Full Report:

NYC95GA060 HISTORY OF FLIGHT On February 22, 1995, about 0937 eastern standard time, a Eurocopter, AS-350-B, helicopter, N20SP, operated by the Massachusetts State Police (MSP), was destroyed when it collided with a boat house during a forced landing near Cambridge, Massachusetts. The two pilots and two passengers were fatally injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the passenger flight conducted under 14 CFR Part 91. The pilots, Troopers James Mattaliano and Paul Perry, worked from 1500 until 2300, on February 21, 1995. The pilots reported to work the morning of February 22, 1995, about 0700. Their mission that morning was to pick-up two AT&T employees at the Nashua Street Heliport, and transport them to the MSP Headquarters in Framingham, Massachusetts. Trooper Mattaliano was the senior pilot; therefore, he was considered the pilot-in-command. The MSP rented hangar space from Wiggins Airways, at the Norwood Memorial Airport (OWD), in Norwood, Massachusetts. The hangar was shared with another helicopter operator. At 0750, the pilot/manager of this operator reported that he observed Trooper Perry enter the hanger, and walk around N20SP. He saw Trooper Perry approach the right side of N20SP where the tail joins the main fuselage, touch the helicopter, and then walk aft and visually inspect the tail rotor area. Trooper Perry then opened the hangar doors and moved N20SP outside, where the two troopers boarded N20SP and started the engine. He estimated that the run-up lasted about 10 minutes, and the helicopter departed to the northeast. According to OWD Air Traffic Control Tower (ATCT) records, N20SP departed OWD, about 0922. Using the call sign of State Police One, N20SP contacted Boston ATCT, at 0924, and requested clearance into the Boston Class B airspace to land at the Nashua Street Heliport. The helicopter was cleared into the airspace and, at 0930, the pilot of N20SP reported landing assured at the heliport. At 0936:16, N20SP contacted Boston ATCT and requested clearance out of the Class B airspace, at 800 feet. The Boston ATCT granted the request, and the pilot of N20SP stated "thanks," at 0936:29. That was the last transmission received from N20SP. Boston ATCT Radar plotted N20SP reaching an altitude of 600 feet mean sea level, at 0937:00, before beginning a decent below radar coverage. Over 20 witness statements were taken from personnel who observed the helicopter after it departed from the Nashua Heliport. The witnesses observed the helicopter flying westbound over the Charles River. A puff of smoke was seen coming from the helicopter in the vicinity of the engine. The helicopter then turned to the right and descended toward the north bank of the river. The witnesses estimated the angle of descent was between 45 and 70 degrees. Most of the witnesses observed smoke trail from the engine exhaust area. Eleven witnesses stated that the main rotor blades were turning slowly, or not at all. The helicopter struck two metal structures extending from the Harvard Sailing Pavilion and came to rest on the roof. The accident occurred during the hours of daylight approximately 42 degrees, 22 minutes north latitude, and 71 degrees, 00 minutes west longitude. PILOT INFORMATION Trooper James Mattaliano held a Commercial Pilot Certificate with a rating for rotorcraft helicopter, and a Private Pilot Certificate with a rating for airplane single engine land. He was not instrument rated. His most recent Federal Aviation Administration (FAA) Second Class Medical Certificate was issued on April 6, 1994. Trooper Mattaliano's total flight time was estimated at 1,150 hours, of which approximately 900 hours were in this make and model. Trooper Paul Perry held a Private Pilot Certificate with ratings for airplane single engine land, and rotorcraft helicopter. He was not instrument rated. His most recent Federal Aviation Administration (FAA) Second Class Medical Certificate was issued on January 4, 1995. Trooper Perry's total flight time was estimated to be about 340 hours, of which approximately 180 hours were in this make and model. The Safety Board made several requests for Trooper Mattaliano's and Trooper Perry's pilot logbooks. They were not provided to the Safety Board. Additionally, the Safety Board made requests to the Massachusetts State Police to obtain copies of the remaining Air Wing pilot's log books, to review flight hours and training. The requested information was not provided. WRECKAGE INFORMATION An NTSB Investigator examined the helicopter wreckage on February 22, 1995, at the accident