CONE JAMES A RV-6A

Full Narrative

HISTORY OF FLIGHT

On September 15, 2011, at 1223 mountain daylight time, an experimental amateur-built Cone (Vans Aircraft) RV-6A, N641JC, collided with terrain on the property of an elementary school in West Jordan, Utah. The pilot was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The private pilot sustained fatal injuries. The airplane sustained substantial damage during the accident sequence. The cross-country personal flight departed Sierra Vista Municipal Airport-Libby Army Airfield, Fort Huachuca/Sierra Vista, Arizona, at 0822 mountain standard time, with a planned destination of South Valley Regional Airport, Salt Lake City, Utah. Visual instrument meteorological conditions prevailed, and no flight plan had been filed.

The airplane was equipped with a Garmin GPSMap 496 global positioning system (GPS) receiver. The unit sustained impact damage, and was sent to the National Transportation Safety Board Office of Research and Engineering for data extraction. The data revealed the entire flight and accident sequence. The airplane departed from runway 26 at Sierra Vista, and initiated a climbing right turn to the north-northwest, to a GPS altitude of 8,700 feet. The airplane continued for the next 45 minutes, cruising at a groundspeed of about 158 knots. For the next 75 minutes, the airplane followed a northerly track through the Grand Canyon region at altitudes varying between 10,800 and 12,750 feet. After crossing the Utah border, the airplane leveled off at 12,750 feet on a north-northeast heading, where it continued for the next 75 minutes, traveling at a groundspeed of about 145 knots. At 1206, having reached the southern shores of Utah Lake, 45 miles southwest of South Valley Airport, the airplane initiated a descent. The airplane maintained an airspeed of about 160 knots throughout the descent, until it reached an altitude of 5,890 feet (1,240 feet above ground level), 3.5 miles south of the departure end of runway 34.

The airplane was receiving visual flight rules (VFR) flight following throughout the entire flight, and the pilot had been given a clearance to descend through class B airspace as he approached the Salt Lake City area. At 1820, air traffic control personnel reported that he had left class B airspace, clearing him to change to the South Valley Airport common traffic advisory frequency (CTAF), and squawk VFR.

An audio recording of the South Valley Airport CTAF revealed a radio transmission made by the pilot reporting that he was, “on the downwind entry for runway 16”. Twenty-six seconds later, an indiscernible distress transmission was made over the frequency.

Witnesses positioned at vantage points about 1 mile southeast of the departure end of runway 34, observed an airplane performing a spiral, nose-down dive, at altitudes ranging from between 300 and 500 feet agl. Some witnesses reported observing the airplane transition from a spiraling descent, to a spin, as it fell beyond their view.

GPS data revealed that about that location, the airplane was traveling northbound at a groundspeed of 106 knots, and an elevation of 1,000 feet agl. Three seconds later, the airplane had begun a 15-degree turn to the left, remaining at the same altitude, at a groundspeed of 95 knots. Over the next 9 seconds, the airplane had completed a 360-degree left turn, with the last recorded position at 180 feet agl, and a groundspeed of 52 knots. The wreckage was located about 150 feet to the west of the last GPS location.

PERSONNEL INFORMATION

A review of FAA airman records revealed that the 60-year-old pilot held a private pilot certificate with ratings for airplane single-engine land issued on August 27, 2004. He held a third-class medical certificate issued in November 2009, with the limitation that he must wear corrective lenses for near and distant vision.

An examination of the pilot's logbook revealed a total flight experience of 978.6 hours since his first training flight in September 2003, through to his last logbook entry dated September 9, 2010. He had amassed a total of about 810 flight hours in the accident airplane since April 2005. The pilot completed a flight review in accordance with FAR 61.56 on September 25, 2010. No logbook entries were located indicating the pilot had prior experience flying into South Valley Airport.

AIRCRAFT INFORMATION

The low-wing, two-seat airplane was equipped with a four-cylinder Lycoming engine, serial number L-45210-27A. No data plate was located on the engine, and this information was garnered from the serial number stamped into the upper tab of the crankcase. Lycoming records indicated that the engine was originally manufactured in 1976, and was of the O-320-E2D series.

The engine was equipped with an Ellison Fluid Systems EFS-4 throttle body injector, in lieu of a carburetor. Ignition was provided by a single Slick 4371 series magneto, and a Lightspeed Engineering, Plasma I Ignition system. The fixed-pitch propeller was a 70CM6 series, manufactured by Sensenich.

FAA records indicated that the airplane was issued its special airworthiness certificate, in June 2000. The pilot purchased the airplane in April 2005.

