This is the narrative I wrote down shortly after the event. I'm sure it will be entertaining to some and informative to others. I'm sure it will cause a bit of controversy, so be it. We can all learn from my misfortune. I did have the old nose gear fork, but I do not believe it was a factor.
Anatomy of a flip. N131RV
Dec 21, 2007. Depart EYQ at 15:30 (approx) for 1 hour flight to 28TE.
Over Calaveras lake, reduce speed and enter extended left base for 17 at 28TE. On base 10 degrees flaps. Turn final and reduce speed to 75 KIAS, flaps to 25 degrees. Keep reducing power and cross the fence at 65 - 70 KIAS. Hold the aircraft, let speed bleed off and sink down to runway.
Reduce power completely and touch down on mains. Nose wants to drop, so a lot of back pressure to keep it up, Not full back, just enough to keep the nose off, then more until the nose drops gently.
The strip is 2600 feet, with a slight downhill slope from North to South. The upper half is harder and smoother than the lower half, so I always land in the upper half and try to get slowed completely before the lower half.
Rolling out, speed coming down to under 40, then under 30 or so. We are about 1/2 way down the runway.
Nose pops up. Keep stick back. Nose comes down fast. Feel a bit of "shudder" and then the nose starts to go further and further down.
As we come almost to a stop, the ground rises up to meet the cockpit, almost in slow motion.
Panic. "Fire!" is the first thing I think of. No smoke, no heat. Good. It's dark.
Can't see much. Don't smell any fuel. Wiggle feet. Good.
Eyesight fading in, I see a flashing red light. It's the ELT. For some reason, I don't want fire & rescue, so I try to turn it off. Push the wrong button about 10 times until I realize I am upside down and hitting the wrong side. Hear a whirring sound. It's the fuel pump. Hunt around for the master switch. Keep reaching to the wrong area. Finally mentally picture the location and find it and turn it off.
What now?
Unthinking, I unlatch the seatbelt and fall down onto the canopy. Something is jamming into my back. Can see better now. Try to wriggle and turn over. With my legs above me it's not easy. Finally get turned over.
Try to punch canopy with my fist. Ouch. It's tough and just "gives".
OK, what now?
Phone! I have a phone in the cockpit. Where is it? It was plugged in and charging. Spy the cord and start pulling it. It has flown forward under the panel and the cord is tangled in the rudder pedals.
Won't come free. Wriggle, stretch, finally get my head "over" the bottom of the panel and free the phone. Dial my brother (he lives next to the strip) and ask him where he is. He says he is at home (lucky me). I tell him to grab an ax and come get me out of this *#&@#&* plane. He says "what?". I tell him I am upside down on the runway. He says he'll be right there.
Hang up.
Now I'm p*ssed. I want out. I wriggle around some more and finally get a leg free to kick at the canopy. Shatters on first kick and foot goes through. Pull it back and kick some more to make the hole bigger. Looks good! Can't turn around, so stick legs through and wriggle out feet first, on my back, just as my brother comes screaming down the runway.
Post mortem:
The plane is resting upside down. I backtrack the landing gear tracks to try and see what happened.
About 70' feet back up the runway, the nose gear track ends at a small "gopher pile". It appears the nose wheel passed over the side of the pile (about 3 inches of soft dirt) and lifted off the runway. Pace off 12 steps and the nose track resumes, just the other side of a similar pile. About 6 feet from there, the track starts getting wider and deeper. In 10 paces, it's about 6 inches deep and there is a 1 foot deep gouge where the prop hit the ground.
The nose gear strut is folded back and the wheel pant is almost perpendicular. There is a deep crease in in the forward floor skin where the wheel pant contacted the fuselage. It appears the wheel pant kept the gear from folding all the way back (which might have allowed the plane to come to rest upright).
The forward part of the nose wheel pant is intact. I had just rebuilt it a couple of days ago from a taxi incident that happened at EYQ. I had taxied into a small "dip" in the grass taxiway and it crunched the nose wheel pant. This time I built it back "really strong" with 3 layers of bid inside and two on the outside. It's about 3/16ths of an inch thick.
The wheel turns freely. It is not packed with dirt and the castle nut is still covered by the wheel pant.
My analysis:
Anatomy of a flip. N131RV
Dec 21, 2007. Depart EYQ at 15:30 (approx) for 1 hour flight to 28TE.
Over Calaveras lake, reduce speed and enter extended left base for 17 at 28TE. On base 10 degrees flaps. Turn final and reduce speed to 75 KIAS, flaps to 25 degrees. Keep reducing power and cross the fence at 65 - 70 KIAS. Hold the aircraft, let speed bleed off and sink down to runway.
Reduce power completely and touch down on mains. Nose wants to drop, so a lot of back pressure to keep it up, Not full back, just enough to keep the nose off, then more until the nose drops gently.
