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N5006F accident description

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Tail numberN5006F
Accident dateJune 24, 2004
Aircraft typeBell 206-L1
LocationVermillion Bay, LA
Near 29.755556 N, -92.079723 W
Additional details: None

NTSB description

HISTORY OF FLIGHT

On June 24, 2004, approximately 1350 central daylight time, a single-engine Bell 206-L1 helicopter, N5006F, registered to and operated by American Helicopters Inc. (AHI), of Angleton, Texas, was destroyed when it impacted water following an in-flight encounter with severe weather near Vermillion Bay, Louisiana. The commercial pilot and two passengers sustained fatal injuries. Instrument meteorological conditions prevailed in the area of the accident, and a company flight following plan was filed for the Title 14 Code of Federal Regulations Part 135 on-demand air taxi flight. The 114-nautical mile over water flight originated from offshore platform Eugene Island 349 approximately 1258, with an intended destination of Abbeville Municipal Airport (0R3), near Abbeville, Louisiana.

The AHI flight was contracted by Flow Petroleum Services, of Lafayette, Louisiana, to transport personnel from offshore platforms to 0R3. According to recorded excerpts extracted from the operator's flight following system, the helicopter departed from offshore platform East Cameron 321 at 1213, en route to Eugene Island 349, with one passenger and three hours of fuel onboard. The 70-nautical mile flight arrived on offshore platform Eugene Island 349 at 1252, and picked up a second passenger. The flight departed Eugene Island 349 at 1258, with three persons and 2.15 hours of fuel onboard. The estimated time of arrival at 0R3 was 1355.

At 1329, the pilot contacted AHI flight following with a normal position report and reported inbound to 0R3. At 1337, the pilot again contacted AHI flight following and changed his destination from 0R3 to Intracoastal City Heliport, near Intracoastal City, Louisiana (7R4). [Note: The pilot did not give a reason for the change of destination.] During the radio call, the pilot gave an estimated time of arrival time of 1350 at Intracoastal City, with 45 miles to go and 1.15 hours of fuel remaining. At 1351, AHI flight following attempted to contact the accident aircraft; however, communication could not be established.

The pilots of a Chevron S-76 helicopter, N7266K, operating in the vicinity of Intracoastal City, reported hearing a Mayday call approximately 1350 on VHF frequency 122.85. They stated that they heard "Mayday-Mayday-Mayday." They then asked for their location but received no response. They then heard another "Mayday-Mayday-Mayday, going in the water." A land based radio operator located in Intracoastal City reported hearing a Mayday call on VHF frequency 122.85. The operator reported the call to AHI flight following at 1405. The reported Mayday call was "Mayday, Mayday, going in the water." There were no further communications or reported distress calls on frequency 122.85, and no reported eyewitnesses. The distress calls that were heard were not recorded, and it is unknown whether the pilot's of the S-76 were hearing the same distress calls as reported by the Intracoastal Operator.

Note: The AHI company flight following frequency was FM 151.5200. The 7R4 common frequency was VHF 122.85. According to the operator, it was standard practice to switch from the flight following frequency to the common frequency when within 10 miles of Intracoastal City.

Flight History for N5006F on June 24, 2004:

The first flight of the day for N5006F began at 0649, from 0R3 to 7R4. Actual time of arrival (ATA) was 0655. Three passengers, fuel onboard 1 hour and 30 minutes.

Departed 7R4 at 0708 en route to West Cameron (WC) 39 ATA 0745. Three passengers, fuel onboard 2 hours 30 minutes.

Departed WC39 at 0745 for a local flight and returned to WC39 ATA 0815. Three passengers, fuel onboard 2 hours 30 minutes.

Departed WC39 at 0831 en route to WC205 ATA 0848. Three passengers, fuel onboard 1 hour and 30minutes.

Departed WC205 at 0858 en route to East Cameron (EC) 321 ATA 0955. Three passengers, fuel onboard 3 hours.

Departed EC321 at 0959 en route to WC661 ATA 1025. One passenger, fuel onboard 2 hours.

Departed WC661 at 1059 en route to EC338 ATA 1115. No passengers, fuel onboard 1hour and 30 minutes.

Departed EC338 at 1126 en route to EC321 ATA 1130. No passengers, fuel onboard 3 hours.

Departed EC321 at 1213 en route to Eugene Island (EI) 349 ATA 1255. One passenger, fuel onboard 3 hours.

Departed EI349 at 1258 en route to 0R3 estimated time of arrival (ETA) 1355. Two passengers, fuel onboard 2 hours and 15 minutes.

At 1329, pilot gave normal position report, about 45 miles south of 7R4.

At 1337, pilot changed destination from 0R3 to 7R4 and reported new ETA as 1350.

At 1350, Chevron S-76 heard Mayday calls.

