[0]: https://en.wikipedia.org/wiki/Human_Factors_Analysis_and_Cla...
This should be a major point for a maintenance shop. Documentation should always be available, both online and in offline versions.
" The Rolls Royce SBs were also listed in the Trent Illustrated Parts Catalogue, accessible from any computer at the facility, but he was apparently unaware of this, so he instead switched to plan B and called the Air Transat Maintenance Control Center for help."
TechPubs teams often have no control over the compliance (Optional, Mandatory, etc) of the SBs - that, at least in my experience, always came from way up high in the chain, sometimes from a VP who wasn't even tangentially involved in MRO. The required procedures - MX or ACRW - also are often coming from a costs concern, rather than criticality. The whole process of figuring out what's critical and what's not - that's a problem still being smacked into, every day.
It's not hard to make a Sanity Check for pubs vs ERP/PDM, but often people involved REALLY DON'T WANT TO SEE THAT. Because it's horrifying.
The commenter who mentioned HFACS is right on the money. Unless you implement something equivalent, you're gonna be chasing your own tail.
What a great article.
These are the kinds of failures you get when you try to proceduralize everything with foolproof procedures, checklists, run-books, processes, etc. The maintenance people didn't even know they were making a judgement call.
Had the technicians sleeved the offending tubes with appropriate chafing gear and secured them to reduce movement as would be common place in more earthly situations instead of trying to get it "technically in spec" without thinking about the implications of what they were actually doing this problem may very well have been averted. But maintenance people in aviation aren't really ever exercising those creative problem solving skills since it's such a book driven workflow they're always dealing with so of course they missed the forest for the trees (not that they would have been allowed to implement a one-off fix like that).
This is the opposite of what happened. The engineers were confronted with a novel and unexpected problem, and instead of following procedure (which they lack access to) they applied "creative problem solving skills". From TFA:
> Although it was possible to install the post-SB fuel lines and hydraulic pump with a pre-SB hydraulic tube, the tube would rest against one of the fuel lines at a point where it rounded a 90-degree bend close to the pump. Aware that the plane could not be dispatched unless there was clearance between the tubes, the technicians torqued a nut on the end of the hydraulic tube until it rose approximately 0.635 mm off the face of the fuel line.
Torquing a nut so that the hydraulic tube isn't technically rubbing against the fuel line is pretty creative and seems to solve the problem. But it didn't take into account pressure and vibration while in flight, and almost caused the death of 306 people.
If 0.635mm (an odd number itself which happens to be exactly 1/40th of an inch, or "25 thous" in American sizes) and they let it go that sounds really odd. That's literally the size of a grain of sand. If the concern is rubbing, sure that implies it will move during flight.
> These are the kinds of failures you get when you try to proceduralize everything with foolproof procedures
> Had the technicians
The report makes it clear that the problem was their lack of access to the relevant details, not that the process was defective. If they had seen the need to replace the hydraulic hose, they would have presumably changed it or flagged the problem to someone higher up.
> The maintenance people didn't even know they were making a judgement call.
It seems like they did. If you replace a part and something is touching, you are not trusted in aviation to try and make some space with a bit of fiddling for exactly this reason. They did make a judgment call. If they had relied on the process, again, they could have queried why the new pump was touching when the old one wasn't.
"Read and follow the directions exactly" is a rule that is written in blood.
Aviation safety is utterly dependent on procedures, checklists, run-books and processes. The fact that things sometimes fall through the cracks is no argument against them.
https://news.ycombinator.com/item?id=31315234
> There are way too many jobs where management doesn't give the front-line worker an appropriate amount of time and/or resources, and when things inevitably go wrong, the front-line worker is blamed, and the problem is studied as if the only factor was the front-line worker.
On the contrary, the evidence strongly suggests that the maintenance crew did not feel they were under any special pressure: in their minds, they had found the correct solution, one which would allow them to complete the job on time, so there was no issue of flights being delayed or canceled.
You do not even have to work in the airline industry to see that unscheduled maintenance risks creating delays, and that is less than optimal for everyone involved - no-one has to be told it. If that knowledge creates too much stress and conflict of interest to be safe, commercial aviation would simply be untenable.
Now as a senior developer it's hard for me see why I was so terrified. Some managers yell and bluster. (Or, they used to, back in the day.) Some managers shame and insinuate. Some managers obliquely threaten. But they all, no matter how they express their authority, have to face up to the unpredictability of project planning. The question is not whether your manager is nice or mean. The question is, do they really think they're better off firing you and replacing you? Whether because they think they can get an upgrade or simply to pin the blame on you for something. After you've been around the block once or twice, you understand that a manager who is chill to your face is ultimately subject to the same motivations as a manager who uses stress as a weapon.
I wonder what it's like for airline mechanics? They are represented by unions. I would think that safety infractions would be the real potential career killers, but that's just me guessing.
Is this really the defense we're using?
Somebody who has been in the industry for a while and seen people fired and laid off has learned that someone's job is no more or less safe with a friendly, empathetic manager. (Your personal stress levels are another question, and an important one, but complying with a toxic manager doesn't decrease your stress levels, so it isn't leverage to make you do or not do anything besides change jobs.)
That's why I mentioned aviation mechanics being unionized, and I wondered if a worker's history of safety infractions follows them. Those would seem to be very important factors. A safety-critical worker should be able to say, "Look boss, you're telling me if I don't break this rule I could lose this job, but 1) the union has my back, and 2) if I do break this rule I might not get my next job."
That's important, because threatening in a loud and obviously abusive way is not the only way to make someone afraid for their job. You could even say that it's the amateur hour way to manipulate an employee. If management wants to scare people into skimping on safety, they can do it without doing anything you could point at specifically as "abusive" behavior, so you need protections that don't rely on identifying obvious misbehavior by management.
Now if management had for example knowingly procured inferior replacement parts or hired non-certified personnel to work on the aircraft, they would be at fault.
One of my pet peeves: the first 7 "causes and contributing factors" effectively blames the engine technicians for taking shortcuts. Nowhere does it say anything about the scheduling pressure from management that made the technicians consider shortcuts in the first place. If you have hiring and firing power and you tell someone they need to get the plane back in the air a few days later, they will do things to get the plane back in the air a few days later.
This is considered simply a "risk" by the report, and not a direct cause. As a consequence, the actual actions taken basically all belong to the category of "fix the engineers", "fix the flight crew", or "fix the plane". Not a single "fix the stressful maintenance environment".