Recommendation

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.