scene, and on February 23 and 24, 1995, after the wreckage was moved to a facility in Boston, Massachusetts. The examination revealed that all major components of the helicopter were accounted for at the scene. The helicopter main fuselage came to rest on a boat house roof, on an approximate magnetic bearing of 360 degrees. The tail boom was separated from the fuselage and submerged in water next to the boat house. The main fuselage and cabin were destroyed. The pilot's instrument and caption panel were intact. Examination revealed that caption chips for the generator, bleed air valve, and engine oil pressure contained broken or deformed light bulb filaments. The yellow and blue star arms of the main rotor head were fractured on the leading edge. The fractures continued aft and inboard, at a 45 degree angle, and the star arms were bent opposite the direction of rotation. The red star arm was not fractured. The pitch change rods, and the main rotor collective and cyclic servos remained connected. Except for the fore and aft cyclic servo, the servo piston rods moved freely and pumped fluid. The fore and aft servo was damaged from impact with the main transmission. The main transmission support rods were separated, and the transmission was shifted forward. The three main rotor blades (MRB) were attached to their respective star arms of the main rotor head. The three MRBs displayed black marks on the bottom of each blade tip. The roof area under the MRBs was covered with black tar. The yellow and red blades were intact, and displayed chord wise scratches on the lower leading edges. The red blade also displayed chord wise scratches on the lower skin surface. The blue blade was broken about 3 feet from the root, and the tip cap was peeled upward. Trailing edge debonding was observed on the red and blue blades. The tail boom was bent in the vicinity of the number two bearing support. The right side tail boom mount was torn, and the left side was separated along the rivet line. The tail rotor drive shaft was uncoupled at the point of separation from the fuselage. The tail rotor gear box, hub, and blades where intact. These components remained attached to the tail boom and were not damaged. When the tail rotor drive shaft was rotated, the gear box output shaft turned the tail rotor. Flight control continuity was verified from the mixing unit to the servo controls. Rotation of the main rotor mast confirmed drive train continuity from the transmission to the engine, and to the tail rotor drive shaft. The free-wheeling capability of the transmission was also confirmed. Examination of the transmission revealed lubrication through out the transmission, and the gears rotated freely. A bore scope inspection of the upper and lower chip detector areas revealed no internal damaged. The upper and lower chip detectors were absent of debris. The fuel tank was ruptured and destroyed. The airframe fuel filter was intact and a fuel sample was taken from the filter for further examination. The power turbine and the freewheel section of the engine rotated freely. The compressor section would not rotate. Examination of the engine chip detector revealed that it was absent of debris. The engine was removed for further examination. MEDICAL AND PATHOLOGICAL INFORMATION Autopsies were performed on Troopers James Mattaliano and Paul Perry, on February 23, 1995, by Dr. Richard Evans of the Chief Medical Examiners Office, Cambridge, Massachusetts. The toxicological testing report, from the FAA toxicology Accident Research Laboratory, Oklahoma City, Oklahoma, was negative for drugs and alcohol for Troopers Mattaliano and Perry. TESTS AND RESEARCH Engine Examination On March 13 and 14, 1995, the engine was examined at the Turbomeca facility, Grand Prairie, Texas, under the supervision of a Safety Board Investigator. Parties to the investigation were also present during the examination. The examination revealed that the P2 air fitting, which supplied pressurization to the rear bearings, was not secured and was safety-wired backwards. The axial compressor would not rotate while attached to the gas generator. After Module Two and Three were separated, the axial compressor rotated freely. A rub mark was observed on the compressor cover, and on the turbine nozzle envelope, at the second stage turbine blade path. A build-up of a reddish-brown substance was observed on the fuel injection manifold, labyrinth ring and labyrinth envelope assembly. It was determined that this reddish-brown substance was preventing the axial compressor from rotating. Samples