Amateur/Home Built/Experimental
Flight Crew Private
Flight Crew Last 90 Days 9; Flight Crew Total 189; Flight Crew Type 12
Confusion; Situational Awareness
Aircraft Equipment Problem Less Severe; Ground Event / Encounter Ground Strike - Aircraft; Ground Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Fuel Issue
Aircraft Aircraft Damaged
Aircraft
Private pilot of a new Zenith Cruzer CH-750 was required to fly alone during flight testing.I flew first 3.2 hrs in aircraft alone. During flight I found evidence of wing tank fuel transferring from left tank to right wing tank while in continuous left pattern around ZZZ. This produced a heavy right wing; tendency of right wing to drop and significant difficulty centering the ball on the EFIS. The left-wing tank reading on the EFIS went from 11 gallons to minus 2 gallons during flight of 1.7 hrs. The right-wing tank never changed from 11 gallons (The EFIS fuel level indicators are electronically calibrated to read 12 gal when full to 15 gallons.) The expected fuel burn during 1.7 hrs is approximately 6 gallons. The EFIS left wing tank reading was reported as 4 gallons at landing yet the right wing remained heavy during landing on Runway XX.Upon transfer of aircraft back to hangar after incident; equilibration and support with engine hoist; approximately 5 gallons was removed from left tank and right tank. Approximately 1-2 gallons remained in wing tanks and 2.1 gallons in header tank. This is consistent with approximately 6-gallon usage during 1.7 hr flight.IncidentThe Zenith CH-750 Cruzer fixed nose gear collapsed after main wheel touch down and folded underneath fuselage. The resultant damage included the nosewheel cylinder and support; radiator and mount; cowling; exhaust; prop strike; destruction of 3 propeller blades and engine cessation at 2;000 RPM and approximate 900 RPM propeller (based on engine reduction gear of 2.33/1); and windshield damage. There was minimal damage to fuselage at radiator mount. There was no injury to pilot in command.On preflight exam; I was unable to identify any preexistent damage to nose wheel structure. There were 3 landings during 3.2 hrs flight testing. This is excluding aggressive taxi testing and short runway landings prior to first flight (approximately 16.5 hrs) which included engine static testing and taxi testing.Fuel ConnectionsThe fuel connections as constructed show the right- and left-wing tanks plumbed together at wing level and are teed connected to a header tank located in fuselage. There is a separate fuel return to both tanks from the header tank. There are separate J type fuel vents in both wing tanks. The header tank fuel pumps pressurize the fuel output to approximately 48 PSI to engine and fuel injector.Human Performance ConsiderationsPilot was current with biannual flight review and Basic Med. Special Airworthiness Certificate was in force and effect. Insurance stipulation required at least 1 hr dual instruction in make and model. A total of 9.1 hrs of dual instruction in Zenith make and model equivalent was noted within the last 90 days. Over 100 landings were documented with same make and model.It remains unclear whether the identified fuel shifts from left to right wing contributed to nose gear collapse. Upon personal review and with my aircraft building group; it was suggested that some cross control may have been required to land aircraft with heavy right wing. Avionics indicated appropriate pattern altitudes and speeds of 70 KTS on downwind; 60 KTS base and 50 KTS at final.There was no hard touch down of mains prior to collapse of the nose gear. I have exposed the aircraft nose wheel by removal of cowling awaiting insurance visit. My initial evaluation demonstrates a 90-degree bend front to back of the nose gear cylinder which is fully extended and not compressed. The bungee cord is intact. The wheel and nose wheel cylinder are impinging on the fuselage mounted radiator and mounting shroud. There is some bending of doubled aluminum fork surrounding the nose wheel axle. It is unclear whether this occurred during compression skid on runway or from lateral forces on the nose wheel during touch down.
Zenith CH-750 Cruzer pilot reported after having a problem with fuel imbalance; upon landing the nose wheel collapsed.