Shaver Lake, CA, USA
N700EM
CESSNA 421C
The private pilot departed about 90 minutes after sunset in the high-performance multiengine airplane on the cross-country flight. The climb and level off at cruise altitude were uneventful and, based on the radar data, appeared to have been accomplished with the use of the autopilot. The cruise altitude of 27,000 feet was the highest the airplane had been flown in recent history, and the highest altitude it had been operated at with the pilot flying. The pilot made a routine radio exchange with air traffic control personnel shortly after levelling for cruise. Five minutes later, the airplane, with no further radio transmissions, rolled to the right and rapidly descended 10,000 feet, where it subsequently broke apart. Both wings, along with the horizontal stabilizer and elevators, separated during the breakup sequence. Analysis of their fracture surfaces, along with the debris field distribution and radar data, revealed that the breakup sequence was most likely inadvertently induced by the pilot, as he attempted to recover control of the airplane during the dive. The airplane sustained extensive thermal damage after ground impact, and examination of the engine components, surviving primary airframe components, the cabin heater, and the autopilot system remnants did not reveal any mechanical malfunctions or failures that would have precluded normal operation. There was no evidence of bird strike, inflight fire, or that the engine fire extinguisher system had been activated. The airplane was flying toward an uninhabited mountain range and a largely unpopulated desert area at the time of the upset. The moon had set, and the pilot would have had limited reliable external visual cues should the airplane have experienced a failure of either the flight instruments or autopilot. The pilot was instrument rated, however the majority of his flight experience was garnered in aircraft equipped with modern "glass cockpit" avionics, as opposed to the traditional flight instruments installed in the accident airplane (which he had recently purchased). The airplane was equipped with a dual vacuum pump system, which drove the primary flight instruments and, in turn, the autopilot. One of the vacuum pumps had failed on the previous flight, and the pilot was unable to get it repaired in time for the accident flight. The dual nature of the vacuum system allowed for flight with a single failed pump, however failure of the remaining pump or associated vacuum system components would have left the pilot to hand fly the airplane, using backup flight instruments, at an altitude perilously close to the limit of the airplane's flight envelope (the maximum altitude was 30,200 feet). Examination revealed that the second pump was most likely operational; however, fire damage precluded an accurate assessment of the operability of the remaining vacuum system components. Although operation of the airplane did not require adherence to a minimum equipment list, the airplane's FAA Master Minimum Equipment List stated that one of the vacuum pumps can be inoperative, provided the airplane is operated under VFR and not operated at night. Given the pilot's overwhelming experience with "glass cockpit" instruments, as opposed to the traditional type in the accident airplane, along with the failure of one of the vacuum pumps, he should have reconsidered making the flight, particularly during night conditions. The airplane had experienced multiple anomalies with the autopilot and vacuum system prior to the accident flight. Maintenance records indicated that these discrepancies had been resolved; however, damage to the airplane precluded a substantive confirmation of their operation. Additionally, an oversight by an avionics repair facility 1 week before the accident resulted in the airplane's pitot/static system being inadvertently tested and certified to 20,000 feet, rather than the airplane's service ceiling of 30,200 feet. The relevance of this finding, if any, could not be determined. The airplane was equipped with a supplemental oxygen system; however, maintenance records indicated that the pilot's mask, while operational, had degraded. Additionally, the mask had been relocated to a position behind the pilot's seat, which would have been hard to reach in the event of a rapid decompression. Ultimately, the NTSB was unable to determine the cause of the rapid descent because of the postcrash damage to the airplane systems and components.
