Bob Collins
Joined: 11 Mar 2006
Posts: 470
Location: St. Paul, Minnesota
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 Posted: Sat Apr 05, 2014 7:35 pm Post subject: RV-List: Engine out over KOCF |
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They were attached to the message I got.
Do not archive
Sent from my Verizon Wireless 4G LTE Smartphone
----- Reply message -----
From: "Bob-tcw" <rnewman(at)tcwtech.com>
To: <rv-list(at)matronics.com>
Subject: RV-List: Engine out over KOCF
Date: Sat, Apr 5, 2014 12:50 PM
The original listing had pictures when I posted it. Did anyone else see them?
Here’s a url to one of the pics I put on my google+ album.
https://lh3.googleusercontent.com/-36L4ELs0R10/Uz8rUckKBfI/AAAAAAAAUCE/Fu3xneaqtWQ/w769-h577-no/2014-04-03+13.22.23.jpg
Bob
From: Charles Brame (chasb(at)satx.rr.com)
Sent: Saturday, April 05, 2014 11:06 AM
To: List RV (Rv-list(at)matronics.com)
Subject: RV-List: Engine out over KOCF
Bob,
Great job and great report. No photos attached, however. Any chance of a url or a web site to show the photos?
Charlie Brame
RV-6A N11CB - with a vertical mount AFP fuel injection.
San Antonio
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[quote]Time: 03:59:59 PM PST US
From: "Bob-tcw" <rnewman(at)tcwtech.com (rnewman(at)tcwtech.com)>
Subject: RV-List: Engine out over KOCF
Fellow RVs,
Monday afternoon at 7000 ft. right over KOCF on our way to Sun-n-Fun I had
the opportunity to put all that engine-out training to work. The good news
first: This was the best case possible, no one hurt, no airplane damage,
flew the plane, declared emergency, landed on the paved runway, made the
first taxiway. Guardian angle working overtime!!
Now for the important details that I believe can have a positive effect on
others building or flying RV's.
Root cause of the engine failure was that the filtered airbox came off the
throttle body, wedged under the intake portion of the throttle body and
disrupted the airflow through the metering venturi. This caused the mixture
to go way out of wack as the engine went to an extreme rich condition, I saw
fuel flow rates pegged at >30 gph as soon as the event occurred.
My airplane is an RV-10 with a stock engine install and a stock cowling. I
have the Airflow Performance fuel injection system with a vertical mount
FM-200 fuel servo. This is the critical issue. The FM-200 uses an aluminum
clamping doughnut to retain the filtered airbox assembly. This system does
not use safety-wired bolts on the filtered side of the airbox, just this
clamping doughnut. If the doughnut looses it's grip on the throttle body the
whole filtered airbox can slide downwards and fall off, in this case that is
exactly what happened. When we pulled the top cowling off, there in the
bottom sat the entire filtered airbox, clamping doughnut and all.
Now for the fix: The filtered airbox bolts are located right underneath the
mounting studs for the throttle body assembly. I simply replaced these bolts
with drilled head bolts and made some drilled coupling nuts to put on the
throttle body studs, there was plenty of extra threads exposed on these
studs so I didn't have to make any changes to the studs or the nuts that
hold the throttle body in place. Then just safety wire the whole thing
together. I used 0.040 wire to tie each filtered airbox bolt up to the
mounting studs. Below are pictures of the drilled nuts and the final
installation.
Obviously I would highly recommend that if you have an Airflow Performance
fuel injection system with a vertically mounted fuel servo you take a look
at your installation and consider adding some securing means to ensure this
thing can't come apart on your airplane. They key issue is that disrupting
the airflow inside the fuel servo can make the engine STOP RUNNING!
Lastly, I've collected the flight data out of my AFS EFIS system which I
just happened to have running at 2 second intervals. Its been very
instructive to see exactly how the whole event played out. I could see my
various attempts to get the engine to run properly by changing throttle
positions and the hopeless lack of actual power. You could see the excess
fuel just crater the EGTs, and now in hind sight I may have been able to get
some power back if I had the insight to try and close the mixture radically.
However, I can say with confidence my total focus after about 1 or so
minutes of trying to get power was on flying the plane to a safe landing....
mission accomplished.
Pictures attached are of the drilled retention nuts and the updated
installation.
Bob Newman
N541RV 200 hrs
href="http://www.matronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List
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_________________
Bob Collins
St. Paul, Minn.
Letters from Flyover Country
http://rvnewsletter.blogspot.com/ |
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