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Interim Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: IR19990084
Date issued: 28 July 1999
Safety action status:
Background: Why this Interim Recommendation was developed

Output text

The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority issue a directive for an immediate check of the fitment of passenger oxygen system mask container doors on all Australian Beech King Air B200 aircraft and, all other aircraft similarly equipped.

As a result of the investigation into this safety deficiency, the Bureau simultaneously issues the following interim recommendations:

IR19990088

The Bureau of Air Safety Investigation recommends that Raytheon Aircraft issue a directive for an immediate check of the fitment of passenger oxygen system mask container doors on all Beech King Air B200 aircraft and, all other Raytheon aircraft similarly equipped.

IR19990089

The Bureau of Air Safety Investigation recommends that the Federal Aviation Administration issue a directive for an immediate check of the fitment of passenger oxygen system mask container doors on all Beech King Air B200 aircraft and, all other aircraft similarly equipped.

IR 19990090

The Bureau of Air Safety Investigation recommends that Raytheon Aircraft examine and implement methods of preventing incorrect passenger oxygen system mask container door fitment as installed in Beech King Air B200 series aircraft, and all other Raytheon aircraft similarly equipped.

Initial response
Date issued: 16 September 1999
Response from: Civil Aviation Safety Authority
Action status: Closed - Accepted
Response text:

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.

 
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Last update 01 April 2011