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N45EL accident description

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Tail numberN45EL
Accident dateAugust 01, 2008
Aircraft typeLONG Lancair ES
LocationCliffdell, WA
Near 47.052222 N, -121.225556 W
Additional details: None

NTSB description

HISTORY OF FLIGHT

On August 1, 2008, about 1433 Pacific daylight time (PDT), an amateur built experimental category, Long Lancair ES, N45EL, disappeared from radar and radio contact was lost 40 miles northwest of Yakima, Washington. The airplane wreckage was located 9 miles northwest of Cliffdell, Washington. The private pilot operated the airplane under the provisions of Title 14 Code of Federal Regulations, Part 91. The pilot and single passenger were killed, and the airplane was destroyed. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. The flight originated at Ketchikan, Alaska, about 0957 Alaska daylight time (ADT).

The pilot and his passenger were traveling from Ketchikan to Mountain Home, Idaho. A review of the Federal Aviation Administration (FAA) air traffic control documents revealed that the pilot received a standard weather brief from the Juneau Automated Flight Service Station at 0608 ADT, and filed an IFR flight plan. At 0954 ADT, N45EL was released for departure. While en route the pilot received normal services from Anchorage Air Route Traffic Control Center (ARTCC) and Seattle Terminal Radar Approach Control Facility (TRACON). At 1422 PDT, the pilot checked in with Seattle ARTCC at 11,000 feet mean sea level (msl) with a clearance to proceed direct to Yakima. At 1432 PDT, the pilot confirmed his altimeter setting, 29.87, which was the pilot's last transmission. At 1433 PDT, an altitude deviation to 9,700 feet was noted by the controller and then radar and radio contact were lost. Repeated attempts to contact N45EL were unsuccessful.

Examination of the radar file depicted the airplane on a steady southeast course at 11,000 feet msl. At 1431:30, the track started a descending right-hand turn. The final radar return was at 1432:06, at 9,700 feet msl. The airplane wreckage was located about 1 mile west of the final radar return, at a terrain elevation of 3,830 feet. The debris field consisted of individual airplane parts, left wing, right wing, horizontal stabilizer, fuselage, and engine, distributed over a distance of 0.5 miles, in a densely wooded mountain slope. No initial point of impact was identified.

PERSONNEL INFORMATION

The pilot, age 68, held a private pilot certificate for airplane single-engine land with an instrument airplane rating, issued on December 9, 2001. He held a third-class medical certificate, issued in May 2008, with the limitation that he wear lenses for distant vision, and possess glasses for near vision. The pilot's logbook was examined. The most recent entry was dated July 16, 2008, with a recorded 592.7 hours total time, 176 hours simulated instrument time, and 4 hours of actual instrument time. In the last 30 days he had logged 10.8 hours, all in the accident airplane. He had logged a total of 266.2 hours in the accident airplane. The pilot's most recent flight review was on May 14, 2008, and his instrument proficiency check was dated July 9, 2008.

AIRCRAFT INFORMATION

The four seat, single engine, low wing, fixed gear, experimental category airplane was constructed by the pilot, and was issued an airworthiness certificate on September 12, 2004. The airplane was powered by a Teledyne Continental IO-550 motor. The propeller was an Aero Composites three bladed propeller. The maintenance logbook recorded the most recent annual inspection was completed on April 5, 2008. The most recent oil change was on July 14, 2008, at a total time of 267.2 hours.

METEROLOGICAL INFORMATION

The northwest portion of the National Weather Service (NWS) Surface Analysis Chart for 1400 PDT (2100Z) depicted a low pressure system with a central pressure of 1007 hectopascals (hPa) over southeastern British Columbia north of the Washington and Idaho boarders, and a high pressure system located off the Pacific northwest coast. A cold front extended from the low southwestward through Washington, Oregon, and into the Pacific Ocean. The accident site was located behind the cold front. Several station models over western Washington and Oregon, to the west and southwest of the accident site, indicated light to heavy rain showers, with overcast skies. The closest station model depicted was from Yakima (KYKM) located southeast of the accident site, which depicted winds from the west-southwest at approximately 10 knots, scattered clouds, temperature of 78 degrees Fahrenheit (F) and a dew point of 48 degrees F, with a sea level pressure of 1010.8 hPa. The station model northwest of the accident site from Stampede Pass (KSMP) indicated calm winds, overcast skies, temperature of 52 degrees F, dew point of 48 degrees F, and sea level pressure of 1015.4-hPa.

The northwest portion of the NWS Weather Depiction Charts for 1500 PDT (2200Z) depicts the coastal section of Washington near the Seattle area indicated IFR conditions due to low overcast ceilings near 600 feet above ground level (agl). Surrounding that area was an area of marginal visual flight rules (MVFR) conditions that extended over western Washington and a second area over Oregon and northern California. Visual flight rule (VFR) conditions were depicted over the accident site and all of central and eastern Washington and Oregon. The Yakima station mode indicated ceilings broken at 9,000 feet agl in the immediate vicinity of the accident site.