Maintenance records revealed that the airplane had undergone a conditional inspection on April 14, 2011, at a total time of 1,052.5 flight hours. The total flight time of the engine, which had been installed at the time of the original airworthiness certificate issuance, could not be determined. Damage to the instrument panel precluded a determination of the total airframe flight hours at the time of the accident.

The airplane was not equipped with a supplemental oxygen system.

METEOROLOGICAL INFORMATION

The closest aviation weather observation station was located at Salt Lake City International Airport (SLC), 10 miles north of the accident site. The elevation of the weather observation station was 4,227 feet mean sea level (msl). An aviation routine weather report (METAR) was recorded at 1153. It reported: winds from 180 degrees at 9 knots; visibility 10 miles; few clouds 7,500 feet; temperature 22 degrees C; dew point 08 degrees C; altimeter 30.01 inches of mercury. Towering cumulus clouds observed distant northeast, southeast, and southwest.

AIRPORT INFORMATION

South Valley Regional Airport is at an elevation of 4,606 feet. The airport is positioned below Salt Lake City class B airspace, within a notched lower shelf, the ceiling of which is 6,000 feet msl. The airport is centered about 1-mile west of the central core of the class B airspace, which extends from the surface to 10,000 feet msl.

The airport is not equipped with a control tower, and has one active runway (16/34), which is 5,862-foot-long, and 100-foot-wide. An abandoned 3,500-foot-long, 15-foot-wide runway, oriented on a heading of about 305 degrees magnetic is positioned on the east side of the airport, and intersects the approach end of runway 16.

Runway 16 utilizes a right-hand traffic pattern flow, and a traffic pattern altitude of 800 feet.

WRECKAGE AND IMPACT INFORMATION

The airplane wreckage was located 4,800 feet east of the approach end of runway 34. The entire aircraft structure was located on the concrete surface of a sidewalk, at the entrance to a school, 5 feet from the main building structure. No witness marks or damage was noted to any of the school structure, or surrounding trees and lampposts. The airplane remained upright and intact on a heading of about 110 degrees magnetic. Extensive fragmentation and crush damage was observed from the firewall through to the aft cabin. Both wings remained attached to the center cabin through the main spar. The wings exhibited similar leading edge crush damage along their entire length, with a crush angle of about 30 degrees relative to the chord. The empennage section remained intact, and sustained minimal damage. All control surfaces were accounted for at the accident site.

MEDICAL AND PATHOLOGICAL INFORMATION

A postmortem examination was conducted by the Utah Department of Health, Office of the Medical Examiner. The cause of death was reported as the effect of blunt force injuries to the head, torso, and extremities.

Toxicological tests on specimens recovered from the pilot by the Medical Examiner, were performed by the FAA Civil Aerospace Medical Institute (CAMI). Analysis revealed no findings for carbon monoxide, or cyanide. The results were negative for ingested alcohol, with a result of Montelukast detected in blood. Refer to the toxicology report included in the public docket for specific test parameters and results.

According to CAMI, Montelukast (brand name Singulair) is used to prevent difficulty breathing, chest tightness, and wheezing and coughing caused by asthma. It is also used to prevent bronchospasm (breathing difficulties) during exercise, as well the symptoms of seasonal and perennial allergic rhinitis.

The pilot reported the use of Montelukast on his most recent application for an FAA medical certificate, stating a history of milk, dust, and pollen allergies, as well as asthma due to dust. The Aviation Medical Examiner who performed the examination noted, “Asthma well controlled on listed meds no side effects, no wheezing at this exam.”

The Medical Examiners report documented a microscopic analysis of heart and lung tissue with the following results,

“HEART: A few hypertrophic nuclei are noted but this is not a diffuse change. Fibrosis is minimal. There is no inflammatory process.

LUNG: No significant natural disease process identified. There are no histologic changes consistent with asthma identified.”

TESTS AND RESEARCH

Engine and Airframe Examination

The airplane was recovered from the accident site and examined by the NTSB investigator-in-charge (IIC), and an inspector from the Federal Aviation Administration. A subsequent examination was performed by the IIC and a representative from Vans Aircraft, Inc.

The right aileron remained attached to the wing at its respective hinge points, with its push-pull tube and bellcranks continuous through to the control stick. Similar continuity was noted to the left aileron, with the exception of the outboard eyebolt of the push-pull tube, which had separated, sustaining bending damage at its threaded portion.

