To Solve or Not to Solve: The Art of Delay – Oil and Hydraulic Fluid Fumes Onboard

2023 marks the 70th anniversary of the first published report that I know of about synthetic oil fumes in the bleed air being a problem for crewmembers. If anyone is counting, that’s 25,394 days. This 1953 report describes B52 pilots reporting symptoms inflight coincident with the presence of smoke and odor sourced to the air supply. They noted that the contamination was the worst immediately after the air conditioning system was turned “on.” And returned “intermittently during engine power changes.” A lot of things have happened since 1953. QEII has been coronated. There was an uprising in East Berlin against Soviet occupation. And Americans were driving the Hudson Hornet, watching “From Here to Eternity.” There have been so many tremendous technological leaps forward since 1953 – the integrated circuit all the way up to ChatGPT and the ISS, with an honorable mention for the B787. But why aren’t bleed filters and sensors and more non-bleed systems also on this list? Fox News, July 27, 2018: „Spirit Airlines flight diverted due to hazmat (hazardous material) situation after passengers sickened from 'dirty socks' odor“ (https://perma.cc/FH4A-GGMX). Why are we still here? In the aviation industry, there is, what seems to be a long-standing practice of promoting uncertainty on the question of whether breathing engine oil fumes can either compromise flight safety or cause ill health. The oft-repeated claim is that “there is no consensus on this cabin air quality issue,” which – on its face – is true. A recent review paper by Hayes et al. made that claim on their review of a subset of the literature which found that 80% of the papers which acknowledged crew experience or perspective concluded that chemicals in cabin air did pose an occupational health risk, but only 5% of the papers which acknowledged manufacturers or airlines drew that conclusion. The vast majority of those who claim either “no problem” or “not sure that there’s a problem” are either employed by or consult for the industry. And even if that’s done with the best of intentions, the optics are not good. In contrast, crewmembers are clear that oil fumes are a problem. Now, some of you may be thinking, “This is a complex technical issue – it takes time to solve.” And others may be thinking, “Is it even a problem?” Some of you may even be undecided. But for 70 years now, crewmembers - whose only commercial interest is that they depend on their airlines to be financially viable so that they can work – have been saying that the air isn’t reliably clean, it’s not clean enough. And they’ve also been saying that, when there are oil fumes in the air supply, some people get really sick. And sometimes, flight safety is compromised. Given that it’s been 70 years now, it is a good time to delve more deeply into the issue of delay, starting with a definition. Delay is “a tactic of slowing down a decision-making process in order to maintain the status quo.” You may know about the field of “motivation theory” where academics discuss what motivates behavior. I came across a researcher at the University of Calgary who coined an equation to describe motivation which I have simplified here as: DCT = ES · VC ÷ ATD DCT (Desire to Complete Task) ES (Expectation of Success) VC (Value that you place on Completion) ATD (Acceptable Time Delay) Generally - and not universally - we have seen limited desire from regulators, manufacturers, and airlines to complete the task of preventing exposure to oil fumes. I say that because fume events still happen. All but one aircraft type uses engine bleed air. And bleed filters and sensors barely exist. That is the status quo which is being maintained. And in the context of this equation, part of that “low desire for getting the job done” is about the numerator: Some filtration companies may want to develop a marketable product but may question if they can succeed, especially without an aircraft manufacturer as a reliable partner and without guaranteed airline customers. Similarly, aircraft manufacturers probably don’t see much “value of completion” – why spend money to make changes that aren’t required, which would make your product more expensive and, therefore, less competitive? The biggest part of the minimal progress to complete the task, though, is the denominator – the ATD. We are at 25,394 days and counting. Primary school math taught us that when the denominator in a fraction is big then the value of the fraction is small. The task at hand here is to “prevent exposure to oil fumes on aircraft”. It is my view that there have been some powerful and effective tactics to slow down any decisions. These are important to acknowledge so that we can all focus, instead, on getting the job done. I will start by saying that, in fairness, delay tactics were not the initial response to oil fumes. The language in that 1953 report in my first slide shows that, initially, industry swiftly treated fumes in the air