A 2014 searey lsa elite pilot reported an engine failure followed by a successful calm water landing...

Narrative:

While operating a seaplane in conjunction with a private yacht the engine quit while in level flight. The seaplane was over calm water and landed without damage. The yacht dispatched a tow boat and recovered the airplane on board.subsequent investigation found that fuel was not being delivered to the engine (total time aircraft and engine was 59.25 hours). Fuel present on board was 4.0 gallons as indicated on the EFIS (electronic flight instrument system) and visual sighting of the tank. The pilot operating handbook lists unusable fuel as 1 gallon. Subtracting the listed unusable fuel leaves 3.0 gallons providing over 30 minutes of fuel at cruise settings with the indicated fuel quantity (for 5 gph). The fuel filter was checked for blockage and found to be partially obscured (estimated blockage less than 50%); but still capable of fuel flow. The threaded fuel filter cover was found to be snug; but not requiring significant wrench torque to open (an o-ring provides the primary seal for the cover). Fuel was added and the engine started and ran normally. Further investigation found the inlet head for the fuel pumps exceeds the maximum specified in the rotax engine installation manual. The measured distance from the bottom of the tank to the inlet fuel filter was found to be 14 inches (310 mm); exceeding the maximum of 10 inches (250 mm) specified in the rotax document. The problem is easily avoided by allowing for a greater margin of unusable fuel. Unfortunately in an airplane with limited useful load the additional weight is a consideration. A modification of the fuel system to meet rotax engine specifications is the real solution. It would also help to have a factory specification for torque to secure the fuel filter housing cover.

Original NASA ASRS Text

Title: A 2014 Searey LSA Elite pilot reported an engine failure followed by a successful calm water landing. Troubleshooting revealed fuel starvation because the fuel line from the tank to the fuel pump filter inlet was too long resulting in low head pressure when the fuel quantity got low.

Narrative: While operating a seaplane in conjunction with a private yacht the engine quit while in level flight. The seaplane was over calm water and landed without damage. The yacht dispatched a tow boat and recovered the airplane on board.Subsequent investigation found that fuel was not being delivered to the engine (Total Time Aircraft and Engine was 59.25 hours). Fuel present on board was 4.0 gallons as indicated on the EFIS (Electronic Flight Instrument System) and visual sighting of the tank. The Pilot Operating Handbook lists unusable fuel as 1 gallon. Subtracting the listed unusable fuel leaves 3.0 gallons providing over 30 minutes of fuel at cruise settings with the indicated fuel quantity (for 5 GPH). The fuel filter was checked for blockage and found to be partially obscured (estimated blockage less than 50%); but still capable of fuel flow. The threaded fuel filter cover was found to be snug; but not requiring significant wrench torque to open (an O-ring provides the primary seal for the cover). Fuel was added and the engine started and ran normally. Further investigation found the inlet head for the fuel pumps exceeds the maximum specified in the Rotax engine installation manual. The measured distance from the bottom of the tank to the inlet fuel filter was found to be 14 inches (310 mm); exceeding the maximum of 10 inches (250 mm) specified in the Rotax document. The problem is easily avoided by allowing for a greater margin of unusable fuel. Unfortunately in an airplane with limited useful load the additional weight is a consideration. A modification of the fuel system to meet Rotax engine specifications is the real solution. It would also help to have a factory specification for torque to secure the fuel filter housing cover.

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	1334056
Time
Date	201602
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZZ.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	Light Sport Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	None
Flight Plan	VFR
Component
Aircraft Component	Fuel Line Fittings & Connectors
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Commercial Flight Crew Instrument Flight Crew Sea
Experience	Flight Crew Last 90 Days 100 Flight Crew Total 10000 Flight Crew Type 4000
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy Inflight Event / Encounter Fuel Issue

A 2014 searey lsa elite pilot reported an engine failure followed by a successful calm water landing. Troubleshooting revealed fuel starvation because the fuel line from the tank to the fuel pump filter inlet was too long resulting in low head pressure when the fuel quantity got low.