The NWS Radar Summary Chart for 1421 PDT (2121Z) depicted several areas of light to strong intensity echoes over central Washington associated with rain showers with tops to 29,000 feet. The regional radar mosaic chart from the National Center for Atmospheric Research (NCAR) for 1502 PDT indicated a band of echoes along the Cascade Mountain Range to the west of the accident site, with several areas of scattered echoes over central Washington and northern Oregon to the southwest of the accident site. A small area of echoes was identified in the immediate vicinity of the accident site.

The closest weather reporting facility was from the NWS remote automated surface observation system (ASOS) located at Stampede Pass, in Kittitas County, Washington, 13 miles northwest of the accident site at an elevation of 3,967 feet msl. The following conditions were reported surrounding the time of the accident; Stampede Pass weather at 1423 PDT (2123Z), automated, wind from 290 degrees at 9 knots; visibility 10 miles; scattered clouds at 800 feet, ceiling overcast at 1,500 feet; temperature 11 degrees C; dew point 8 degrees C; altimeter 30.01 inHg.

The next closest weather reporting facility was from Bowers Field (KELN), Ellensburg, located approximately 28 miles east of the accident at an elevation of 1,764 feet. The airport had an automated weather observation; Bowers Field weather observation at 1453 PDT (2153Z), automated, winds from 310 degrees at 9 knots; visibility 10 miles; few clouds at 7,500 feet, scattered at 9,000 feet; temperature 25 degrees C; dew point temperature 9 degrees C; altimeter setting 29.89 inHg. Remarks: automated observation system, rain began at 1432, ended at 1442 PDT; sea level pressure 1010.9 hPa; hourly precipitation total trace or less than 0.01 inches; temperature 25.0 degrees C; dew point 9.4 degrees C.

Upper wind data documented the wind profile over the region. The profile indicated surface winds from the southwest at 13 knots, with little directional variation with height and wind speeds increasing to 25 knots at 4,800 feet, then decreased and increased again, with wind speeds in excess of 50 knots above 18,000 feet. The mean 0-6 kilometer (18,000 feet) wind was from 236 degrees at 38 knots, with the maximum wind from 230 degrees at 98 knots identified at 41,000 feet. At the accident airplane's cruising level of 11,000 feet, the wind was from 245 degrees at 27 knots with a temperature of -1 degree C. The sounding indicated a chance of light to moderate turbulence at that level.

The sounding wind profile was also favorable for mountain wave development. The standard default values of the rawinsonde observation (RAOB) program identified the predominate wave at 42,650 feet or 175 hPa with a wavelength of 14.4 miles, an amplitude of 2,260 feet, and maximum vertical velocity of 1,246 feet per minute (fpm). Near the accident airplane's cruising level, a wave at 10,113 feet or 700 hPa was identified, which was 72 percent of the predominate wave strength with winds from 240 degrees at 32 knots, a wavelength of 10.4 miles, with vertical motions of 2,316 fpm, and potentially moderate-to-severe turbulence. Modifying the mountain wave program data for Mt. Rainier at an elevation of 14,411 feet, located 24 miles southwest of the accident site, increased the predominate waves strength at 42,000 feet to an amplitude of 8,255 feet, and a maximum vertical velocity of 4,551 fpm with severe turbulence likely. The height of Mt. Rainier is higher than the default values of the RAOB program, which had the effect of raising the lowest wave height to 16,388 feet. That wave had a wavelength of 4.46 miles, an amplitude of 446 feet, maximum vertical velocity of 523 fpm, with light turbulence likely.

Reflectivity is the measure of the efficiency of a target in intercepting and returning radio energy. With hydrometeors it is a function of the drop size distribution, number of particles per unit volume, physical state (ice or water), shape, and aspect. Reflectivity is normally displayed in decibels (dBZ), and is a general measure of echo intensity. The chart in the Meteorologists Factual Report relates the NWS video integrator and processor (VIP) intensity levels versus the WSR-88D's display levels, precipitation mode reflectivity in decibels, and rainfall rates.

The KATX WSR-88D base reflectivity image for the 0.5-degree elevation scan completed at 1431 PDT, and with a resolution of 1° X 1 kilometers was examined. The flight track from 2129 to 2132 PDT was overlaid with the airplane heading on a southeasterly direction. The image depicted an area of echoes with reflectivities from 5 to 35 dBZ or very light to light intensity echoes extending from Mt. Rainier east-northeastward through the accident site. The accident airplane was then observed encountering the band of echoes and making a right turn towards the west when the upset occurs.

Numerous photos of Mt Rainer were taken by the occupants minutes before the accident sequence. These photos were recovered from a personal camera that survived the accident. The accident airplane recorded altitude at this time was approximately 11,000 feet and operating immediately above a broken to overcast cloud layer. A band of higher clouds extended immediately downwind from Mt. Rainier with tops as high as the mountain, which was also confirmed by satellite radiative cloud top temperatures. The last known picture taken shows similar features with the band of higher clouds with some signs of undulation motions or wave action at the cloud top, with a higher band of cirriform cloud layer further south along the track.

