CH12419 SEA KING
04 May 1999
Shearwater, NS
During a maintenance ground run, the pilot started
the number two engine without first starting the number
one engine and spreading the rotor blades.
The pilot had briefed the three-person start crew of
his intentions to deviate from the normal start procedure,
and to do so single pilot.
In order to accomplish the briefed start procedure,
the pilot used the 'emergency start' switch to override
the 'safety interlocks', which are designed to ensure
that the number two engine cannot be started without
the rotor system spread and number one engine running
with the utility hydraulic system pressurized.
With the number two engine started, the pilot observed
the Ng was fluctuating, and two members of the start
crew joined the pilot in the aircraft. In an attempt
to stabilize the fluctuations, the pilot elected to
advance the number two Speed Selector Level (SSL). When
the SSL was advanced to between 85-95 % Ng, the rotor
head shifted causing damage to the folded rotor blades,
the tail rotor and the pylon structure. During this
action, a loud bang was noted in the cockpit and the
pilot secured the number two engine.
With the blades folded, the only mechanical device
stopping the main rotor head from rotating was the rotor
brake. It is designed to hold the folded head in a fixed
position. The rotor brake's maximum holding capacity
is about 80 shaft horsepower. The output shaft horsepower
of a normal operating Sea King engine is up to 1350
shaft horsepower. When the SSL was advanced from ground
idle towards the normal operating range (85-95 % Ng),
the engine shaft horsepower exceeded the design holding
capacity of the rotor brake resulting in the rotor head
shifting and contacting the airframe. The rotation of
the main rotor head in the folded position directly
caused the C category damage. There were no injuries
sustained in this occurrence.
The AOI for the CH124 contains a 'Caution' about not
starting the number two engine without the rotor system
in the flight-spread position. Also, the ground crew
voiced concerns to the pilot about the proposed procedure;
but they did not do so emphatically, nor did they seek
advice from superiors. The pilot did not perceive the
concern as an indication that his plan was ill advised,
and proceeded to use the 'emergency start' switch to
override a 'safety interlock' with the result being
a badly damaged aircraft.
The investigation concluded that the pilot had contravened
the operating instructions by intentionally starting
the number two engine while the blades were folded.
His decision to advance the throttle was a further error
in judgement.
This was not the first time this pilot had demonstrated
what could be called undisciplined behaviour and squadron
supervisors may not have been as attuned as required
to fully address the situation. The absence of Human
Performance in Maintenance (HPIM) training was also
noted as contributory to the occurrence.
It has been recommended that all flying supervisors
be equipped with the knowledge and resources required
to detect undisciplined tendencies and behaviour, and
to address them formally through a recognized process.
It was suggested that HPIM training be considered as
mandatory training for all ground crew and that a case
history of this accident be included in Crew Resource
Management (CRM) training, as a preventative measure.
| 
