Joined: 07 May 2013
Location: Tullahoma, TN
|Posted: Wed Feb 01, 2017 4:20 pm Post subject: Another RV-10 flying! (with some performance questions)
My experience is much thee same as Tim says below. I found that 125kts climb keeps my cylinders the coolest in climbs and you don’t sacrifice much in rate of climb either.
And like Tim, on the days when my pressure drops while climbing (usually on warm temp days) I just turn on the fuel pump or silence the warning.
So far, no engine stumbling when the pressure drops down to around 12 as Tim has seen.
N184JM flying since 2007
| On Jan 31, 2017, at 10:14 AM, Tim Olson <Tim(at)MyRV10.com> wrote:
At higher altitudes the fuel will vaporize easier. Additionally, most
of the time while you're climbing the airflow thru the cowl isn't
as good. So, you have heat buildup causing vapor, and altitude making
vapor easier to form. With the fuel pump behind the
engine, it's in an area of higher heat. So, vapor can be a
problem. There are PLENTY of people who have noticed this
in their RV-10s. There are some who have not.
I certainly wouldn't replace a fuel pump over it, because it
is common enough that I don't believe it to be highly abnormal.
This has happened to me maybe 25 times or 30 times in
1200 hours...maybe more, but not every flight. Usually
it happens when I get over 8000'. Never has the pressure
actually dropped enough that the engine felt it.
I have seen as low as 12PSI. Leaning for climb helps,
because you reduce the flow which increases the pressure.
Climbing slower helps because you cool better.
I HAVE seen it happen where running the boost pump for 30 seconds
takes care of it and it doesn't re-occur. Other times it may
come back in a minute or two. Maybe it's a pocket of vapor
that gets blow thru with the boost pump. Either way, the
important thing is you know it's happening and most EFIS
systems will audibly alert you. When I get the alert I
just look at the gauge, turn on the pump, and the problem
I did buy a fuel pump cooling shroud from Aircraft Spruce at one
with the intent of adding blast cooling to my fuel pump.
I never bothered to install it because it's kind of a
pain to get into that area and install it, or even
replace the fuel pump in the first place. I decided that
it wasn't worth the effort for an occasional occurrence.
It's not bad that you're going to go thru all the inspection work,
but I wouldn't sweat it too much about the fuel pressure in
climb unless it happens to you all the time. Try climbing
at 120kts and try a few things before you spend too
much worry over it.
On 1/31/2017 4:32 AM, Dan Charrois wrote:
> What I just don't understand though is why at low altitude and high
> power settings (25"/2500, and around 20 gph), I'm seeing an OK fuel
> pressure of around 22 psi.. but for some reason when I did my climb,
> the pressure went way down even though the flow stayed the same.. and
> then when I got back to a lower altitude, the pressure went right
> back up again. I'm not sure if it was related to altitude, high
> power for an extended period, or climb attitude. Once I finish going
> through the system for leakage, blockages, etc. and get the plane
> back in the air, if I'm still having trouble, my plan is to try a
> step climb to try and isolate whether altitude or attitude is more
> likely causing the issue in the first place.
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