Farmersville, TX, USA
N451BB
Aircraft Mfg & Dev. Co. (AMD) CH601XLi
According to the private pilot receiving instruction, during the flight he became aware of increased airflow on his side of the airplane and noted that the canopy on the flight instructor's side had become unlatched. He mentioned this to the flight instructor and the flight instructor attempted to relatch the canopy. The canopy came completely unlatched and opened to a position of 50 degrees. The nose of the airplane pitched down violently to 60 degrees. The open canopy disrupted the airflow over the empennage resulting in a stalled condition. Neither the private pilot nor flight instructor was able to close the canopy or recover the airplane from the nose low attitude. An examination of the airframe, power plant, and flight control surfaces revealed no anomalies. The latching bolts and latches related to the canopy exhibited scratching consistent with the flexing and movement of the canopy assembly. There is no mechanism to relatch just one side of the canopy without opening the other side of the canopy. According to the pilot operating handbook emergency procedures, in the event that the canopy becomes completely unlatched, the pilot is to ignore the open canopy and wind noise and land the airplane normally. The emergency procedures imply that the airplane is controllable when the canopy is open. The emergency procedures do not address a partially open canopy. Further review of the pilot operating handbook revealed conflicting airspeed information between several chapters in the book and with the markings on the airspeed indicator in the airplane.
HISTORY OF FLIGHT On August 14, 2008, approximately 1100 central daylight time, an Aircraft Manufacturing and Development Company (AMD) CH601XLi special light sport airplane, N451BB, was substantially damaged when it impacted terrain three miles east of Farmersville, Texas. Visual meteorological conditions prevailed at the time of the accident. The instructional flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91, without a flight plan. The private pilot receiving instruction sustained minor injuries and the flight instructor sustained serious injuries. The local flight departed Collin County Regional Airport at McKinney (KTKI), McKinney, Texas, approximately 1030. According to a telephone conversation and subsequent written statement provided by the private pilot, he had scheduled a familiarization flight the morning of the accident with the flight instructor in the accident airplane. He stated that the instructor "seemed to be having trouble moving about, so he sat in a chair" while the private pilot and the instructor's wife performed the preflight inspection. Once in the airplane, they lowered the canopy and the instructor visually verified that the left side canopy latch was closed which was accomplished by the private pilot leaning forward. The private pilot reported that he could not see the flight instructor's canopy latch and could not verify that it was "properly latched." During the flight at approximately 2,500 feet mean sea level (msl) and 80 knots, the private pilot "noticed an increase in the airflow through the canopy vent on [his] side." He "noticed that the canopy on the right side was raised." When he brought this to the flight instructor's attention, the instructor attempted to "re-latch" the canopy. He could not recall if this was done by use of the center canopy lever or by pushing down on the right side of the canopy. Both sides opened and the canopy "shot up to about 50 degrees and the nose of the airplane immediately dropped to about 60 degrees" nose down. The private pilot stated that he "closed the throttle," grabbed what he could on the canopy to pull it down, and pulled back on the control stick. He stated that the instructor did the same. The private pilot stated that they were able to break the "dive" but were unable to raise the nose to a straight and level attitude. He "steered" the airplane to an open, plowed field, and the airplane impacted the ground in a 10-degree nose low attitude. According to the written statement provided by the flight instructor, he observed the private pilot student perform a thorough preflight and did not see "anything wrong." He stated that after the "upper air work" had been completed, they began to descend to perform "low air work." The flight instructor stated, "Suddenly, the canopy sprung open." He stated that the private pilot student grabbed the canopy with both hands and he grabbed the canopy with one hand and attempted to fly the airplane with the other hand. He stated that the attitude of the airplane was "dangerous" and he was afraid of "losing control of the airplane." He elected to perform a forced landing to a field. He characterized the airplane as being "very dangerously nose heavy" during the forced landing. According to a follow-up telephone interview with the instructor, his "back was hurting" the day of the accident and observed the private pilot conduct the preflight inspection. He did not note any issues with the student's preflight inspection. After the preflight inspection they boarded the airplane and closed the canopy. He stated that they visually verified that both sides of the canopy were closed prior to flight. The instructor reported that after the right side of the canopy came open, he attempted to close it by "pulling down on it." He stated that they did not attempt to "open and reclose the latch since we could not pull the canopy down." PERSONNEL INFORMATION Private Pilot The private pilot, age 73, held a private pilot certificate with airplane single engine land privileges. He was issued a third class airman medical certificate on April 13, 2004. The certificate contained the limitation "must wear corrective lenses" with "miscellaneous restrictions assigned." The private pilot held a valid driver's license for the state of Texas. According to the Pilot Operator Aircraft Accident Report Form submitted by the private pilot, his last flight review