NTSB Factual Report

HISTORY OF FLIGHT

On April 23, 1996, at 1600 hours Pacific daylight time, a Hughes 269C, N9579F, collided with a fence between two residences in San Diego, California, after an in-flight loss of control while orbiting out of ground effect. The helicopter was destroyed. The certificated commercial pilot was fatally injured and one passenger was seriously injured. The helicopter was rented from Civic Helicopters, Carlsbad, California, by the pilot for a personal flight. The flight originated from Montgomery Field in San Diego at 1540, and was destined for Carlsbad after completing an aerial video shoot at a local hospital. Visual meteorological conditions prevailed at the time.

The pilot departed Carlsbad about 1000. Review of data downloaded from the pilot's global positioning system (GPS) receiver revealed the pilot had flown north from Carlsbad along the Pacific coast to Los Angeles. The GPS data indicated the pilot landed at the Fullerton Municipal Airport and then headed south along the coast to San Diego. The data revealed the helicopter made eight clockwise orbits around the Kaiser Permanente Hospital located across the street from the accident site. The accident occurred in the beginning of the ninth orbit as the helicopter was traveling east over Zion Avenue.

A videotape was recovered from the helicopter. The tape illustrated portions of the helicopter's flight, but did not record the helicopter's descent before impact. The tape did show that the helicopter was orbiting the hospital at a low altitude. The altitude was constant in relation to the elevation of the hospital roof. The terrain in the area around the hospital was sloping and the helicopter's elevation above the ground varied. At one point in the orbit, the helicopter's shadow was cast on Zion Avenue. The length of the shadow was about the same as the length of parked cars.

According to ground witnesses, the helicopter was orbiting the local hospital at a low altitude and at a slow airspeed. The helicopter yawed left followed by a uncontrolled descent while spinning to the right. Several witnesses reported the engine sputtered before the loss of control.

The surviving passenger told inspectors from the Federal Aviation Administration that the pilot indicated it was time to leave moments before the loss of control. The surviving passenger did not indicate that there was a loss of engine power.

OTHER DAMAGE

The helicopter struck a boundary wall between two residential homes damaging the wall, both homes, two wooden fences, and two campers parked at the residences.

PILOT INFORMATION

The pilot held a commercial pilot certificate for single and multi-engine airplane and rotorcraft/helicopter. The certificate was issued on December 16, 1994, as the result of the pilot completing the commercial helicopter pilot practical exam. Prior to the most recent issue, the pilot held private pilot privileges for helicopters.

The most recent second-class medical certificate was issued to the pilot on May 19, 1995, and contained the limitation that correcting lenses be worn while exercising the privileges of his airman certificate. The pilot indicated on his application for medical certificate that there were no changes in his health since his last physical on May 2, 1994. He also indicated he was not taking medications at the time of his physical and had not visited a health professional in the past 3 years.

The pilot's total aeronautical experience consists of about 693 hours, of which 42 hours were accrued in the Hughes model 269 helicopter. In the preceding 90 days before the accident, the pilot's logbook listed a total of 16 hours flown in the Hughes 269C.

AIRCRAFT INFORMATION

The helicopter, a Hughes 269C, was manufactured on July 29, 1974, and had accumulated a total time of 6,000.9 hours. Examination of the maintenance records revealed that the most recent annual inspection was accomplished on November 11, 1995, 132.1 flight hours before the accident. In addition, a 100-hour inspection was completed on February 29, 1996, and a 50-hour inspection was completed on April 22, 1996, 6.7 flight hours before the accident.

A Lycoming HIO-360-D1A engine, serial number L14249-51A, was installed in the airframe on November 23, 1994, after a factory overhaul. The engine accrued a total time in service of 1,403 hours since new. The maintenance records note that a major overhaul was accomplished on May 27, 1994, about 428 operational hours before the accident. Annual and other hourly inspections were accomplished on the dates specified above for the airframe.

Fueling records at Aviation Facilities, Inc. Fullerton, California, established that the helicopter was last fueled on the day of the accident with the addition of 27.6 gallons of 100LL octane aviation fuel.

