NORTHFORD, CT, USA
N97LC
HUGHES 369A
THE ARMY NATIONAL GUARD HAD TRANSFERRED THE HELICOPTER TO A LAW ENFORCEMENT AGENCY THE DAY PRIOR TO THE ACCIDENT. THE HELICOPTER WAS CRUISING ABOUT 800 FEET ABOVE GROUND LEVEL IN LOOSE FORMATION WITH ANOTHER HELICOPTER, WHEN RADIO AND VISUAL CONTACT WERE LOST. WITNESSES SAW THE HELICOPTER IN A DESCENT AND OBSERVED IT IMPACT TREES. NO DISTRESS CALLS WERE HEARD FROM THE PILOT. EVIDENCE INDICATED THAT THE MAIN AND TAIL ROTOR BLADES WERE AT LOW RPM. EXAMINATION OF THE ENGINE AND COMPONENTS INDICATED LOW POWER AT IMPACT. NO DISCREPANCIES WERE NOTED DURING THE EXAMINATION. A POST IMPACT FIRE DESTROYED MAJOR PORTIONS OF THE ENGINE AND FUSELAGE. THE PILOT FLEW WITH A FLIGHT INSTRUCTOR FOR 1.1 HOURS THE DAY BEFORE THE ACCIDENT. THIS WAS THE PILOT'S ONLY FLIGHT TIME IN THIS MODEL HELICOPTER PRIOR TO THE ACCIDENT. ALSO, OTHER THAN THIS FLIGHT, HE HAD NOT FLOWN ANY HELICOPTER IN OVER 5 YEARS.
HISTORY OF FLIGHT On Saturday, March 19, 1994, at 0950 eastern standard time, a Hughes 369A, N97LC, registered to the Lake County Sheriff's Office, and piloted by Deputy Sheriff William J. Marie, was destroyed during impact with trees and the terrain in Northford, Connecticut. The pilot was fatally injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight was being conducted under 14 CFR Part 91. N97LC departed the Quonset State Airport, Kingston, Rhode Island, about 0840, on a ferry flight to Leesburg, Florida, with the first destination of Morristown, New Jersey for refueling. The helicopter had been transferred from the Rhode Island Army National Guard to the Lake County Sheriff's Office, as part of a surplus aircraft program between the United States Government and the Drug Law Enforcement Agency. The pilot of N97LC was flying loose formation with another helicopter, which had been transferred to a different sheriff's department in Florida. The two helicopters were maintaining radio and visual contact with each other. No distress calls from the pilot of N97LC were heard by the pilots of the lead helicopter. A witness stated: ...my wife and I both heard what sounded like a turbo prop screaming. It seemed to be coming from east to west. I looked out my window and saw a chopper now going north to south just over the tree tops. I also saw another one headed west about 1000 to 1500 ft high due west.... [The helicopter heading north to south] was on a gradual decline making a screaming noise. I watched it until it went out of sight, but I did hear a crash or impact shortly... Another witness said: ...I noticed a small helicopter coming from the north behind my house. I did not hear the engines. I only saw the...top rotor blades were not rotating fast...This helicopter was on a steady decline...it was below the tree tops....I could tell it was in trouble and going to crash....the helicopter was nose down and just before it crashed it turned to the left. It disappeared behind the trees and then I saw...smoke come from...where it went down. The accident occurred during the hours of daylight, at about 41 degrees, 25 minutes North; 73 degrees, 0 minutes West. PERSONNEL INFORMATION Mr. Marie held an Airline Transport Pilot Certificate, with multiengine land, single engine land and sea, and rotorcraft- helicopter ratings. In addition, he held a Flight Instructor Certificate, with airplane single engine and rotorcraft- helicopter ratings. The pilot was issued a First Class Airman's Medical Certificate, on November 19, 1993, with no restrictions. At the time of the accident, Mr. Marie had a total flight time of 8250 hours, of which 415 hours were in helicopters. On March 18, 1994, he flew what was described as an "orientation" flight in N97LC, with a pilot from the Rhode Island National Guard. This pilot held an FAA Flight Instructor Certificate (CFI). At the completion of this 1.1 hour flight, the CFI, at the request of Mr. Marie, completed and signed FAA Form 8410-3, Airman Competency/Proficiency Check, indicating the type of check as a BFR (Biannual Flight Review). Mr. Marie's pilot logbook indicated that he had no other helicopter flight time since December 10, 1988. Acquaintances and co-workers of the pilot stated that they "thought" Mr. Marie had flown some type of helicopter in the past 2 or 3 years. During the investigation, no record or confirmation of such flights were located. A review of his logbook revealed the following helicopter flight time: Year Type helicopter Flight time 1981 Bell 47 293.8 hours Hiller 12B 3.6 " Bell 206 15.8 " 1984 Robinson 22 .8 " 1985 Bell 206 49.3 " 1986 Bell 206 11.8 " 1987 Bell 206 5.6 " 1988 Bell 206 