of the substance were removed for further examination. The fuel control unit (FCU) was placed on a test stand. The FCU filter was replaced, due to the visible debris on the original filter. The FCU was run through all parameters with no discrepancies. The fuel injection manifold (wheel) was placed on a test bench and flow checked. Five of the six manifold ports were clogged, and produced a zero fuel flow. The 6th port delivered 16 liters per hour (LPH) of fuel. Specifications required the 6 ports to deliver 230 to 260 LPH. During the disassembly, fuel samples were obtained from the engine inlet hose and the fuel control unit. These samples were sent to the Atomus Laboratory, Arlington, Texas, for analysis. Fuel and Filter Testing The fuel control unit and several filters were removed from the helicopter for testing. This included the Michigan Filter, which was designed to capture ice particles, and eliminate the requirement for anti-ice additives in the fuel system. Also, fuel samples were taken from the MSP Framingham fuel tank and the Wiggins fuel truck for laboratory analysis. Samples from the helicopter fuel system were analyzed by the Atomus Laboratory. This analysis revealed that the Michigan Filter contained a two phase fuel sample. The upper portion of the sample was a clear, light colored fuel. The lower sample was a dark heavy substance. The lighter sample contained 90 parts per million of water, and the dark brown sample contained 84 percent water. The laboratory report stated: ...when placed on a microscope slide, it [the dark brown heavy sample] dries to a white/gray solid, with red to red brown inclusions. The deposit contains an iron compound, most probably iron oxide from corrosion of iron in the fuel or the handling system. The Michigan Filter element also contained white/gray deposits. Additionally, the report stated: ...Water is present, but evaporates into a heavy brown, brittle, but transparent film. The physical appearance of this film is identical, even to the inclusions of the red to red brown material recovered from the lower phase of the sample..." The report also stated that an infrared analysis of the fuel deposit film indicated that the material had properties consistent with polyamide polymers. The red to red brown inclusions were also observed in the airframe fuel filter, the fuel control unit (FCU), FCU filter, and FCU inlet hose. The analysis of the fuel samples for water revealed the following: SOURCE WATER IN FUEL PARTS PER MILLION (PPM) Michigan Fuel Filter..................90.0 FCU Filter............................30.5 Airframe Filter-Fuel Control..........25.4 FCU Inlet Hose #1.....................55.7 FCU Inlet #2................less than 35.0 FCU B040B...................less than 35.0 MSP Framingham Fuel Tank Testing Fuel samples from the MSP Framingham fuel tank were analyzed by the Atomus Laboratory, and Saybolt Inc., Boston, Massachusetts. Atomus Laboratory testing reveled that fuel samples from the bottom of the tank contained water and a collection of hydrous iron oxide and rust. No polymer particles were observed in the samples from the tank or the tank pump. The report stated, "The heavy phase, containing the iron oxide is water, 100%." The analysis of the fuel samples for water revealed the following: TEST FACILITY SOURCE WATER IN FUEL PPM Atomus Laboratory.....Tank bottom................... 510.0 Atomus Laboratory.....Tank Pump.......................57.0 Saybolt Inc...........Tank Pump....................7,800.0 According to the Eurocopter Standard Practices Manual, Chapter 20.07.03, page 2, the maximum allowable concentration of water in fuel was 10 ppm. The United States Army Field Manual 10-68, also stated that 10 ppm of water in jet fuel was the maximum acceptable. Jet Fuel Thermal Oxydation Tests (JFTOT) were conducted by Saybolt Inc., of fuel samples from the MSP Framingham tank, and the Wiggins Airways Jet Fuel truck, that refueled N20SP. The maximum fuel pressure drop allowed for the test was 25 mm/Hg, for a test duration of 150 minutes, at 260 degrees Celsius. The fuel sample from the Wiggins Airways truck tested with a zero pressure drop. After 30 minutes of testing, the MSP tank sample experienced a pressure drop greater than 25.0 mm. The JFTOT machine shut down at 62.8 minutes into the test of the MSP fuel. Two samples from the Michigan Filter were sent to the NTSB Materials Laboratory for examination. The Metallurgist's Factual Report stated that both samples were submitted to ARTECH Corporation for analysis. The ARTECH Corporation report stated: ...The spectrum from the acetone dry film lacks the absorption at 3200 cm which is characteristic of oxygen-hydrogen bonds, indicating that this part of the sample may be due to waters of hydration rather than a bound part of the compound. The remainder of the spectra are characteristic of the cellulose derivative, cellulose acetate. Cellulose acetate is used as a blending compound in thermoplastics. Cellulose pentaacetate is soluble in alcohol. It is thus possible that a thermoplastic was in contact with the fuel in this incident and dissolved due to an alcohol additive in the fuel... ADDITIONAL INFORMATION Air Wing Organization * NOTE: In order to protect the anonymity of the law enforcement officers still performing police functions, names will be substituted with capitol letters. The Massachusetts State Police (MSP) Air Wing was a "Public Use" organization. The helicopters and airplane assigned to the Air Wing were of civil certification and registry. The MSP Air Wing had existed for over 20 years. The investigation revealed that the only written document relating to the operation of the Air Wing, was MSP General Order TOP-06. The purpose of the three page General Order (GO) was to establish guidelines for the utilization of MSP Aviation. The GO described the type of missions the Air Wing would support, and how flights were requested. The only specific direction provided to the Air Wing personnel was paragraph 4.1.3, that stated, "There will be a pilot and co-pilot for all night and instrument rated flights." The last section of the GO referred to Unit Qualification and Training. This section dealt with the selection process for assignment to the Air Wing, and listed the types of associated training that could be involved. Paragraph 4.3.6 stated, "Air Wing officers are required to periodically demonstrate acquired abilities and continued proficiency to the Air Wing Leader and/or Special Operations Commander." The last paragraph of the GO stated that at least one officer within the Air Wing would be an FAA certificated flight instructor. The Air Wing aviation personnel consisted of a Lieutenant (Lt.) Air Wing commander, a Sergeant (Sgt) chief pilot, a Sgt designated as the operations officer, another Sgt designated as the maintenance officer, and four line trooper (TRP) pilots. A MSP Major, in charge of the Special Operation/Tactical Division, was the immediate supervisor over the Air Wing. Procedures The MSP Air Wing did not possess standard operating procedures (SOP), or operation specifications. The wing did not have a documented description of the Wing structure, or a statement of it's mission. During interviews with wing pilots, specific missions such as high intensity spotlight, search and rescue, and surveillance were identified; however, there were no documents that identified the aircraft equipment requirements, the conditions in which the missions could be performed, the standard expected during the missions, and a description of how to perform the missions. Additionally, pilot prerequisites, qualifications, and training requirements to perform the missions, were not identified. The wing personnel had different opinions about who was a senior pilot, or pilot-in-command (PIC), in the Air Wing. The wing did not publish a roster of designated PICs. There was no formal program to identify PIC selection, training, evaluation, or their duties and responsibilities. The Eurocopter Flight Manual stated that the minimum crew for the AS-350 was one pilot in the right, "starboard," seat. The Air Wing PICs occupied either pilot station at random. The PIC of the accident helicopter was occupying the left seat. The Air Wing Operations did not record nor track pilot flight hours flown, duty hours worked, or bi-annual flight reviews completed. The chief pilot stated that these items were monitored, "through personal knowledge." The Air Wing had no minimum weather requirements published for the conduct of missions. During interviews, the chief pilot stated that he "thought" there was a hand written, weather minimum policy. The other pilots interviewed stated that they were not aware of such a policy, and each had developed their own minimums. The wing did not possess a formal or documented training program. There was no training program published for new personnel, and no guidelines for the conduct of night, instrument, refresher, or annual training for Air Wing pilots. Although missions were flown both day and night over water, the helicopters were not equipped with floats, personal floatation devices, or rafts. The