N81SP
Bell 206L-3
Approximately 10 seconds after takeoff from an offshore platform, the 3,299-hour pilot heard a loud bang and the engine lost partial power. The pilot initiated an autorotation to the water, and then heard a subsequent bang. Prior to touchdown, the pilot attempted to inflate the floats; however, the floats did not inflate. The pilot executed a flare, "pulled in pitch"; the helicopter "still had power" and entered into a hover. The pilot reported the helicopter "seemed to still be pulling in power when the [helicopter] touched the water then rolled and the blades hit [the water]." Inspection of the engine revealed minor damage to the compressor diffuser vane and the impeller, and foreign object damage (FOD) in the combustion chamber. It was not determined if the FOD occurred prior to the impact with the water. The reason for the partial loss of engine power was not determined.
On March 6, 2004, approximately 1623 central standard time, a Bell 206L-3 single-engine helicopter, N81SP, sustained substantial damage during an autorotation to open ocean following a partial loss of engine power during takeoff from offshore platform West Cameron 149, in the Gulf of Mexico. The helicopter was registered to and operated by Petroleum Helicopters Inc. (PHI), of Lafayette, Louisiana. The commercial pilot and one passenger were not injured, and one passenger sustained minor injuries. Visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed for the 14 Code of Federal Regulations Part 135 on-demand air taxi flight. The flight's intended destination was offshore platform West Cameron 98. According to the pilot's statement, approximately 10 seconds after takeoff, he heard a "loud bang." The pilot initiated an autorotation, and then heard a "second bang." While descending, the pilot attempted to inflate the skid-mounted floats; however, the floats did not inflate. The pilot executed a flare, "pulled in pitch"; the helicopter "still had power" and entered into a hover. The pilot reported the helicopter "seemed to still be pulling in power when the [helicopter] touched the water then rolled and the blades hit [the water]." Inspection of the engine by a PHI representative revealed minor damage to 13 blades of the impeller with .030 inches maximum depth on 3 blades. The compressor diffuser vane exhibited a 1/4 inch torn and bent vane that caused blockage. Damage to a second vane appeared to have a spring imprint matching a piece of ferrous material that was lodged inside of the combustion liner. The material appeared to be a portion of a camloc fastener spring. It was not determined if the foreign object damage (FOD) occurred prior to the impact with the water. The PHI representative reported that before the flight, a 360 degree walk around inspection for FOD was performed, and no foreign objects were found. The engine's last AAIP inspection was accomplished on January 27, 2004, and had accumulated approximately 150 hours up to the time of the accident. Examination of the fuel control system revealed that a large piece of the governor body was broken-off and missing. A fuel control pneumatic leak check was not performed due to damage sustained to the governor. The fuel control was tested "as received" with no anomalies noted. The Apical Emergency Float System, Supplemental Type Certificate (STC) SR00067LA, is a mechanically designed cable system that inflates three emergency floats on each skid. This is accomplished by pulling a lever attached to the cyclic. By squeezing the lever, a series of cables are pulled tight, which in turn pulls a disk that separates from a nitrogen container, allowing the nitrogen to inflate the floats. Inspection of the float system rigging by a PHI representative found an excess of slack in the rigging approximately 3/4 to 7/8 of an inch in length. Further examination revealed that, even after squeezing the actuator lever all the way to the cyclic, there was still approximately 1/8 of an inch of slack in the cable.
A partial loss of engine power due to undetermined reasons. A contributing factor was the emergency floats not being deployed.
Source: NTSB Aviation Accident Database
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