20.7 " Enstrom F-28 13.9 " Mr. Marie received no "formal" ground training in this aircraft. He had obtained OH-6A Technical Manuals, including the Operators Manual, from the Army National Guard, and according to a family member and working associates, Mr. Marie had studied these manuals prior to the ferry flight. Mr. Marie had no flight time in the Hughes 369A prior to the flight on March 18, 1994. AIRCRAFT INFORMATION N97LC was delivered to the United States Army on August 20, 1968, as an OH-6A, tail number 67-16334. It had accumulated a total of 4082 hours on the airframe. The engine was changed, on January 26, 1994, in order to provide the Lake County Sheriff's Office an aircraft with more flight time before engine overhaul. The Rhode Island Army National Guard Maintenance Officer stated in a written report: The reason for the engine change in aircraft S/N 67-16334 was to transfer the aircraft with an engine having less operating time. The engine removed had approximately 150 hours remaining until TBO (Time Between Overhaul). The engine that was installed had 837 hours remaining until TBO at the time of installation .... The aircraft was stored in a hanger protected from the elements.... After installation, ground operation was conducted to accomplish the necessary maintenance operational checks and engine vibration checks. A maintenance test flight was conducted on 15 March to include an engine performance check....The aircraft was fueled, serviced, and parked until 18 March when it was flown as an orientation flight by a facility instructor pilot and the individual that was to accomplish the...ferry flight. The aircraft and engine maintenance records were on the aircraft and were destroyed by post-impact fire. WRECKAGE The wreckage was examined at the accident site on March 19, 1994. All the wreckage was contained in an area about 106 feet long. There were trees about 25 feet high with broken branches. Approximately 25 feet from these trees on a magnetic heading of 120 degrees, the left skid was buried in mud at an angle of about 45 degrees. On the same magnetic heading, and about 30 feet away, a main rotor blade was buried in the mud about 1/3 its length at an 80 degree angle. The main wreckage was located 25 feet from this blade on a magnetic heading of about 120 degrees. It was inverted in a muddy, snow covered, marshy area. There was an open field approximately 75 feet from the wreckage, on a magnetic heading of 180 degrees. The fuel cell was ruptured and was on the top of the wreckage. A post-impact fire had occurred. The fuel shutoff valve was not located. Three main rotor blades were located with the main wreckage. The blades were bent, but none of the rotor blades exhibited leading edge marks, nicks or chord-wise scratches. The tail rotor assembly was located 26 feet beyond the main wreckage on the same magnetic heading. It was fractured at about station number 250. There was no evidence of blade strikes on the boom assembly. The fractures surfaces were twisted and bent. The tail rotor blades were intact, and there were no leading edge gauges, nicks or chord-wise scratches on these blades. The engine was located at the bottom of the wreckage and was damaged by fire. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot by Dr. H. Wayne Carver, II, Chief Medical Examiner, on March 20, 1994, at the Office of the Chief Medical Examiner, Farmington, Connecticut. Toxicological testing was performed by Dr. Richard D. Pinder, Director, Toxicology Laboratory, at the Office of the Chief Medical Examiner, Farmington, Connecticut, on March 21, 1994. The results of this testing were negative for alcohol, drugs and carbon monoxide. TESTS AND RESEARCH The U.S. Army Safety Center, Analytical Investigation Branch, Corpus Christi, Texas, examined the following components/parts from N97LC: 1. Main drive shaft 2. Overrunning clutch 3. Main rotor head 4. Main rotor drive shaft and static mast 5. Main rotor swashplate/scissors/transmission 6. Tail rotor/gearbox/assembly 7. A 16" piece of tail rotor drive shaft 8. Flight control tubes 9. Miscellaneous light bulbs In a report, the Army Safety Center stated: Conclusions a. Examination of the components/parts disclosed the following conditions: (1) The damage noted (dents, bends, scars, and tears) on the tail rotor blades, and the main rotor head, indicated that the drive train was at a low or no rotor speed when it entered the trees and impacted the ground. (2) The overrunning clutch failed to show evidence of a sprag "roll over" or any other anomalies. This suggests that the aircraft was not established in a