What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Narrative: pilot performed normal preflight and did not note any discrepancies with the aircraft. Pilot departed uki at 1545 PST under VFR conditions. Pilot experienced uneventful flight to smf, where he was cleared by ATCT for landing on runway 16R. The pilot initiated the landing gear down sequence, he reported hearing the landing gear unlock and travel to the down position. Upon verification of the instrument indication for landing gear down and lock the pilot reported the nose landing gear was not indicating down and locked. Main landing did indicate a down and locked condition. Pilot contacted smf ATCT and requested fly by for visual verification that the nose landing gear was down. Pilot also reinitiated the landing gear down sequence by recycling the landing gear selector. Additionally, the pilot reports he verified the landing gear control circuit breaker to be reset and engaged; and he attempted to lower the landing gear utilizing the emergency extension handle. All procedures were failed. The pilot reported his condition of two main landing gear indicating down and locked and the nose landing gear was not. The smf tower reported that the nose landing gear was extended, but did not appear to be all the way down. The pilot elected to return to uki to verify the landing gear extension sequence with maintenance personnel. The pilot returned to uki with the landing gear in the down position. Upon arrival at uki maintenance verified the procedures to be correct and that the nose landing gear appeared full down. The pilot initiated an approach and final landing. The pilot reported a normal approach. At 1720 PST, upon contact with the runway the nose landing gear collapsed. No injuries to the sole occupant. Aircraft damage was limited to the propeller and lower nose cowl. Maintenance inspection revealed a loose hydraulic fitting located between the pilot and copilot seats under the floor panel. This fitting is the main line output from the hydraulic reservoir. Maintenance personnel determined the loose fitting allowed hydraulic fluid to leak from the system and subsequently, loss of hydraulic pressure. This make model aircraft uses positive hydraulic pressure to keep the landing gear in the down and locked position. All landing gear were checked and measured within tolerance for overcenter and lock condition. Maintenance personnel report that the nose landing gear is unique due to the angle of overcenter for the drag brace assembly. This assembly is not a true overcenter adjustment, but rather exactly even with both halves of the drag brace assembly. Additionally, this make model has only one down lock spring to hold the drag brace halves at center. There is a service bulletin to install a second spring this was not accomplished on this aircraft. It is determined that the loss of hydraulic pressure was causal in this incident. It is unknown how the fitting may have worked it's way loose, as maintenance personnel state that this item is inspected at each condition inspection. The last condition inspection was accomplished November 1997. privacy data omitted A material and defect report is being submitted by the oakland FSDO. It is determined that airworthiness is an issue. For an unknown reason the main line hydraulic fitting became loose. Although this fitting is an inspection item as part of the annual condition inspection the fitting is reported by maintenance as being secured in November 1997 during the inspection. privacy data omitted
