flight deck and cabin air quality cliff barrow ecs and cabin safety specialist uk caa safety regulation group

1. FLIGHT DECK and CABIN AIR QUALITY

3. Early Service Experience CAQ issues from early days, adverse odours from air conditioning from first systems using bleed air. As far as is known considered as nuisance value, addressed by masking agents etc. Also complicated by additional contamination from oil bearing compressors and air cycle machines.

4. More Recent Service Experience that Initiated Specific Investigation BAE 146 CAQ issues from early days, three minor flight deck events in early 90’s – irritation, nausea, headaches. More serious reports from 1997. Australian flight deck events (4 off) – Impairments. Swedish ‘Malmo’ flight deck event, 1999 – Partial incapacitation. UK flight deck event November 2000 – Incapacitation. B757 High number of reported events (mostly from one operator) UK events in 1999, 2000, and 2001 - Impairments

5. CABIN AIR QUALITY- SAFETY CAA focus primarily on events representing a threat to continued safe flight and safe landing. CAA attention also to events that might impair efficiency of crew in performing duties. Flight Crew adverse effects classified in terms of potential impact on safety.

6. Classification of Effects on Flight Crew Incapacitation – Unable to perform any duties. Partial Incapacitation – Able to perform duties but with great difficulty. NOTE: PRIMARY SAFETY FOCUS IS ON EVENTS FALLING INTO ABOVE. Impairment – Able to perform duties with some difficulty and/or minor mistakes made (e.g. missed ATC calls) Slight Impairment – Able to perform duties with little difficulty but with reduced efficiency (e.g. light-headed, dizzy). NOTE: SAFETY FOCUS IS CONCENTRATED ON EVENTS FALLING INTO THE ABOVE . Feeling unwell but no impairment (e.g. headaches, nausea) Irritation but no impairment (e.g. of eyes, nose, throat)

7. Initial Investigations Systematic investigation by UK CAA initiated as a result of November 2000 incident and safety concern. Strong circumstantial evidence toward oil contamination of cabin air from engine/APU oil seal leaks, e.g. very visible oil contamination of ECS components. Many theories and claims pointing toward toxic products of pyrolysed oil, e.g. TOCP. No explanation why serious events are in recent times and isolated to certain types.

8. CAA Research Assuming problem is engine/APU oil related what did we need to find out: Are the constituent parts and products of oil known? Do the products vary with temperature and other conditions such as pressure and humidity? Can these substances be identified by practical experimental techniques? Is toxicological data available for these substances? Is it practical/economically viable to conduct such research?

9. CAA Research Sample of engine oil heated to typical engine internal temperatures and products collected and identified. Toxicological review of oil constituents and breakdown products. Dstl Porton Down, primary UK defence establishment for biological weapons research, chosen as most capable and independent facility.

10. CAA Research Findings: ‘No single component or set of components can be identified which at conceivable concentrations would definitely cause the symptoms reported in cabin air quality incidents.’ There is no single symptom or set of symptoms which is characteristic of cabin air quality incidents. The major oil constituents have low toxicity. The occurrence of symptoms is not necessarily related to the presence of an odour in the cabin.

11. CAA Research Findings: The symptoms of irritation could be induced by short chain organic acids formed during pyrolysis of aircraft lubricants. It is not believed that either of the meta and para isomers of tricresylphosphate identified following pyrolysis can be identified with neurotoxic effects. There is no rational basis for drawing conclusions about the toxicity of the contaminants reviewed under conditions of low partial pressure of oxygen in pressurised aircraft cabins.

12. CAA Research Questions after initial research: How representative of the contamination in flight were the results from the laboratory work? Are there additional effects of temperature, pressure, humidity etc. in the aircraft ECS? Is the accumulated contamination in the ECS different from the oil? What are the actual concentrations in the cabin air? (Thought to be very low from rough analysis but not known).

13. CAA Research Next stage conducted: BAE notified CAA that section of low pressure flexible ducting had been removed from an in-service aircraft with a significant number of hours. Duct had not been changed since aircraft build. Particular aircraft had suffered odour event with flight crew effect. Ducting made available to CAA. Porton Down had recommended taking contamination sample from aircraft system.

15. CAA Research Conclusions from duct tests: New duct contained no detectable toxic compounds. Material on ducts consistent with pyrolysis products of oil. Two used ducts similar. Compounds found by extraction or thermal desorption not liberated by duct temperature up to 100deg C and 100% humidity. Odour of duct confirmed presence of short chain organic acids. New compounds identified in duct residue (ethylacrolein, TOCP).