wing personnel had not received water survival training. The wing lacked a formal or informal safety program. A safety officer was not designated, and safety meetings and surveys were not conducted. The wing also did not participate in a crew resource management (CRM) program. Air Wing Training During the period, 1985 to 1988, several MSP troopers were assigned to the Air Wing. The newly assigned pilots possessed FAA Private Pilot Certificates, with ratings in single engine airplanes. None of the pilots were instrument rated. Pilot training was conducted locally by the Air Wing Commander, Lt A, who was also an FAA Helicopter Certificated Flight Instructor (CFI). During interviews with Air Wing personnel, they stated that the training was conducted in a Robinson R-22 and a Bell 206, and included touch down autorotations. Through the MSP training program, the trooper pilots obtained a helicopter rating on their Private Pilot Certificates. After additional experience and flight training within the wing, the troopers obtained their helicopter Commercial Pilot Certificates. The training conducted for these ratings was not formally documented, and followed no specific training program or syllabus. Interviews with wing personnel revealed that during Lt A's tenure as commander, separate flights were not scheduled to conduct training or evaluations. Although the commander did not conduct formal annual evaluations, training was conducted regularly during scheduled missions. Lt A conducted no-notice emergency procedure training, which included forced landing practice, and touch down autorotations, which were performed in the wing's Bell 206. The wing's chief pilot stated that touch down autorotations were not performed in the AS-350 with Lt A, only power recoveries. Lt A was transferred from the Air Wing, in 1990. His departure left the wing absent an FAA Certificated Flight Instructor, until the assignment of the current commander, Lt C. At the time of Lt C's assignment, in 1993, he had less than 10 hours of turbine engine helicopter experience, and had only instructed in the Robinson R-22. At the time of the accident, Lt C had not instructed in any of the wing's helicopters, and was not considered a PIC. In August, 1991, Sgt C was transferred out of the Air Wing back to road patrol. In October, 1992, after a union grievance was settled, Sgt C was reassigned back into the Air Wing. The trooper had not flown for 14 months, and was assigned to fly co-pilot duties by Lt B, the wing commander. After a month of co-pilot flying, Sgt C was given an evaluation flight by Lt B, and released to fly as a PIC. Lt B was not a CFI, and no touch down autorotations were performed during this evaluation. In March, 1994, a new trooper pilot, Trp A, was assigned to the Air Wing. Trp A possessed a helicopter Commercial Pilot Certificate and was helicopter instrument rated. At the time of his assignment, he also possessed a current helicopter CFI, which was due to expire at the end of April, 1994. Trp A had accumulated over 2,000 hours of helicopter flight experience prior to his assignment to the wing, and was a current turbine helicopter instructor pilot in the Massachusetts Army National Guard. The MSP Air Wing allowed Trp A's CFI to expire, and continued to operate without a turbine qualified helicopter CFI. In May, 1994, the MSP Air Wing hired American Eurocopter to conduct AS-350 training, at the wing facility in Norwood, Massachusetts. A ground school was conducted for all of the Air Wing pilots on May 16 and 17, 1994. The Eurocopter outline stated that the ground school consisted of 14.7 hours of instruction. On May 18-20, 1994, an American Eurocopter CFI conducted flight training with eight Air Wing pilots. The individual sorties and hours flown were as follows: PILOT SORTIES TOTAL FLOWN HOURS Lt. C............ 2 ........ 3.0 Sgt A............ 1 ........ 1.1 (Chief Pilot) Sgt B............ 1 ....... 1.0 Sgt C............ 1 ........ 0.9 Trp A............ 2 ........ 3.0 Trp B............ 1 ........ 1.0 Trp Mattaliano... 1 ........ 0.9 Trp Perry........ 3 ........ 