Friday, June 8, 2012

Test pilot tales



This morning, I took N614EF up for our first trip together and, as she's been for the 11 years we've been married, it wasn't simple. I am, of course, now into the test-pilot stage and I take these things pretty seriously; there's no time to be distracted by deep thoughts of journeys and self-satisfaction -- that's what Sunday was for. There's work to be done.

I can't say it was a particularly enjoyable half hour of work, because I haven't yet accepted the reality that things are going to go wrong and I'm not going to know what to do about them until I learn what to do about them, pretty much like the previous 11 years.

The weather said the winds were 3 knots this morning at Airlake Airport, but like previous times I've arrived, I found different weather conditions -- slightly windier and a little gustier. That's when I realized the AWOS system at Lakeville sucks and they haven't bothered to add a NOTAM or make an announcement to the effect of, "everything we just told you is mostly BS." But it was manageable, so a flying we would go.

The one thing nobody has told me -- maybe the only thing nobody has told me -- is that the plane makes some interesting sounds -- unfamiliar sounds -- on takeoff. Or at least, mine does.

The mag checked showed a drop of about 60 when I shut it down, leaving only the electronic ignition on (Updated correction: This is wrong. It should have said the drop was when I was operating only on the mag). That's more than I've seen drop in the few times I've started the engine, but it's not significantly lower. Still, it was different, just different enough to get in my head.

I could only get 1900 RPM on a static RPM check, lower than the 2150 Tom Berge reported last Sunday, and lower than the 2300 it should be. People have suggested the RPM would go up once the plane was moving so I attempted a takeoff and aborted it fairly quickly. The plane was making noises and, frankly, I couldn't tell if it was engine noises or airframe noises. It could have been backfiring or the engine could have been missing. I seriously don't know; I still don't know. I didn't have anybody standing nearby to tell me.

I removed my headphones to listen but I honestly couldn't tell what I was hearing because, for one thing, I've not been in this position before and I have nothing to compare things to.

I taxied back to the runup area and tried it again and did not detect any particular noises (the RPM hadn't changed). So I took the active runway and took off and, again, found the noise quite distracting, especially considering the fact I had it in my head the plane wasn't developing full power. But it was developing enough power to get airborne and so we did.

On turning downwind, a warning light cane on the engine monitor, showing a fuel pressure of 19 psi. The operating manual for the engine does not list a minimum fuel pressure, and it registered 37 psi on the ground. So I'm assuming the pressure is reduced because the engine is taking a big drink of juice during takeoff that it's not taking when taxiing. But after reaching pattern altitude, I switched tanks anyway.

I started heading for the test area but was fairly glued to some of the numbers I was seeing. I was at about 90 knots, 2,300 feet, and notice the manifold pressure wasn't going higher than 19 (altimeter 29.91, temp 77 FP prop 85 pitch). Cylinder temperatures were all in the green, though the hottest was the #1 cylinder. Curiously, the lowest exhaust gas temperature was also on the #1. I wish I hadn't followed Van's instructions and riveted the #1 cylinder air dam on the baffle.

Keep going? Or return for landing.

I went out five miles and then circled back to join a downwind for landing, which -- considering the winds had now come up -- wasn't that great. Wasn't horrible, it just wasn't up to par for me.

My left brake problems seem to have dissipated but now the right brake seems to be sticking a bit. I'm going to take that apart and clean it and retorque it, as I did the left one.

Back in the hangar, I pulled the top cowling off and noticed a fairly large amount of oil on the bottom cowling "floor." I now engines spew oil, but one problem is -- like the noises -- I have no benchmark to know what's a problem and what's not. Still, this seemed significant to me.



I noticed a little "spray" of oil on the back side of the baffle, just below the oil cooler.



But I couldn't quite find the source. I didn't see anything on the cooler itself to warrant concern, and both connections to it seemed solid. A hint of fuel lube was still around the base of the steel fittings and there was no drips at the connection with the hoses.

I did find a drop on a couple of the bolts at the base of the fuel pump...



I found some oil around what I presume to be drain plugs -- one safetied, the other is a hex nut. But is it coming from here? I don't know.



Looking closer, I can see oil around the sump bolts. By the way, you may find it more helpful to click the image and see the bigger version.



Kind of a dark, oily soot on top of the filtered air box. As long as I was here, I doublechecked to make sure there was no blockage of the filter. There wasn't.



At the front of the engine, you can see a drop of oil near the bracket for the prop oil line (plumbed but not used). Again, it's at the split of the engine case.



And you can't see it here but there appeared to be a small drip at the hose connection to the fitting for the oil cooler return to the engine (or maybe it's from the engine, I forget).



I also noticed oil on the sump bolts that are used to hold the hangars for the exhaust.

I'm pretty sure we're looking at two separate issues here. The oil situation is, perhaps, a matter of just tightening stuff, unless I'm missing something.

The engine power situation is an entirely different one. Frankly, I've stopped trusting that left magneto. I don't know whether that has anything to do with; I just don't trust it.

I inspected the rest of the engine for any telltale signs and didn't see anything, but then again, I don't really have any knowledge of a systematic way of working my way through analyzing what's going on here.

I do wish I'd hooked up the computer to gather the engine readings for later analysis, but I didn't bring it with me.

It's supposed to be a pretty crappy weekend so flying is probably out of the question, but a crow hop or two is possibly doable. If you've got a good set of ears and a little bit of knowledge about engines, how about standing by and listening from the outside of the plane?

(Update here)




11 comments:

  1. Congrats on your first flight with your bird Bob!!!

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  3. Not RV specific, but with my o-360 engine, if I fill the oil to the recommended capacity (8 quarts), it will blow 1.5 quarts out in the first hour, then settle in at about 6.5 and sit there until time to change it 50 hours later. It gets messy inside the cowl and outside on the fuselage. Regardless of the details, Congrats on the first (of many) flights!

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  4. i see that oil on the front of the engine.. by the starter. the only thing i can think of to make oil get that far forward .. with the propwash and all.. is a nose seal leak. its a pain, you'd have to take the prop off to really confirm.. there is a rubber/viton gasket that may not have been put on properly, etc. when mine went, i was seeing oil on the airbox, the nose wheel pant.. and on the inside surface of the bottom cowl.. and elsewhere.

    your max rpm concerns me - could just be the pitch of your prop, find someone else who has the same prop and engine and see what their static rpm is.

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  6. The "low static" was judged -- by an A&P -- not to be significantly abnormal with this prop. I was out of the pattern when the MP/FP problem presented.

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    1. I don't have a constant speed prop.

      The first step is to check the accuracy of the tach reading, and in so doing, confirm whether there is a problem.

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  9. I spent the money to have it plumbed for constant speed to enhance resale value. But your question is a good one and we were asking it on Sunday. Basically, it comes out of the engine somewhere and goes somewhere else. (g) We concluded it doesn't actually have any oil in the line.

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