The tail section sustained minimal damage. Both the horizontal and vertical stabilizers were intact and attached to the tailcone. The rudder and elevators remained attached at their respective hinge points and moved freely by hand. The rudder control cables were continuous from the rudder horns through to the foot pedal. The elevator push pull tube remained attached to the elevator interconnect tube and was continuous to the aft tailcone. The remaining section of the tube had fractured into two sections, with bending damage noted at the fracture surfaces. The remaining elevator control tubes had sustained similar bending damage separation and impingement through to the control stick. The elevator trim tab push-pull tube sustained bending damage, and as such, the tab position could not be accurately determined.

The left-side pilot’s control stick remained in place in its weldment. The right-side stick was not located, and a spring-clip was present in its securing hole at the weldment. As such, it was determined that the stick had been removed prior to flight.

The flaps remained attached at their respective hinges. The flap actuator was in the fully extended position, corresponding to the flaps raised position.

No evidence of feathers or bird matter was noted to any of the airplane skin surfaces, or the canopy roll bar.

Engine and Propeller

The engine remained attached to its mounts at the firewall, and had sustained crush damage and fragmentation in the area of the oil sump. All ancillary components had sustained varying degrees of crush damage. The alternator, starter, and starter ring gear had become fragmented and were separate from the engine. The propeller had become separated from the crankshaft at the forward bearing. The forward engine case was bent to the left, impinging the crankshaft at the forward bearing.

The propeller remained attached to the crankshaft hub, which had separated from the crankshaft flange. One blade exhibited 15 degrees aft bending midspan, with inboard leading edge abrasions. The second blade sustained chordwise scratches and abrasions along its entire length, with trailing edge wrinkles, and about 180 degrees of twist from root to tip.

Examination of the engine and airframe did not reveal any anomalies which would have precluded normal operation. A complete examination report is contained within the public docket.

Canopy

The airplane was equipped with a steel-framed clear plastic sliding canopy. According to a representative from Vans Aircraft, the area of the canopy sliding portion was 15.25 square feet, with the area of the fixed forward windscreen portion 7.20 square feet. A friend of the pilot submitted a photograph of the canopy taken about 2 months prior to the accident. The photograph revealed a lateral crack about 30-inches-long to the sliding canopy, in an area directly over the pilot's head. The crack appeared to have been laced in place with wire, and sealed on the underside with duct tape. The maintenance logbooks did not contain any entries regarding the canopy repair; however, a receipt issued by the mechanic who performed the conditional inspection on May 17, 2007, contained a line item stating, “Laced canopy with safety wire.” The logbook associated with the invoice indicated that the airplane had amassed a total of 778 flight hours at that time. The mechanic who performed the repair stated that the owner bonded the crack with acrylic. He continued to monitor the crack over subsequent inspections, and did not observe any deterioration or increase in its length.

FAA Advisory Circular AC 43.13 (consolidated edition), Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair, defines specific procedures for repairing minor windshield cracks in non-pressurized airplanes. The AC allows for temporary repair of windshield cracks utilizing safety wire laced through equally spaced holes drilled along the crack edge.

All sections of the metal canopy frame were recovered from the accident site; subsequent examination of the frame revealed 30 to 45 degrees downward bending of both canopy latch pins. The right roller wheel remained partially attached to the canopy frame, with its associated cabin channel bent open at its forward limit. Additionally, the forward section of the center canopy sliding rail, located along the upper aft section of the cabin spine, had become bent downwards and towards the tailcone. These signatures were consistent with the canopy frame being in the closed position at the time of impact. The empennage was free of nicks, chips or any indication of contact with canopy debris. The retractable canopy shade, which was normally positioned directly below the crack, was located in the forward cabin area.

Airport Common Traffic Advisory Frequency Recording

The audio recording of the South Valley Airport common traffic advisory frequency was sent to the NTSB Office of Research and Engineering in an effort to determine the background sound energy levels for the two radio transmissions, and thus determine if the canopy was open during the last transmission. Analysis revealed that the background noise level of the radio transmission made by during the downwind leg was about 60 percent louder than the following open microphone “distress” transmission.

Fuselage Markings

Photographs of the airplane taken prior to the accident revealed a series of grey markings to the paint on the left side of the fuselage, about 5-foot aft of the wing trailing edge. Examination revealed a 1-foot-square patch of patina damage to the paint surface at that location, with no damage to the aluminum skin structure. The mechanic who performed the most recent conditional inspection stated the pilot would often tie his dogs leash to the wing step, and that these marks were a result of him flying the airplane with the leash inadvertently attached.

