LAX03FA060

A loss of engine power for undetermined reasons, and the pilot's failure to maintain main rotor rpm during the subsequent autorotation. A factor in the accident was the unsuitable nature of the terrain for a forced landing.

The helicopter was in normal cruise flight when it suddenly descended steeply into a shallow tidal marsh/swamp area. Two witnesses in a boat observed the helicopter flying about 500 feet above the terrain and water. One reported seeing it in normal straight and level flight while over the water. The witness described the engine sound as "tinny." The helicopter suddenly turned toward land, the engine sound became quiet, and it descended rapidly to the ground. The other witness reported that his attention was drawn to the helicopter when he heard a "pop" followed by a grinding noise. He noticed that the rotors were slowing down as the helicopter dropped while in a left-hand turn or rotation. Examination of the rotor blades revealed evidence of low rotor energy at impact. The engine was removed from the airframe, cleaned, and then installed on an instrumented test cell where it was test run for 50 minutes at various power levels according to a factory acceptance test protocol with no abnormalities detected. Continuity was established throughout the control system, the fuel delivery system, and the drive train to the main and tail rotors. On the day of the accident, the accident pilot's partner in the helicopter discussed an erratic fuel pressure issue with an aviation maintenance technician (AMT) at the FAA Approved Repair Station where the helicopter was parked and serviced. The discrepancy was not resolved at the time the pilot departed on the accident flight. There is no verified evidence that the pilot was aware of the discrepancy.

