The Never-Fail Turbo-Prop

Aircraft engines made a radical change with the advent of the turbo-prop engine. The old engines were classified as reciprocating engines, similar to what we have in automobiles. The turbo-prop engine worked completely differently. It had a small turbine as the power generating source, similar to a jet engine, except the turbine turned a propeller. These new engines were smaller, lighter, had more horsepower and were supposedly much more reliable.

We ag-pilots were anxious to try one of these new-fangled engines because with the light weight and extra power we could increase the "payload" and thereby do more work in a given time. Plus we liked that the engines were said to be much less likely to fail.

My first opportunity to fly an ag-plane with this type of power plant came when I hired out to an ag-operator located in the Gulf Coast. It was in rice growing country near the small town of Katy, Texas.  

Before I was cleared to aviate with a turbo-prop at the pointy end of the airplane, the insurance company insisted that I be sent to school so as to know how to handle this here highly complicated and tremenjusly complex apparatus. Even though I had years and years of experience and thousands and thousands of hours flying back and forth over the vegetables, it made no difference to them. 

So they sent me to Hartford, Connecticuty, where the Pratt-Whitney Aircraft Co. had a school for beginners to be learnt about these jet fuel burning engines. I spent a week in classrooms listening to some young, self-important individual spout off, displaying his vast knowledge of turbo-prop aircraft engine. Mostly his talk was giving high praise of the reliability of the PT6-E turbo-prop engine. He assured us that our days of engine failure were over. THIS ENGINE DOES NOT FAIL. IT WILL GO 6000 HRS BETWEEN OVERHAULS. THIS ENGINE DOES NOT FAIL.

I came back to Katy with about the same amount of knowledge that I left with, except I knew that the turbo-prop engine DID NOT FAIL. Yeah, I had that phrase ringing in my ears. Me and my partner went to work and I was enjoying flying with the comforting new knowledge that there would be no more flight interruptions due to engine failure. I had launched myself into the future of ag-aviation feeling safe and secure. 

About the third week and somewhere around 80 hours on the new engine, I was working off a dirt strip surrounded by rice fields - some dry, some flooded. I had a hopper full of liquid fertilizer, about 300 gallons as I recall. I had just broken ground when I noticed that a couple of puffs of smoke came out the exhaust pipe on the left side. 

At the next instant I noted that my engine rpm was decreasing and I could feel the loss of power. I reached the end of the strip and slapped the dump gate lever open and the load was dumped instantaneously. Lighter of wing, I swung the Ag-Cat out to the right with the intention of making a 180-degree turn to the left and landing back on my landing strip. Nothing around me looked favorable for an emergency landing.

The engine continued to lose power (a new word - "unspooling" it was called). About half-way around the turn I realized I wasn’t going to make it. I leveled the wings and prepared to make contact with a newly plowed rice field. I sat it down as smoothly as possible and held the stick back so hard that the tail wheel touched first. As soon as the weight of the Ag-Cat settled on to the main landing gear, the wheels quickly sank into the soft powdery dirt of the recently plowed field. Up came the tail and down went the new engine into the soft dirt and over the plane went on its back. I slammed down hard upside down. Thankfully, the Ag-Cat being a bi-plane, the upper wing held the fuselage off the ground high enough that the cockpit enclosure wasn’t crushed.

It is very disconcerting to find oneself upside down even though strapped securely in the seat. Believe it or not the danged engine was still running. Of course the prop was not turning. The blades were bent back at a 90 degree angle. But since in this particular type engine there was no mechanical connection between the power section and the propeller, the turbine was still going. How strange. 

I had to shut it down. I unbuckled my seat harness and as I had done at other times, fell on my head. I managed to open the exit window/door and wiggle out on to the powdery earth. I wasn’t injured in any way, but my poor engine didn’t fare so well. Black smoke began to issue forth because the oil in the engine was draining into the hot combustion chamber. There wasn’t much chance of a fire,but it did put up a nice plume of black smoke. I had to hand it to the Pratt-Whitney person who said the engine didn’t fail. Even after it had quit producing power, it was still running!

To make a long involved story shorter, the Pratt-Whitney Co. sent a tech-rep out to collect the engine and take it back to some place in Canada where they analyzed it and pronounced the cause of the engine failure was fuel contamination. Sure, sure. Fuel contamination is the only thing that wasn’t covered in the warranty.

Whatever the cause, it ruined my day and demolished my confidence in turbo-prop engines. My conclusion was that any mechanical contraption can fail PERIOD! 

Someone who saw the plane go down and start smoking called the fire department who then called for ambulances. And along the way a crowd collected of (I'm guessing) newscasters, TV reporters, environmentalists, save-the-whales folks, vegetarians, a couple of couple of local preachers, a pair of politicians, and the county sheriff.

Fortunately, there was a farmhouse nearby. I walked over there and even though I was a bit dirty, they welcomed me in, gave me a cup of coffee and a piece of fresh baked pie, and promised not to tell a soul where I was. I managed to hide out until my boss came looking for me. How he found me, I don’t know. 

Here is a picture of my dead AG-Cat lying on its back with its feet in the air... but as you will notice, I am not in it.