HISTORY OF FLIGHTOn November 10, 2012, about 1920 Pacific standard time, a Cessna 421C, N700EM, impacted terrain following an in-flight breakup near Shaver Lake, California. The private pilot/registered owner was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The pilot and passenger sustained fatal injuries. The airplane sustained substantial damage during the accident sequence, and was partially consumed by postimpact fire. The cross-country flight departed Salinas Municipal Airport, Salinas, California, at 1837, with a planned destination of Eppley Airfield, Omaha, Nebraska. Visual meteorological conditions prevailed, and an instrument flight rules (IFR) flight plan had been filed. The pilot was the son of the passenger. Both had spent the weekend attending a driving academy at the Laguna Seca Raceway, having arrived in the accident airplane earlier in the week. According to the pilot's wife, they had encountered strong headwinds during the outbound flight from Omaha, and had decided to take advantage of tailwinds for the return flight that night, rather than stay in a hotel. The pilot planned to return his father to Omaha, and then fly to his residence in Missouri the following day. Radar and voice communication data provided by the Federal Aviation Administration (FAA) revealed that prior to departure, the pilot was given an IFR clearance to Omaha, and that during his interaction with clearance delivery personnel he read back the clearance correctly. A few minutes after departing Salinas the airplane was cleared to fly direct to the Panoche VORTAC (co-located very high frequency omnidirectional range (VOR) beacon and tactical air navigation system). The airplane followed a direct course of 60 degrees; reaching Panoche at a mode C reported altitude of 17,200 feet, about 14 minutes later. The airplane continued on that course, reaching the Clovis VOR at 1912, coincident to attaining the pilots stated cruise altitude of 27,000 feet. The pilot reported leveling for cruise, and flying direct to Omaha. The sector controller reported that the pilot should fly direct to the Coaldale VOR and then to Omaha, and the pilot responded, acknowledging the correction. For the next 5 minutes, the airplane continued at the same altitude and heading, with no further transmissions from the pilot. The airplane then began a descending turn to the right, with a final mode C reported radar target recorded 60 seconds later. During that period, it descended to 22,600 feet, with an accompanying increase in ground speed from about 190 to 375 knots. For the remaining 6 minutes, a 6.5-mile-long cluster of primary targets (no altitude information) was observed emanating from the airplane's last location, on a heading of about 150 degrees. Following the initial route deviation, the air traffic controller made five attempts to make contact with the pilot with no success. Throughout the climb and cruise portion of the flight, the airplane flew directly to the assigned waypoints with minimal course variation, in a manner consistent with the pilot utilizing the autopilot. PERSONNEL INFORMATIONReview of FAA airman records revealed that the pilot held a private pilot certificate with ratings for airplane single-engine land, multiengine land, and instrument airplane. He held a third-class medical certificate issued on July 18, 2010, with no limitations or waivers. An examination of the pilot's logbook indicated a total flight experience of 637.7 hours since his first training flight in July 2010, through to his most recent logbook entry dated October 26, 2012. His initial training was conducted primarily in the Diamond DA-40, following which he purchased a Mooney M20TN in January 2011. Over the next 16 months, he flew exclusively in the Mooney amassing a total of 410.7 flight hours. The Mooney was equipped with a Garmin G1000 Integrated Flight Deck, "Glass Cockpit", which included a primary and multifunction flight display. He received flight training for both complex and high performance airplanes in the Mooney on January 27, 2011. His initial multiengine flight training occurred in a Piper PA34-200 during the 2 day period from May 31, through to June 1, 2012, during which time he amassed 8.4 hours of flight time. His checkride occurred the following day, and for the next 11 days he accumulated an additional 15.7 hours of dual flight training in the accident airplane. During this period, he completed the required training for pressurized aircraft capable of high altitude operations, as well as accomplishing an instrument proficiency check. He flew a total of 79 flights in the accident airplane leading up to the accident, for a total flight time of 102 hours. His total flight time for all aircraft in actual instrument meteorological conditions was 142 hours (29.8 in the accident airplane), with 38.8 in simulated conditions. The accident airplane was equipped with conventional flight instruments, and according to a mechanic familiar with the airplane, the pilot had planned on upgrading it to include a "glass cockpit." AIRCRAFT INFORMATIONThe pressurized, multiengine airplane, serial number 421C1010 was manufactured in 1980. Maintenance logbooks were not available for examination. As such, maintenance history was compiled utilizing copies of the logbooks provided by the airplane's previous owner, as well as work orders provided by the various repair facilities that had maintained the airplane since its purchase by the accident pilot on June 8, 2012. The records revealed