Aviation Accident Summaries

Aviation Accident Summary NYC04LA059

Nicholasville, KY, USA

Aircraft #1

N224LC

Robinson R-22

Analysis

During takeoff, at an altitude of about 150 feet, the helicopter lost power and altitude. The pilot then performed an emergency landing to an open field, and a post-crash fire ensued. Examination of the engine revealed the main fuel line to the carburetor was separated and sitting just below its 90-degree elbow fitting. The threads of the elbow fitting displayed severe fire damage and downward melting, and the line end of the fitting was filled with melted aluminum. The "B-nut," used to secure the fuel line to elbow fitting, was loose, and "tooling marks" were observed on the fitting. The last 100-hour inspection was performed approximately 7 hours prior to the accident. According to 14 CFR Part 43 Appendix D - Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100 Hour Inspections, "Each person performing an annual or 100 hour inspection shall inspect (where applicable) components of the engine and nacelle group...(7) Lines, hoses, and clamps - for leaks, improper condition and looseness."

Factual Information

On January 19, 2004, at 1430 eastern standard time, N224LC, a Robinson R-22, was destroyed during a forced landing, following a loss of engine power after takeoff from a private residence, in Nicholasville, Kentucky. The certificated private pilot was not injured. Visual meteorological conditions prevailed and no flight plan was filed for the maintenance test flight conducted under 14 CFR Part 91. According to a mechanic, who had performed adjustments to the helicopter prior to the flight, he observed the helicopter liftoff and hover about 20 feet above the ground. The helicopter appeared to be operating satisfactorily and the pilot began a departure toward the northwest. As the helicopter climbed to about 200 feet, the mechanic heard the engine sputtering, and the helicopter began to oscillate slightly. The helicopter started descending, and then disappeared behind trees. The pilot reported that at an altitude of about 200 feet, the helicopter lost power and altitude. The pilot then performed an emergency landing to an open field. After landing, the pilot observed fire on the left side of the helicopter and exited the helicopter from the right side. According to a Federal Aviation Administration (FAA) inspector, examination of the helicopter revealed severe post-crash fire damage. Examination of the engine revealed the main fuel line to the carburetor was separated and sitting just below its 90-degree elbow fitting. The threads of the elbow fitting displayed severe fire damage and downward melting, and the line end of the fitting was filled with melted aluminum. The fitting was removed from the carburetor, and it was noted that the "B-nut," used to secure the fuel line to elbow fitting, was loose. Additionally, "tooling marks" were observed on the fitting. The elbow fitting and fuel line were sent to the Safety Board Metallurgical Laboratory in Washington D.C. for further examination; however, due to the severe fire damage, no pre-impact fractures were visible. An interview with the mechanic revealed maintenance was recently performed to the main rotor blades and trim system. No maintenance was performed on the carburetor. The last 100-hour inspection was performed on December 9, 2003, and the helicopter had flown approximately 7 hours since that date. According to 14 CFR Part 43 Appendix D - Scope and Detail of Items (as Applicable to the Particular Aircraft) To Be Included in Annual and 100 Hour Inspections: "Each person performing an annual or 100 hour inspection shall inspect (where applicable) components of the engine and nacelle group as follows: (1) Engine section - for visual evidence of excessive oil, fuel, or hydraulic leaks, and sources of such leaks. (2) Studs and nuts - for improper torquing and obvious defects. (3) Internal engine - for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs. If there is weak cylinder compression, for improper internal condition and improper internal tolerances. (4) Engine mount - for cracks, looseness of mounting, and looseness of engine to mount. (5) Flexible vibration dampeners - for poor condition and deterioration. (6) Engine controls - for defects, improper travel, and improper safetying. (7) Lines, hoses, and clamps - for leaks, improper condition and looseness. (8) Exhaust stacks - for cracks, defects, and improper attachment. (9) Accessories - for apparent defects in security of mounting. (10) All systems - for improper installation, poor general condition, defects, and insecure attachment. (11) Cowling - for cracks, and defects."

Probable Cause and Findings

A leak in the fuel system due to a loose fitting, which resulted in a loss of engine power, and the inadequate maintenance inspection, which failed to detect/correct the security of the fitting.

 

Source: NTSB Aviation Accident Database

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