4.0 An American Eurocopter flight training sheet was completed for each of the eight pilots. All areas were initialed as completed by the pilot and the CFI, except for autopilot operations. A review of the training sheet, and the Eurocopter AS-350 Flight Training Syllabus, revealed that the following items were completed for each of the pilots: * Preflight - A minimum of two starts and two shutdowns. * Cruise - During cruise flight the student pilot was to perform a best rate of climb, fast cruise, economic cruise and VNE maneuvers. Also required was an engine condition check and simulated engine failure. * Other Maneuvers - Hovering turns and taxi, hovering autorotation, confined area landing and takeoff, slope operation, quick stop, normal takeoff and landing. Also required were a maximum performance takeoff and a steep approach, running landing, simulated hydraulic servo-control system failure in flight and at a hover, simulated governor malfunction, and simulated tail rotor malfunctions to a landing and a go-around. * Autorotations - As a part of the training, straight-in autorotations and autorotations with turns were required. Note number four in the AS-350 syllabus stated, "A minimum of 10 autorotations shall be performed by each student pilot, which includes two 180 degree autorotations." To complete the listed maneuvers, a minimum of 18 takeoffs and landings were required, in addition to the cruise flight maneuvers. Five of the pilots accomplished the listed training events in .9 to 1.1 hours of flight time. After Lt A's departure from the Air Wing, in 1990, through the date of the accident, in 1995, the Air Wing did not conduct any formal or informal helicopter training, except the May, 1994, American Eurocopter training. During that 5 year period, no touch down autorotation practice or training was accomplished, and there was no flight training or evaluations conducted by a CFI. Except for the May, 1994 training, none of the pilots attended any organized pilot standardization or training program. AS-350 Training During an interview with the chief pilot, he stated that the Air Wing received the first AS-350 in March, 1987. The purchase of the AS-350 entitled the Air Wing to two pilot transitions at the Eurocopter facility in Grand Prairie, Texas. Lts A and B attended these transitions. Upon his return from Eurocopter, Lt A conducted transitions for three of the Air Wing pilots, Sgts A, B, and C. The initial ground and flight training for the AS-350 was conducted at the MSP facility. The flight training included hydraulic-off running landings, oral anti-torque procedures, hovering autorotations, and power recovery autorotations. According to Sgt A, no touch down autorotations were performed. At the completion of the training, the three pilots then flew the AS-350 as PIC. In November 1988, the Air Wing purchased another AS-350, and Sgts A, B, and C, attended the AS-350 pilot transition training at American Eurocopter. During this training, Sgt A performed his first touch down autorotations in the AS-350. Two of the three Sgts interviewed did not recall performing touch down autorotations in the AS-350 with Lt A. Sgt B recalled "doing some" touch down autorotations with Lt A. Three of the four pilots interviewed, stated that a CFI was a required crewmember to perform power recovery autorotations in the AS-350, due to the location of the throttle. The same Sgt who recalled "doing some" touch down autorotations with Lt A, stated that only another qualified pilot was required to perform power recovery autorotations in the AS-350. Trooper Mattaliano Trooper Mattaliano transferred into the MSP Air Wing, in 1988. At the time of the transfer, he possessed a Private Pilot Certificate with a rating for airplane single engine land. He received his initial helicopter flight training with the Wing Commander, Lt A. Trooper Mattaliano received his initial training in the Air Wing's Bell 206. He received his AS-350 training from Lt A, in 1988, and he obtained his helicopter Commercial Pilot Certificate, in 1990. Trooper Mattaliano was designated a PIC by Lt A. During his assignment in the Air Wing, the only formal flight training that Trooper Mattaliano received was during May, 1994, with the American Eurocopter CFI. During that training flight, all maneuvers were completed during a single flight period which consisted of 0.9 of an hour. This was the only documented flight in the AS-350, where Trooper Mattaliano performed touch down autorotations. Trooper Perry Trooper Perry transferred into the MSP Air Wing during March, 1994. Prior to his arrival, he obtained his initial helicopter Private Pilot Certificate, at a civilian flight school in Beverly, Massachusetts. His flight training had been predominately in the Robinson R-22. Trooper Perry flew as a co-pilot in the wing helicopters. Trooper Perry received his only formal training in the Air Wing during May, 1994, with the American Eurocopter CFI. During that training, all maneuvers were completed during three flight periods totaling 4.0 