a total airframe time of 5,118.0 hours at the last annual inspection (Hobbs hour meter time of 623.8), which was completed on February 8, 2012. The airplane was equipped with two Continental Motors Incorporated (CMI) GTSIO-520-N turbocharged engines, with serial number 234166R installed on the left, and 808359R on the right side. Both engines were overhauled by RAM Aircraft LP; the left engine was overhauled in April 2011, and had accrued 139.5 hours at the last annual inspection. The right engine was overhauled in January 2006, and had accrued 748.2 hours at the time of the annual inspection. Both engines were equipped with three-blade McCauley constant-speed propellers. The last recovered logbook entry indicated maintenance was performed during the period from October 29, 2012, through to November 7, 2012, at a Hobbs hour meter time of 755.8. The work orders generated during that period documented the replacement of the cabin heater as well as the pilot reporting the following discrepancy items: "Intermittently at a hi rate of descent, the altitude hold didn't capture. He [pilot] had to move the pitch modifier to make it capture. When disengaging from altitude hold the aircraft pitches up, he disengages. ...IFR cert due, one shop spent a day repairing leaks, another said it still leaks. The pilot checked operation pressurized and unpressurized, no change. ...Check altitude information to both transponders." The discrepancies were addressed with the overhaul of the encoding altimeter, rewiring of both the transponder encoding altimeter and the GPS receiver input/output data lines, and the repair of the autopilot control unit and pitch actuator. The maintenance facility also repaired loose hoses and fittings throughout the pitot/static system, and performed an altimeter system test and inspection through to 20,000 feet in accordance "FAR 43 Appendix E, Paragraph B". According to a representative from Cessna, the airplane had a service ceiling of 30,200 feet. When asked why the altimeter test was not performed up to the airplanes service ceiling, the president of the maintenance facility stated that it was most likely an oversight. Fueling records provided by Jet West LLC, located at Salinas Airport established that the airplane was serviced with the addition of 173 gallons of 100-octane low-lead aviation fuel just prior to departure on the day of the accident. The general manager of Jet West reported that multiple aircraft had been serviced with fuel from the same dispenser following the accident, and none had reported encountering any difficulties. METEOROLOGICAL INFORMATIONThe pilot received both a weather briefing, and filed a flight plan utilizing the ForeFlight software application on his iPad. The closest aviation weather observation station was located at Madera Municipal Airport, Madera, California (KMAE), which was 42 miles west-southwest of the accident site. The elevation of the weather observation station was 255 feet mean sea level (msl). An aviation routine weather report (METAR) was recorded at 1853 PST. It reported calm wind, visibility 10 miles, skies clear, temperature 06 degrees C, dew point 02 degrees C, altimeter 31.17 inches of mercury. An infrared image taken by the Geostationary Operational Environmental Satellite number 15 (GOES-15) at 1930, depicted clear skies over the route of flight. A National Weather Service model sounding for 27,000 feet over the accident site indicated wind from the north-northwest at 122 knots, and a temperature of -35 degrees C. There were no SIGMETs (Significant Meteorological Information) or Convective SIGMETs issued for California during the accident period; an AIRMET (Airmen's Meteorological Information) for occasional moderate turbulence between 18,000 and 41,000 feet was current for the route and accident site. No specific pilot reports were noted in the vicinity of the accident site. According to the United States Naval Observatory, sunset in Salinas occurred at 1701, with the end of Civil twilight following at 1728. Moonset occurred at 1446, with moonrise at 0404 the following day. At the time of the accident, both the Sun and the Moon were more than 15 degrees below the horizon and provided no illumination. AIRPORT INFORMATIONThe pressurized, multiengine airplane, serial number 421C1010 was manufactured in 1980. Maintenance logbooks were not available for examination. As such, maintenance history was compiled utilizing copies of the logbooks provided by the airplane's previous owner, as well as work orders provided by the various repair facilities that had maintained the airplane since its purchase by the accident pilot on June 8, 2012. The records revealed a total airframe time of 5,118.0 hours at the last annual inspection (Hobbs hour meter time of 623.8), which was completed on February 8, 2012. The airplane was equipped with two Continental Motors Incorporated (CMI) GTSIO-520-N turbocharged engines, with serial number 234166R installed on the left, and 808359R on the right side. Both engines were overhauled by RAM Aircraft LP; the left engine was overhauled in April 2011, and had accrued 139.5 hours at the last annual inspection. The right engine was overhauled in January 2006, and had accrued 748.2 hours at the time of the annual inspection. Both engines were equipped with three-blade McCauley constant-speed propellers. The last recovered logbook entry indicated maintenance was performed during the period from October 29, 2012, through to November 7, 2012, at a Hobbs