Last year a large modern airliner was approaching London’s Heathrow when, much to the dismay of the pilots, the engines refused to add that little extra power needed to make the runway.
Exceptional airmanship stretched the resulting glide over the inevitable highway cut (airports after all are large flat areas surrounded by obstacles) so the aircraft ended short of the runway but on the flat so everyone survived. This is not a critique of that accident, save this: After much tortuous investigation and testing, the suspected culprit was some ice collecting on the inlet of the fuel-cooled oil cooler, thus restricting the supply of fuel to the engine. It must be admitted that it took the extreme conditions found at a very high altitude and very long-range operations over the far north to bring this about. Modifications to the engine fuel system are in the works to prevent this.
I have over the years had the responsibility of writing the technical manuals for several airlines. A fair bit of the material in those manuals involves the care and handling of the fuel that goes into the aircraft. There is a lot of information out there when you research it. The fuel companies are always helpful with material concerning fuel specifications and the handling of fuels. They will eagerly share it with you. This is a god-send when you are involved with overseas operations into Russia and its former republics and in parts of Asia. It can be quite fascinating to read the fuel specs.
The airline auditors then have to go to these far-off places and see that the vendors comply with the manuals.
One of the things that comes up time and time again is that water will get into fuel at different stages of its handling and it is up to the supplier and operator to make sure it gets removed before it gets into the aircraft. Also it is important to remove it from the aircraft tanks because the simple fact is, as you burn fuel from a tank, the air venting in will have moisture in it. This will inevitably condense on the cold tank structure and enter the fuel supply. Regular sumping of the aircraft will detect it and prevent future bacterial growth in the tanks. No one, however, has come up with a good way to do this in frigid conditions.
Fuel quality control has improved over the years. On the other hand, aviation gasoline did not hold water as easily as the kerosene blends we now use. Water settles out of gasoline faster than it does from kerosene for one thing and, to a certain extent, the lead and other additives tended to inhibit the formation of the nasty slimes and bacteria that so like kerosene. Then too much of the fuel was delivered to the airport by truck and barge and not in the usual sealed pipelines we have today. Some airports were really tight on fuel storage and it was literally hand-to-mouth at LaGuardia Airport, which depended on barge-loads of fuel to keep it supplied. An uncle of mine at American described how they were literally praying the tug captain could get the barge through the ice one cold winter before they ran out of fuel. Obviously, too, bringing in fuel by barge is another means for water to get in the fuel.
A Lesson learned
Up in Boston, Eastern had an underground tank farm behind its hangar. Fuel was delivered to it by tank truck. I asked why they had never hooked up to a pipeline for the fuel supplier was nearby. I was shown a pit on the edge of the tank farm. On one side was a pipe protruding from the wall with a cap over it. Opposite was another capped pipe. Three feet separated them. One line led to the fuel supplier. The other line led into our tank farm. Some long ago dispute between the airline, airport authority and suppliers prevented the hookup and so there was a regular parade of tank trucks delivering the fuel. With the shuttle operation and regular system, flights that was a lot of fuel.
In some ways it was not a problem. The fuel vendor’s trucker handled all the operation. He hooked up to a filtration station, selected the tank to be filled and let it run. Inevitably, one of truckers overfilled one of the storage tanks and vented some thousand gallons of fuel on the ground. I had a merry time diking off the overflow before it ran into Boston Harbor. I can say you have not lived until you have had the Port Authority on one side of you and the United States Coast Guard on the other side, all uttering the direst threats of fines and imprisonment for, “polluting a navigable waterway,” while you are working with the fuel spill contractor to contain it. At the same time you have to keep the airline operations in Miami informed of everything. This was pre-cell phone times, too.
The lieutenant from the Coast Guard kept urging me to accept full responsibility for the flow, and it would ease the penalties that were hanging over me. My position was the fuel company screwed up and caused the spill, so I resisted. I am proud to say, in the end, the Coast Guard finally wrote it off as not creating even a sheen on the ever-so-pure Boston Harbor waters.
From the tank farm, the fuel went to an underground hydrant system, which the airline had to maintain. This had to be checked regularly by pumping it up to pressure, shutting off the pumps and measuring the decay in pressure. Any leakage was detectable. I can say it was so sensitive that it had to be done at night, as a cloud coming over on a sunny day would cool the ramp enough to affect it.
Keeping water out of the underground tanks was a task. Each was fitted with a hand pump that sucked from the bottom. Daily, the stores department was tasked with pumping a couple of gallons from each tank into a white bucket to detect any water. This, in accordance with our fueling manual, was to be logged and signed for. There were regular audits by the Quality Assurance Department out of Miami, which always made a point of going over the log. It was, I must say, meticulously kept. Day after day, religiously, the stores people went out and pumped the sumps and recorded the results.
Unfortunately, about four days after a heavy snow, I did a walkaround of my base. Walking the fences is always a good way to see what is going on. After a look at the tank farm, I took the manager of stores — whose responsibility it was to oversee the sumping outside — to the fuel farm. I had the fuel log in one hand and showed him that the tanks had been sumped and signed for each day. He boasted that his boys were good and conscientious. I pointed out that his stores people were indeed miracle workers, for they had left no tracks in the snow over the last four days.
There was still snow on the wobble pump handles. As usual, human sloth can overcome the best regulations.
Fortunately, the fuel tenders are fitted with the best of microporous filters and water prevention. Still, it is discouraging to occasionally see a tank cover open in a heavy rain. I attended a seminar up in Minneapolis given by a fuel tender manufacturer and was impressed with the equipment built in to prevent water entry into the fuel supply. All equipment, however, is only as good as its regular maintenance. Having flown on many off-line charters, I can say that it is always smart to be suspicious and check what you are getting.