hours. Helicopter Refueling During the 10 days preceding the accident, N20SP was refueled on five separate occasions with a total of 180 gallons of Jet A fuel. During that time frame, N20SP refueled once from the MSP fuel tank in Framingham, Massachusetts. On February 17, 1995, N20SP was refueled with 45 gallons of Jet A from the Framingham tank. The next refueling occurred on February 18, 1995, with 35 gallons of Jet A from Wiggins Airways, in Norwood, Massachusetts. The last refueling was also at Wiggins on February 21, and consisted of 30 gallons of Jet A. At the time of the accident, it was estimated that N20SP had approximately 100 gallons of fuel on board. During an interview with the Wiggins Air Service line person who refueled N20SP on February 21, 1995, he stated he had been assigned to refuel an airplane and had selected the fuel truck's Prist valve to the [on] position. Prior to reaching the airplane, he was rerouted to fuel the State Police helicopter. He proceeded to fuel N20SP without turning off the Prist valve, and the helicopter was refueled with 30 gallons of Jet A containing Prist. The additives section of the AS-350 Flight Manual stated: Anti-ice additives. If the fuel does not contain fuel system icing inhibitor, the use of such an additive is compulsory at O.A.T. below 0 degree C. The additive shall conform to French Specification Air 3652... MIL-I-27686...Maximum concentration: 0.15% by volume. Minimum concentration: 0.08% by volume... N20SP was equipped with the optional Michigan Dynamic Fuel Filter System, in accordance with STC Number SH6022SW-D. The Michigan filter was designed to capture ice particles and eliminate the requirement for anti-ice additives in the fuel system. The STC specifically stated fuel anti-ice additives were not required for use with the basic fuel system through out the certified temperature envelope. As described by the manufacturer, Prist is a microbiocidal and anti-icing aviation fuel additive, which inhibits bacterial and fungal growth in jet fuel and controls icing in aircraft fuel by depressing the freezing point of water. The primary ingredient of Prist is ethylene glycol monomethyl ether (2-methoxyethanol). Framingham Fuel The MSP operated an aviation jet fuel dispensing system at their headquarters in Framingham, Massachusetts. The system consisted of a 6,000 gallon in-ground tank, pump, and hose dispenser. The aviation tank was installed in conjunction with motor vehicle fuel tanks about 1979. A review of MSP construction data revealed that the helicopter pad and pump were installed in the Spring of 1981. The specifications for the installation of the equipment listed full flow filters for the vehicle fuel tanks; however, it did not list, or specify, any filter for the aviation tank, which was equipped with a single in-line filter. The last fuel delivery to the Framingham tank was made on September 9, 1992. At that time, 5,473 gallons of aviation jet fuel were delivered by Costal Oil New England, Inc. After the refueling of N20SP on February 17, 1995, the tank contained approximately 2,900 gallons of jet fuel. During an interview, the Framingham Supervisor of Building Maintenance stated that the Air Wing ordered their own fuel, and he had never observed an actual delivery. The main tank filler caps, which were located adjacent to the road, were never locked. The only aviation pump filter change that the supervisor was aware of, occurred about 7 years ago, by the ZECCO Company. The ZECCO serviceman who performed the work on the MSP aviation pump filter was interviewed. He stated that the filter change occurred between 1984, and 1986. He also stated that he would have replaced the filter with whatever was specified on the filter casting. Except for the one filter change, there was no record of any other maintenance performed on the Framingham aviation fuel system, during its 14 year history. Also, there were no written or verbal maintenance procedures established. The filter removed from the aviation pump filter casting was a FACET CC-21-C. The filter and the casting did not contain the date of the last filter change, or when the next change was due. According to Mr. Dennis Thompson, of FACET International, Tulsa, Oklahoma, the CC-21-C was a 25 Micron separator element that was normally used in diesel fuel applications. The filter recommended for jet fuel application was the CC-21-7, which was a 1/2 to 1 Micron element filter. The separator elements of both filters were constructed with a silicon treated cellulose paper. The primary difference between the two