was successfully completed on July 17, 2008, in an IndUS Aviation Thorpedo, also a light sport airplane. He reported 359 hours total time; one hour of which was logged within the last 24 hours and two hours of which were logged in the previous 90 days. The private pilot had logged one hour in the make and model of the accident airplane; the hour during which the accident took place. Flight Instructor The flight instructor, age 65, held a commercial pilot certificate with an airplane single engine land, multiengine land, and instrument airplane ratings. He also held a flight instructor certificate with airplane single engine, multiengine, and instrument ratings. He was issued a second class airman medical certificate in July of 1990. The certificate contained the limitation "must wear lenses for distant - possess glasses for near vision." The flight instructor held a valid driver's license for the state of Texas. A review of the logbook indicated that the flight instructor had not logged flight time in his logbook since February of 1992. In March of 2008, the flight instructor resumed flight logbook entries. According to the logbook he successfully completed the requirements of a flight review on April 12, 2008. His flight instructor certificate was issued on June 17, 2008. The checkride was conducted in the accident airplane. A tally of the flight log revealed that the flight instructor had logged no less than 3,800 hours total flight time; 68 hours of which had been logged in the previous 90 days and 25 hours of which were in the previous 30 days, all in the accident airplane. The logbook revealed no less than 84 hours total time in the make and model of the accident airplane. AIRCRAFT INFORMATION The accident airplane, an Aircraft Manufacturing and Development (AMD) Co., Inc. "Zodiac" CH601XLi (serial number 601-051S), was manufactured in 2008. It was registered with the Federal Aviation Administration (FAA) on a special airworthiness certificate for light sport operations on January 14, 2008. The airplane was powered by a Teledyne Continental Motors O-200-A (82) engine rated at 100 horsepower at 2,750 rpm. The engine was equipped with a two-blade, Sensenich propeller. The airplane was registered to and operated by LCI Solutions Incorporated. The flight instructor used the airplane for the purpose of flight instruction. A review of the maintenance records indicated that a "100 hour" inspection had been completed on July 8, 2008, at an airframe total time of 131.5 hours (tachometer time of 99.7 hours). The airplane had flown approximately 36 hours between the last inspection and the accident. According to the maintenance manual provided by Zodiac, they prescribe 50 hour, 100 hour, 500 hour, and 1,000 hour interval inspections. No evidence of a 50-hour inspection was noted within the airplane maintenance records. According to the flight instructor, he had previous issues with the canopy latching mechanism. The canopy had come open on him in-flight on at least one previous occasion. In addition, he had difficulties in the past properly latching the canopy and opening the canopy, once the canopy was properly latched. He had requested that AMD replace/redesign the latching mechanism. On July 28, 2008, at a tachometer time of 118.2 hours maintenance was performed on the airplane canopy. The maintenance entry stated in part that the canopy latch and seals were lubricated and the system was inspected with no defects noted and "all canopy operations on the ground were good." On August 1, 2008, at a tachometer time of 118.2 hours the canopy latching system was replaced. It was noted that "canopy operational checks on the ground were good." This maintenance and replacement was performed with materials and drawings supplied by AMD. METEOROLOGICAL INFORMATION The closest official weather observation station was Majors Airport (KGVT), Greenville, Texas, located 15 nautical miles (nm) east of the accident site. The elevation of the weather observation station was 535 feet msl. The routine aviation weather report (METAR) for KGVT, issued at 1105, reported, winds, 210 degrees at four knots, visibility, ten miles; sky condition, clear; temperature 31 degrees Celsius (C); dewpoint, 18 degrees C; altimeter, 29.94 inches. Density altitude at the time of the accident was calculated to be 2,800 feet at the surface and 5,100 feet at altitude. WRECKAGE AND IMPACT INFORMATION The accident site was located in an open, sparsely vegetated field, three miles east of Farmersville, Texas, just north of highway 380. The accident site was at an elevation of 620 feet msl. The FAA inspector who responded to the accident site reported an approximate 50 foot ground scar preceding the main wreckage. The main wreckage included the fuselage, empennage, and the right and left wing assemblies. The engine separated partially from the fuselage and the canopy was open and displaced to the left. MEDICAL AND PATHOLOGICAL INFORMATION According a telephone conversation with the flight instructor in January of 2009, he had been in the hospital since the accident. He sustained four broken ribs, two broken ankles, and a broken pelvis, in addition to a concussion, cuts, and bruises. TESTS AND RESEARCH The wreckage was recovered to a hangar in Lancaster, Texas, for further examination. On August 21, 2008, the wreckage was examined by the National Transportation Safety Board Investigator-in-Charge and an inspector with the FAA. The wreckage consisted of the fuselage, empennage, right and left wing, and engine assembly. The wings had been removed from the airframe for the purpose of transporting the airplane to the storage facility. The fuselage included the engine assembly, instrument panel, canopy, and cabin area. The fuselage frame exhibited up and aft accordion crushing initiating at the firewall and continuing to just aft of both cabin seats. The fuselage aft of this point was unremarkable. The floor of the fuselage, near the rudder pedal assemblies, was crushed up and to a greater extent on the right