The strip is 2600 feet, with a slight downhill slope from North to South. The upper half is harder and smoother than the lower half, so I always land in the upper half and try to get slowed completely before the lower half.
Rolling out, speed coming down to under 40, then under 30 or so. We are about 1/2 way down the runway.
Nose pops up. Keep stick back. Nose comes down fast. Feel a bit of "shudder" and then the nose starts to go further and further down.
As we come almost to a stop, the ground rises up to meet the cockpit, almost in slow motion.
Panic. "Fire!" is the first thing I think of. No smoke, no heat. Good. It's dark.
Can't see much. Don't smell any fuel. Wiggle feet. Good.
Eyesight fading in, I see a flashing red light. It's the ELT. For some reason, I don't want fire & rescue, so I try to turn it off. Push the wrong button about 10 times until I realize I am upside down and hitting the wrong side. Hear a whirring sound. It's the fuel pump. Hunt around for the master switch. Keep reaching to the wrong area. Finally mentally picture the location and find it and turn it off.
What now?
Unthinking, I unlatch the seatbelt and fall down onto the canopy. Something is jamming into my back. Can see better now. Try to wriggle and turn over. With my legs above me it's not easy. Finally get turned over.
Try to punch canopy with my fist. Ouch. It's tough and just "gives".
OK, what now?
Phone! I have a phone in the cockpit. Where is it? It was plugged in and charging. Spy the cord and start pulling it. It has flown forward under the panel and the cord is tangled in the rudder pedals.
Won't come free. Wriggle, stretch, finally get my head "over" the bottom of the panel and free the phone. Dial my brother (he lives next to the strip) and ask him where he is. He says he is at home (lucky me). I tell him to grab an ax and come get me out of this *#&@#&* plane. He says "what?". I tell him I am upside down on the runway. He says he'll be right there.
Hang up.
Now I'm p*ssed. I want out. I wriggle around some more and finally get a leg free to kick at the canopy. Shatters on first kick and foot goes through. Pull it back and kick some more to make the hole bigger. Looks good! Can't turn around, so stick legs through and wriggle out feet first, on my back, just as my brother comes screaming down the runway.
Post mortem:
The plane is resting upside down. I backtrack the landing gear tracks to try and see what happened.
About 70' feet back up the runway, the nose gear track ends at a small "gopher pile". It appears the nose wheel passed over the side of the pile (about 3 inches of soft dirt) and lifted off the runway. Pace off 12 steps and the nose track resumes, just the other side of a similar pile. About 6 feet from there, the track starts getting wider and deeper. In 10 paces, it's about 6 inches deep and there is a 1 foot deep gouge where the prop hit the ground.
The nose gear strut is folded back and the wheel pant is almost perpendicular. There is a deep crease in in the forward floor skin where the wheel pant contacted the fuselage. It appears the wheel pant kept the gear from folding all the way back (which might have allowed the plane to come to rest upright).
The forward part of the nose wheel pant is intact. I had just rebuilt it a couple of days ago from a taxi incident that happened at EYQ. I had taxied into a small "dip" in the grass taxiway and it crunched the nose wheel pant. This time I built it back "really strong" with 3 layers of bid inside and two on the outside. It's about 3/16ths of an inch thick.
The wheel turns freely. It is not packed with dirt and the castle nut is still covered by the wheel pant.
W&B of the incident flight:
Empty 1102
Pilot 275
Baggage, 50 est.
Fuel, 33 gals.
Calulated weight, 1630
Calculated CG 82.54.
Calculated Nose gear load, 346.
Empty 1102
Pilot 275
Baggage, 50 est.
Fuel, 33 gals.
Calulated weight, 1630
Calculated CG 82.54.
Calculated Nose gear load, 346.
My analysis:
- My landing was just about perfect. Some may argue, but I was the only one there.
- I held the nose up and let it fall "gently".
- There is a speed range where small disturbances on the runway can displace the nose of the airplane upward in an uncontrolled fashion. You don't have enough airspeed to counter or control this motion. When the nose falls again, if there is any forward resistance to couple with the downward force of gravity the nose gear can (will) fail. No "drop test" can uncover this design flaw, since a drop test does not combine the forward motion, drop and effects of forward resistance.
- It is very bad design in that the failure GUARANTEES the aircraft will flip. The gear becomes displaced rearward at a 45 degree angle. With the nose low, this becomes a lever in back of the CG. Then when you slow down to almost stopped, it springs forward and throws the aircraft onto it's back.
- The nose wheel pant "conspires" and contributes to the ill fortune by limiting the range the nose gear strut can be deflected rearward. Maybe, just maybe, if the the nose gear strut had bent further back and not retained all the energy it did, the aircraft would have not flipped. That is just my opinion.