At 1351, AHI flight following attempted to contact the accident aircraft on FM frequency 151.5200; however, no communication was established. The pilot did not report landing at 7R4, and radio contact was not re-established.

At 1405, a mayday call was reported by an Intracoastal (PHI) radio operator to AHI flight following.

PERSONEL INFORMATION

The commercial rated pilot was employed by AHI on December 22, 2003, and held a rating for rotorcraft, and private privileges for airplane single-engine land. He had previously been employed by AHI as a line pilot from January 23, 2001 to August 25, 2002. The pilot held a valid Federal Aviation Administration (FAA) class-II medical certificate, with no limitations or waivers. The date of his last medical examination was June 4, 2003.

The operator reported that the pilot had accumulated a total of 6,562 flight hours, with a total of 5,309-hours in the accident aircraft make and model. On December 24, 2003, the pilot satisfactorily completed an airmen competency/proficiency check in a Bell 206B-III. The operator also reported that the pilot had a total of 5 hours of actual instrument training in helicopters prior to his employment with AHI.

AIRCRAFT INFORMATION

Manufactured on November 20, 1978, the Bell 206 L-1 single-engine helicopter, serial number 45181, had accumulated 23,489.2 hours of total airframe time as of the time of the accident. The helicopter was maintained in accordance with a FAA approved AAIP program. Entries in the airframe maintenance logbooks showed that the last inspection (300-hour inspection) was conducted on June 12, 2004. The helicopter had accumulated 59.5 hours since the last inspection. The accident aircraft was configured for six passengers and one pilot.

The helicopter was not equipped with a Flight Data or Cockpit Voice Recorder.

All observed damage to the airframe structure and controls appear consistent with water impact in an abnormal attitude. No pre-impact discontinuities have been noted.

The Rolls-Royce 250-C28B, 500-horsepower engine, serial number CAE-860050, was manufactured in October, 1978. Entries in the engine maintenance logs and recent daily flight time sheets showed a total time of 21,761.6 hours at of the time of the accident. The last engine inspection performed was a 300-hour inspection conducted on June 12, 2004. At the time of the inspection, the engine had accumulated a total of 21,702.1 hours.

METEOROLOGICAL INFORMATION

The Federal Aviation administration (FAA) Advisory Circular AC 00-24B titled "Thunderstorms" dated January 2, 1983, defines the echo intensity levels and potential weather phenomena associated with those levels. If the maximum VIP level is 3, it is defined as "strong" and severe turbulence is possible with lightning. VIP level 4 is defined as "very heavy" and severe turbulence is likely with lightning. VIP level 5 is defined as "intense" with severe turbulence, hail likely and organized surface wind gusts. These levels are also referenced in the Aeronautical Information Manual (AIM) under the Pilot/Controller Glossary under radar weather echo intensity levels.

A plot of the direct route of flight to the accident site was overlaid on a base reflectivity image taken at 1347 to identify the potential weather that may have been encountered along the route of flight. The image depicted a broken line of echoes extending north of Lafayette Regional Airport (LFT) near Lafayette, Louisiana, to 7R4, southward into the Gulf of Mexico. The line bows outward over Marsh Island and Vermillion Bay with echo intensities ranging from level 3-4 thunderstorms ("strong-to-very strong") and several cells were defined ahead of the line east of the accident site with maximum intensities of level 5.

The National Weather Service (NWS) Storm Prediction Center (SPC) located in Norman, Oklahoma, issued a Severe Weather Forecast Alert (AWW) or Weather Watch number 518 at 1325 for severe thunderstorms over southeast Louisiana, southern Mississippi, and coastal waters. The advisory was valid from1325 to 2000. The advisory warned of severe thunderstorms with hail 1 inch, wind gusts to 60 knots, with maximum tops at 50,000 feet. The route of flight from the 1337 radio contact to the accident site was located approximately 12 west of the southeast boundary of the advisory.

The NWS Aviation Weather Center issued a Convective SIGMET (Significant Meteorological Information) 74C at 1245 valid until 1455 for portions of Mississippi, Louisiana, Texas and coastal waters. The advisory warned of embedded thunderstorms moving from 210 degrees at 20 knots with tops above 45,000 feet. The accident site was located within the boundary of this advisory.

At 1355 Convective SIGMET 76C was issued and valid until 1555 for portions of Texas and Louisiana, and Texas coastal waters. This SIGMET continued to warn of embedded thunderstorms moving from 220 degrees at 25 knots, with tops above 45,000 feet. This advisory encompassed the accident site.

The closest weather reporting location to the accident site was from 7R4 located approximately 2 miles west of the accident site. The heliport had an Supplemental Aviation Weather Reporting System (SAWRS) and reported the following conditions surround the time of the accident:

1203, wind from 180 degrees at 15 knots gusting to 22 knots, visibility 5 miles in mist, ceiling broken at 1,500 feet, temperature 31 degrees Celsius (C), dew point temperature 25 degrees C, altimeter setting 29.99 inches of Mercury.

