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Recommendation issued to: Civil Aviation Safety Authority

Recommendation details
Output No: R20010085
Date issued: 11 December 2001
Safety action status:
Background: Why this Recommendation was developed

Output text

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority review the potential side effects on humans of the cocktail of HFC-134a refrigerant, in its gaseous form, and the associated lubricant. If that review finds the use of such materials is significantly adverse to human health, the use of HFC-134a refrigerant and its associated lubricant as an airconditioning refrigerant in pressurised aircraft should also be reviewed.

Initial response
Date issued: 22 February 2002
Response from: Civil Aviation Safety Authority
Action status: Closed - Partially Accepted
Response text:

Dear Sir,

I refer to Air Safety Occurrence Report 200005948 on the serious incident involving a Beech Super King Air aircraft, VH-KFN, which occurred 102km west of Southern Cross, WA on 2 December 2000. Please accept my apologies for the delay in my reply.

In response to the Recommendations R20010085 and R20010124, the Civil Aviation Safety Authority advises the following:

Recommendation R20010085
The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority review the potential side effects on humans of a mix of cocktail of HFC-134a refrigerant, in its gaseous form, and the associated airconditioning system lubricant. If that review finds the use of such materials is significantly adverse to human health, the use of HFC134a refrigerant and its associated lubricant as an airconditioning refrigerant in aircraft should also be reviewed.

Recommendation R20010124
The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority advise the aviation industry of the potential side effects on humans of the mix or cocktail of HFC-134a refrigerant, in its gaseous form, and the associated lubricant.

HFC-1 34a is the manufacturer-approved agent used in the aircraft airconditioning system. Following the release of the ATSB recommendations, CASA sought comment regarding both the agent and the system lubricant from the FAA and the agent manufacturer. Copies of their responses are enclosed.

Their advice confirms that HFC-1 34a has been very widely tested for toxicity. Two reasons for the major testing program is that HFC-1 34a is widely used as the propellant in Ventolin dispensers and the agent is also widely used for fire suppression, both of which applications can expose humans directly to the agent in the gaseous form.

Subsequent to issue of your final report we sought a separate independent consideration of the subject by a professor of the university of NSW. He concluded that the incident was most probably a result of a combination of factors, including; HFC-1 34a, the lubricating oil, the cable tie emissions, and hypoxia. He supported acceptance of the FAA review, but cautioned that some special factors in aircraft may not have been thoroughly tested during the program to test HFC-1 34a, such as:

aircraft operate with a reduced cabin pressure, which may amplify the effect of the agents; and

other fumes can react with the agent and amplify any affect, such as heating of plastic (which can produce fumes at temperatures considerably below charring temperature).

[name supplied] suggested that CASA should encourage reporting of incidents involving HFC-1 34a and monitor the outcomes of these incidents carefully. CASA has therefore decided to publish an article in Flight Safety Australia noting that HFC-134a is an approved agent, but reminding people of their responsibility to submit defect reports. A copy of the draft article is enclosed.

CASA has therefore acted on Recommendation R20010085 and reviewed the potential side effects of HFC-134a and the lubricating oil. The agent manufacturer, the FAA, and an independent review have all confirmed that the substances should be allowed to continue in use. However, CASA has decided to advise industry of the issues involved and to encourage reporting of defects which involve HFC-134a.

Finally, HFC-134a and associated lubricating oils are widely used in various forms of transportation, including cars and buses. The vast majority of aviation passengers are carried in aircraft which use engine bleed air for air-conditioning rather than a refrigerant agent, and in relative terms, aviation is a small user of HFC-1 34a. However, should the ATSB wish to pursue Recommendation R20010085 further, CASA would be pleased to participate in any broad review of the use of HFC-1 34a that you may care to arrange.

 
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Last update 01 April 2011