Demise of the MiniMax
2001 - Well it started out as a CAVU afternoon. I preflighted the
mini and warmed it up. This was to be the first flight since the airspace
restrictions that shutdown all civilian operations after September 11, 2001..
After warming it up I shut it down and went and got into my flight suit. I
came back out restarted the mini and climbed in. Just as I was ready to start
to taxi out, my wife flagged me down. The pickup had dropped its muffler and
needed to be fixed so I shutdown again and was gone for 5 to 10 minutes.
Finally, to take flight. I restarted and climbed in. I taxiied out to my strip which is 1000 foot long and since the beans were out of the field I went back another 200 foot into the field for the takeoff. I started my roll, all the instruments seem to be reading normal. I started my climb and at about 70 feet the engine lost power. It didnt outright die but the sounded like it was being choked. I dropped the nose and pulled the throttle back. At about 1/2 throttle the engine surged. Thinking that the problem may have cleared, I pulled the nose up again at which time it again lost power. I then realized I was committed to making a landing.
Had I initiated an emergency landing on the first power loss I think I would have been better off. I would have had several hundred feet more runway and field to work with. because of the 2 seconds or so that I delayed my glide path was putting me very close to having to contend with several ditches, a road that I could not see traffic from one direction and having to pass underneath 30 foot
I did what I thought was the safest thing and pushed the nose over to try and get the airspeed up to where I would have the energy to flare. I was either slower than I thought or I was moving faster than I realized because when i started the pull back on the stick
the ground came up a lot quicker. I had control of the mini all the way to the ground but was not able to get the nose up in time.
I hit on the mains, drove the wheels into the ground far enough that the solid axle between them dug in for about 6 inches before the gear collapsed. I then travelled another 10 foot or so lightly skidding before the fuselage settled to the ground. The total skid was about 35 feet. The impact force was sufficient to buckle the seat bottom and bruised my tail bone. It is still occasionally twinging. My lower spine was sore for several days and I have bruises just under both knees from the slight forward slide in the seat allowing my knees to hit the corners of the fuel tank.
Both rear spar/strut attach points failed. The right aileron became detached other than the teleflex cable and it pivoted up and hit me on the head and right arm. Fortunately, I had a helmet on and the ailerons are light enough that it did not have sufficient energy to really hurt me.
The fuselage is in pretty good shape, there is some damage caused by the radiator getting driven through the bottom of the fuselage and the force of my body being drive through the seat. Dad is planning on building a new set of wings and converting to a hi-max style configuration. Not trivial, but a good winter project.
It had been about 2 months since I had flown it last, due to a bout with a nasty virus and the entire USA airspace being shutdown. I had started it and ran it on the ground a number of times but this was the first real workout in 2 months. I had several distractions while getting ready, they don't directly seem to be contributing factors. But very few accidents are the results of a single failure.
I have run the engine on the airframe without the prop and was able to reproduce the problem. I believe that the mikuni fuel pump failed. It was one of the older pumps without a drain hole and was overdue for a rebuild. The diaphram area appeared to possibly have been half full of gasoline. The gaskets may have been leaking.It was pumping fuel, but at full throttle was unable to provide sufficient fuel flow for sustained power. My runup on this flight was not of sufficient length to have detected it. So as in a high percentage of incidents of this nature it appears that it was ultimately my, the pilots, error.