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Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R20000289
Date issued: 17 December 2000
Safety action status:
Background: Why this Recommendation was developed

Output text

The ATSB recommends that CASA advise relevant operators of its interpretation of CAO 108.26 in relation to the applicability of the requirements for a device to provide the flight crew of pressurised aircraft with a warning whenever the cabin pressure altitude exceeds 10,000 feet.

Initial response
Date issued: 02 February 2001
Response from: Civil Aviation Safety Authority
Action status: Monitor
Response text:

The Civil Aviation Safety Authority accepts this recommendation and is now considering how best to clarify the intent of CAO 108.26, paragraph 3.1, for relevant operators.

ATSB response:

On the 28 May 2002 an e-mail was sent to CASA and stated, in part:

I am following up on a recommendation produced concurrently with the release of the ATSB incident report, BO/199902928, a report concerning the inflight incapacitation of the pilot of a Beechcraft 200 aircraft, VH-OYA.

The final report included two final recommendations to the Civil Aviation Safety Authority (CASA). One recommendation, R20000288, was for CASA to:

"... advise relevant operators of its interpretation of CAO 108.26 in relation to the applicability of the requirements for a device to provide the flight crew of pressurised aircraft with a warning whenever the cabin pressure altitude exceeds 10,000 feet."

Could you please forward a copy of CASA's actions to clarify the intent of the CAO to the ATSB to enable us to finalise the safety deficiency.

Further correspondence
Date issued: 11 June 2002
Response from: Civil Aviation Safety Authority
Response status: Monitor
Response text:

I refer to an email dated 28 May 2002...... requesting an update of CASA's actions to clarify the intent of the Civil Aviation Order (CAO) 108.26, paragraph 3.1 in relation to Recommendation R20000289.

CASA has reconsidered its original response dated 2 February 2001 to Recommendation R20000289. A copy of the response is attached. The original response was misleading and CASA now wishes to clarify the status of CAO 108.26 and, in particular, paragraph 3.1.

Some of the requirements in CAO 108.26 are Australian design standards. These design standards were intended to be applied to the oxygen systems of types and models of aircraft when those types and models were first offered for acceptance in Australia. In 1990 the Civil Aviation Authority abandoned its practice of applying Australian design standards to aircraft that were manufactured outside Australia and certificated in any of five major aviation countries.

New legislation promulgated in 1990 facilitated the entry to Australia of new aircraft types and models without having to comply with Australian design standards. The design standards to which these aircraft were certificated in any of the five major aviation countries were accepted by the Civil Aviation Authority as being adequate. Consequently the design standards in CAO 108.26 are not consistent with regulations in force since the early 1990s and the design standards have not been applied to any type and model of aircraft that has entered Australia since that time.

The effect of the amendment to CAO 108.26, paragraph 3.1, in July 1987 was to require warning of cabin depressurisation at a cabin pressure altitude of 10,000 feet. This design standard is no longer consistent with the Civil Aviation Regulations and CASA does not apply it to new types and models of aircraft.

All pressurised aeroplanes certificated in the country of manufacture to Part 25 of the USA Federal Aviation Regulations, or to Part 23 at amendment 23-17 or later, will have a warning of cabin depressurisation at 10,000 feet so paragraph 3.1 will not have an impact. The only aeroplanes on which paragraph 3.1 had an impact were those of a type and model certificated prior to Part 23 at amendment 23-17; which are intended to be operated above 25,000 feet; and which entered Australia in the period between July 1987 and promulgation of regulation 22A in 1990. It is likely there is no such aeroplane in Australia.

Further information is provided in an Attachment to this letter.

ATTACHMENT

In April 2002 CASA issued Notice of Proposed Rule Making 0216CS "Proposal for aural warning to operate with cabin altitude warning systems". During preparation of this NPRM CASA gave renewed consideration to Recommendation R20000289 and it is now clear that CASA should revise the response provided on 2 February 2001.

CAO 108.26 contains requirements of two kinds. Some requirements are directed at operators and pilots in command of aircraft equipped with oxygen systems. These requirements relate to the amount of oxygen and the number of oxygen dispensers that must be carried on a particular flight, and at what altitudes oxygen must be used. The remainder of the requirements are design standards applicable to aircraft equipped with oxygen systems and intended to be operated above 10,000 feet. These design standards were intended to be met prior to issue of a certificate of airworthiness and compliance would need to be shown whenever the aircraft was repaired or modified in a way that affected the oxygen system.

