In response to the subject recommendation, CASA has considered
the issue of a directive to check the installation of passenger
oxygen system mask container doors on all Australian Beechcraft
King Air B200 aircraft, and similarly equipped aircraft. The BASI
recommendation notes that the maintenance manual has a cautionary
note regarding potential for incorrect fitment of the passenger
oxygen mask container doors. In view of this, CASA does not
consider issue of an Airworthiness Directive to comply with
existing maintenance instructions is warranted.
An advisory letter (copy attached) was sent to all Certificate of
Registration holders of Raytheon pressurised twin-engine aircraft,
in line with the 30 June 1999 interim advice that BAS1 provided to
CASA, to raise awareness of the incident with affected operators of
the aircraft. The letter strongly recommended checking each
passenger oxygen system mask container door for correct
installation, but did not make such a check mandatory. An
Airworthiness Advisory Circular, AAC 1-112, was also issued. No
further reports of incorrectly installed passenger oxygen masks
have been received by CASA.
Further action will be considered when the BASI final report into
the incident is made available.
CASA advisory letter
Certificate of Registration Holders
All Beech pressurised twin engine aircraft
Faulty installation of emergency oxygen system cover plates.
A recent incident involving a Beech 200 aircraft has highlighted a
potential safety hazard with the cover plates on the emergency
oxygen system. This letter is to draw your attention to the
deficiency in order that you may take appropriate actions for the
safety of persons flying in your aircraft. Although found on a
Beech 200, any Beech aircraft with m emergency oxygen system may be
similarly affected.
Following an incident involving the emergency oxygen system, a
maintenance investigation was carried out. Although not the primary
cause of failure, this investigation found that some of the covers
over the passenger mask headliner compartments had been incorrectly
installed. If the emergency oxygen system had been activated,
automatically or manually, the incorrectly installed covers would
not release and the oxygen masks would be unavailable. The operator
of the incident aircraft has since inspected four other Beech 200
aircraft. These four aircraft are maintained by a different
maintenance organisation. Of the four aircraft, two had oxygen mask
covers improperly installed such that they would not be able to
operate.
The covers are designed to be pushed open by a plunger which is
operated by pressure in the oxygen line. If the cover is installed
180 degrees out of proper position the plunger no longer contacts
the striker block fixed to the cover, and the cover remains in
place. The Beech 200 maintenance manual notes that caution should
be exercised when installing the cover plate. However, when the
cover is fitted there are no obvious signs which show that the
cover is not properly installed.
When more details are available CASA will contact the manufacturer
to determine what further actions may be required to prevent
incorrect installation of the covers.
The Civil Aviation Safety Authority strongly recommends an
inspection, or test, to ensure that each oxygen mask cover is
installed properly as shown in the applicable aircraft maintenance
manual at the earliest opportunity. The inspection, or test, should
confirm that the striker block in the cover is located below the
plunger. If any cover is found to be fitted incorrectly, remove and
refit the cover correctly and notify CASA through your nearest
district office.
