires lying ahead are approaching, the approaching
understanding what the person is doing.
obstacles may not be recognized visually. With
the posture of the mechanic mentioned above
Lesson 6: We can understand the situation of the
engine by analyzing the sound. (1), the forward view was blocked because the
position of the head was lowered.
When looking at the pilot’s face with the
Captain’s Helmet Visor visor lowered, the opening state of eyes and
From the fact that the captain’s helmet visor his facial expressions were not recognized.
had an impact mark near the center and ap-
proximately half of its right side was missing, 3) Different views with and without visor
although the visor cover was not broken, it The different views with and without the visor
is probable that the visor received an impact that is attached to the helmet was confirmed.
from the right side while in a lowered state. Without the visor, the contrast between
From the fact that the captain’s visor was outside and inside the helicopter was clear,
raised at the time of takeoff, it is probable that and when looking outside, it seemed that the
the captain lowered his visor while in flight. view was too bright. Immediately looking at
The captain’s right upper arm moved 1 minute the instruments inside the helicopter, it was
and 30 seconds before the collision with trees. not to say that anything could not be seen but
It is somewhat likely that it was because turn- eyes seemed tired. With the visor lowered,
ing right at that time would have the helicop- the outside view was clear and not too bright.
ter face the direction close to the sun, and the Immediately looking at the instruments inside
captain lowered his helmet visor to ward off the helicopter, it seemed a little dim, but the
the glare of the sun; however, this could not be instrument indicators were readable.
specified.
With the visor lowered, the outside view
was clear and not too bright, and the instru- Lesson 7: Verification will require new discover-
ies or proofs of certainty.
ment indicators were readable. Therefore, it is
probable that the use of the visor had no effect
on flying the helicopter. However, with the ELT
visor lowered, the opening state of eyes and The helicopter was equipped with an emer-
the facial expressions were not recognized gency locator transmitter (ELT) with switches
from outside. (G switches) designed to automatically acti-
vate with impact from six directions. When an
examination was conducted by an agent of the
Verification by Same Type Helicopter manufacturer following the accident, it was
1) Position of the mechanic’s right hand found that the ELT had not activated in this
16 • January-March 2021 ISASI Forum