At first I thought it was just me "hearing" things since I only have just over 300TT piston. But when the entire airplane is shaking and the jumpers are getting worried (these guys are unshakeable due to being insane meatballs ), I know it's not just me. The first time it happened, the engine completely cut out for a moment...when combustion resumed, it was way down on power and missing badly. Mind you this was at 2500 MSL (1800 agl) so the mixture was not the problem. Temps were good, oil pressure was good, and the mixture was properly leaned 25 degrees rich of peak. I quickly checked fuel, primer, mixture, carb heat, and moved the power lever. Upon doing a mag check, the engine nearly quit on either individual mag. I booted the jumpers out immediately and landed without incident. The airplane had a very strong odor of fuel on the postflight. The second time was in a different plane the next weekend. On climbout, the airplane started shaking and the engine was missing badly. The mixture again was leaned properly with good temps all around. The miss cleared up after about 2 minutes. On descent from 10k, the engine was missing the entire time and I simply made a very high approach with a normal landing. The mag check revealed no abnormalities. Airplane number 1 has been sitting since I said I wouldn't fly it until an A+P came over. Airplane 2 had it's plugs and oil changed. The plugs on the right bank were somewhat fowled. I did the standard "run it up and lean it out" trick to clean them but obviously it didn't work. If anybody has experience with these suckers, drop the advice, I am all ears.
Not sure what type engine that I had in the 182 that I draged rags in, but we had a huge carb ice problem. It got to the point that I was doing over 95% of the flight with the carb ice turned on. Hope this helps, and I hope that your able to get ouf ofthe 182 soon and back with AWAC. Let me know what it looks like as far as call backs go there....
The C-182 is a good plane for skydiver hauling but the O-470 is touchy when colder weather comes. It gets worse in winter, esp since you are always at max performance climb or max descent power settings. This is the reason skydive planes rarely make it all the way to published TBO. Sometimes in very cold weather, the only way to keep it running after startup is with several shots of primer until it warms up. The Cessna CHT gauge isn't much good so a GEM is very useful - experienced skydive clubs find this a good investment. Maintenance is a costly headache for clubs with a lot of members who jump but don't fly the planes. Oil changes on schedule are an absolute must. When it's really cold outside it's a good idea to warm up the oil for about 10 mins before the first flight and close the cowl flaps a bit on the climbout while monitoring the temps. They should always be closed on descent to avoid shock cooling the engine.
You handled the rough running engine appropriately. Despite your leaning and corrective actions it sounds like yours was still running rich (smell of gas afterward) and probably fouled the plugs. Anytime it runs rough or misses in cold weather, lean it out a little more, try carb heat, and give it time to kick in. Finally, always remain within gliding distance of homeplate for obvious reasons, and be sure the jumpmaster always briefs the divers esp students for an early, low departure from the plane. Jumpers are not used to landing in a plane and you don't need them milling around in there or asking questions when you are busy shooting a precautionary approach. I've had 2 engine out landings in a couple hundred hrs of flying skydivers in 182's. Keep your speed up, spiral down directly over the field and set up for a power off landing, i.e. do not assume you will get any power out of a rough runner. The 182 sideslips nicely with or without wing flaps down, as you noticed in crosswind landings, so you can bleed off several hundred feet of altitude without picking up much airspeed once you know you have the field made. Touch down with enough speed to coast off the runway, if possible, all the way to the fuel pump, tarmac or hangar.
The O-470 is temperamental on its best day but it can get downright ornery when the OAT drops down. I guess that's to be expected from 1940's technology. Other than these engine peculiarities the 182 is an excellent workhorse machine. About the time you get comfortable with it you will be back in turbines!
Have a compression check done on the engine before you fly it again. You have a bad exhaust valve that is burned or sticking. The reason that you have to lean the mixture is due to the fact that one cylinder is not combusting. You will eventually suck the valve and there will be extensive damage to the cylinder and piston and stress on the crankshaft.
Ask your boss at the strip what the standard practice is for climbout and descent on the 182's. All the previous answers hit the nail on the head about temp extremes being a source of problem for skydiving planes. Slow heavy climbouts followed by rapid descents for the next load. Pulling back the power to idle and screaming down for the next load might be bad for the engine in the long run.
Try and seek out a jumper who is the most mechanical there and ask him what the past history and so on for the planes are.
Compression check is a good idea. Also inquire as to the oil consumption history on the engines and make sure you record oil levels during your first preflight before youve started the engines every single day you fly. Always idling engine long enough to get all needles into green before your first flight is also a good idea. Always been told you can shred an engine apart from the inside out if you cool it down to fast or pull away with power before you have the engine warm.
Both airplanes have aftermarket CHT gauges. I was instructed by the owner on the checkout to run no lower than 17 inches on descent. I usually keep it at 17-19 inches. I also do not allow the cylinders to cool rapidly letting it take a few minutes for the temps to drop from 400 to 310 degrees. I've also checked out the info on Chris Schindler's site www.diverdriver.com as it has a bunch of info on flying 182s. Turbo, when you are referring to burnt valves, are you talking about plane #1 or plane #2? Carb ice is not the problem. I know that because the 2nd load of jumpers I ever flew I got carb ice and after that I constantly have a small amount of carb heat on. Even though that richens the mixture slightly, I still am leaning the motor based on EGTs so it shouldn't be a factor. Thanks for the tips everyone. For now the worst of the planes is sitting in tiedown (probably for the winter as I don't see the owner paying a mechanic to look at it). Some low time kid will fly it in the spring I'm sure....giddyup!
Sounds like a lot of good advise. I may have missed it, but do you have a carb temp gauge? One thing that you mentioned seemed to stick out at me. You said something about always keeping a little carb heat on. Without a carb temp gauge that could be causing you a lot of trouble. With partial carb heat on, you can raise the temp in the carb to a temperature that can be very conductive to carb icing, (even when it's pretty cold, or warm out). I would recommend only using full carb heat when conditions warrant (low power, or suspected carb icing) or none. If you don't have the temp gauge, you could be causing yourself a lot of trouble with carb icing. Also if you think you are getting carb ice, be patient and let the carb heat work. Also even with the carb heat on, during a low power descent, you may not be generating enough heat to solve the problem. I know it is counterproductive when flying jumpers, but you may need to add power to near cruise settings to generate enough heat to melt the ice. May cause you a little more time between jumps, but better than having the engine shut down! Low power settings don't generate very much heat at all, so just another thing to consider. Hope this helps, and good luck getting back on line, hopefully soon!