Yuba City, CA, USA
N158MD
Aircraft Mfg & Dev. Co. (AMD) CH601XL SLSA
Recorded radar data showed that the airplane was at 2,600 feet mean sea level cruising on course. It entered a gradual climb to 2,800 feet, leveled off, and then entered a 2,000-foot-per-minute rate of descent, which was followed by a profusion of primary radar targets around the secondary target. The wreckage was found within 1/2 mile of the last radar return with signatures consistent with an in-flight breakup. Several witnesses were found and none saw any adverse weather conditions in the area. One witness said the airplane had been in straight and level flight just prior to the breakup. The airframe was examined by Safety Board engineering and metallurgical specialists. Other than some assembly anomalies unrelated to the breakup, no evidence of any assembly contrary to design plans or material deficiency was found that related to the integrity of wings, stabilizer, or flight control surfaces. No evidence of fatigue, corrosion, or previous damage was found. The separation of the wings and horizontal stabilizer was in a downward direction. All observed fracture surfaces were overload, and no oscillatory loading of the control surfaces was apparent. Analysis of the radar data revealed that the climb and descent that occurred before the breakup did not require aggressive control inputs. The pitch angle would have changed about 0.4 degrees per second during the climb, and would have decreased about 0.75 degrees per second in the descent, with generated load factors ranging between 1.04 G and 0.88 G. A radar return is only received once every 4.5 seconds and contains uncertainties in both altitude and position measurements. Consequently, the radar may not have detected an abrupt control input that would overload the aircraft structure before the airplane position and altitude changed significantly. While there is no evidence of an abrupt control input or aggressive maneuvering in the available radar data, because of the limitations in the data, the possibility of an abrupt control input cannot be excluded. This airplane is very responsive in pitch control. One of the handling quality characteristics designed by the airplane's manufacturer is that movement of the control stick produces large and rapid changes in pitch attitude.
HISTORY OF FLIGHT On November 4, 2006, about 1139 Pacific standard time, an Aircraft Manufacturing & Development Co. (AMD), CH601XL SLSA, N158MD, experienced an in-flight breakup while cruising approximately 11 miles south-southeast of Yuba City, California. The special light sport airplane (S-LSA), referred to as a "Zodiac," was destroyed. The private pilot and passenger were killed. The pilot operated the airplane using the Federal Aviation Administration (FAA) registered name "Zodiac LSA, Inc." Visual meteorological conditions prevailed, and no flight plan was filed. The personal flight was performed under the provisions of 14 Code of Federal Regulations Part 91 and originated from Lincoln, California, about 1129. The pilot's son reported to the National Transportation Safety Board investigator that his father and he jointly operated the airplane. The son was listed as the president of Zodiac LSA, Inc., which was the name that the pilot and his son gave to their company. The family purchased the newly manufactured airplane directly from AMD in July 2006. Following their purchase and the son's introductory flight provided by AMD personnel, the son flew the airplane from AMD's factory in Georgia to his California home. The pilot's son also stated to the Safety Board investigator that in California he and his father flew the airplane together on several occasions. They became familiar with the airplane's operating characteristics, which according to the son were somewhat different than those of the other airplanes their family had owned or operated. The accident flight commenced after the pilot refueled the airplane at the Lincoln Regional Airport. Upon departure, the pilot headed in a westerly direction toward his intended destination, the Willows-Glenn County Airport, Willows, California. Willows is located about 63 miles west-northwest of Lincoln. The pilot's son reported that his parents planned to fly to Willows for lunch. While cruising toward Willows, about 10 minutes after takeoff and 16 miles west of Lincoln, five ground-based witnesses heard the airplane. Two of the witnesses also observed the airplane prior to the breakup. In summary, three of the auditory witnesses reported hearing a "bang" sound. One of these witnesses reported that for about 10 seconds prior to hearing the "bang," the engine was misfiring or sputtering. The sound increased in loudness and ended with a loud "bang." The fourth witness reported to a Sutter County Sheriff's deputy that he had been working in his field when he heard an airplane overhead. The witness opined that the airplane's engine was missing really badly. A few seconds later, as he was looking at it flying an estimated 800 to 1,200 feet above ground level, the airplane "blew up." The wings flew off, parts went everywhere, and the cockpit turned in circles as it descended. The fifth witness reported to the Safety Board investigator that he was a retired United States Air Force mechanic and was familiar with light airplanes. The witness was standing outside his residence, about 0.5-mile southeast of the accident site. In summary, the witness reported that he heard the sound of the airplane's engine, and it sounded fine. It was operating smoothly, its rpm sounded steady in that it was producing a constant tone, and it was not backfiring or sputtering. Then, the witness looked upward in the direction of the engine sound and immediately observed the airplane. The airplane was northwest of his location, and it was cruising in a northwesterly direction. Its wings were level. The airplane was not turning, climbing, or descending. The witnesses further stated that he could clearly see the airplane and saw no evidence of fire or smoke trailing from it. The fifth witness additionally reported that, after a few seconds, he stopped looking at the airplane and started talking on his cell phone. The