Narrative:

A passenger and I took off and flew to [a nearby airport]. The weather was VFR; and even though later in the day we had to go around some rain showers; we remained VFR all day. At this first takeoff with my weight of 160 pounds; my passenger's was 212 pounds; the anchor in the forward compartment; the normal 'stuff' in the back seat and cargo compartment; and 51 gallons of fuel aboard (determined by sticking the tank during preflight); we were 192 pounds under gross and well within our cg limits. We took off from the airport and flew to the lake for lunch; landing and beaching without incident. We left the lake an hour and a half later; flew around some rain showers; and made it back to the lake a half hour later. Listening to the nearby ASOS the wind was out of the northwest; but looking at my windsock it was out of the west and not limp; but not straight out either so I assumed in the 5 to 10 range. I overflew the landing area at 400 ft; while staying over the lake. There appeared to be quite a bit of wave action on the west side of the island; and since there were no boats in the way; I elected to land on the east side of the island fairly close to its shore where the water was relatively calm; even though it gave me a 90 degree cross wind. I have done this many times before in similar conditions with no problem. I was using about 15 inches of mp to help keep the rate of descent low so I would land closer to the north where it was calmest. We touched down just half way down the island with a gentle skip. I eased off back pressure to maintain pitch attitude and added a little power to help set down softer. The second time we bounced higher which really surprised me. I don't know if I hit a boat wake; or some other wave; but I maintained directional control and pitch attitude; adding more power; but not enough to push the nose down. At this point I did not feel that I had enough distance and speed to go around; so continued to try to salvage the landing. The last touchdown was very hard with little airspeed; and I was surprised to find the starboard sponson gone.directional control while taxiing was harder than usual with the sponson gone and it took me two approaches to get in the lift. With the fuel onboard at the time of landing; before we lost the sponson; we were 258 pounds under gross and still well within the cg envelope. We would not have been on the front edge of the envelope until we burned off 25 more gallons of gas. Looking back on the events the next morning I noticed that we had a very similar wind with the windsock out of the west. This would indicate I probably had a quartering tailwind instead of the direct crosswind I was expecting. With hindsight; I probably should not have even considered what the ASOS said; and paid more attention to the windsock and local conditions.

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Original NASA ASRS Text

Title: LA4-200 pilot reports a bounced water landing in windy conditions that results in the right sponson separating from the aircraft.

Narrative: A passenger and I took off and flew to [a nearby airport]. The weather was VFR; and even though later in the day we had to go around some rain showers; we remained VFR all day. At this first takeoff with my weight of 160 pounds; my passenger's was 212 pounds; the anchor in the forward compartment; the normal 'stuff' in the back seat and cargo compartment; and 51 gallons of fuel aboard (determined by sticking the tank during preflight); we were 192 pounds under gross and well within our CG limits. We took off from the airport and flew to the lake for lunch; landing and beaching without incident. We left the lake an hour and a half later; flew around some rain showers; and made it back to the lake a half hour later. Listening to the nearby ASOS the wind was out of the northwest; but looking at my windsock it was out of the west and not limp; but not straight out either so I assumed in the 5 to 10 range. I overflew the landing area at 400 FT; while staying over the lake. There appeared to be quite a bit of wave action on the west side of the island; and since there were no boats in the way; I elected to land on the east side of the island fairly close to its shore where the water was relatively calm; even though it gave me a 90 degree cross wind. I have done this many times before in similar conditions with no problem. I was using about 15 inches of MP to help keep the rate of descent low so I would land closer to the north where it was calmest. We touched down just half way down the island with a gentle skip. I eased off back pressure to maintain pitch attitude and added a little power to help set down softer. The second time we bounced higher which really surprised me. I don't know if I hit a boat wake; or some other wave; but I maintained directional control and pitch attitude; adding more power; but not enough to push the nose down. At this point I did not feel that I had enough distance and speed to go around; so continued to try to salvage the landing. The last touchdown was very hard with little airspeed; and I was surprised to find the starboard sponson gone.Directional control while taxiing was harder than usual with the sponson gone and it took me two approaches to get in the lift. With the fuel onboard at the time of landing; before we lost the sponson; we were 258 pounds under gross and still well within the CG envelope. We would not have been on the front edge of the envelope until we burned off 25 more gallons of gas. Looking back on the events the next morning I noticed that we had a very similar wind with the windsock out of the west. This would indicate I probably had a quartering tailwind instead of the direct crosswind I was expecting. With hindsight; I probably should not have even considered what the ASOS said; and paid more attention to the windsock and local conditions.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.