By the end of the 1980s Australia had a large number of design standards applicable to aircraft. Most were published in Part 101 of Civil Aviation Orders. Others were published in Parts 105, 108 and elsewhere in Civil Aviation Orders. The design standards in CAO 108.26 are an example. These design standards were a controversial part of Australian aviation legislation. In the late 1980s the Board of the Civil Aviation Authority commissioned Mr Ronald Yates to investigate these design standards.

Mr Yates advised that the design standards were inappropriate when applied to aircraft which had already been certificated by competent aviation authorities and he recommended their use be discontinued. The Board accepted the recommendation and, as a result, Australia's aviation legislation was amended in 1990 to introduce the concept of automatic acceptance of aircraft type certificates issued by the aviation authority in certain recognised countries. This was achieved by promulgation of regulation 22A, and amendment of regulation 24, of the Civil Aviation Regulations. The effect of this change was to render Australian aircraft design standards ineffective when new aircraft types were introduced to Australia, even though those design standards had not been cancelled.

The amendment to CAO 108.26 in July 1987 reducing the activation altitude for depressurisation warnings from 14,000 to 10,000 feet was only applied to new types and models of aircraft entering Australia from July 1987 until promulgation of regulation 22A in about late 1990. It was also only applied to pressurised aircraft intended to be operated above 25,000 feet.

The Australian design standards were not actively applied throughout the 1990s. In October 1998 most of the design standards in CAO Part 101 were cancelled. After that, CASA promoted a procedure for re-issue of the certificate of airworthiness to allow aircraft operators to legally abandon modifications that had been introduced to comply with the Australian design standards. If any operator had enquired about how to eliminate a burden associated with any of the design standards in CAO 108.26 CASA would have recommended re-issue of the certificate of airworthiness.

Since the early 1990s CASA management has advocated harmonisation with major aviation countries and avoidance of uniquely Australian requirements except where they can be publicly justified. Successive Australian governments have supported this approach to aviation regulation. As a result the Australian design standards were first rendered ineffective and are now being progressively cancelled.

ATSB response:

On the 1 July 2002, the ATSB sent an e-mail to the Civil Aviation Safety Authority which stated, in part:

Is CASA planning to clarify the intent of CAO 108.26, paragraph 3.1, for relevant operators by an article in the magazine Flight Safety Australia or some other public medium, or is the position as stated in your email, the official and final position re clarification to relevant operators?

Further correspondence
Date issued: 12 July 2002
Response from: Civil Aviation Safety Authority
Response status: Monitor
Response text:

I wish to clarify an issue relating to CASA's response to ATSB Recommendation R20000289, repeated below:

The ATSB recommends that CASA advise relevant operators of its interpretation of CAO 108.26 in relation to the applicability of the requirements for a device to provide flight crew of pressurised aircraft with a warning whenever the cabin pressure altitude exceeds 10,000 feet.

The Recommendation was made in ATSB investigation report 199902928 covering an in-flight pilot incapacitation that occurred on the 21st June 1999.

Section 108.26 of Civil Aviation Orders ("CAO") contains specifications for oxygen systems in aircraft intended for operation at altitudes up to 40,000 feet. These are mostly pressurised aircraft. CAO 108.26 was amended occasionally but the amended specifications were only applied to new types and models of pressurised aircraft entering Australia for the first time after the date of the amendment. Amendments were never intended to be applied to aircraft of a type and model already established in Australia, nor were they intended to be applied retroactively to aircraft which already had certificates of airworthiness. In 1990 Australia adopted a process of automatic acceptance of aircraft type certificates issued in any of five major aviation countries. Uniquely Australian standards for aircraft, including the design specifications in CAO 108.26, have not been applied to new types and models entering Australia since the introduction of automatic acceptance. CAO 108.26 remains applicable to pressurised aircraft which received their Australian certificates of airworthiness prior to implementation of automatic acceptance.