As the FAA filed it
NARRATIVE: PILOT PERFORMED NORMAL PREFLIGHT AND DID NOT NOTE ANY DISCREPANCIES WITH THE AIRCRAFT. PILOT DEPARTED UKI AT 1545 PST UNDER VFR CONDITIONS. PILOT EXPERIENCED UNEVENTFUL FLIGHT TO SMF, WHERE HE WAS CLEARED BY ATCT FOR LANDING ON RUNWAY 16R. THE PILOT INITIATED THE LANDING GEAR DOWN SEQUENCE, HE REPORTED HEARING THE LANDING GEAR UNLOCK AND TRAVEL TO THE DOWN POSITION. UPON VERIFICATION OF THE INSTRUMENT INDICATION FOR LANDING GEAR DOWN AND LOCK THE PILOT REPORTED THE NOSE LANDING GEAR WAS NOT INDICATING DOWN AND LOCKED. MAIN LANDING DID INDICATE A DOWN AND LOCKED CONDITION. PILOT CONTACTED SMF ATCT AND REQUESTED FLY BY FOR VISUAL VERIFICATION THAT THE NOSE LANDING GEAR WAS DOWN. PILOT ALSO REINITIATED THE LANDING GEAR DOWN SEQUENCE BY RECYCLING THE LANDING GEAR SELECTOR. ADDITIONALLY, THE PILOT REPORTS HE VERIFIED THE LANDING GEAR CONTROL CIRCUIT BREAKER TO BE RESET AND ENGAGED; AND HE ATTEMPTED TO LOWER THE LANDING GEAR UTILIZING THE EMERGENCY EXTENSION HANDLE. ALL PROCEDURES WERE FAILED. THE PILOT REPORTED HIS CONDITION OF TWO MAIN LANDING GEAR INDICATING DOWN AND LOCKED AND THE NOSE LANDING GEAR WAS NOT. THE SMF TOWER REPORTED THAT THE NOSE LANDING GEAR WAS EXTENDED, BUT DID NOT APPEAR TO BE ALL THE WAY DOWN. THE PILOT ELECTED TO RETURN TO UKI TO VERIFY THE LANDING GEAR EXTENSION SEQUENCE WITH MAINTENANCE PERSONNEL. THE PILOT RETURNED TO UKI WITH THE LANDING GEAR IN THE DOWN POSITION. UPON ARRIVAL AT UKI MAINTENANCE VERIFIED THE PROCEDURES TO BE CORRECT AND THAT THE NOSE LANDING GEAR APPEARED FULL DOWN. THE PILOT INITIATED AN APPROACH AND FINAL LANDING. THE PILOT REPORTED A NORMAL APPROACH. AT 1720 PST, UPON CONTACT WITH THE RUNWAY THE NOSE LANDING GEAR COLLAPSED. NO INJURIES TO THE SOLE OCCUPANT. AIRCRAFT DAMAGE WAS LIMITED TO THE PROPELLER AND LOWER NOSE COWL. MAINTENANCE INSPECTION REVEALED A LOOSE HYDRAULIC FITTING LOCATED BETWEEN THE PILOT AND COPILOT SEATS UNDER THE FLOOR PANEL. THIS FITTING IS THE MAIN LINE OUTPUT FROM THE HYDRAULIC RESERVOIR. MAINTENANCE PERSONNEL DETERMINED THE LOOSE FITTING ALLOWED HYDRAULIC FLUID TO LEAK FROM THE SYSTEM AND SUBSEQUENTLY, LOSS OF HYDRAULIC PRESSURE. THIS MAKE MODEL AIRCRAFT USES POSITIVE HYDRAULIC PRESSURE TO KEEP THE LANDING GEAR IN THE DOWN AND LOCKED POSITION. ALL LANDING GEAR WERE CHECKED AND MEASURED WITHIN TOLERANCE FOR OVERCENTER AND LOCK CONDITION. MAINTENANCE PERSONNEL REPORT THAT THE NOSE LANDING GEAR IS UNIQUE DUE TO THE ANGLE OF OVERCENTER FOR THE DRAG BRACE ASSEMBLY. THIS ASSEMBLY IS NOT A TRUE OVERCENTER ADJUSTMENT, BUT RATHER EXACTLY EVEN WITH BOTH HALVES OF THE DRAG BRACE ASSEMBLY. ADDITIONALLY, THIS MAKE MODEL HAS ONLY ONE DOWN LOCK SPRING TO HOLD THE DRAG BRACE HALVES AT CENTER. THERE IS A SERVICE BULLETIN TO INSTALL A SECOND SPRING THIS WAS NOT ACCOMPLISHED ON THIS AIRCRAFT. IT IS DETERMINED THAT THE LOSS OF HYDRAULIC PRESSURE WAS CAUSAL IN THIS INCIDENT. IT IS UNKNOWN HOW THE FITTING MAY HAVE WORKED IT'S WAY LOOSE, AS MAINTENANCE PERSONNEL STATE THAT THIS ITEM IS INSPECTED AT EACH CONDITION INSPECTION. THE LAST CONDITION INSPECTION WAS ACCOMPLISHED NOVEMBER 1997. ^PRIVACY DATA OMITTED^ A MATERIAL AND DEFECT REPORT IS BEING SUBMITTED BY THE OAKLAND FSDO. IT IS DETERMINED THAT AIRWORTHINESS IS AN ISSUE. FOR AN UNKNOWN REASON THE MAIN LINE HYDRAULIC FITTING BECAME LOOSE. ALTHOUGH THIS FITTING IS AN INSPECTION ITEM AS PART OF THE ANNUAL CONDITION INSPECTION THE FITTING IS REPORTED BY MAINTENANCE AS BEING SECURED IN NOVEMBER 1997 DURING THE INSPECTION. ^PRIVACY DATA OMITTED^