No weather observations were available between 1203 and 1700.

There was no report of the pilot obtaining any formal preflight weather briefing (from a company, flight service station, DUATS or WSI weather program) prior to departure or en route.

There were no offshore weather reporting stations to support flight operations to the oil platforms. The lack of such reporting stations made it difficult to determine the departure and en route conditions that existed prior to the accident.

WRECKAGE AND IMPACT INFORMATION

The airframe sustained severe damage consistent with a high-speed water impact in a nose down attitude. The upper forward fuselage structure was hydro dynamically shredded and compressed. The direction of metal deformation is from upper front toward the lower rear. The floor structure (honeycomb) exhibited separations at points where the panels are joined during construction. The cross tubes were rotated aft and pulled from the floor structure. The skid tubes were separated in apparent overload at the cross tube attach points. There was no apparent bending of cross tubes or skid tubes. The float bags were out of their storage bags. They did not appear to have been intentionally deployed. It was reported that the float bottle had been discharged for safety after the wreckage was recovered. The instrument panel and pedestal appear to have been hydro dynamically crushed aft and down. Several cockpit instruments were hydro formed in this manner.

Fixed Flight Controls and Hydraulic System:

The vertical control tube compartment (broom closet) shows aft and downward crushing. The control tubes and linkages were bent front to rear. The severely damaged hydraulic actuators were still attached to a portion of the upper deck. The entire cowling associated with the upper main fuselage was heavily crushed and shredded. A portion of the cowling above the hydraulic actuators was hydro formed around the linkages it normally covers. The tail rotor pitch change tube in the tail boom was moved partially and was connected forward to the tail boom separation point.

Transmission, Mast, Main Rotor Hub, Main Rotor Blades:

Portion of the transmission deck to which the transmission is mounted is missing as is the transmission pylon, mast, main rotor assembly, and main rotor blades.

Airframe Fuel System:

The forward fuel cell compartments exhibited minimal damage and no apparent bulging. The aft (main) fuel cell appeared to have hydro dynamically bulged prior to yielding. The left under-seat structure was bulged up and out. The forward vertical bulkhead of the fuel cell cavity was fractured and bulged outward. The fuel bladder was torn in a manner consistent with hydrodynamic exploding. It is estimated that there was more than1 hour of fuel on board at the time of impact.

Tail boom:

The tail boom was recovered separately from the main fuselage together with the vertical fin that was separated. The tail rotor drive shaft cover and the 90-degree gearbox cowling were hydro dynamically deformed from the top downward along the entire length of the tail boom around the gearbox and the drive shafting. All tail rotor drive shaft segments were present. The 2nd shaft aft of the oil cooler blower was bent and separated at the point of the tail boom separation from the fuselage. The drive shaft on the tail boom exhibited twisting and bending consistent with longitudinal tail boom compression. The 90-degree gearbox, tail rotor mast and tail rotor assembly were in place and when rotated by hand, moved freely in rotation and pitch change. The tail rotor assembly appeared to have been capable of rotation and pitch change prior to impact and immersion.

The right horizontal stabilizer was separated along its chord at a point 11 inches outboard of its attach point to the tail boom. The separation was along the line of a doubler. The section of the horizontal stabilizer outboard of the separation point has not been recovered as of June 30, 2004. The tail boom exhibited torsion deformation aft of the horizontal stabilizer. The vertical fin upper leading edge was hydro dynamically compressed. There was impact damage on the top of the vertical fin. The lower leading edge of the vertical fin was not hydro dynamically deformed. There was a dent approximately 6" from the bottom on the lower leading edge. The freewheeling unit appeared unremarkable. The clutch assembly appeared to be functional when rotated by hand. The steel drive shaft (#1) was not bent. It had rotational scouring coinciding with adjacent engine components from the lower engine compartment.

Flight Controls:

The cyclic was broken midway down the shaft. The cyclic grip was broken at mid grip. The throttle was observed at the full open position. The flight control linkages were incomplete and severely distorted/destroyed due to impact forces. The damage observed appeared consistent with the overall gross distortion of the fuselage. None of the fixed or rotating controls associated with the transmission has been observed.

TESTS AND RESEARCH

An engine disassembly and examination was conducted on August 17, 2004 by representatives from Rolls-Royce and supervised by an NTSB investigator. The following observations were noted: Examination of the engine and components did not reveal any evidence of any pre-impact failures. All damages to the engine were the result of impact forces caused by the accident sequence. The engine was operating at the time of impact with the water. Evidence of engine operation at the time of impact was evidenced by the compressor impellor rub on the compressor shroud 180 degrees.

ADDITIONAL INFORMATION

The wreckage was recovered to Air Salvage of Dallas, in Lancaster, Texas.

(c) 2009-2011 Lee C. Baker. For informational purposes only.