Despite automatic acceptance of aircraft type certificates, certain requirements in CAO 108.26 are specified in CAO 20.4 and therefore remain in force. Sub-section 3 of CAO 20.4 requires that oxygen storage, dispensing and control equipment, and minimum rates of oxygen flow must be in accordance with CAO 108.26. Sub-section 3 of CAO 20.4 specifies only a small number of operational requirements in CAO 108.26 and these do not include the area in contention (CAO 108.26, para 3.1) which refers to inclusion of a warning device.

The changing role of Australian design standards for aircraft has contributed to confusion among people who do not have an understanding of the process for issue of certificates of airworthiness. CASA is therefore considering amendment of CAO 108.26 to delete all requirements except the operational requirements imposed by CAO 20.4, sub-section 3, and the specification for protective breathing equipment imposed by CAO 20.4, sub-section 10.

If CAO 108.26 is amended the background to the amendment will be explained in an article in Flight Safety Australia.

ATSB response:

ATSB Note: The ATSB will maintain this response status as MONITOR pending CASA's publication of advice to industry.

Further correspondence
Date issued: 30 August 2002
Response from: Civil Aviation Safety Authority
Response status: Monitor
Response text:

On 12 July 2002 I wrote to you regarding the above Recommendation which states:

The ATSB recommends that CASA advise relevant operators of its interpretation of CAO 108.26 in relation to the applicability of the requirements for a device to provide flight crew of pressurised aircraft with a warning whenever the cabin pressure altitude exceeds 10,000 feet.

In my 12 July letter I stated that CASA was considering amendment of CAO 108.26 to delete all requirements except the operational requirements imposed by CAO 20.4, sub-section 3, and the specification for protective breathing equipment imposed by CAO 20.4, sub-section 10. I am pleased to advise that CASA has now formally taken the decision to initiate an Advanced Regulatory Change project to carry out this amendment. Consequently I can give you a commitment that the work will be done. I expect the CAO to be amended before the end of 2002.

An article will be published in Flight Safety Australia to explain the amended CAO and the background to the change.

ATSB response:

ATSB Note: The ATSB will maintain this response status as MONITOR pending CASA's promulgation of the amended CAO and publication of an explanation to industry.

Further correspondence
Date issued: 04 December 2002
Response from: Civil Aviation Safety Authority
Response status: Monitor
Response text:

CASA advised on 4 December 2002 that CAO 108.26 was revised today by Amendment No. 101 and was on CASA's web site at the following address:

www.casa.gov.au/avreg/rules/orders/108.htm

Further correspondence
Date issued: 05 March 2003
Response from: Civil Aviation Safety Authority
Response status: Monitor
Response text:

The following response, dated 28 February 2003, was received from the Civil Aviation Safety Authority on 5 March 2003:

ATSB Recommendation R20000289 states: "The ATSB recommends that CASA
advise relevant operators of its interpretation of CAO 108.26 in relation to the
applicability of the requirements for a device to provide the flight crew of pressurised
aircraft with a warning whenever the cabin pressure altitude exceeds 10,000 feet."

CASA and ATSB have corresponded on several occasions about the need to amend CAO 108.26 so that its meaning is clear to aircraft operators and others. The effect of CAO 108.26 was altered significantly in 1990 by the promulgation of regulation 22A of the Civil Aviation Regulations which introduced automatic acceptance of foreign type certificates. I wrote to you on 30 August 2002 advising that CAO 108.26 would be amended to delete superfluous material.

I am now able to advise that the amendment to CAO 108.26 was signed on
27 November 2002 by the Director of Aviation Safety, Mr Mick Toller. That amendment became effective upon gazettal on Wednesday 4 December 2002. A revised version of the CAO now appears on CASA's web site. CASA is also planning an explanatory article in Flight Safety Australia.

Further correspondence
Date issued: 23 April 2004
Response from: Civil Aviation Safety Authority
Response status: Closed - Not Accepted
Response text:

The Civil Aviation Safety Authority provided the following response on 23 April 2004.<br><br>Civil Aviation Order (CAO) 108.26 was substantially amended in November 2002 to delete all references to audible warning systems and other confusing elements. Therefore, explanatory material on the interpretation of the CAO is no longer necessary.<br><br>

 
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Last update 05 April 2012