Wednesday, March 21, 2012

Look Ma - No Engine

It seems like every pilot, hanger pilot, airport bum and even occasional airline traveler has some kind of story about an engine failure. When a single-engine pilot encounters a non-flyer at a party: the first question is always something like "what would you do if the engine quit running"? Of course the answer has to be that you would land; just not where you planned to when you took off. With the exception of mountainous terrain and large urban areas, a small single engine aircraft pilot can usually glide to a suitable flat spot to land. It is not that easy at night. Power lines, fences and hidden obstructions often ruin a perfectly executed engine-out landing attempt. Walking away from the airplane is a higher priority for the people in the airplane than the condition of the airplane. I made a landing once that involved penetrating the fence located at the end of the flat place I had chosen. The wire farm fence would have done no damage except scrape the aircraft paint a little bit. A stump that was hidden in tall weeds growing along the fence line snagged the right landing gear strut and the insurance company decided to total the aircraft. My passenger (first airplane ride) and myself walked away without a scratch or a dry-cleaning bill. Therefore, it was a successful landing.
Small aircraft engines are quite reliable. I know several pilots that have flown thousands of hours in light aircraft and never experienced an engine failure. Larger aircraft engines are also very reliable on a per hour basis. Larger aircraft usually rack up many more flying hours and make it seem like there is a disproportional number of failures. If everything else is equal, simple mathematical probability dictates that twin-engine aircraft will have twice as many engine failures as single engine aircraft. Four-engine aircraft would be expected to have twice as many failures as twin-engine aircraft. Howard Hughes' spruce goose had eight engines. If it had become a production aircraft, it would have had engine failures on a regular basis.
An engine failure on a twin-engine aircraft results in a loss of fifty percent of the available power. Even with the FAA certification requirements that "guarantee" the aircraft will be capable of flying on a single engine, many aircraft are lost because of engine failure. With maximum allowable gross take-off weight and most unfavorable wind conditions, a pilot's skill is taxed to a maximum if an engine fails during takeoff.  Three-engine aircraft only lose thirty-three percent of their power and four-engine aircraft only lose twenty-five percent. Most airline and military pilots I know with lots of hours in four-engine aircraft have landed with only three engines operating more than once. One close friend few B-24's with the 489th Group in World War II. On his first combat tour of twenty-five missions, he returned to home base fourteen times with at least one engine not running. Jet engines are much more reliable than piston engines so the jet engine failure stories aren't as many. Often they are more dramatic. I was on a Delta DC-8 flight from SFO to CVG that aborted takeoff twice at SFO because of engine flameout due to gusting crosswinds.
Much of the training for a AMEL (Airplane Multi-Engine Land) or AMES (Airplane Multi-Engine Sea) rating involves learning how to cope with an engine failure. This is also true with training for a type rating for a multi-engine aircraft. I was a new private pilot at the time of this story and building hours to get my Commercial certificate. I was also grabbing multi-engine time whenever I could get a chance. I got a chance one night to ride from CVG to STL and return. It was a Part 135 air tax trip and we were flying a single passenger out and returning empty in PA23-150 Apache. I rode in the back seat on the way out. It was a beautiful night with a three-quarter moon and not a cloud in the sky. I could see the lights (the Gateway Arch hadn't been built yet) of Saint Louis when we were still sixty miles away. After we unloaded the passenger, smoked a cigarette and drank some foul machine coffee, the pilot said the words I was hoping to hear. "Hop in the left seat and fly me home. I want to get a little sleep."
We got back to airplane and I did the engine start and taxi-out check list from memory. Fred was doing the radio and soon we got clearance to taxi to the active runway. I did the run-up on both engines and the pre take-off check list. We were cleared for take-off and everything was great. Fred stayed awake until we were out of STL's airspace. This was way before Alphabet Airspace or even TRSA's and TSA's. We were operating VFR (Visual Flight Rules) and cruised at odd thousands plus five hundred feet altitude when on an easterly heading. I asked Fred if he wanted me to climb to 3500, 5500, 7500 or 9500 feet. He told me to do whatever I wanted: he was going to sleep. I decided on 9500 and Fred's snoring was almost enough to drown out the engine sound by the time I leveled off and got all trimmed and leaned for the rest of the flight. There was really not much to do for the next hour so I tried to find some classical music on an AM station that I could turn on the ADF (Automatic Direction Finder). I couldn't find any classical but I did find some pretty decent jazz on an Evansville, Indiana station.
Now the story really begins. I was just enjoying the music and the ride. The air was so smooth at 9500 feet that I just had my hands and feet resting on the controls. I really wasn't having to do anything to maintain heading and altitude; the plane was flying itself. Then the plane lurched. I felt the lurch before I noticed any difference in the sound level. My whole three hours of official dual instruction in this aircraft came flooding into my mind at once. Fred was still snoring. I remembered the old saw "dead foot-dead engine" and I was sure that the left engine was the problem. I was surprised at how I checked stuff like the mag switches and fuel pump and finally pulled the prop control back through notch. It actually worked. The prop feathered and quit spinning Fred was still snoring. A turned on the map light on my side and looked for the real type written checklist  to make sure I hadn't missed anything.
Then another lurch. Even with Fred's snoring, it was very quiet. I didn't have any simulations in my limited training about how an Apache flies with the left engine feathered and the right engine wind milling. A little voice told me to concentrate on maintaining airspeed and attitude and NOT to feather the other engine until I woke up Fred. He was a sound sleeper but a quick waker. He took the controls immediately and began accessing the situation. His expression told me not to say a word until he asked me for information. He seemed to grasp the whole situation in just a few seconds. Then he looked between the front seats at the fuel selectors. The first words he said were "Aw shoot" or a very similar sounding phrase. As soon as he turn the right engine fuel selector to the Main position, there was another lurch and the wonderful sound of an engine running.
Now the problem was starting the other engine since there was no un-feathering device. The procedure was to use the electric starter for a restart just like on the ground. The starter controls were on my side, so he told me to try just like a normal start. It worked! All of this happened in less than three minutes but it seemed like hours. I decided to fly the rest of the way at 7500 feet. Fred was snoring again in a few minutes and didn't wake up again until I taxied up to our hanger at CVG.
What happened was easy to explain in hindsight. The Apache has two main fuel tanks and two auxiliary fuel tanks. With the auxiliary fuel tanks full, you can't carry as much load but you can fly a greater distance. Most of our air-taxi business was lots of people and baggage for very short distances. Because of that, we tried to keep the auxiliary tanks empty except when we made a long trip. Fred had switched the engines to auxiliary tanks on the way to STL so that he could burn them dry. With a single passenger load and good weather, we had plenty of fuel in the main tanks. The written check list requires the engines to be switched to the main tanks for take-offs and landings. Fred did the check list from memory when he landed and I did it from memory when I took off. We both forgot the fuel selector check. Fred and I agreed that the incident didn't need to be told to everybody in the pilots lounge but we both agreed that we would never kiss off the written checklist again.
And that's the truth
Bowinkle T. Propwash