HISTORY OF FLIGHT On January 4, 2003, about 1532 Pacific standard time, a Schweizer 269C, N98TH, descended into terrain in a marsh area of the Sacramento River Delta near Collinsville, California. The helicopter was operated by the airline transport rated pilot under the provisions of 14 CFR Part 91. The pilot, the sole occupant, sustained fatal injuries, and the helicopter was destroyed. Visual meteorological conditions prevailed for the local area personal flight that departed from the Concord, California, airport about 1430. No flight plan was filed. Two witnesses in a boat observed the helicopter flying about 500 feet above the terrain and water. One reported seeing it in normal straight and level flight while over the water, and the engine sounded "tinny." The helicopter turned toward land, the engine sound became quiet, and it descended rapidly to the ground. The other witness reported that his attention was drawn to the helicopter when he heard a "pop" followed by a grinding noise. He noticed that the rotors were slowing down as the helicopter dropped while in a left-hand turn or rotation. PERSONNEL INFORMATION The pilot held a airline transport pilot certificate, he had private privileges for helicopters, and held a certified flight instructor certificate for airplane single and multiengine land airplanes. He was type rated for Cessna 500 series airplanes. His last recorded third-class flight physical occurred on May 14, 2001, and he was provided an exemption by the Federal Aviation Administration (FAA) Medical Advisory panel for a two vessel heart by-pass operation. A separate medical records information report is included in the docket. At the pilot's medical application he reported 5,360 total combined fixed wing and rotary wing civilian flight hours. According to FAA records, the pilot received his rotorcraft add-on rating on August 30, 2002, reporting a total of 74 helicopter flight hours with 59 hours of dual instruction. The pilot's logbook was not obtained and no determination could be made for helicopter hours or currency. AIRCRAFT INFORMATION Examination of the logbook records revealed that the most recent maintenance occurred on December 6, 2002, at 662.9 total flight hours as recorded on the Hobbs hour recording meter. The work was documented under a 200-hour inspection checklist for the 269C helicopter. Noted in the entry was an installation of a maintenance Hobbs meter kit P/N SA-269K 098-01. Post accident examination of the wreckage revealed the landing skid actuated Hobbs meter was indicating 689.2, and the second Hobbs meter indicated 32.2 hours. On the day of the accident, the accident pilot's partner in the helicopter discussed an erratic fuel pressure issue with a certified aviation maintenance technician (AMT) at the FAA Approved Repair Station where the helicopter was parked and serviced. In a written statement from the AMT, he said the partner had discussed the issue with the accident pilot. The issue went unresolved. WRECKAGE AND IMPACT INFORMATION The accident site was in the swamplands area of Suisun Bay, near Collinsville, in tide affected water levels about 24 inches deep. Water, swamp grass, and dirt had ingested into the engine induction system and into the cooling impeller and scroll assembly. The helicopter was sitting near upright, leaning to the left, and slightly nose down in the swamp grass. The National Transportation Safety Board investigator did not go to the accident site. A post accident examination of the helicopter and its systems was performed by the Safety Board investigator, Federal Aviation Administration personnel, and manufacturer representatives. The engine was examined for valve train continuity, cylinder compression, appearance of the spark plugs, magneto timing, and oil filter contaminants. Also, portions of the fuel system were examined, including the fuel screens and the fuel boost pump, which was functionally tested. The remaining fuel onboard was measured to be about 10 gallons between both fuel tanks. Its quantity was found above the level required to activate the low level switch, which was functionally tested satisfactorily. The helicopter clutch, drive system, and controls were examined. The continuity of the control system was confirmed. All chip detectors were found to be clean. Annunciator light bulbs were examined for filament stretch; no stretch was found. Flight control continuity was established for all rotor controls. Distortion of the cabin restricted motion but the main rotor swashplate responded properly to movement of the cyclic and collective controls. The collective upper control rod was distorted and bent below the mixer from main rotor blade impact marks. Tail rotor continuity was established from pedals to the forward end of the tail boom where the control rod was fractured and separated by impact forces. Continuity was established aft through the boom to the tail rotor bellcrank at the gearbox, the pitch control, and tail rotor blades. The aft tail rotor cable was broken and frayed into a broom straw pattern. Both boom support struts were broken and the boom was broken down and to the left. The tail rotor system was examined. Minimal damage was observed to the tail rotor blades and the still attached gear box assembly. Two of the three main rotor blades exhibited minimal damage. The red blade was bent at the root end; there was also tip damage and minor airfoil crushing, with a corresponding impact mark and color transfer noted on the tail boom. The red blade droop stop restraint was broken out. The blue blade was intact and straight with minor damage inboard; the damper elastomer was pulled out. The blue pitch link upper bearing was bent and the droop stop restraint was broken out. The yellow blade was intact, and straight with minor root end damage, chordwise wrinkles, and minor tip damage as a possible result of the tail boom strikes. The damper elastomer was pulled out. The yellow upper pitch link bearing was slightly bent. Continuity was established for the drive train from the main rotor through the main gearbox and overrunning clutch to the engine. The tail rotor drive shaft exhibited a rotational fracture at the tail boom forward bulkhead. The direction of the twist, according to the manufacturer, indicates the tail rotor stopped turning while there was still rotational energy in the main rotor. The tail rotor gearbox rotated freely and exhibited continuity of drive. The belt drive clutch spring, cable, and actuator assembly were intact; the tension was released as a result of damage and main frame collapse. Main and tail rotor gearbox chip detectors were pulled and examined, and no indications of internal damages were noted. The main rotor tachometer cable was disconnected at the transmission and the drive was found functional. The teeth of the main transmission were inspected through the housing inspection ports. All teeth were intact and the gear pattern was satisfactory. The belt drive system was intact and appeared undamaged. The lower pulley and bearings rotated satisfactory. The idler pulley rotation and end play were satisfactory. The upper pulley and overrunning clutch turned and operated satisfactorily. The belts were intact. The lower left strut to the main frame was bent and collapsed from impact. The clutch spring housing was slightly distorted. The clutch cable was intact with no sign of fraying. The lower pulley coupling shaft was intact and appeared properly lubricated. During the post accident examination of the engine, a fuel mixture control rod to arm connection was found to be missing a wave washer and cotter safety pin; however, the rod was still in position and appeared to be functional. The arm bushing appeared to be worn oversize or missing a bushing. Both boom support struts P/N 269 A2015-13, serial nu