Low oil pressure warning in climb at WOT

[John Courte]

Today, I started climb tests. I finally got the prop adjusted to where it actually runs at 2700 on takeoff (Ok, 2690), and I got the baffles sealed up so that I don't go over 390, ever. I know there's room for improvement, and I'll fix it.

But today scared the **** out of me. I was doing a climb test, from 3500 to 7500, 100mph, WOT, 2680rpm. Just before I made it to 7500, my OP warning went off and my pressure reading dropped to 0. Of course, I put the nose down and backed off the throttle to 2300 (not instantaneously, but smartly) and reduced the prop rpm to 2300.

Oil pressure went back to a nice, comfortable 70psi, then I reduced power again for descent to the airport (I still stay close, I'm glad I do). The issue didn't reoccur. I got myself back on the ground and checked the oil. Same amount I had when I took off (short flight).

Not sure if this was terribly smart, but after checking the oil, checking the inside of the cowl, everything, I went up again. As long as I didn't push the RPM past 2600, no issues. If I increased to WOT/2700 and stayed level, no issues. If I climbed at 100mph for more than a couple of minutes, pressure would drop. There is a slight vibration at 2700, very slight, which may mean I need to balance my prop.

No change in RPM or engine sound, Oil temp remained normal and consistent, CHT's in normal range.

I'm really, really hoping this is a bad ground or a bad sensor.

Any ideas? I've searched the threads and it seems like I'm dealing with a bad ground, a bad sender, or I need to adjust the oil pressure on the engine.

This is a parallel-valve O-360-F1A6 converted to FI with AFP.

[dlloyd3]

O Oil pressure and your Hartzell will go to fine pitch. Since you could still control the speed it is unlikely you lost oil pressure. My sensors losing a ground will give a high pressure indication, don't know what yours would do but check both the ground and signal wiring.

[Bugsy]

Good luck with phase I. I just finished last week. Boy she sure does have a personality and it took me all of 40 hours to learn it. My fuel pressure drops off every so often. Pretty predictable during climb and maneuvering. Carb.

We have so much information that you almost have to get used to intermittent announcements. I'm not suggesting that your warning wasn't valid, fingers crossed it's not a problem.

[John Courte]

Every so often, my #1 CHT will go to 0 as well. This I can safely blame on probe wiring or the probe itself.

I'm using a MGL Odyssey 2 EFIS and RDAC XD engine monitoring module. The RDAC is mounted on the firewall, and its connectors are a screw-down and they look like miniature versions of garage doors. It's entirely possible that the insulation in pinned in this fastener and not just the wire, on both the errant CHT probe and the oil pressure sender.

I will also check the wiring on the EFIS, because the RDAC gets its power from a connector on the back of it.

Dave, thanks for pointing out that the prop still operated while alarm was on. I did not think of that, and it totally makes sense. I feel a little better, but I will install a mechanical gauge as soon as I can.

As others have said, if there is absolutely one indicator that needs to work all the time, every time, it's the oil pressure indicator.

Paul, congrats on nearing the finish line! Aside from this, I'm not far behind. I've got about 11 more hours to go!