It kind of depends on where you draw the line on "events like this". Jet fuel is routinely shipped in multi-product pipelines and you always get some mixtures at the interfaces. The pipeline companies try to sequence the products so that the the mixture is still within spec for one of the products so they don't lose anything...for a long time, diesel would be sequenced around jet fuel because you can mix any amount of jet fuel into diesel and still have it be good diesel. They'd cut over to the jet fuel after all the jet/diesel mixture was passed (low sulphur diesel requirements in the US screwed this up a bit).
So if the event is "jet fuel gets mixed with other things a pipeline," that happens all the time.
However, in this case, it's a dedicated pipeline so that's probably not what happened. It sounds like the refinery either had some off-spec Jet-A (which the would normally sell as diesel or kerosene) that they accidentally sent into the pipeline (contaminating everything in there) or they accidentally sent the wrong product into the line. That's not very common.
|Quoting BruceSmith (Thread starter):|
Some readers commenting on the article in question argued that it isn't an event worth worrying about since they "happen all the time" and it was detected before the fuel was pumped into aircraft.
I agree that this is not something worth worrying about; regardless of the competence of the pipeline operator, large airport fuel farms have very good quality control. Every one I've seen puts delivered fuel into holding tank(s) and pulls a sample for analysis; they don't release the fuel into the airport fueling system until the tests show the fuel is in-spec. So it would take a whole different slew of independent failures for the off-spec fuel to make it onto an airplane.
Even after all that, for it to actually threaten an aircraft is another set of independent failures; off-spec fuel can be off-spec in many ways. The most potentially dangerous are significant water contamination (damage to fuel system components and/or flameout), off-spec freeze point (fuel waxing at altitude), and particulate contamination (clogging of the fuel system). Significant water contamination is caught by water monitors that are typically somewhere in the airport fuel system and again at the pump trucks. Filters achieve the same thing for particulate contamination. Off-spec freeze point is not monitored or caught in real-time but it's also relatively well protected within the aircraft fuel system...you have to be *way* off before the airplane actually has problems. So even if you got off-spec fuel through the QA
checks at the fuel farm, what actually got onto the aircraft isn't likely to be immediately dangerous.
There are other off-spec things that are more difficult to catch. If the thermal stability is off, the fuel control unit may eventually gum up and seize or the nozzles may coke/plug. If the lubricity is off, several fuel system components will wear out prematurely. If the distillation curve is off the fuel vapor pressure may be too high, which can lead to loss of suction feed at altitude. However, most of these require something else to go wrong first (e.g. you need multiple fuel pump failures to end up on suction feed in the first place) or they're cumulative issues that take time to build up, giving you more time to detect what happened and correct it before it causes engine damage.
The whole event is not good, but the chance of this pipeline event threatening the safety of an aircraft is pretty low if the rest of the system is functioning properly.