CF188798
Hornet
25
June 2003
Aalborg, Denmark
The accident aircraft CF188798 was part of a 10 aircraft
detachment, which had deployed to Aalborg, Denmark in
support of EX Clean Hunter. On the day of the accident
the aircraft had flown once and on the "A/B"
check the a/c was producing a MMP (maintenance monitor
panel) code 916, which is listed as "Arresting
Damper Pressure Low". This code is associated with
the arrestor hook actuator requiring nitrogen servicing
and is triggered when the accumulator pressure falls
below 300 PSIG. This was confirmed through visual inspection
of the gauge.
The two technicians involved informed manpower (servicing)
that they would be performing the nitrogen top up of
the hook actuator on a/c 798. Based on previous experience
they requested and received Danish assistance in order
to operate the Danish nitrogen cart properly.
The Danish operator arrived and the cart was towed to
the aircraft. Once there, the senior technician proceeded
to connect the hose from nitrogen cart to the air charge
valve on the aircraft and requested 3400 [thirty four
hundred] PSI from the Danish operator. The Danish operator
then informed the technician that the nitrogen cart
had reached the requested 3400 PSI.
Once aware of the cart pressure the technician proceeded
to open the air charge valve allowing nitrogen from
the cart to fill the arrestor hook actuator. The technician
saw the actuator gauge reach 600 PSIG (max pressure
on gauge) and within one second the pressure accumulator
of the hook actuator exploded due to a massive over-pressurization.
The aircraft suffered significant damage. Both technicians
escaped without injury.
The aircraft suffered B category damage which included
damage to both engines, critical former damage and the
webs that form the protective firewall in the engine
bay. The aircraft had been a candidate for the Incremental
Modernization Program (IMP). The airframe is currently
awaiting disposition.
The investigation is on going and focusing on technician
training and certification. Additional investigation
is continuing into manning and supervision levels at
the sqns.
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