N349AL
Bell 206L-3
The helicopter was in cruise flight at an altitude of 1,200 feet msl, 22 miles south of its destination, when the engine lost power. The pilot verified that the engine had failed, made a "May Day" call, initiated an autorotation to the water and inflated the emergency floats. Prior to contact with the water, the pilot pulled all available collective pitch, and the helicopter "impacted in a slight nose low, right banking attitude. During impact the right front float bag ruptured." The helicopter rolled right and remained floating inverted as the pilot egressed. According to an FAA inspector, the pilot reported having a problem determining the helicopter's height above the water. "The weather was VMC with the wind from the southwest at an estimated 10 knots and the seas state displayed wave heights of two to three feet." Examination of the helicopter revealed that the PC air line between the tee for the power turbine governor and the fuel control was found fractured under the "B" nut at the fuel control. An examination of the tube assembly at NTSB Materials Laboratory, revealed fatigue cracking within the flared portion of the tube end. The origin areas were located on the inside surface of the tube, at circumferential scoring marks. The location of the origin areas approximately corresponds to the inside diameter of the fitting ("B" nut) that mates with the flared end. According to the engine maintenance manual, excessive torque on pneumatic sensing system connections results in cracking of the flare or adjacent tube area in contact with the ferrule.
On January 8, 2002, at 1552 central standard time, a Bell 206L-3 helicopter, N349AL, was substantially damaged during a forced landing to the water following a loss of engine power near Grand Isle 74, in the Gulf of Mexico. The helicopter was owned and operated by Air Logistics LLC of New Iberia, Louisiana. The commercial pilot, sole occupant, was not injured. Visual meteorological conditions prevailed, and a company visual flight rules (VFR) flight plan was filed for the 14 Code of Federal Regulations Part 91 positioning flight. The flight originated at Grand Isle 102, in the Gulf of Mexico, at 1539, and was en route to Fourchon, Louisiana. The 1,384-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that the helicopter was in cruise flight at an altitude of 1,200 feet msl, 22 miles south of Fourchon, when the engine lost power. The pilot verified that the engine had failed by the N1, N2, and T.O.T. gauges, made a "May Day" call to the company dispatcher, and initiated an autorotation to the water. Prior to the helicopter touching down on the water, he inflated the emergency floats. As the helicopter landed on the water, it rolled over to the right and remained floating inverted. There was no visible damage to the helicopter; however, the right front float was deflated. The operator reported in the NTSB Form 6120.1/2 that the pilot pulled all available collective pitch just prior to contact with the water, and the helicopter "impacted in a slight nose low, right banking attitude. During impact the right front float bag ruptured." The helicopter rolled to the right and remained floating inverted as the pilot egressed. "The weather was VMC with the wind from the southwest at an estimated 10 knots and the seas state displayed wave heights of two to three feet." According to an FAA inspector, the pilot reported having a problem determining the helicopter's height above the water and deployed the emergency floats when the altimeter indicated 100 feet. Examination of the helicopter by the FAA inspector revealed that the right front float was deflated and the front portion of the right skid was separated. The tailboom was bent and separated from the fuselage. One main rotor blade was separated and the left front mount of the main transmission was fractured. Examination of the engine revealed that the PC air line between the tee for the power turbine governor and the fuel control was found fractured under the "B" nut at the fuel control. The PC tube assembly, MFR 3T336, S/N 6893073, was sent to the NTSB Materials Laboratory in Washington, D.C., for examination. An examination of the tube assembly revealed fatigue cracking within the flared portion of the tube end. The origin areas were located on the inside surface of the tube, at circumferential scoring marks. The location of the origin areas approximately corresponded to the inside diameter of the fitting ("B" nut) that mates with the flared end. The 250-C30 engine Series Operation and Maintenance Manual on page 331, paragraph 6, Rigid Tube Installation, under WARNING states "Proper tightening of engine tubing connections is critical to flight safety. Correct torque values must be used at all times. Excessive torque on pneumatic sensing system connections results in cracking of the flare or adjacent tube area in contact with the ferrule. This produces an air leak which can cause flameout, power loss, or overspeed."
The pilot's misjudged landing flare. A contributing factor was the fatigue fracture of the PC air line due to the improper installation by company maintenance personnel, which resulted in a loss of engine power.
Source: NTSB Aviation Accident Database
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