Friday, June 22, 2012

Flight Test Follies: Time to stretch

As you know if you've been following this blog of late, I've been struggling with learning the engine of N614EF and figuring out rumbles and reduced power. Even when I reported a restoration of power after finding a slight blockage in the fuel injector on the #1 cylinder, people were warning me about too-high exhaust gas temperatures and higher-than-normal temperatures on the the #1 cylinder head.

Finding a little more blockage on the #1 injector led me to believe that whatever problem the engine was having, we've found the reason, but until you take it up into the air, you just don't know for sure.

So last night I took her up and, again, orbited the airport at 3,000 feet (actually 3,200 based on this article by my RV mentor, Doug Weiler).

I didn't have the engine monitor hooked up to my laptop so merely passing along observations as I remember them, I can report that I developed about 2450 RPM on the takeoff roll and, most important, all of the CHTs and EGTs were close to each other.

As I circled the airport, I had no problem developing 2500 RPM (I have the engine monitor set to show an alarm if I go beyond that), and the cylinder head temperatures were all within about 10 degrees of each other at about 373 in level flight. #1 was slightly higher, which I still blame on having the air dam in place to encourage more air to get to the back cylinders (3 & 4).

The exhaust gas temperatures were similarly fairly equal. I saw nothing close to the 1400 on the #1 I saw on takeoff (at 2350 RPM) the other day. #1 was still the coolest of the EGTs, but I'm still not convinced the probe is entirely accurate. I also think at this point, comparing EGTs can lead you in a wrong direction.

The plane is using very little oil -- almost none it seems -- which continues to baffle me. Theoretically, if the engine isn't broken in, it should be using a lot of oil. Is the engine broken in? I have no idea, but I'd like to think it is so I can throttle back and save some money.

After orbiting the field for 20 minutes or so, I headed southeast to lose altitude and at one point, got the plane up to about 150 knots indicated airspeed, which is pretty darned good (I think) considering there are no intersection fairings, gear leg fairings, or wheel pants on the plane at the moment.

At some point soon, I'm going to have to take the plane over to the gas pumps and bite the bullet and fill each tank to the brim, so I can fully calibrate the FlowScan fuel-flow meter and also check exactly how heavy the heavy wing is (it's much better than it was).

But I have a lot of confidence in the engine now, and it's time to take the plane out to the test area and do some serious flight-testing work to determine the entire airframe's performance ability.

1 comment: