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Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R20020109
Date issued: 03 July 2002
Safety action status:
Background:

Shortly after commencing descent from flight level (FL)310, the pilot of the Cessna Conquest noticed that the cabin altitude indication was rising. When passing through FL270, the cabin rate of climb rose to 3,000 ft/min with an accompanying decrease in cabin differential pressure and both master warning and "ALT" annunciators illuminating. When the annunciator lights illuminated, the pilot observed that the cabin oxygen masks failed to auto-deploy at this time as required. As the patients were already on oxygen and the flight nurse had donned a spare mask, he did not deploy the cabin masks manually. The pilot donned his own oxygen mask and commenced a rapid descent to 10,000 ft.

The pilot reported that the cabin altitude indication increased to a peak of 17,000 ft before decreasing during the descent. A subsequent maintenance inspection found water contamination present in the cabin door seal pressurisation solenoid valve and it was suspected that this water froze, preventing the correct operation of the valve.

The failure of the oxygen mask auto-deployment system was also investigated and the wiring to the barometric activation switch was found to have a high resistance. This wiring was replaced. As a precaution, the wiring to the barometric switch that activated the cabin altitude annunciator warning light was also replaced. During these rectifications, the maintenance personnel discovered that there was no procedure published by the manufacturer to correctly adjust and test either barometric switch set point after maintenance.

A sampling of maintenance manual procedures for aircraft types manufactured in countries such as the United States, United Kingdom and Switzerland was carried out. This sampling concluded that the maintenance deficiency for test and return to service of the oxygen deployment and cabin altitude alert barometric switches, found in the occurrence aircraft maintenance procedures, was also apparent in all but one of the other aircraft type manufacturer's maintenance procedures.

Output text

Safety Recommendation

The Australian Transport Safety Bureau recommends that the Australian Civil Aviation Safety Authority liaise with the United States Federal Aviation Administration, the United Kingdom Civil Aviation Authority and the European JAA on implementation strategies to address these safety deficiencies.

 

Initial response
Date issued: 05 September 2002
Response from: Civil Aviation Safety Authority
Action status: Open
Response text:

The Civil Aviation safety Authority (CASA) wrote to the United States FAA, the European JAA, UK CAA and NZ CAA on 31 July 2002 inviting liaison on the safety deficiencies identified in Occurrence Brief 200200095. Questions were also asked about these authorities' views and intentions regarding periodic maintenance of barometric switches in pressurised aircraft.

The following response dated 29 November 2002 was received from CASA on 03 December 2002:

Thank you for providing a copy of aviation Occurrence Brief 200200095 on the incident involving Cessna 441 Conquest VH-NFD which occurred 22km north west of Perth VOR, Western Australia on 31 January 2002.

In its response to the draft Brief, the Authority, in respect of Recommendations R20020101 and R20020102, stated that:

CASA intends raising an Airworthiness Bulletin (AWB) to provide advice on how this feature may be incorporated into maintenance documentation covering periodic maintenance of barometric pressure switches in Australian registered pressurised aircraft. CASA's long-term approach will be influenced by the response of other aviation authorities to the liaison initiated by CASA as the result of Recommendation 20020109.

The AWBs have been published as AWB 21-1 Issue I and AWB 35-1 Issue 1. Copies are enclosed for the Bureau's information.

CASA also notes that the Bureau has classified each of these Recommendations as CLOSED-ACCEPTED.

In respect of Recommendation R20020109, CASA advises that it has not yet
received responses to its invitations - the United States Federal Aviation
Administration, the United Kingdom Civil Aviation Authority and the European
JAA - to the liaise on the safety deficiencies identified in the Brief.

Thank you for bringing this matter to the attention of the Authority.

Further correspondence
Date issued: 11 December 2002
Response from: Civil Aviation Safety Authority
Response status: Closed - Accepted
Response text:

The following additional information dated 9 December 2002 was received from CASA on 11 December 2002:

I am writing in relation to Recommendation R20020109 which arose from Occurrence 200200095.

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority liaise with the United States Federal Aviation Administration, the United Kingdom Civil Aviation Authority and the European JAA on the implementation strategies to address these safety deficiencies.

In its responses, dated 29 August 2002 and 28 November 2002, the Authority advised the Bureau that it had written to the relevant bodies but had yet to receive a response.

The Federal Aviation Administration (FAA) has recently advised that they had taken earlier action on the issues raised in the Occurrence Brief, released on29 October 2002, and it appears that they will not be taking further action. A copy of the FAA's response, for the information of the Bureau, is enclosed.

CASA notes the comments at page 7 of the Occurrence Brief in relation to the United Kingdom Civil Aviation Authority. That Authority advised that "their research revealed, apart from the example cited by the ATSB that complied, the only other UK built aircraft to which these recommendations could apply was no longer the responsibility of the UK CAA". Their production had moved to the United States. Type certification responsibility now rested with the FAA.

As notified earlier, CASA addressed the safety deficiencies, that were set out in Recommendations R20020101 and R20020102, through the issue of Airworthiness Bulletins AWB 21-1 and AWB 35-1.

On this basis, the Authority believes that there would be no further benefit in pursuing the issue with the national bodies. The Authority considers that it has now met the requirements of Recommendation R20020109.

Thank you for bringing this matter to the attention of the Authority.

 
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Last update 03 April 2012