side. Both main landing gear were bent aft and partially separated from the fuselage frame. The attach points for the left and right wings were wrinkled and bent aft. The instrument panel was unremarkable. The following arc markings were noted on the airspeed indicator: White arc - 30 knots to 80 knots Green arc - 35 knots to 108 knots Yellow arc - 108 knots to 140 knots Red arc - 140 knots to 160 knots (end of gauge range) The engine remained partially attached to the airframe. Both lower mounts separated from the airframe. The cowling was bent slightly and wrinkled. One propeller blade separated from the assembly at the propeller hub and was fragmented. The second propeller blade exhibited chord wise scratches. The canopy frame remained attached to the fuselage at the forward mounting locations. The frame was bent and twisted to the left. Most of the Plexiglas was broken and missing from the canopy frame. A small amount of Plexiglas remained attached towards the aft portion of the canopy frame. Both canopy latches (right and left) exhibited scratches on the outer face of each latch. The canopy latching bolts exhibited scratching/scoring on the upper portion of the bolt, inboard from the bolt head, and outboard from the canopy arm. The spring on the left side remained attached and both latches were continuous from the latch to the center canopy handle. The left wing leading edge was crushed aft at the wing light and the wing root. The aileron cable was continuous from the control stick to the aileron push/pull rod. The only separation noted was a cut at the fuselage that occurred during the recovery process. The right wing leading edge was crushed aft at the wing root. The right aileron and right flap were unremarkable. The aileron cable was continuous from the control stick to the aileron push/pull rod. The only separation noted was a cut at the fuselage that occurred during the recovery process. The empennage, including the horizontal and vertical stabilizer, rudder, and elevator remained attached to the airframe. The rudder and elevator control surfaces were unremarkable. Control cables were continuous from the control stick in the cabin, aft to the respective control surfaces. ADDITIONAL INFORMATION Canopy and Latch Assembly The canopy on the CH601XLi was constructed of two square arms mounted to the fuselage adjacent to the firewall. The arms extended aft and were joined together by a tube that arches up and around to form the frame of the canopy. A forty pound air spring was mounted on both the right and left side of the canopy frame and fuselage. The Plexiglas measured 0.0920 inches thick. A canopy latch bolt was secured to the inner portion of the aft frame on both the left and right side of the canopy frame. Forward of the canopy latch bolt, a plate measuring four inches by two inches was mounted to the frame. This plate can be utilized like a handle to pull the canopy down. The latching mechanism on the airframe consisted of a "C" latch on both the left and right side of the fuselage, mounted on the upper aft portion of the fuselage near the seats. These latches were joined together and controlled through a connecting rod and handle centrally located on the aft wall of the fuselage. A second handle is located on the outer portion of the fuselage on the left side. When either handle is activated both latches simultaneously rotate aft. A spring attached to the left latch brings both latches back to their forward position. When the canopy is closed, the C latches cover the top, aft, and lower portion of the latching bolt. Aside from the right and left latches, there were no other mechanisms to ensure the canopy remains closed while in flight. There is no mechanism to relatch just one side of the canopy without opening the other side of the canopy. Pilot Operating Handbook (POH) A review of the Pilot Operating Handbook (POH) located in the airplane wreckage revealed multiple discrepancies. The cover illustrated that the POH was applicable to the "Zodiac 601Xli SLSA" manufactured by Aircraft Manufacturing and Development Co., Inc. Each page, with the exception of the supplement pages, was marked with the date "Dec. 05" in the lower right hand corner. The supplement pages carried the date "Jan-2006." Section 2 - Airplane and System Description - page 2-3 and 2-4 provided general airspeed terminology definitions. Specifically VA was defined as "Maneuvering Speed is the maximum speed at which application of full available aerodynamic control will not overstress the airplane." Further, VC was defined as "Maximum Structural Cruising Speed is the speed that should not be exceeded except in smooth air and only with caution." Section 3 - Operating Limitations - page 3-1 provided an overview of the operating limitations including airspeed limitations in both KCAS (knots calibrated airspeed) and KIAS (knots indicated airspeed). The following speeds were identified: VS - 40 KIAS, VSO - 33 KIAS, VA - 90 KIAS, VNE - 140 KIAS, and VC - 110 KIAS. Section 5 - Performance provided performance information for the airplane. On page 5-2 the table on the center of the page "Take-off Roll + Climb to Clear 50 ft. obstacle at 60 KCAS:" stated that "On grass, decrease above values by 20 [percent] approximately. With head wind above values are increased by 25 [percent] for 10 kts headwind and 40 [percent] for 20 kts headwind." Page 5-4 identified the stall speeds at 1,320 pounds. "Flaps up VS= 40 KIAS, 43 KCAS. Flaps down VSO = 33 KIAS, 38 KCAS." Section 7 - Normal Procedures provided normal procedures for the operation of the airplane. Page 7-1 defined airspeeds for safe operation. In part, the following was stated: "(c
The inadvertent tail stall and subsequent loss of airplane control as a result of the open canopy. Contributing to the accident was the inadequate emergency procedures provided by the airplane manufacturer and the inadequate design of the canopy latching mechanism.
Source: NTSB Aviation Accident Database
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