METEOROLOGICAL INFORMATION

The closest official weather observation station is at Montgomery Field which is located about 3 nautical miles from the accident site. The elevation of the weather observation station is 423 feet msl. At 1549, a record surface observation was reporting in part: sky condition clear; visibility 30 statute miles; temperature 81 degrees Fahrenheit; dew point 36 degrees Fahrenheit; winds 300 degrees at 9 knots; altimeter 30.02 inHg.

Review of the videotape recovered from the helicopter revealed an American Flag at the corner of Mission Gorge Road and Zion Avenue was being blown by a wind from the west at 8 to 12 miles per hour.

WRECKAGE AND IMPACT INFORMATION

The helicopter came to rest across the end of a block wall in the residential area. The block wall was found collapsed in the area under the helicopter's engine. The left side of the landing gear system was destroyed from contact with the wall. The right side of the landing gear system extended beyond the end of the wall and did not exhibit any damage from collision with the wall.

The cockpit came to rest in a nose down attitude. The area beneath the right and left seat structures was found displaced in a downward moment about 1.5 inches. The helicopter's windshield was shattered. The windshield and door jamb structure was broken. The left door was found open and was attached to the windshield frame at the hinges. The door frame was found broken along a vertical axis and was resting on the tongue of a trailer parked on the west side of the block wall.

The tail boom was displaced to the left of the helicopter's longitudinal axis. The tail boom struck a wooden fence that was perpendicular to the block wall. There was a black paint transfer that was found on the left side of tail boom at the vertical stabilizer. The color of the paint matched the color of the main rotor blades. The 90-degree gearbox remained attached to the tail boom. One of the tail rotor blades was broken off. The separated piece was found about 15 feet south of the gearbox under another trailer parked in a side yard. A small hole with a red paint transfer was found in the sheet metal siding of the trailer above the location of the separated piece. The color of the paint transfer and the shape of the hole conformed to a portion of the separated tail rotor blade.

Drive train continuity was traced from the engine to the transmission and to the tail rotor. The tail rotor drive shaft was found fractured at the forward end. The fracture area was near the bend in the tail boom which displaced it to the left. The fracture surfaces did not exhibit any rotational smearing. The forward end separated and was found about 5 feet south of the wreckage adjacent to the fuselage station where it is installed. All eight drive belts were found intact with no unusual wear patterns noted. There was no evidence of mechanical failure or malfunction found with the drive system that could have been attributed during the operation of the helicopter before impact with the ground.

Flight control system continuity was traced from the cockpit to the corresponding control surfaces on the rotor systems. A single cyclic and collective were installed on the left side of the helicopter. There was no evidence of mechanical failure or malfunction found with the helicopter's flight controls.

MEDICAL AND PATHOLOGICAL INFORMATION

A post mortem examination was conducted by San Diego County Medical Examiner's Office with specimens retained for toxicological examination. The specimens were sent to the Federal Aviation Administration Civil Aeromedical Institute for analysis. The results of the toxicological analysis revealed Desalkylflurazepam, Hydroxyethylflurazepam, Pseudoephedrine, Phenylpropanolamine, Ephedrine, and Salicylate were detected in the specimen samples.

According to the FAA, the Desalkylflurazepam, and Hydroxyethylflurazepam are metabolites of prescription medication used to induce sleep. The "Physicians' Desk Reference" states patients using such medications should be cautioned about engaging in hazardous occupations requiring complete medical alertness after ingesting the drug because of potential impairment of performance of such activities.

Also according to the FAA, Pseudoephedrine, Phenylpropanolamine, and Ephedrine are compounds commonly used in oral preparations for the relief of nasal and sinus congestion.

TESTS AND RESEARCH

Restraint Systems

The helicopter's occupant restraint system was examined on July 31, 1996, at Pacific Scientific facilities in Yorba Linda, California. There were three lap belts and two shoulder harnesses installed in the helicopter. The cloth data tags on the shoulder harnesses were missing. The origin or installation date of the shoulder harness was not determined. According to the FAA, the shoulder harness along with the seat belts are type certificated components and are required by federal regulations to be permanently and legibly marked (14 CFR Part 21.607(d).

