Carburetor Heat

One of our 182s had returned from “Annual” out of state. I had not flown it back to our dropzone. The first time I took it out to fly a load I did a normal engine run-up, system check and checked for free controls. However, when the carburetor heat was applied nothing happened. Rather than go airborne without carb heat I elected to shutdown and use another one of our 182s to fly the load. Upon returning after dropping jumpers we took the cowl off the engine. Sure enough the carb heat cable had fallen out of attachment with the lever arm which opens up warming the air entering the intake. What also bothered me was the bird’s nest that was built quite extensively along the left side above the engine. I was not happy with how thorough I had done my preflight to begin with. On the right side of the engine on top of the baffling lay a wrench. This aircraft had flown back to our DZ in this condition.

While I was not happy about what I had found at least I found it before I flew it again. But what happened next was one of the most harrowing experiences I’ve ever had flying aircraft. Our onsite mechanic reattached the carb heat cable and we cleaned out the bird’s nest and removed the wrench. The cowl was reattached and I did another run-up on the engine. Carb heat worked fine and all other systems seemed to work normal. We loaded up four more jumpers and took off. A normal climb, drop and descent (or so I thought) were made. Soon after landing a rain shower moved through during the lazy summer day. It gave the skydivers enough time to pack and the next student time to suit up and review their dive.

Once the rain shower had moved through we loaded up and I probably made one of the biggest mistakes ever flying an aircraft: I didn’t do a full run-up and system check again. I looked at the engine oil and pressure and both were in the green. CHT was also in the green so I elected to takeoff on the 2,500’x30′ paved runway. All seemed normal. A fully loaded 182 with a pilot and four jumpers on a hot summer day is not a stellar performer as it is. But at about 400′-500′ AGL the engine just quit. It surged again then died again. Having flown out of the airport for almost two years by then I knew I had trees, houses and rising terrain ahead of me as I had just started my turn to exit on a 45 from the traffic pattern. I continued the left turn while adding in the flaps. It had the old style “parking brake” manual flap handle. After the first notch of flaps I made sure the throttle was in, mixture RICH, Ignition was ON, Fuel was on BOTH instead of OFF. I tried Ignition LEFT then RIGHT with no success and put it back to BOTH. We were now going downwind back to the runway. I had made a 180 from the departure runway but not the “impossible turn”. It was a true 180 and I lined up on the grass area where the jumpers landed. I extended the flaps to full and kept the airspeed. I gave it enough flare to keep the nose off the ground and we touched down firm. The grass area was very soggy as we had been getting periodic showers for days. Water and mud flew up as we quickly decelerated. Coming to a stop and not knowing what caused our forced landing we evacuated quickly.

After a few minutes of catching our breath and kind of staring at the plane wondering why it didn’t like us anymore we talked about what happened. It was decided that we could try to crank the engine to see if it would turn over. It did. We checked for fuel and we had plenty in the tanks. Fuel selector was still on BOTH. So, I turned the ignition on and the engine started! It ran smooth. It’s moments like this that can make you question your sanity. I knew it had failed. The jumpers knew it had failed. But now it was running smooth. So I taxied it out of the soggy grass and over to our hangar where we pulled the cowl. As soon as the bottom cowl was dropped there was the carb heat cable dangling from the lever arm. It had become disconnected again.

What we surmised was that on the load prior to this flight the carb heat cable became disconnected again. So on descent when I thought I had heat being applied in very moist conditions I did not. Ice built up and since I had not needed power for landing I didn’t detect the buildup. When the plane sat for a time the ice was loosened and melted from the radiant heat of the engine. On the final flight the water and ice chunk let loose and killed the engine. After the forced landing the radiant heat finished the melting job and the engine started fine and ran smoothly.

Lessons learned were to never assume that even though a plane was signed off for having ANY maintenance done that it was done correctly or thoroughly. Never assume that even though engine indications are in the green that a full run-up before each takeoff is a waste of time. It only takes catching something one time to know that you must be sure before going airborne that all is working correctly.

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