The FAA Airman's Information Manual (AIM), Chapter 4 - Air Traffic Control, Section 6 - Operational Policy/Procedures for Reduced Vertical Separation Minimum (RVSM) in the Domestic Airspace, provides the following information on encountering turbulence and mountain wave activity (MWA) under section 4-6-6. That section is as follows:

(c) Inflight MWA Indicators (Including Turbulence). Indicators that the aircraft is being subjected to MWA are: (1) Altitude excursions and/or airspeed fluctuations with or without associated turbulence. (2) Pitch and trim changes required to maintain altitude with accompanying airspeed fluctuations. (3) Light to severe turbulence depending on the magnitude of the MWA.

FAA Advisory Circular AC 00-57 "Hazardous Mountain Winds And Their Visual Indicators", identified several turbulence generation methods in mountain wave activity. "Laboratory studies suggest that a surge of wind across a ridge can initiate a vortex downwind of the ridge. The vortex rolls up to maximum strength of rotation as it continues to move downwind away from the ridge and slowly dissipates. In its wake, with a return to steady flow, Kelvin-Helmholtz (K-H) waves develop at the top of the shear layer."

The entire Meteorological Factual Report is contained in the public docket of this accident investigation.

MEDICAL & PATHOLOGICAL INFORMATION

Kittitas County Coroner could not locate a pathologist to perform an autopsy or collect tissue samples for toxicology analysis. Other than the Coroner's on-scene observation of the victims, no other medical examination was performed. The victims' remains were released to the funeral home for cremation on August 7, 2008.

TESTS & RESEARCH

The primary flight display (PFD) and the multifunction flight display (MFD) were recovered and sent to the Safety Board's Vehicle Recorders Laboratory. The non-volatile memory containing flight data was recovered. The following parameters had been recorded at 1-second intervals during the accident flight; date, time, latitude, longitude altitude, pitch, bank, heading, course, indicated air speed, true air speed, ground speed, rate of climb, glide path angle, g-loading, corrected wind speed, corrected wind direction, outside air temperature, density altitude, fuel total quantity, engine rpm, fuel flow, center fuel tank level, left fuel tank level, right fuel tank level, fuel pressure, oil temperature, oil pressure, volts, cylinder head temperature, cylinder exhaust temperature, and torque. The time, altitude, latitude, longitude, pitch, roll, and heading parameters were written into a file that could be read by the X-Plane program. X-Plane has a built-in capability to "replay" a flight utilizing specified parameters. Utilizing the compiled PFD data and X-Plane animation, a timeline of events was created.

Approximately 5 minutes 36 seconds before the end of the flight data, at 11,000 feet msl, the airplane experienced continuous turbulence, ranging from 0.77 to 1.5 vertical g's. Approximately 1 minute prior to the end of the flight data, at 11,000 feet msl, the airplane entered a right-hand turn using approximately 30 degrees angle of bank, and enters in a 600- to 900-feet-per-minute (fpm) rate of descent. Approximately 25 seconds before the end of the flight data, at 10,500 feet msl, the angle of bank increases past 30 degrees towards 100 degrees, the rate of descent increases from 1,000 to 11,500 feet per minute, and the airspeed increases from 150 to 280 knots; however, the average g-load remained about 1.1-g's. The last 6 seconds of data depict a rapid increase of g's from 1 to 4.8. The last data point depicts the airplane at 6,135 feet msl, 88.6 degrees nose down, 113 degrees angle of bank, 290 knots, and 4.8 g's. Throughout the entire event the engine rpm stayed approximately 2,400 rpm, fuel flow was a steady 11.8-12.0 gallons per hour.

ADDITIONAL INFORMATION

Elevator Push Rod

While moving the airplane wreckage for final disposition the recovery contractor identified what he thought was an unusual finding regarding the elevator control rod. He notified the Safety Board investigator-in-charge (IIC), and preserved that portion of the wreckage. FAA inspectors examined the elevator control rod (torque tube/idler arm push rod) and the remaining portions of the wreckage on March 16, 2009. The inspectors identified the 'elevator torque tube/idler arm push rod' end that connected to the 'elevator torque tube' behind the cockpit seats, had the lock nut on the rod end bearing positioned such that only 2-3 threads were exposed from the end. The push rod end, at that location, consists of a fixture manufactured out of anodized aluminum. The threads in the anodized aluminum showed wear on the first 2-3 threads. All thread grooves after the first 2-3 threads remained unworn, with the anodized surface undamaged. At the opposite end of the push rod, the rod end bearing was screwed all the way in to the rod end fixture with the lock nut up against the shoulder of the rod end bearing (minimum extension length). The Lancair ES builders guide states that the builder should, "Thread the rod end bearings into the rod ends until the bearing hole is 2 7/16" (62mm) f

(c) 2009-2011 Lee C. Baker. For informational purposes only.