hour meter time of 755.8. The work orders generated during that period documented the replacement of the cabin heater as well as the pilot reporting the following discrepancy items: "Intermittently at a hi rate of descent, the altitude hold didn't capture. He [pilot] had to move the pitch modifier to make it capture. When disengaging from altitude hold the aircraft pitches up, he disengages. ...IFR cert due, one shop spent a day repairing leaks, another said it still leaks. The pilot checked operation pressurized and unpressurized, no change. ...Check altitude information to both transponders." The discrepancies were addressed with the overhaul of the encoding altimeter, rewiring of both the transponder encoding altimeter and the GPS receiver input/output data lines, and the repair of the autopilot control unit and pitch actuator. The maintenance facility also repaired loose hoses and fittings throughout the pitot/static system, and performed an altimeter system test and inspection through to 20,000 feet in accordance "FAR 43 Appendix E, Paragraph B". According to a representative from Cessna, the airplane had a service ceiling of 30,200 feet. When asked why the altimeter test was not performed up to the airplanes service ceiling, the president of the maintenance facility stated that it was most likely an oversight. Fueling records provided by Jet West LLC, located at Salinas Airport established that the airplane was serviced with the addition of 173 gallons of 100-octane low-lead aviation fuel just prior to departure on the day of the accident. The general manager of Jet West reported that multiple aircraft had been serviced with fuel from the same dispenser following the accident, and none had reported encountering any difficulties. WRECKAGE AND IMPACT INFORMATIONThe Town of Shaver Lake was located on the western foothills of the Sierra Nevada Mountain Range, within the confines of the Sierra National Forest, at an elevation of about 5,600 feet. The main wreckage, which consisted of the cabin, inboard wings, both engines, tailcone, and vertical stabilizer, came to rest inverted on a heading of about 125 degrees within a rocky outcropping, located about 1 mile southeast of the town. The site was at an elevation of about 5,700 feet, and surrounded by trees ranging in height from 50 to 150 feet; none of the trees sustained damage. The entire lower portion of the main cabin was consumed by fire from the footwell through to the rear bulkhead. The inboard right wing and engine nacelle sustained vertical crush damage, and remained partially attached to the cabin. The left inboard wing was partially consumed by fire through to the left engine nacelle, which sustained similar vertical crush damage. A ballistics trajectory analysis was performed on the primary radar targets by specialists within the NTSB Vehicle Performance and Operational Factors divisions. The results of the analysis revealed that the debris field most likely continued on a southeast heading, at least 6 miles beyond the location of the main wreckage, and into heavily wooded terrain. Utilizing this data, the Fresno County Sheriff Search and Rescue Department, along with the NTSB investigator-in-charge (IIC) conducted 4 days of search activities during the period from November 13 to December 2, 2012. During that time, the left and right wings outboard of the engine nacelle were located 2,500 and 3,200 feet respectively from the main wreckage. The right elevator tip and left horizontal stabilizer aft spar were located 1,000 and 1,700 feet further downrange. Sections of composite wing fragments along with rudder rib and skin sections were located 4.5 miles beyond the main wreckage the following week during a patrol conducted by the Forest Service. Another patrol discovered a section of the outboard right wing skin 2 miles beyond the main wreckage on March 13, 2013. All located debris was confined within a 1,500-foot-wide corridor on a heading of 150 degrees from the main wreckage. ADDITIONAL INFORMATIONPerformance Study A performance study was conducted by a specialist from the NTSB Vehicle Performance Division in an effort to determine the airplanes breakup sequence. The study utilized radar data, winds aloft information, and debris locations, and spanned the last 20 minutes of flight. Having factored in winds aloft velocity, the mode C reported radar data revealed that about 6 minutes after having leveled off at 27,000 feet, the airplane began a descending right turn to 150 degrees, while accelerating from an airspeed of 220 to 320 knots. The mode C data then ended, and was replaced for the next 6 minutes by a cluster of primary radar targets distributed along a heading of 150 degrees. The wreckage debris path was relatively straight and aligned with both the wind direction (which remained fairly constant from the ground through to 27,000 feet) and the direction of the primary radar target field. A ballistic trajectory program was utilized to resolve a breakup altitude. After multiple iterative calculations, the data consistently converged on an altitude at breakup of 17,000 feet. A full report is contained
The pilot's failure to regain airplane control following a sudden rapid descent during cruise, which resulted in an in-flight breakup. Contributing to the accident was the pilot's decision to make the flight with a failed vacuum pump, particularly at high altitude in night conditions.
Source: NTSB Aviation Accident Database
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