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Sump samples

A good instrutor is always learning

On January 4, 2006, a student and I ended a short training flight in a muddy field in California, upside down, hanging by our seat belts. For me, it was an eye-opening lesson in what I didn't know about instructing.

Of course, I'd always believed wholeheartedly in the motto of this magazine, that a good pilot is always learning. This crash taught me that continued learning is doubly important for CFIs, since any ignorance on our part gets passed along and magnified, student after student. In fact, that's exactly how my accident occurred.

During the post-crash investigation, the NTSB found that a large amount of water in the fuel strainer and carburetor of our Cessna 152 was the reason my student and I were left hanging from our seatbelts in that muddy field, just off the Rancho Murieta Airport. How could this have happened? Before takeoff, I'd been very careful to check for fuel contamination, exactly as I'd been taught.

The morning of our crash began well enough. My student arrived promptly, so I gave him the binder for our Cessna 152 and asked him to preflight. As I had taught him, he had pulled fuel samples from both wing tanks, checking for water or other contamination. Then he opened the engine access flap and pulled on the fuel strainer handle until a nice puddle of liquid--presumably 100LL avgas--was on the ramp beneath the airplane. When I met him at the airplane a short time later, we refueled and again sumped the tanks. We found a small amount of water in the right wing, so we continued to sump until no more water appeared.

Once at cruise altitude, I decided to give my student a practice engine failure over the airport. He dealt with the simulated failure by properly attempting a restart, followed by a simulated shutdown when the restart attempt "failed." All was well, although his turn to the base leg for the simulated emergency landing was too soon, so we were too high when he turned final. He opted for a go-around. Full power, carburetor heat in, flaps 20 degrees, positive rate of climb--and that's when it happened. The roar of the Cessna 152's engine ceased.

"Your airplane!" my student shouted, as the stall warning horn blared. I grabbed the controls.

"Fly the airplane! Keep us flying!" my student encouraged.

"How's our airspeed?" I asked nervously, as my student broadcast over the CTAF, "Mayday, mayday, Rancho Murieta traffic, we're having an engine failure!"

After our engine failure, a stall at about 250 feet agl was prevented only by an aggressive forward push on the yoke by both of us. There was a line of trees straight ahead, so I turned the airplane to the right, about 90 degrees from the runway, toward an empty field. Because that field was saturated from recent storms, I performed a soft-field landing, keeping the nose off the surface for a fair amount of time, and then pulling the nose up again when it touched down once. When the nosewheel finally touched ground for the last time, we nosed over and came to a halt upside down, about a quarter-mile from the airport. We were able to safely evacuate the airplane.

The NTSB's discovery of water in the fuel answered the question of why the Cessna's engine stopped. What it didn't answer was why my preflight sumping--done exactly the way I'd been taught--hadn't discovered the water contamination. Obviously, I didn't want a forced landing to happen to me or any of my students again, so I began a quest to find the answer. I started reading accident and incident reports on the NTSB Web site, looking for other accidents like this one. I did not want to fly again until I knew what I should have done differently to prevent it.

With the help of a friend, I found some hints on the FAA Web site, in the Advisory Circular section. There I found two helpful ACs related to fuel contamination, AC 20-125, Water In Aviation Fuels, and AC 20-43C, Aircraft Fuel Control. AC 20-125 says, "Water in fuel continues to contribute to aircraft incidents and accidents and, at times, fatal accidents. Aviation fuel can only serve its ultimate purpose if it is delivered to the aircraft engine(s) free from water." No kidding.

Further in AC 20-125 was the first hint that something in my own private pilot training had been missed. Paragraph 7(c)4 of that AC says that pilots should drain a "generous sample of gasoline (10 ounces or more)...into a transparent container from each of the fuel sumps and from the main fuel strainer or gascolator (and) visually check the fuel sample for water." That was it! Like many pilots, I had been taught to drain and inspect fuel from the wing tanks, but just to let fuel from the engine fuel strainer drain out onto the ramp. AC 20-43C verified this discovery.

Eureka! Why hadn't I known about this before? The important fact is that I learned something new that I can pass on to my students and other flight instructors, breaking the chain of misinformation that probably already had dozens--if not hundreds--of links.

After I discovered how useful advisory circulars could be, I was on a roll. I began searching other Web sites for additional information and found the AOPA Air Safety Foundation site. For the working CFI, there is an enormous amount of information here: accident analysis, safety quizzes, free online safety courses, safety briefs, and much more.

One of the most popular parts of the ASF Web site is the accident database, the world's largest nongovernmental opportunity for pilots to continue learning without having to make mistakes themselves. A search for accidents related to fuel contamination yielded 173 results. Wow! My student and I weren't the first. I clicked on a few and shook my head in amazement as I read them. You would think that 173 accidents would not have to happen in order to come up with a solution.

Could this knowledge have prevented my accident? Maybe, maybe not. What I learned did make me aware of the problem, though, and you can bet that no future student of mine will ever be able to claim he or she didn't know that fuel from the engine sump should be checked for contamination.

All those accident analyses in the ASF accident database were helpful, but links specifically related to fuel management gave me even more information. I found articles on many different facets of fuel awareness, including misfueling, fuel starvation, fuel exhaustion, and fuel system blockage. All of these articles were tremendously helpful; I have learned more about fuel contamination in airplanes than I thought existed, and it's made me a better instructor.

It's too bad I had to learn the hard way of the omission of a key safety check in my own training through a forced landing with one of my students. But on the bright side, it led me to a wealth of information on the Internet and an unshakeable resolve to do my best to never again omit any crucial training elements in my students' training. The FAA's Aviation Instructor's Handbook says, "Aviation is changing rapidly and aviation instructors must continue to develop their knowledge and skill in order to teach successfully in this environment."

Indeed, a good flight instructor is always learning.

Dionne Ilene Mitchell is a 900-hour CFI who instructs full-time in the Sacramento, California, area.

By Dionne Ilene Mitchell

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