supply as an engineering problem that required an engineering solution. Boeing acknowledged that the fumes and smoke were from engine oil, especially during power setting changes. They said the bleed temperature influenced oil breakdown. And said that “without doubt, the materials in question are numerous and complex.” So, they injected oil into a bleed air simulator and tested different bleed air filtration options – activated charcoal, particulate filters, catalysts – much like we talk about today. They predicted having an “excellent opportunity of success.” But by 1957, Esso proposed a different response. Esso had run some tests with guinea pigs breathing fumes from heated oil (temps from 400-900F). Some of the GP died, others had degenerative changes in the brain, lung, liver, and kidneys, esp. at higher temperatures. Still, Esso said they weren’t sure which chemicals in the mixture caused the toxic effects. And, even then, they said not to worry because the concentration of each individual chemical wasn’t high enough to be a problem. That is, they applied what sounded logical to counter their own observations of guinea pigs getting sick and dying to justify the status quo. Esso also cited some UK MOD human exposure data in which pilots reported irritated eyes and headache but could still “carry out normal functions”. Esso concluded that oil fumes “should be eliminated” but were “principally a nuisance.” Note: Esso Turbo oil 15 was first oil used in bleed systems per Jean Szyudar, French expert on aviation engine oil history. VC went down. The ATD went up. Delay #1: Claim that the symptoms are minor, and pilots can still fly the plane. Therefore, it’s safe. But the problem was that the problem of oil fumes didn’t go away. Even with smoking permitted during commercial flights which masked many odors, cabin crew at AA and UA were reporting routine headaches on the DC10 associated with a distinctive and strange smell. (Three PW JT9D engines on DC-10-30 vs. PW JT8D engines on DC-9). Those airlines, to their credit, hired a consultant who concluded that the most likely source of the smell and the headaches was pyrolyzed oil in the bleed air stream – from leaking oil seals, and so on. Presumably, this information was shared with the manufacturer of the DC10, Douglas Aircraft Corporation. 1973 would not have been the first time that Douglas had heard about oil fumes. In 1966, Douglas wrote an internal memo about whether engine bleed air was suitable for ventilation on civil aircraft. They said that various fatal crashes had been attributed (rightly or wrongly) to oil fumes. But they also said that, to certify aircraft, they’d simply need to show that pilots could smell the fumes before the fumes were dangerous. And if pilots can smell the fumes, then they can isolate the fumes. Problem solved. Four months before the first DC-10 flight by AA, Douglas, Esso, and Humble Oil had met with FAA to discuss oil fumes on the DC10. Those three companies told the FAA that odor is detectable long before CO will degrade crew performance. And, they said, the levels of CO and aldehydes were below workplace exposure limits, so it was fine. Again, VC went down and ATD went up. Delay #2: Pilots will smell fumes before it gets bad. And the FAA certified the aircraft. So, it must be safe. Reports kept coming. During the 1990s, pilots in Australia reported ill health and also impairment while flying the Bae146 aircraft. And they spoke loudly enough that a Senate committee conducted a two-year enquiry, including eight in-person hearings. And the Senate report concluded that… -- Pilots have been and can be impaired while flying this aircraft -- compromising flight safety. And they said that, even though this aircraft seems worse than others, the problem applies to all commercial aircraft because, at the time, all aircraft used unfiltered bleed air. As a result, they recommended a long list of exposure control measures. And it is interesting to read some of those submissions to the Senate Committee. The Senior VP of BaE said that, with the weight of human evidence and suffering … The director of the Civil Aviation Safety Authority said that oil fumes are a feature of the basic design of systems that use bleed air for ventilation. Ultimately, all that came of that two-year Senate enquiry and its recommendations was that – on a precautionary basis only – British Aerospace made mandatory what had been a recommended practice of inspecting and cleaning the ducting, and ECS for oil. Aviation regulators, eventually, also mandated those inspection and cleaning procedures for this aircraft type. But the design of that bleed air system - or any bleed air system – didn’t change. Delay #3: Accept that oil fumes are “a feature of the basic design” of bleed air systems. Meanwhile, in the Northern hemisphere, also in the year 2000, the US Congress told an NRC committee to conduct a one-year independent study, both to identify contaminants in th

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