PA24-250 Normal Speed

[Richard Lanning]

I am beginning to believe my plane may have some issues.

My speed has never been greater than 140kts IAS.

My most recent flight I was flying at 22"MP and 2300rpm at 5000ft. IAS varied between 132 and 127kts. Ground speed according to GPS was consistently about 1-3kts slower than IAS. Air temp was around 85 degrees F. Three bladed prop. And yes, the gear was up.

So I think I know the answer already but I'll ask anyway, is this what I should be seeing?

One other recent development. On this particular flight as I was taxiing out to the runway the #3 EGT probe pegged high. I suspected a bad probe since all other indications were normal. On takeoff the probe indicated normal again. As I was flying over Lake Okeechobee which is about 25 miles across the engine seemed to be running rough though sometimes I wonder if this is all in my mind. The lake is only 9 feet deep but it has a lot of nasty critters in it and I never see any boats in it. Not a place I want to do a forced landing. Anyway, on landing at my destination with power back the probe once again pegged high. Needless to say, it is going in the shop. This engine has less than 700 hours on it.

Another flight, another problem. Sure hope I run out of problems before I run out of money.

[Hank Spellman]

Richard,

I would ascribe the roughness over the alligators as "automatic rough". Every airplane I have ever flown has had it.

The egt problem is possibly a probe problem. Swap the wire on the probe with another probe to see if the problem follows the probe.

For the power problem, my best guess is that there is a hole in the manifold pressure line between the engine and the gauge, especially if the full throttle power seems OK. Look for a hole in the line other than the drilled tiny little hole in the metal part of the line, on the bottom of the line at its lowest point. That hole is supposed to be there. When I had exactly this symptom on my 250 (with a carburetor), there was a hole about 1/8 by 3/8 inches under one of the clamps. This leak made the gauge read higher than it should for any power setting other than full throttle.

Hank
Henry A. Spellman

[William Hughes]

North Saskatchewan: we call it "bush rough". Once your over the trees with no roads in site you become hyper sensitive to engine sounds.

An indicated airspeed of 132 knots at 5000 feet sounds a bit low at 22/23

[Richard Lanning]

Hole in manifold line is worth looking at but I don't think that is the case. The fuel consumption seems consistent with the power settings.

Over the last couple of months I developed a small oil leak. Been watching it closely. About 1 qt every 8 hours now. My mechanic hasn't been too concerned about it. Of course his butt isn't in the airplane either. After every flight and when I go to preflight I see a small drop of oil sitting on the DME antenna that is just forward of the firewall. Also noticed some black soot down the right side of the cowl. Bottom of plane is fairly clean. Been running with 10 qts and add when it gets to 9 qts.

Annual is in November so I am sure my mechanic is going to finds lots of things I really don't want to hear about.

[Kristin Winter]

Try running at nine quarts and adding at eight. If the "leak" goes away or substantially reduces, then it is coming out the breather and is not a leak at all.

[N3322G]

Richard,

Don't know the singles speeds but do know that we had to have our air speed gauge O/H'd so I wouldn't suggest relying entirely on that instrument unless it has had some recent attention and on a no-wind day agrees with GPS.

I would also say I find our Twin to be like our house - there is always something to fix, work on or enhance

Hope this helps.

[Richard Lanning]

Thanks everyone. I'll try 9 qts to 8 qts. I really don't want to get too low. Rather have too much than too little oil, especially if the small leak all of a sudden becomes a big leak. I went back through the archives and someone else who experienced an increase in oil consumption was told to increase the amount of oil to 11 qts which seemed to solve that person's issue. I guess I could try that too.

I have looked at the breather line and of course the belly and I really don't see that much oil. The drop on the end of the DME antenna is what concerns me. If it was coming out of the breather it would never get to the DME antenna. I have a little soot coming out of the lower half rear of the right cowling. Might tie into my EGT probe issue. Mechanic is going to take a look this week so I'll let everyone know what he finds.

I do have my suspicions on the airspeed gauge. Originally if I landed at 90kts it would plunk in so my landings have been at 100kts. Now that I got the wing fairing and fillets installed I come in at 90kts and they are greasers. I need to have someone look at the GPS while I do an approach. I am too focused to divert my attention to the GPS on landings. Still, in cruise my groundspeeds seem slow whatever direction I am flying.