HISTORY OF FLIGHT: On February 14, 1995, at 1534 central standard time, a Bell 206L-4, N172AL, during cruise flight impacted water in the Gulf of Mexico. The commercial pilot and three passengers sustained fatal injuries. A fourth passenger, not recovered, is presumed to have received fatal injuries. The Title 14 CFR Part 135 flight, operated by Air Logistics, departed an offshore oil platform (East Cameron 335) at 1445 en route to Intracoastal City, Louisiana. Instrument meteorological conditions due to low ceilings and fog existed throughout the area. Flight following via radio contact was maintained with company dispatch personnel. The flight originally departed Intracoastal City at 0657 and arrived at the offshore platform (East Cameron 335) at 0803. Throughout the day, N172AL made several flights to other offshore platforms (see enclosed radio log). The operator stated weather for flights departing the offshore platforms could be obtained by calling the company dispatcher; however, records did not indicate preflight weather briefings for N172AL. Following the departure from the offshore platform, the pilot made several position reports. At 1529, the pilot of N172AL made a position report 32 miles south of Intracoastal City. At 1534 the company dispatch operator received a series of 4 mayday transmissions from N172AL indicating inadvertent flight into instrument meteorological conditions. PERSONNEL INFORMATION: A review of Federal Aviation Administration (FAA) records indicated that the pilot satisfactorily completed the military competence instrument written examination on December 3, 1991, and was issued the commercial pilot certificate with the helicopter and instrument ratings. The pilot satisfactorily completed a Title 14 CFR Part 135 flight check on November 18, 1994 for flight in VFR conditions. The flight check included emergency vertical helicopter instrument recovery procedures. Company flight records indicated a flight time of 0.2 hour of simulated instrument time during the last 6 months. Company personnel reported that the pilot started flights in the East Cameron field on April 7, 1994, with a work cycle of 7 days on followed by 7 days off. Flight hours on February 8, 1995, was 7.5 followed by 23.3 hours during the first 5 days of the current work cycle which began on February 9, 1995. AIRCRAFT INFORMATION: The helicopter was maintained in accordance with a continuous airworthiness program. There were no open discrepancies found in the maintenance records. Company personnel stated that the helicopter was not certified for flight in instrument meteorological conditions. METEOROLOGICAL INFORMATION: A review of meteorological data for the coastal areas and the Gulf of Mexico revealed a trough along the Texas coast and a stationary front in the southeast portion of the Gulf of Mexico with IFR conditions throughout the day. The area from Sabine Pass, Texas, to New Orleans, Louisiana, included ceilings below 1,000 feet MSL and visibility below 1 mile due to rain and fog. Company pilots reported that weather offshore from Intracoastal City varied from company minimums (500 foot ceiling/3 mile visibility) to obscured ceilings with visibility less than 2 miles due to fog. The pilot of N172AL acknowledged the weather information, reported deteriorating weather at his location (platform East Cameron 335), and reported a planned departure to Intracoastal city. WRECKAGE AND IMPACT INFORMATION: Until February 19, 1995, search and rescue efforts were hampered by fog and IFR ceilings. Through March 23, 1995, bodies of the pilot and three of the four passengers were recovered south of Lake Charles, Louisiana. All four bodies had life jackets on them, and one had been inflated. An additional life jacket was found floating in the water at West Cameron block 225. These jackets are manually inflated. On March 16, the left horizontal stabilizer and winglet were recovered from High Island block A239 (latitude 28.37.59 W; longitude 093.54.47 N) south of Galveston, Texas. The right horizontal stabilizer and winglet with approximately 4 feet of the tailboom was recovered on March 20, 1995, by a research vessel south of Galveston, Texas. On June 20, 1995, a portion of the oil cooler cowling was recovered south of Sabine, Texas. The area searched was in excess of 10,000 square miles and the official search was terminated on March 30, 1995, with the missing components presumed as destroyed. MEDICAL AND PATHOLOGICAL INFORMATION: The autopsy was performed by Forensic Pathologist, Vladmirir M. Parungao, M. D., at Galveston, Texas. Toxicology was positive for alcohol; however, Dr. Canfield of the Federal Aviation Administration Civil Aeromedical Institute at Oklahoma City, Oklahoma, stated that the ethanol level was "below allowable levels and there was some putrefaction of specimens." He further stated that he could not "confirm ingestion of alcohol." ADDITIONAL INFORMATION: The recovered helicopter components have not been released pending the possibility of further investigation if other components are recovered.