16. CAA Research Conclusions from research: Oil contamination most likely cause of adverse effects. Adverse effects on flight crew most likely caused by irritants. Organophosphates not likely to be cause because of incompatible symptoms and low concentration. No further research justified. Safety issue can best be addressed by in-service actions and controls to limit contamination. Health aspects a separate concern.

17. Controlling Actions BAE 146: ECS Mandatory action to require operators to clean up system and replace contaminated ducting in the event of reports. Engines Compressor oil seals recognised as source of contamination. Mods being implemented by Honeywell. APU Leaks at inlet and exhaust duct connections. Inlet leak could result in ingestion of APU bay air or, if exhaust leak also present, of exhaust air. Inlet mod. mandatory, exhaust mod available.

18. Controlling Actions B757: Maintenance surveillance revealed that BA were not following approved oil servicing procedures. Oil being topped up when engine cold, therefore overfilling likely. Evidence has shown strong relationship between oil overfilling and reports of odours. BA audited to ensure that proper oil servicing procedures being followed. Consultation with other operators to try and minimise transfer of problem. Assumed that most operators already using correct procedures but some local problems apparent. No mandatory action taken on B757.

19. Reporting Primary reporting means to CAA is Mandatory Occurrence Report (MOR). MOR is established UK safety reporting system using documented criteria for reporting. Reporting criteria for fumes event would include: Effects on flight or cabin crew, Persistent odour during flight or series of flights, Flight crew use of oxygen (subject of CAA notice to operators), Diversion or turn-back.

20. Reporting Note that many odour events would not be subject to MOR but under operator procedures flight crew have discretion to submit MOR for any event. In addition to MORs each operator has their own system for reporting (e.g. ASR) which should be used to monitor fleet status. CAA have confidence in MORs and will continue their monitoring as the prime means of assessing the UK fleet.

21. Reporting It has also become clear that the most significant variable in reporting is the individual crew member. For example: Any person, including pilots, can feel ill at any time for one of many reasons. One pilot can report a strong smell and his/her colleague report nothing. It is also clear that there are other ‘reporting issues’. CAA Airworthiness has tried to keep to the facts and not get involved in political and industrial issues.

22. Organophosphates CAA research indicated presence of organophosphates (OP) as expected, both in oil pyrolysis products and in ducts. OPs present in the form of tricresyl phosphates (TCP). Used as anti-wear agent. About 3% oil constituent or sometimes much less. Mixed isomers of tricresyl phosphate found, including the ortho isomer (TOCP) which can induce ‘Organophosphate Induced Delayed Neuropathy’ (OPIDN). Porton Down conclusion was that any possible ‘worst case’ concentration of TOCP was orders lower than that which could conceivably cause OPIDN and, furthermore, the reported symptoms did not correlate.

23. Irritants Organic acids found in oil products and duct residues. Some such as pentanoic (valeric), decanoic, and octanoic have established data on effects. Produce stinging of the eyes and irritant effects on nasal membranes. Characteristic odours such as ‘acrid’, ‘old socks’, which match up well to reports. Pentanoic acid is an irritant chemical and could produce the acute symptoms reported in cabin air incidents, if present at high enough concentrations.

24. Summary on Symptoms Irritants could account for the symptoms reported, certainly for the less serious ‘irritation’ and ‘feeling unwell’, but also the more serious ones up to full incapacitation. OPIDN is not ‘conceivable’ because even the theoretically worst concentrations are orders away from that required and also the reported symptoms are not consistent. However, the biggest variable appears to be the individual person.

25. Wider Interest Since early days some questions asked about potential safety and/or health effects but until more serious events in late 1990s little evidence to support concern. More serious events triggered intense and widespread interest in many quarters: BALPA – UK pilots union Other Crew Unions UK politicians News media Other interest groups

26. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.

27. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.

28. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.

29. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.

30. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.

31. This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.This slide details the elements of the CAA Safety Intervention Plan for ‘Hazardous contamination of flight deck air’. A tick denotes where the work is essentially complete. CAA and DGAC are to be JAA Members of the planned ‘ARAC’ Cabin Environment Harmonisation Working Group looking at the JA/FAR25 design requirements. The intention is to address safety + health + comfort. See separate briefing paper for new DfT/ CAA ‘Health Unit’.