Amateur/Home Built/Experimental
Flight Crew Private
Flight Crew Last 90 Days 30; Flight Crew Total 830; Flight Crew Type 530
Confusion
Aircraft Equipment Problem Critical; Ground Incursion Runway; Inflight Event / Encounter Fuel Issue
Air Traffic Control Provided Assistance; Flight Crew Landed in Emergency Condition; General Maintenance Action
Human Factors; Aircraft
Approximately seven miles South of ZZZ; a low fuel pressure alert was given by the aircraft MFD\EFIS. Initial trouble shooting was performed by switching fuel selection. Engine RPM reduced; followed by reduced engine noise and then a surge.  ATC was contacted initally with an urgent situation. A landing location was selected. As the engine struggled more; the call was changed with a Mayday. Under reduced power; a landing without incident was performed at a Radio Control (RC) Model airplane landing strip; five miles South of ZZZ. No injuries or damages to the plane or the property occurred. A Mechanic was called and it was determined that the Rotax ULS Fuel Pump had failed. It was replaced in field. After testing; the aircraft was flown off the RC field and returned to ZZZ.
Reporter stated his Zenith CH701 aircraft had a Rotax-912 ULS; 100 HP uncertified Experimental engine. He was not operating under a Part 23 for certified operations.  The Service Bulletin (S/B) SB-912-063UL to replace the old mechanical fuel pump with a new style pump had been accomplished approximately one and a half years ago. The pump is located towards the front of the engine; on the left side of the crankcase.Reporter stated he was at the end of a long flight when he got a low pressure fuel alert on his Diamond 180 MFD/EFIS display. He switched fuel tanks and realized the problem was not from the fuel tank lines because the Fuel Transfer switch has separate; direct fuel lines from the fuel tanks to the switch. The aircraft does not have an electric fuel boost pump. By dropping the nose; he could get some fuel using gravity to feed the engine; but as soon as he started to level the engine would lose power. With only 6-8 gallons of fuel left; the engine would not maintain a cruise attitude because the angle of the wing prevented gravity feed. If he had more fuel onboard; there would have been enough fuel pressure to gravity feed the engine and he probably could have maintained a cruise attitude longer.After landing; a Mechanic verified the fuel tanks and multi-hole fuel tank cap were properly venting. No fuel leaks noted in the engine compartment; meaning fuel was not leaking from the pump's drain hole. The fuel pump is at a Repair Station going through a Pump Tear Down Inspection. He does not know the current status of that inspection. Due to his experience; even with the supposedly better designed fuel pump; he would suggest that Operators of the CH701 with Rotax Engine Type 912 (Series) practice more emergency procedures and carry more fuel.
Pilot reports a low fuel pressure alert appeared on his MFD/EFIS display while flying his Zenith CH701 Amateur Build Experimental aircraft with a Rotax 912 Engine Type. A newer designed engine fuel pump that was previously installed to comply with Service Bulletin (S/B) SB-912-063UL had failed. Pilot landed on a Model Airplane strip.