The pilot's shoulder harness was found broken at a faded area in the webbing corresponding to a point where the harness bends over the pilot seat back. The original equipment manufacturer of the shoulder harness indicated that the webbing was 1/8 inch narrower than the webbing used, and the stitch pattern did not match the stitch pattern of their product. A pull test of the shoulder harness webbing was accomplished in a nondamaged area. The webbing withstood a 1,500 pound load for a 10 second duration.

Both shoulder harness inertial reels were examined and tested. There was damage to the inertial reel deforming webbing guides allowing the webbing to rub on the reel. There was no fraying or wear pattern noted that indicated the webbing was cycled after the webbing guides were deformed. Inertial reel extension/retraction and lock tests were performed at manufacturer facilities. There was no mechanical failure or malfunction found with the inertial reels.

Engine Examination

The engine was examined at the operator facilities on April 25, 1996. During the examination the No. 3 cylinder would not produce "thumb compression." The No. 3 cylinder exhaust valve was not seating properly, allowing air to escape when the engine was rotated. The valve was "staked" and carbon-like debris was noted dropping from the exhaust port. Thumb compression was then obtained in the No. 3 cylinder.

Overall examination of the engine revealed the engine capable of operation and the engine was subsequently shipped to manufacturer's facilities in Williamsport, Pennsylvania, for operation in an engine test cell.

On May 20, 1996, the engine was examined before placement in a test cell. The No. 3 cylinder was removed and the valves were examined for any evidence of malfunction that may be lost during operation in the test cell. It was noted that the No. 3 exhaust valve reciprocating movement felt to move across a gritty surface rather than glide. This observation was prevalent when the valve was moved beyond the reciprocating limits of operation for removal. Also, the valve seat was contaminated with oily carbon deposits.

The No. 3 cylinder valve guide was measured for clearance and found within service limits. The exhaust valve was examined and was found free of any damage, which according to the manufacturer, would be visible if the valve was sticking. The No. 3 cylinder was reinstalled on the engine and the engine was prepared for operation in a test cell.

On May 21, 1996, the engine was run in a test cell and met new engine specifications for set airflows. The engine was then disassembled and examined. An exhaust valve mark was found on top of the No. 4 piston. The No. 4 cylinder valves were sectioned out of the aluminum head and deposits in the valve guide were analyzed. According to the laboratory report, the primary element was lead with trace amounts of bromine, carbon, oxygen, phosphorus, calcium, and zinc. According the engine manufacturer, the deposits were consistent with products of combustion and engine operation at a high temperature.

The helicopter operator indicated to the Safety Board that the valve most likely stuck open during an engine start. The engine manufacturer publishes preventative maintenance procedures to prevent valve sticking. One procedure involves reaming to remove valve guide deposit buildup. The procedure is found in the Textron Lycoming Service Instruction 1425. The helicopter operator also indicated that he did not perform the recommended maintenance procedure because it was not mandatory.

Height Velocity Diagram

The pilot operating handbook publishes a height velocity diagram to warn pilots of operational areas to avoid. One of the areas to avoid was airspeeds below 60 miles per hour between 50 and 200 feet above the ground. According to the helicopter manufacturer, operations in this area may result in high rates of descent that are not controllable.

WRECKAGE RELEASE

The wreckage was released to the owner on April 25, 1996. The Safety Board retained custody of the helicopter's engine and occupant restraint system for further examination. The retained items were subsequently released to the owner on September 19, 1996.

NTSB Probable Cause

the decision of the pilot to fly at low altitude and low airspeed within a hazardous performance area published in the pilot operating handbook. Factors in the accident were tailwinds, lack of operator preventative maintenance impairing engine power, airworthiness of the restraint systems, and the pilot's use of prescription drugs that can impair human performance.