witness estimated that he looked away from the airplane for about 5 seconds. Then, he heard the sound of the airplane's engine rapidly change rpm. Within about 0.5 seconds, it decreased and then increased, as if the pilot had retarded the throttle and then suddenly changed his mind and restored the power. When the rpm came back up, it did not sound like the engine had over revved. The tone sounded the same as before the power had decreased. The witness reported that immediately after the engine power came back up, he heard the sound of an explosion, which was followed by the sound of metal scraping. Thereafter, he saw what he believed were three distinctive large components falling. The components were the wings and the fuselage. The witnesses stated that it took perhaps 6 to 8 seconds for the airplane to fall, and it fell straight down. As the components descended, the fuselage spiraled around. There was no fire or smoke. The witness opined that, originally, he thought there had been a mid-air collision. However, there was no other aircraft in the area. PERSONNEL INFORMATION Pilot The pilot, age 79, held a private pilot certificate with an airplane single-engine land rating. The pilot's last aviation medical certificate was issued in the third class on February 16, 2005. The certificate bore the following limitation: "Must wear glasses for near and distant vision." Also, the certificate stated "Not valid for any class after February 28, 2006." (The FAA does not require that pilots operating a S-LSA under the accident flight conditions hold any class of medical certificate.) On the February 2005 medical certificate application form the pilot reported that his total pilot time was 1,184 hours. In previous years, when the pilot was issued aviation medical certificates, he reported the following total pilot times: 1,025 hours in February 2003, and 783 hours in February 2001. The pilot's personal flight record logbook indicates that he commenced flying the accident airplane on August 18, 2006. His logbook was endorsed by a certified flight instructor as having satisfactorily completed a flight review and "Zodiac checkout" in the accident airplane on October 28, 2006. According to the logbook, by the accident date the pilot's total logged flight time in all airplanes was about 1,281 hours. The Safety Board investigator's review of the airplane's utilization flight logbook found in the wreckage revealed that between August 18, 2006, and November 4, 2006 (accident date), the pilot was listed as having flown the airplane on nine dates for a total of 20.2 hours. More recently, between October 4, 2006, and November 4, 2006, the logbook indicated that the pilot flew the airplane on six dates for a total of 15.3 hours. Passenger Family members reported that the accident occurred during the wife's first flight in the airplane. The wife was not a pilot and had not received flight instruction. She had previously flown in other family-owned airplanes. The wife was reportedly in good physical condition, swam frequently, and was not handicapped. AIRCRAFT INFORMATION Manufacture The accident airplane was purchased as a factory-assembled S-LSA from AMD. The manufacture of the accident airplane began in Ontario, Canada. The accident airplane's components were then transported to Eastman, Georgia, where the airframe was assembled. The assembly included attaching the wings, stabilizers, flight controls, avionics, and engine. Certification AMD reported that the airplane, serial number 601-016S, was designed and manufactured in accordance with the American Society for Testing and Materials (ASTM) industry consensus standard for light sport aircraft. AMD's Director of Quality Assurance issued the following consensus standard certification statement to the FAA: "I hereby certify that aircraft serial number 601-016S complies with the Consensus Standard(s) identified on this statement of compliance and that the Manufacturer's Continued Airworthiness System will be adhered to support the aircraft throughout its life. This aircraft (1) was manufactured following the consensus standard(s) procedures and Manufacturer's Quality Assurance System identified on this statement, (2) conforms to the manufacturer's design data, (3) was ground and flight tested successfully, and (4) is in condition for safe operation." AMD contracted with a Designated Airworthiness representative (DAR) to issue the airplane its airworthiness certificate, and the certificate was issued on July 10, 2006. The DAR indicated to the Safety Board investigator that he followed industry procedures that included, in part, looking at the airplane's exterior and cockpit, and examining applicable paperwork presented by AMD. Finding nothing outstanding with the airplane and no safety issues, the DAR accepted AMD's statement of compliance with the ASTM standards. He issued the airplane a special airworthiness certificate on behalf of the FAA. The DAR was neither required to nor did he fly the airplane during the certification process. A few days later, on July 18, 2006, the consensus standard certification statement was issued. According to the airplane log, the airplane was flown by a test pilot on July 19, 2006, and he certified "that its performance flying qualities, performance of controls, powerplant and landing gear, etc., were equivalent to the standard of the type." Documents found in the wreckage indicate an FAA special airworthiness certificate was issued in the Light Sport Category on July 20, 2006. Registration and Usage On July 20, 2006, an airplane registration certificate was issued indicating the owner applicant was Zodiac LSA, Inc. The pilot's son reported that in Eastman, Georgia, he flew the airplane with an AMD employee. Anomalies were noted with the airplane and, according to AMD, they were corrected prior to the pilot's departure from its facilities. The pilot's son reported that the airplane was operated by his family for its personal use. The airplane was not rented to other pilots. By the time of the accident, the airplane's total flight time was about 98 hours. Design Strength In Section 3 of the "Pilot Operating Handbook" for the accident model of Zodiac airplane, AMD