controlled autorotation flight during the impact sequence. (3) Both main drive shaft flexible diaphragms severed at their outboard ends. The fractures at the severed ends were due to overload/overstress. b. All other bend, tears, and fractures occurred as a result of contact with the trees or impact with the ground. c. Examination of the light bulbs revealed that the bulbs were not illuminated at the time their filaments fractured or deformed. The examination of these components/parts did not reveal any anomalies. The engine was examined at the Allison Engine Company, Indianapolis, Indiana, on April 14, 1994, under the supervision of the Safety Board Investigator-In-Charge. The magnesium gearbox section was destroyed by post-impact fire. The drive gears were accounted for, and no gear teeth were missing or broken. The starter/generator was damaged by fire. The compressor section was nearly separated from the main housing. The fuel pump was burned and the shaft could not be rotated. The N2 shaft was seized and would not rotate. The N1 shaft rotated freely. There were no missing/distorted blades on the turbine. The N0. 5 bearing was seized. It rotated after the application of heat by investigators. Distortion of the turbine blades and rubbing marks on the shroud associated with rotational damage were not present. The turbine blades were not bent opposite to the direction of rotation. There was "soot" on the outer combustion case and the fuel nozzles and igniters. During this examination, no anomalies were noted. The following components/parts were secured and left at the Allison Engine Company for examination under the supervision of the Federal Aviation Administration: 1. Fuel pump 2. Gas producer fuel controller 3. Fuel nozzle 4. PC air filter 5. Fuel line to the fuel pump inlet 6. Power turbine governor 7. Turbine nozzle ADDITIONAL INFORMATION The McDonnell Douglas pilot training syllabus for MD 500 (which included the Hughes 369A) series aircraft recommended the following: Lesson #1 - Familiarization: 1.0 - 1.5 hours Lesson #2 - Hover & pattern work: 1.0 - 1.5 " Lesson #3 - Emergency procedures: 1.5 " (autorotations) Lesson #4 - Failure indications/emergencies 1.0 " Total: 4.5 - 5.5 hours The United States Army publication, TC-215, Qualification Training for Helicopter Pilots Transitioning to the OH-6A Aircraft, stated: During flight training, the aviator is trained to proficiency in the base tasks identified in Chapter 5. Minimum flight time will not be less than ten hours. The following excerpts are from a book by R.W. Prouty, entitled Helicopter Aerodynamics. The fact that a single engine helicopter has a much better chance to make a safe landing following a power failure than a single-engine airplane...comes up in more general discussion than any other talking point. Failure to make a good entry into autorotation after the engine stops is one of the primary causes of helicopter accidents. The key to making a good entry is to keep the rotor speed up. If the rpm is allowed to decay too much, the rotor may stall and come to a fatal stop when asked to support the full weight of the helicopter.... The accepted way to stop the decay is to quickly reduce the power demands on the rotor by lowering the collective stick. This results in an initial loss of thrust but does get the helicopter going down through the air - the first prerequisite for autorotation. In the United States Army publication, Fundamentals of Flight, dated October, 1988, it stated: Entry into autorotation is performed after loss of engine power....In most helicopters, it takes only seconds for the RPM decay to fall into a minimum safe range. Aviators must quickly reduce collective pitch to prevent excessive RPM decay. In the Emergency Procedures Chapter of the United States Operators Manual for the OH-6A, TM 55-1520-214-10, it stated: Complete Power Loss. Under a complete power loss condition, delay in recognition of the malfunction, improper technique or excessive maneuvering to reach a suitable landing area reduces the prob- ability of a safe autorotational landing. The aircraft wreckage was released to Charles M. Bowman, the insurance adjuster, on March 22, 1994.
THE LOSS OF ENGINE POWER FOR UNDETERMINED REASONS, AND THE PILOT'S FAILURE TO MAINTAIN ROTOR RPM DURING THE FORCED LANDING AUTOROTATION, RESULTING IN A LOSS OF AIRCRAFT CONTROL AND COLLISION WITH TREES. ALSO CAUSAL TO THE ACCIDENT WAS THE PILOT'S LACK OF RECENT HELICOPTER EXPEREINCE AND HIS LACK OF EXPERIENCE IN THIS MODEL HELICOPTER.
Source: NTSB Aviation Accident Database
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