182 lacking performance
 

The 182 at the school I instruct at just got back after a gear up landing repair. The engine was completely redone but now it feels like it lacks power. The takeoff role is almost twice as long as published in the poh. It's a Lycoming o-540 making good rpm and normal manifold pressure. Maintainence says It's fine. Any ideas what could be causing poor performance on a rebuilt engine?

Even though you may have max rated MP & RPM and engine power, a different propeller could have been installed, causing issues. Also check wheel alignment; Does it seem to take more power to taxi? Does it seem to perform satisfactorily once in the air?

Our club 172 had an engine rebuild - with the valve springs installed up-side down. Could not get over 6,000 ft and would climb like a brick. Probably a long shot.

If you know you are right, you need to demand that it be corrected. Compression values? There's always a reason and with modern maintenance requirements the aircraft performance not should be that far off, that's the whole point of engine rebuilds and maintenance. If you are still concerned something is up with it and nothing gets done, call FAA airworthiness. Otherwise, it could kill someone. I've been through similar situations, where an engine would constantly overheat that never gave an ounce of trouble in the years past. Something changed rather drastically and it would constantly go to redline. Forget what the issue was, but there was an actual issue, despite the initial "there's nothing wrong with it".

Though the OP's problem could have many more possibilities, which I'm too tired to list, I wouldn't necessarily say valve train problems would be that much of a long shot, at least something to consider. I had an O-540 (Fresh Factory Reman, direct from Lycoming) that would not
achieve required oil pressure. I did not fly the airplane. I sent the engine back to Lycoming and they actually admitted they discovered an oil galley plug that was left out... I do need to at least give them credit for the admission rather than trying to BS me. Also tell maintenance you want to see the engine uncowled. Look for anything loose or out of place, especially on the induction side ( I believe it is normally aspirated?) Also look for rags/shop towels potentially left in the engine... (seen that happen more than once)

It could be a number of issues. How long was it down for the engine swap? I would imagine if you last flew it in the winter the performance would have naturally degraded due to density altitude.

What if one cylinder was completely dead? It wouldn't show a difference during the magneto check. Can you check EGT individually at each cylinder?

In light aircraft with constant-speed props, you can get rated RPM and manifold pressure, even if the engine is weak. The blade angle will adjust to make the parameters fit. But it doesn't mean you are getting the expected thrust.

In a turboprop, you check torque. Not a 100% guarantee, but pretty certain you are getting the thrust you expect. (The exception I can think of is a bad blade). Obviously, not available in a C-182RG.

Double the takeoff roll? Even winter to summer shouldn't cause that much difference. I say have a different mechanic look at it before someone dies. Unless they did a lot of structural repair that significantly increased the weight of the airplane, I think something is wrong.

In my OV-10 Bronco Squadron, we had an airplane that took three times the normal roll to get airborne, and had half the climb rate of all the other airplanes. If it was in a 4-ship when we went to the bomb range, we would have to take extra passes around the pattern so he could get up to pattern altitude.

They sent it back to Rockwell twice and weighed it and checked it for straightness. They swapped the engines, and checked the torque on the ones they took out.

They never found anything. When the Air Force Museum said they wanted an airplane, it was the first one to go.

(If you've seen it at Wright-Patt, I've flown it, and it is this clunker!!)

If you have a dead cylinder, the vibrations would be terrible.

Had a car worked on once, and as I drove away, it was obvious something was wrong. It was smooth, just gutless. (V-6).

One cylinder dead---plug wire.

With a flat-four, probably true about vibration....but maybe not. Partially-dead; ie, burned valve, broken valve?

What other repairs were done to the airframe? The rigging could be way out. If something is misaligned it can rob performance and be dangerous. If the engine appears to be developing full power this is the next thing to check.