Ralph Hoover
Joined: 09 Jan 2006
Posts: 206
Location: Central Ohio
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 Posted: Tue May 09, 2006 4:22 pm Post subject: Redundancy.. I’m not gonna repeat myself ! |
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Last Saturday, I was taking my shinny new DRE -2000 John Jung specials (communication equipment) into the air for some landing time. They worked great and I discovered Ohio farm field hospitality up close and uncomfortable. I was taking off from my instructors field (1000 feet long) with my instructor aboard. As we climbed we lost a tad bit of air speed, not unnatural for 430 # of student and instructor and 60 degree temps. But then a surprise presented itself to us rather rudely. The engine went to idle! Looked to my left (the plane is a Challenger two place) and saw the throttle in its proper location, full open. As was appropriate, my instructor took control. We were not more than 300 feet above ground level and the landing needed to be now. There were several farm fields below us and he grabbed the closest one, unfortunately at a little bit of an angle with the plowed rows. Keeping trike front wheel up as long as possible, he brought it down as smoothly as could be done. The field was rough but we were no worse for wear nor was the Challenger, thank God! This ride just gave me more interest to go flying not less, so I am ok with the landing. Now if I am ever faced with this choice or need, I will do it knowing what I will be getting into. Recently plowed corn fields are not fun. But I'm sure better than standing stalks!
Now you probably want to know what this has to do with redundancy! Well here goes. The 503 DIDC and duel fuel supplied motor had a laps of NO or very low fuel. One cylinder didn’t act funny, both were even. One carb would have allowed the engine to run at higher rpm’s but rough. Two fuel lines; one from the existing mechanical fuel pump and one from an added electric fuel pump were plumbed into the system with appropriate check valves and “T‘s“ . Apparently one check valve stuck and allowed fuel to backflow into the other fuel pump or there was an air leak between the hand pump choke (enricher from my old Harley days) . In an effort to be sure of fuel redundancy a new problem came about. I know that there are two schools that apply here and that both have been successful. School one says “ keep it simple Stupid”. The Rotax people know what their doing and if it were needed, they would have made a second fuel pump part of the package, even though a snowmobile stopping isn’t the end of someone's life. The other school applies the “its better to be safe than sorry. After all, they have two carbs, two mags, two plugs, they would be better to have two fuel pumps”.
Anyone else experience this or anything like it? If so how did you correct the problem and does anyone have a specific suggestion to routing the fuel lines from both the mechanical pump and an electric fuel pump. I have read on this site where many use their electric fuel pump taking off and then shut it off for normal flight. I am about to re hose and add an electric fuel pump. I would very much appreciate any suggestions of success that you Kolbers have had.
Sucking air here in Ohio Ralph
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