Fuel

A fuel receipt located in the pilot’s belongings indicated that the airplane’s 38-gallon fuel tanks had been serviced with the addition of 24.86 gallons of 100 low-lead aviation gasoline from Sierra Vista Airport at 0657 on the morning of the accident. Examination of damage sustained to the wing leading edges revealed evidence of hydraulic deformation to the lower section of their skins. The leading edges were also split laterally along their entire length. The fuel filter sustained crush damage exposing the paper element; the filter canister was about half full with blue-colored fuel, consistent in color and odor to 100 low-lead aviation gasoline. Fuel was present within all fuel lines from fuel selector valve through to the throttle body injector. Both fuel caps remained in place at their respective filler necks.

GPS Airspace Alerts

The Garmin GPSMap 496 is capable of producing altitude-sensitive airspace alerts. According to representatives from Garmin, the unit does not record the historical issuance of such alerts within its non-volatile memory. Garmin representatives declined to provide further support to the NTSB regarding such alerts.

Radar

Salt Lake City Airport was equipped with an Airport Surveillance Radar (SLC-ASR), located on the airfield. An Air Route Surveillance Radar (ZSLC-ASRS) was positioned at Francis Peak, 30 miles north-northeast of the accident site. Both sites provided radar coverage for the Salt Lake City area including South Valley Airport. Data from both sites for the time period 1201 to 1227 was archived by the FAA following the accident. Analysis of this data revealed the airplanes flight track leading up to the accident. The data indicated that no other aircraft were in the vicinity during the time of the accident.

Primary radar data (no altitude information) for the 26-minute period revealed two individual targets observed by SLC-ASR, and thirteen by ZSLC-ASRS, clustered both adjacent to the accident site, as well as overlapping the airplane's flight path. The majority of the targets were situated within a 2,500-foot-wide area, centered about 3,500 feet southeast of the approach end of Runway 34.

Bird Activity

The Airport remarks section of the FAA Airport/Facility Directory, dated 26 July through 20 Sep 2012, for South Valley Regional Airport cautions for flocks of birds on and in the vicinity of the airport. The airport manager stated that water fowl are attracted to the vicinity following a rain event strong enough to fill the airport detention pond. During such events, the birds are mitigated using “poppers.” He reported that no such rain event had occurred before the accident, with no bird activity noted.

The operations manager responsible for bird mitigation at Salt Lake City International Airport reviewed the primary radar data. He stated that turkey vultures and raptor-type birds are common for the region at that time of year, and that they are typically present during the noon period, where they can be observed circling in thermal air currents at traffic pattern altitudes. He further stated that flocks of American White Pelicans, and California Gulls, can often be seen flying in similar circular patterns.

Performance

GPS data indicated that the airplane's groundspeed as it began the final turn was 106 knots, with a turn radius of about 500 feet. Referencing Aerodynamics for Naval Aviators (NAVWEPS 00-80T-80), Figure 2.29, General Turning Performance (Constant Altitude, Steady Turn), the airplane's angle of bank would have been about 65 degrees. The calculated bank angle remained relatively constant as the turn progressed, and the groundspeed decreased to 75 knots, with a corresponding turn radius of 300 feet.

According to Vans Aircraft, Inc., the stall speed of the RV-6A at solo weight is typically about 45 knots.

According to the FAA Airplane Flying Handbook (FAA-H-8083-3A), under the Accelerated Stalls section,

“At the same gross weight, airplane configuration, and power setting, a given airplane will consistently stall at the same indicated airspeed if no acceleration is involved. The airplane will, however, stall at a higher indicated airspeed when excessive maneuvering loads are imposed by steep turns, pull-ups, or other abrupt changes in its flightpath. Stalls entered from such flight situations are called ‘accelerated maneuver stalls,’ a term, which has no reference to the airspeeds involved. Stalls which result from abrupt maneuvers tend to be more rapid, or severe, than the unaccelerated stalls, and because they occur at higher-than-normal airspeeds, and/or may occur at lower than anticipated pitch attitudes, they may be unexpected by an inexperienced pilot. Failure to take immediate steps toward recovery when an accelerated stall occurs may result in a complete loss of flight control, notably, power-on spins.”

The weight and balance documentation, located onboard the airplane, indicated a maximum gross weight of 1,825 pounds and a center of gravity limit between 68.7 and 76.8 inches.

The contents of the airplane were weighed following the accident. The aft cabin area contained about 93 pounds of baggage, and according to law enforcement personnel, a 5- to 10-pound dog was located on the passenger seat within a carrying cage. Utilizing the pilot's reported weight at his most recent medical examination of 191 pounds, 8 gallons of fuel, and a basic empty aircraft weight of 1,110 pounds, the center of gravity was calculated to be 75.75 inches.