reports that the airplane's load factor (limit) is +4 positive G, and -2 negative G. A note states that the ultimate load factor is 1.5 times the limit. In AMD's internet advertising, the company provides specifications for the Zodiac airplane. In part, AMD states the aforementioned load factors by indicating that at a gross weight of 1,320 pounds, the design load (ultimate) is +6 G and -3 G. Weight and Balance The pilot's family reported that the probable weight of the pilot and passenger was 375 pounds. The Safety Board investigator estimated 7 pounds of baggage was on board. AMD estimated that, based upon 10 pounds of fuel burning off since takeoff, the fuel weight was 170 pounds. The airplane's empty weight was 836 pounds. In total, the airplane weighed about 1,388 pounds at the time of the accident. This is about 68 pounds over the maximum authorized gross weight of 1,320 pounds. The airplane's calculated center of gravity was 15.264 inches aft of datum, near the center of the balance envelope. Maintenance and Operation AMD provided the airplane's owner with documents specifying the operation, maintenance, and inspection procedures that were to be followed. The pilot's son holds a private pilot certificate with an airplane single-engine land rating. The son enrolled in a training program to obtain FAA certification as a repairman, light sport airplane. He received certification following the accident. The pilot's son reported to the Safety Board investigator that he was aware some of the maintenance he performed on the airplane as a private pilot-owner (prior to his being repairman-certified), was permissible under the Federal Aviation Regulations. However, he was also aware that some of the maintenance he had performed was not permissible, and it had not been recorded in the airplane's maintenance records. According to the airplane's FAA "Operating Limitations: Light Sport Aircraft" form issued July 20, 2006, non compliance with the limitations "...will render the airworthiness certificate invalid..." and "[a]ny change, alteration, or repair not in accordance with the manufacturer's instructions and approval will render the airworthiness certificate invalid...." Also, any maintenance must be recorded in the aircraft's maintenance records. METEOROLOGICAL INFORMATION At 1139, an aviation routine weather report (METAR) for the Yuba County Airport (about 9 miles north of the accident site) indicated the wind was from 340 degrees at 7 knots; the visibility was 7 miles; and there was a ceiling 1,300 feet above ground level (agl). The temperature and dew point were 18 and 13 degrees Celsius, and the altimeter was 30.21 inches of Mercury. About 14 minutes later, at 1153, the cloud condition had changed, and the sky condition was reported as few clouds at 1,300 feet agl. The Yuba County Airport's elevation is 62 feet mean sea level (msl). At 1153, a METAR for the Sacramento International Airport (about 19 miles south of the accident site) indicated the wind was from 360 degrees at 6 knots; the visibility was 8 miles; and there were few clouds at 1,500 feet agl. The temperature and dew point were 19 and 14 degrees Celsius, and the altimeter was 30.20 inches of Mercury. The preceding hour, at 1053, there were scattered clouds at 1,300 feet agl. The Sacramento International Airport's elevation is 27 feet msl. Three witnesses, who were located within 1.5 miles of the accident site, reported that at the time of the accident they noted the weather condition. One of the witnesses, who was located southeast of the accident site, reported that he observed the airplane cruising (its altitude was about 2,800 feet agl). The witness did not report experiencing any difficulty observing the airplane. He stated that the visibility was good, and the sky was broken and in some places it was overcast. The sun was peaking through the clouds. The second witness, who was about 1.5 miles west of the accident site, reported that the sky was "very, very, clear," and there was a light wind. The third witness reported that it was "clear and sunny," and there was little wind. COMMUNICATION The FAA reported that a search of facilities near the accident site did not reveal evidence that any air to ground communications or services had been provided to the pilot or the accident airplane. FLIGHT RECORDER The airplane was equipped with a Dynon electronic flight display. The display was sent to the Safety Board's Research and Engineering Vehicle Recorder Division laboratory, Washington, D.C., for examination. The laboratory reported that, by design, the display did not record data or have memory. WRECKAGE AND IMPACT INFORMATION The Safety Board investigator's examination of the accident site and airplane wreckage, in conjunction with witness statements, revealed that the airplane experienced an in-flight breakup. All of the airplane's structural components were located and found in sparsely vegetated level fields, having an estimated elevation of 30 feet msl. The wreckage was scattered in an oval shaped area about 1,900 feet long by 500 feet wide. The heaviest components were found at the northern end of the wreckage path. These components (referred to as the main wreckage) consisted of the cockpit, engine, and the main landing gear. The two occupants were found within 125 feet of the main wreckage and about 100 feet from each other. The lightest components were found in the middle and southern end of the wreckage path. These components consisted of Plexiglass fragments, a carpet fragment, one seat cushion, and wheel fairings. The magnetic bearing between the heaviest and lightest components was about 170 degrees. The wreckage consisted of the following components that were found separated from each other: 1. Left wing with attached flap (but without the aileron). Note: A rubber-like smudge, consistent with a main landing gear tire transfer mark, was found on the bottom of the left wing, near the aft spar attachment support bracket. 2. Aileron (left wing); 3. Right
In-flight structural failure of the horizontal stabilizer and wings for undetermined reasons.
Source: NTSB Aviation Accident Database
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