Aviation has spent decades controlling the foreign object debris it can see. The one piece it cannot see goes straight into the oil, at a single ordinary moment nobody walks for: opening the can. Here is why the evidence is clear, why the habit survives anyway, and why the companies that make the oil have already acted.
Aviation is genuinely good at foreign object debris. We do the FOD walk before the first movement of the day. We control our tools, shadow board and inventory. We sweep the apron after a panel comes off. Decades of work have gone into the debris we can see, and it works. Safety wire offcuts, a dropped socket, a coin, a cap, a rag: if it can be spotted and picked up, we already have a habit for it.
But there is one piece of debris that never lands on the floor. It goes straight into the oil. It happens at a single, ordinary moment that is not on anyone’s FOD walk and not in anyone’s program: the moment a can of turbine oil is opened. This is the forgotten FOD, and closing the gap it leaves is the most cost-effective piece of contamination control most operators are not yet doing.
The moment we all trust
Watch how a can of turbine oil gets opened on a busy shift. A screwdriver. A knife. A multi-tool. Whatever is on the bench and to hand. The lid is metal, the tool is harder than the lid, and when it punctures the lid it shaves off material. Some of that stays on the tool. The rest falls exactly where the tool is pointing, which is down, into the oil you are about to pour into an engine.
Nobody sees it. The oil looks clean, because it is the same oil that left the factory clean. And so nothing ever corrects the habit.
This is the part that should trouble us more than it does. We audit the oil. We trust the screwdriver. We will trend a wear-metal report to three decimal places and never once ask what tool opened the can. When contamination shows up in a sample, the oil gets the blame first: the batch, the supplier, the storage. A great deal of the time the oil was clean when it left the can. The problem was how the can was opened. The oil did not fail. The opening did.
Why the evidence does not move the habit
What makes turbine oil contamination at the point of opening so frustrating is that the evidence is not ambiguous.
We had our opener independently tested by Saybolt, an accredited laboratory. On a can opened with the tool, microscopy found no metal particles introduced into the oil, on both new and used oil samples. The reports are published in full. We know what a screwdriver puts into the oil, because we have measured the difference, and it is not zero.
We also know the scale of what that debris does downstream. A turbine oil filter is built to catch particles down to around fifteen microns. The oil film protecting a bearing surface is far thinner than that, often a fraction of a micron. So a particle small enough to pass the filter is still large enough to break the film, indent the surface on every rotation, and begin the sequence that ends in spalling. The filter did its job the whole time. It was never designed to catch debris at this scale. The control point was never the filter. It was the moment of opening.
And we have seen what happens when an operator closes that gap. One fleet of ten King Air 250 aircraft, roughly 105,000 engine hours between them, extended time between overhaul from 3,600 hours to 5,600 by taking oil cleanliness at servicing seriously. The cost of the tools that made it possible was around 1,800 US dollars. The estimated saving was in the region of seven million.
So the evidence is clear, the physics is clear, and the economics are almost embarrassing. And yet the screwdriver is still on the bench tomorrow morning.
Why old habits die hard in aircraft maintenance
It is easy to be superior about this. I try not to be, because the habit is not stupid. It survives for reasons that make sense on a busy shift.
- The result is invisible. You cannot correct what you cannot see. If opening a can with a screwdriver produced a visible spray of swarf every time, it would have been designed out decades ago. Instead, it produces a burr you would need a microscope to find, dropped into a fluid you are about to pour inside an engine. The feedback loop that fixes every other bad habit in maintenance is missing here.
- The wrong tool is always there. The screwdriver is in the toolbox, it is free, and it works well enough to get the lid off. The right tool, if it is not within reach at the exact moment of the task, loses to the wrong tool that is.
- Nobody owns the gap. Between one service and the next, the cleanliness of the oil-servicing equipment often belongs to no one in particular. It is not in the procedure, not on the FOD walk, not on anyone’s checklist. A habit with no owner does not get changed.
- The standards are quiet. Neither EASA nor the FAA prescribes a method for opening a turbine oil can, approves a tool, or forbids a screwdriver. When the rulebook says nothing, the bench decides, and the bench reaches for what is nearest.
None of that requires carelessness. It requires only that nobody has decided, clearly, that this moment matters.
The companies that make the oil have already decided
If you want a signal that the moment matters, look at who has already acted on it.
TheCanKey has been produced in co-branded versions for NYCO, Shell and for ExxonMobil. Three of the largest names in turbine oil have put their marque on a certified, FOD-free way of opening the can.
Consider what that means. These are companies that spend enormous resources getting oil quality right: formulation, testing, certification, packaging. They sell a premium product on the promise that it is clean. The one moment they have never controlled is the moment their customer opens the can. When the people who produce the oil choose to extend their quality story all the way to the point of use, they are telling you something about where the real risk sits.
It is not the only signal. The opener carries a NATO Stock Number and is used by more than 520 operators across more than 60 countries. But the oil manufacturers are the ones I would point a sceptic to first, because they have the least reason to worry about a problem that is not theirs, and they acted anyway.
What actually changes the habit
Evidence alone does not change behavior. If it did, this article would not need writing. What changes a habit is making the right action the easy one, and giving the moment an owner.
- Provide a proper tool for the opening step, and keep it where the task happens, not in a drawer on the other side of the hangar.
- Treat a part-used can as a different product from a sealed one, and keep it covered between uses.
- Write the opening of a can into the oil-servicing procedure, just as you write torque values, so it is a defined step and not an improvisation.
- Put the correct tool on the tool list, so its absence is visible, and add the opening method to your internal audit questions. If nobody has ever asked, nobody has ever answered.
- Have someone decide, out loud, that the cleanliness of the oil-servicing equipment between services is their responsibility.
None of this is difficult. That is rather the point. The reason the forgotten FOD stays forgotten is not that it is hard to fix. It is easy to ignore because you cannot see it, because the tool is already in your hand, and because no rule tells you to stop.
Read the evidence and decide for yourself
I have spent a career watching clean oil go into engines through a hole made by a screwdriver. The evidence has been clear for years. What has been missing is the decision to treat the opening of the can as what it is: the last unguarded step in a chain we otherwise control very tightly.
The second edition of our FOD Prevention Guide makes this case in full. It is not a brochure. It is thirty-seven pages on what the forgotten FOD is, what it does inside a turbine engine, and the small habits that keep it out, with the Saybolt reports and the physics laid out so you can judge them for yourself. It is free to read, free to download, and free to circulate inside your own organization.
We invented the tool because I got tired of waiting for the industry to make that decision. But the tool is the easy part. The decision is yours.
