A J3 cub lost power at about 800 ft just off the coast; so the pilot attempted a beach landing. Upon...

Narrative:

While transiting northbound approximately 200-250 yards off the coast (waterline); I experienced a slow loss of engine power. Turned toward isolated stretch of beach and prepared for a precautionary landing to the south as wind was from that direction. Throttle was wide open with about 1/3 power. I initially thought the cause could be carb ice. Very shortly after wheels touched power increased to what seemed to be full power. Lifted off and made a turn; approximate 30 degree; toward north and about two thirds of the way into turn the power reduced again. Turned back toward beach again and another precautionary landing. As wheels touched; aircraft bounced hard twice. Power was restored after approximately 3 second of rolling on mains; tailwheel never touched. Power seemed to be fully restored. I quickly deduced that there must be a partial fuel blockage. I pulled up straight ahead and climbed to approximately 500 ft to make a very gentle turn to the right toward a nearby airport. I was able to climb to approximately 800 ft but had two more episodes of slow engine power loss during this phase. A violent back and forth rocking of wings seemed to help clear the engine and power was at least partially restored. After arriving at the airport and checking all possible causes; the fuel tank was drained of remaining fuel; the line and valve were removed from the bottom of the fuel tank. The strainer in the tank was found to have a small amount of water and was partially plugged with a trash and a flaky substance. Parts were cleaned and reinstalled.

Original NASA ASRS Text

Title: A J3 Cub lost power at about 800 FT just off the coast; so the pilot attempted a beach landing. Upon touchdown power was restored; (happened twice) so he maneuver vigorously to clear a fuel line; then flew to nearby airport where water and debris were discovered in the fuel tank.

Narrative: While transiting northbound approximately 200-250 yards off the coast (waterline); I experienced a slow loss of engine power. Turned toward isolated stretch of beach and prepared for a precautionary landing to the south as wind was from that direction. Throttle was wide open with about 1/3 power. I initially thought the cause could be carb ice. Very shortly after wheels touched power increased to what seemed to be full power. Lifted off and made a turn; approximate 30 degree; toward north and about two thirds of the way into turn the power reduced again. Turned back toward beach again and another precautionary landing. As wheels touched; aircraft bounced hard twice. Power was restored after approximately 3 second of rolling on mains; tailwheel never touched. Power seemed to be fully restored. I quickly deduced that there must be a partial fuel blockage. I pulled up straight ahead and climbed to approximately 500 FT to make a very gentle turn to the right toward a nearby airport. I was able to climb to approximately 800 FT but had two more episodes of slow engine power loss during this phase. A violent back and forth rocking of wings seemed to help clear the engine and power was at least partially restored. After arriving at the airport and checking all possible causes; the fuel tank was drained of remaining fuel; the line and valve were removed from the bottom of the fuel tank. The strainer in the tank was found to have a small amount of water and was partially plugged with a trash and a flaky substance. Parts were cleaned and reinstalled.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1196443
Time
Date	201407
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	J3 Cub
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Fuel Tank
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Instrument Flight Crew Rotorcraft Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 20 Flight Crew Total 3300 Flight Crew Type 400
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural FAR Deviation - Procedural Published Material / Policy Inflight Event / Encounter Fuel Issue

A J3 cub lost power at about 800 ft just off the coast; so the pilot attempted a beach landing. Upon touchdown power was restored; (happened twice) so he maneuver vigorously to clear a fuel line; then flew to nearby airport where water and debris were discovered in the fuel tank.