Forced Landing #3
September 26, 2001
By: Jim Hayward
I now had about 24 hours on the plane since July's forced landing. I was feeling fairly comfortable with things again. I had been checking the temp/dew point spread before flying and being a good little feller!
Wednesday, Sept 26, 2001, I flew out to Black Hawk to meet a buddy for a few minutes. I was out there in about 15 minutes looking for him but not finding him. I just flew around the area, waiting. I had been airborne about 35 minutes when I thought I saw him pulling over in a different vehicle. I kicked in some rudder and aileron to turn and set up for the pasture I had decided on.
No sooner had I throttled back some on downwind when the engine dropped back in power again. A quick glance to the carb temp showed 64.8 degrees so no problem there. I turned base only to find the car gone, so it wasn't my buddy after all.
I added some throttle (power would be an overstatement) to go around but Mr. Rotax wasn't accepting much input. Dang it, now my approach was dinked up. I was a bit high and there were power lines on the other side of the road where this fence was at the end of the pasture.
A few finer expletives later found me slipping pretty hard to get down. Instinct told me I'd probably have an unwanted intimate relationship with the barb wire fence I was rapidly approaching, so I gave it some left rudder while squeezing mightily on the brake handle. I veered left a bit and traveled on across a gravel driveway stopping in a front yard and about 15 feet from the road.
As I stopped, so did the engine. I got out, waiting for someone to come out of the house to see what the hell this airplane was doing in their front yard. No one came out so I went around to the engine and immediately noticed the fuel line was empty. Checking for frost on the carbs, I found none.
'AaaHAAAA!!!!' I thought ... a bad fuel pump. I turned on the Facet auxillary pump and the lines filled. I got back in and cranked it up and it roared to life. I taxied back over to the pasture (trying to look cool) and was getting ready to leave when Bill arrived.
He had been over at the radio controlled flying field waving frantically at me to land there but I didn't see him. He said the guys there wanted to see the plane. We visited a bit and I said I had to get home. The trip home was an uneventful 12 minute flight and I called him to let him know I was back home. At least this pasture wasn't full of rocks... in fact, it was smoother than my own strip!
The next afternoon I tied the plane off to a tree in the back yard, fired it up, and saw one of the prettiest (althought unwanted) sights I've ever seen. The after- noon sun was glistening on the translucent blue fuel lines full of air bubbles.
They were just sparkling and dancing around in the lines depending on the RPM's. I could make them go one way or another, or even stand still just with the engine RPM.
The source seemed to be the outlet port of the fuel filter. I loosened the clamp and the hose slipped right off. Evidently, the manufacturer of the filter housing and the manufacturer of the fuel line had slightly different ideas of what constituted 1/4 inch since it was a loose fit, and the clamp wouldn't clamp tightly enough (so I thought).
Since the filter would also accomodate a 5/16" line, I slid the line on up on the 5/16" shoulder and clamped it down again ... no more bubbles ... well, they were at least 95% gone. I felt there should have been none but there were still a few.
I also noticed them in the aux pump's inlet line. It looked like one of those Christmas tree lights with the bubbles going up to the top continuously. I had no idea why they were forming since that pump wasn't even turned on nor was there fuel in the outlet line. They would go away if I took it down to an idle, but they would come back when the throttle was advanced.
So I put the question on the Challenger e-mail list and got a few responses saying the bubbles were normal but no one knew why. Some had even pressure tested their systems only to find nothing wrong, but they still had some bubbles in their system. Okay, I thought, these guys have been doing this for years; they should know.
I went flying but decided to leave the aux pump on for take-off and landing now, and also for flying "low and slow". I was again feeling comfortable with the plane and decided to allow family to ride along if they wanted.
Well, Bill's folks were out here for a week the first part of October and wanted to see the plane. I told him I'd meet them in that same pasture again. Linda wanted to go too, so I fueled up and we departed for a bit of sightseeing, looking for the powered parachutes that were flying out of their new spot south of town.
They weren't there so we headed on out to our daughter's place. Lynette and the g'kids weren't home either, so we visited with a neighbor until time to depart for our meeting with Bill and his folks. We took off for the 3 minute flight to Black Hawk and the pasture, landed, and visited for about 20 minutes or so. It was getting dark again so we said goodbye and tookoff for home.
It was a georgous evening and, as we headed back towards Rapid, we flew along a creek to a sight of beautiful greens, yellows and some reds. The trees following the creek's winding path gave us a wonderfully colorful treat in the subdued light of dusk. We climbed on up to 4000' cruising along in the smooth air and splendor of everything.
As we neared the mall ,I was about 4200' and thought I'd just go ahead and shut off the auxillary pump until we let down near home. I turned it off and about 20 seconds later the engine slowed down. Linda had a comment I won't repeat here but, needless to say, I knew she was excitedly concerned!
I hit the pump switch and things started perking again. NOW, I was really stumped but feeling really glad I'd added the extra pump. We arrived home okay and put the plane away.
Once more back out to the tree, tie off and run 'er up. This time I got it to cut out just like it did while flying. I let it die down as much as it would (which was about 2500 RPM) and shut it down.
Pulling the carb bowls off, I found one completely empty except for the sump the jet sits in, and the other with about 1/8" of fuel in it. I bypassed the sediment bowl filter to no advantage and was going to do the same for the paper filter when I decided to check the pulse line which runs the pump.
For those not familiar with the 2-stroke, the crankcase pressures are used to run the fuel pump. Well, it was pulsing just fine so I checked the inlet suction to find there was very little.
I also checked the fuel line at the outlet of the paper filter since that's where the bubbles seemed to originate along with a lot of them in the outlet lines. I found a small cut, which apparently resulted from overtightening the clamp, but the cut didn't appear to go completely through the fuel line.
The next day, I bought a pump rebuild kit and installed it.
When I pulled the pump apart, I noticed a small grain of dirt under the thin rubber gasket on the pump's inlet chamber side. I can't say for sure this caused the pump problem, but I can't rule it out either. I would guess the dirt got in there when I had the pump apart after the July incident and just wasn't very careful when putting it back together.
Well, I installed the new gaskets, diaphrams, and check valves, and put the pump back together. I cut off the end of the fuel line that had the cut and installed another paper filter.
I generally don't like to do more than one thing at a time because then I don't know for sure what fixed the problem . Anyway, as I was taking the old filter over to the hangar for disposal, I covered the outlet end with a finger and blew into the other end. It wouldn't hold pressure!
Wonderful! At least I have something definite I can pin this on now. I fired up the engine and no bubbles at all this time ... it just ran ... and ran ... and ran. Evidently, the plastic fuel filter housing was defective, allowing an air leak.
Someone told me I should have been able to feel fuel there but I hadn't before whenever I'd checked it. A pressure test would have shown up the problem. I finally did feel a slight coolness and see a trace of wetness on my finger that afternoon which led me to check that filter.
SO, hopefully, that's the end of this saga. I really don't want to write a "Part III" article!
It appears to me that I had three problems or possible problems: (1) the cut in the fuel line, (2) the grain of dirt in the gasket surface of the pump, and (3) the faulty fuel filter case. Two of those would have been of my own making. I know I'll pay more attention to working on things in the future.
If these articles have helped anyone, great! I know it's been a good learning experience for me ... things could have come out much worse for me all three times.
If I remember correctly, one of the reasons for Experimental Aviation is for "education." I certainly wasn't expecting to be educated in this manner when I decided to build the Challenger, but it has been that for sure!