jbDC9

jbDC9

Well Known Member
I know Paul did a full 10 hr report a year ago, so I don't wanna repeat anything, but the Hobbs on my -8 QB just turned up to 11 (Spinal Tap!) yesterday, and have a couple of questions...

Oil canning/popping noises? I've heard it a few times coming from the tail area, not pulling any Gs, just motoring thru the bumps... an occasional "pop". Have others heard this type stuff? I've pulled the emp fairings, all nuts/bolts back there tight and secure, no noises when I wiggle and shake it... makes me wonder, is it just a "settling in" type thing? Last evening I worked up the nerve to pull a bit over a 2 G turn and all was quiet. I rode in the back of another -8 a month or so ago, did some loops, rolls, Immelmans, a spin, hammerhead, etc, pulling many Gs... I seem to recall hearing a couple of rattles there as well. Perhaps I'm just being a chicken...

Engine temps/CHTs? Cyl head temps (O-360-A1D) seem normal at cruise, 360 to 385 range on a cool (48 deg OAT) day. Rear cyls are warmest, no surprise there. I've noticed though, that during a low speed (85-90kt) climb the CHTs climb pretty rapidly towards 430-440 or so. It seems that a cruise climb at around 110 kts keeps the CHTs around 400/410 and still provides a pretty good climb rate. Does this seem fairly typical? Will the CHTs come down a bit as the engine breaks in and loosens up a bit? As far as oil temps go, all is well using the standard kit oil cooler, right around 178 to 188 degrees so far. Will be interesting to watch the changes next summer flying on 90+ degree days.

Now for a few observations;

At 8 hours I spotted my first skin crack, right where I might've expected it on an 8; it's on the cooling air ramp, F-867D stiffener. It's around a rivet at the end of the stiffener... looks like I get to practice my stop drilling. Even with the 4 into 1 pipe and its long extension down the ramp, it gets pretty rattly and noisy during takeoff and initial climb; smooths out nicely one the speed is up and power is back.

Manual elevator trim; love it! Very good, precise control. I wondered if I'd regret not using elec trim since I'm used to having it at my day job (737 driver), but I don't miss it a bit. Simple, works great, lasts a long time.

Classic Aero seats; expensive, but man are they comfortable. Spent 4+ hours in 'em yesterday, was as nice as sitting in my wife's Honda Accord. I bought the cloth set 2 yrs ago before the prices went up, got lucky there I guess...

Avionics/EFIS/autopilot integration and operation? Ummm, no, nothing to report on like Paul's setup, but my KX-125 navcom and Garmin 296 are getting along just fine! The TruTrak ADI is working as advertised, but the little airplane symbol is vibrating quite a bit and causing rub marks on the background. Might have to send this one in...

John B
RV-8 QB
Houston, TX
 
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hey john,

great report!

You mentioned the oil canning/ pop noise.... I have a similar noise on mine. It only happens in the pattern when I?m slowing up for the base turn. Right around 100 kts there is a very slight thud/pop/oil canning sound coming from the horizontal stab. I've been told its normal and caused by the airflow being disrupted as the angle of attack is increasing. It has come to be a fun little noise that makes the plane unique and it is very predictable. Never heard any rattles during g's though...maybe others will have some thoughts.

Regarding the CHT + EGT's: I had similar temps during the break-in and we were a little uncomfortable with the CHT's getting into the 400 range during climb-out so we took off the cowling and sealed up every little crack and possible location of a leak in the baffling, especially up near the spinner there were some big holes where the air was leaking through the baffle. There was also some major leaking back towards the oil cooler on the baffle. We sealed up the cracks and it brought down the temps significantly (15-20 degrees). Might give that a try.
 
How about the bottom of the tail cone? Any oil canning in that are (seems pretty common, btw..)..
 
Great Report !

Glad your up and flying John - you'll be amazed at how fast those hours go by....

On the CHT's and climb - I think you'll find that best rate of climb is actually going to be closer to 100 knots, so climbing around 85-90 is not going to help you, and yes, it will raise the temps - I'll get up in the 400's on CHT's by 8-10K if I climb that slow. The actually rate of climb versus airspeed curve is really flat, so you're not going to see dramatic gain or loss of ROC between 90 and 110 knots...Once I am above any obstacles that might bother me, I generally accelerate to 110 knots TAS (I have TAS in real time on the EFIS), and hold that throughout my climb. Temps stay nicely within limits up to 15K that way.

On the popping noise - I haven't heard one in flight, but back in Phase 1, I was preflighting one day, and as I pulled up on the leading edge of the Horizontal Stab, I heard this little , faint "click". Bothered the heck out of . I took the empennage fairing off to see if I could see anything moving, but never found a thing. Reassembled it, and it was gone.

Moral of the story? I am sure this isn't what you are hearing, but I know how that can wander around in the back of your mind, so if it bothers you, do some ground inspection to satisfy yourself that nothing is loose....and then go fly!

Paul
 
I believe Dan Checkoway reported some oil-canning in his -7 on his website. If I remember correctly, he installed a few pieces of aluminum angle on the floor behind the baggage area to stop it.


Keep the airspeed up in climb for best cooling. Sustained CHT temperatures above 400 are not desirable. You might want to check out the various John Deakin articles on the Avweb site regarding LOP engine operations.

regards,

erich weaver
 
Hi John
Be sure to check the skin just behind the bagage compartment,between the spars,when you press on it,it might make a poppping noise,mine did and solved the problem with 2 aluminum agles in a V-shape that followed the fuselage tapering!!!!

jorn Moller
OY-RVS RV8
O-360 300 hours
 
Elevator trim

I have electric elevator trim. I cannot ever get the trim just right. The movement of it is not fine enough. Your manual trim sounds much better.

Fellow 737 driver

Wild Blue
RV8a
 
Faster

Congratulations John.
I experimented with different climb speeds during phase one and found that 150 MPH yields me 1500 FPM or more and 160 still yields over 1000 FPM with my fixed pitch Catto and cooling oil or Cylinders was never a problem.
You'll be pleasantly surprised at how well these little rockets climb at higher speeds. .02c.
Regards,
 
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