CH12404
SEA KING
19
July 1999
Shearwater, NS
The crew of aircraft CH124A404 had just returned from
a crew operational readiness exercise (COREX) and was
in the process of shutting down on the Shearwater ramp.
After rotor disengagement, three crewmembers deplaned,
leaving the Co-pilot and the Navigator to conduct the
remainder of the shutdown procedure. After attempting
to cycle the rotor brake in accordance with the checklist
procedure, smoke and flame developed in the forward
part of the main gearbox. The ground crew advised the
co-pilot of the fire and an emergency shutdown was performed.
The co-pilot was unable to reselect the manual rotor
brake. The ground crew commenced fighting the fire using
four 50 lbs. dry chemical extinguishers retrieved from
the surrounding area. The 12 Wing fire fighters arrived
shortly thereafter with the foam truck and quickly extinguished
the blaze. The aircraft suffered "B" category
damage to the engine compartments and main gearbox area.
There were no injuries in this occurrence.
The investigation concluded that improper installation
of the rotor brake hydraulic line during MGB installation
was responsible for the hydraulic line being in contact
with the rotor brake accumulator housing. The automatic
rotor brake pressure line chafed against the "rotor
brake panel package accumulator housing" ultimately
causing the line to rupture under pressure. Furthermore,the
location of the hydraulic line and the lack of mandated
opportunistic inspections made timely detection through
routine inspection extremely unlikely.
Atomised hydraulic fluid from the damaged hydraulic
line contacted the #2 engine exhaust cowling and ignited.
In response to recommendations made by the investigation
team, maintenance personnel were briefed on their responsibilities
during an aircraft ground fire and the Canadian Forces
Fire Marshal is investigating a possible replacement
of the portable fire extinguisher, with a more effective
type of agent.
It was also recommended that
- 12 Wing staff evaluate the benefits of equipping
the local aircraft recovery crew with fire extinguishing
equipment;
- 1 CAD investigate the feasibility of replacing the
50 Lbs. Dry Chemical extinguisher with the compressed
air foam type extinguisher;
- DGAEPM consider procedures and/or orders which would
decrease the probability of improper routing and clamping
and increase the probability of detecting errors in
routing and clamping - with priority given to helicopters
of the same vintage as the Sea King;
- 1 CAD Orders be reviewed to identify regulations
that may have been rendered confusing or impractical
by changes to Sea King Operating procedures.
| 
