THE NAVAL ENGINEER

48
At approximately 1815Z, permission
was obtained from the OOD to cycle
the Search and Attack periscopes
and raise the Snort Induction and
Diesel Exhaust masts. The OOD
granted permission, briefing that
the ‘normal safety precautions’
were to be in place before any mast
movements. Knowing that CPOET 1
was a fully qualified CPOOD, the
OOD was content that this was a
sufficient brief for the task to be
undertaken safely.
Prior to entering the fin, CPOET 1
believed that he had checked that
EHS 629 (shutter supply hydraulic
isolation to ESM and Radar Masts)
was shut. However, this was not the
case and neither the experienced
CPOET 2 nor Lower Deck Trot
(LDT) had checked the position of
EHS 629 beforehand.
CPOET 1 then proceeded to the
Bridge in order to observe the
operation of the Search and Attack
periscope shutters (which cycled
successfully). He then left the Bridge
and proceeded into the Radar Mast
Well (RMW) before attempting to
remove the RMW shutter strongback
(a physical barrier that stops the
shutter from closing). Hydraulic
interlocks associated with the Radar
and ESIX masts prevent the shutter
from closing when either mast is
raised but on this occasion, both
masts were lowered (resulting in
hydraulic pressure still being applied
to the shutter that was now only held
open by the strongback). Finding
the strongback wing-nut too stiff to
loosen by hand, CPOET 1 returned
to the Control Room for a spanner
before proceeding back to the RMW.
Using the spanner, he released the
wing nut, but could not remove the
securing bolt. He then freed the
strongback by hitting it which then
allowed the RMW shutters to move
under hydraulic pressure. This then
caused an injury when the shutters
closed against the head of CPOET 1.
At this point, loud screaming from
the RMW was heard in the Control
Room and on the jetty/casing.
CPOET 2 (located in the Control
Room) was mindful of operating the
shutters without first ascertaining
the position of CPOET 1 and went
into the fin to check it was safe
to open them. Observing CPOET
1’s head trapped in the shutters,
CPOET 2 made his way back to
the Control Room shouting for the
shutters to be opened.
The LDT opened the RMW shutter
by local operation of the hydel,
ensuring that EHS 629 was open
prior to pressing the hydel. Opening
the shutters released CPOET 1,
who then moved unassisted into
the fin. It is assessed that his head
was trapped in the shutters for
approximately one minute.
CPOET 1 was an experienced
CPOOD / CPOET(WESM) and also
a qualified Risk Assessor. As such,
he was a Suitably Qualified and
Experienced Person and should
have been fully conversant with
safe operation of masts, periscopes,
shutters and the hazards and
safety precautions associated
with working in the RMW. He
requested the OOD’s permission
to operate masts but did not state
his intention to enter the RMW
and remove the strongback. The
mandated precautions were not
taken prior to entering the RMW
and EHS 629 was not tagged shut.
Although detailed in more than one
publication, the laid-down control
measures for working in the RMW
are adequate but were not followed
in this instance which directly
contributed to the accident.
Immediately following the incident,
the external hydraulic plant
pressure was 180 bar. Hydraulic
oil to the shut side of the RMW
shutters passes through a variable
restrictor which reduces flow and
allows the shutters to close in a
smooth controlled manner. If this
restrictor was not fitted, it is highly
possible that the injuries sustained
could have been fatal.
This event was entirely avoidable
and could have easily resulted in a
death. The injured person did not
follow the formal safety procedures
and this was the primary cause of
the incident. However, there were
others who should have realised
that unsafe practices were taking
place but did not interject. Although
the OOD was not aware that a
RMW entry was about to take place,
the order to follow ‘normal safety
precautions’ for mast operations is
essentially meaningless. Whenever
safety precautions are required,
it is important that they are stated
explicitly and monitored thereafter.
An SSN at sea experienced
a loss of control of the
afterplanes
The submarine was dived,
conducting high speed planesman
training with the boat in level trim
and at approximately 17 knots.
The foreplanes were centred, the
afterplanes were in automatic
control, and the rudder was in hand
control.
The Officer of the Watch (OOW)
ordered the planesman to take the
submarine deep using a 1° bow
down angle. The planesman took
the afterplanes into hand control
and used a 6° dive plane angle to
achieve 1° bow down. As the bow
down angle began to exceed 1°,
the planesman put rise onto the
afterplanes to correct the pitch
angle. The afterplanes misaligned
and then dropped into position
control hydraulic. On attempting a
misalignment drill, the afterplanes
remained at 6° to dive. The pitch
angle of the submarine continued
to increase. As the auto pilot was
still set to a previously-used depth,
the Ship Control Officer of the
Watch (SCOOW) put depth back
into automatic control in an attempt
to regain control of the submarine.
This had no effect and the
afterplanes remained at 6° to dive.
The SCOOW initiated the EOP action
for the afterplanes jammed to dive,
and the OOW ordered full astern.
The trainee planesman experienced
difficulty selecting air emergency, at
which point his qualified supervisor
completed the correct actions.
Due to the delay, the Commanding
Officer (CO) took the submarine
and ordered Starboard 30 and a two
second blow into No 1 Main Ballast
Tank (MBT). The submarine levelled
out approximately 20 seconds after
the initial failure. The afterplanes
were centred using air emergency