FLIGHT DECK and CABIN AIR QUALITY Cliff Barrow ECS and Cabin Safety Specialist UK CAA Safety Regulat

1
FLIGHT DECK and CABIN AIR QUALITYCliff
BarrowECS and Cabin Safety SpecialistUK CAA
Safety Regulation Group
2
Flight Deck and Cabin Air QualityPrimary Issue
of Concern

• Contamination of Air by Engine and APU Oil and
  Oil Pyrolysis Products
• Directly from Engine and APU
• Indirectly by contamination of ECS components by
  oil and oil products

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 90s 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.

14
(No Transcript)
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
UK Government Action

• Issue addressed in UK Aviation Health Working
  Group (AHWG) includes DfT, DoH incl. AHU, CAA,
  BATA, BALPA, HSE etc.
• BALPA representations were made to government
  through AHWG.
• DfT have addressed BALPA concerns by referring
  to Committee on Toxicity (COT), comprises about
  30 toxicologists and scientists.
• COT have taken evidence on reporting, oil
  product analysis and toxicity (CAA research),
  effects on pilots (BALPA) and other aspects from
  many parties.

27

COT

• Main conclusions so far
• Most likely cause of symptoms is irritants such
  as short chain organic acids and aldehydes.
• Reported symptoms are almost certainly not
  organophosphate poisoning. Even largest possible
  theoretical concentrations are much less than
  required to produce short or long term symptoms.
• Both conclusions similar to those reached by CAA
  funded research at DSTL Porton Down on
  toxicological effects of oil breakdown products
  and aircraft duct residues.

28
COT/DfT Further Actions

• COT preparing report. Due September 2007.
• DfT progressing programme of in-flight
  measurements. One trial flight on a B757 has
  already taken place.

29
Situation Today

• Incidents continue at low level across all
  types.
• UK CAA continues to use MORs as primary means of
  reporting. All such reports investigated and
  closed as appropriate.
• Some reports closed by engineering finding of
  oil overfilling, seal leaks etc. Many others are
  no fault found and aircraft returned to service
  with no further reports.
• Conclusions on medical/toxicological aspects
  corroborated by CAA research and COT but still
  strongly contested by some parties.
• EASA have been updated.

30
Summary

• Flight deck and cabin air contamination appears
  to have emerged as safety and health issue only
  over last ten years.
• Appears across all types but affects some more
  than others.
• Clearly due in part to leakage of oil and oil
  breakdown products into air conditioning supply.
• UK CAA has systematically investigated issue
  using appropriate expertise where necessary.

31
Summary

• Research concludes that symptoms are most likely
  caused by irritants organophosphate poisoning
  very unlikely.
• UK Government investigation is reaching similar
  conclusions but in-flight measurement programme
  in progress.
• UK CAA has taken appropriate controlling action
  where necessary.
• Incidents continue at low level. Situation under
  continuing review.