Williams, CA, USA
N47TR
Schleicher ASW-20
During the takeoff, the glider began an uncontrolled climb at a 45-degree nose up attitude behind the tow plane. The tow plane pilot was forced to cut the tow rope due to the severe pitch down moment caused by the glider. The glider then arced over into a 45-degree nose down dive and hit the ground. The glider's flight control system was equipped with Hotalier quick disconnect fittings at various locations to facilitate the disassembly of the glider for trailer transport. A postaccident examination of the flight control system disclosed that the elevator control push rod was disconnected from the elevator at a quick disconnect fitting in the vertical stabilizer. There was no damage noted to the elevator bell crank or the terminal end of the elevator control push rod. A close friend and former partner in the glider was interviewed. He was present on the day of the accident and knew the pilot very well. He stated that he and the pilot had purchased the glider a little less than a year prior to the accident. The pilot had flown it over 50 times and had assembled it as many as 25 times. On the day of the accident, he and the pilot completed a control check while qued for the tow plane. He stated that he held the elevator while the pilot applied full up elevator control input. He felt the elevator move in the up position. He said neither the pilot nor he attempted to apply full nose down control input, as it was assumed the elevator was properly attached to the control rod fitting. He stated that in retrospect, the only way to positively check the connection is to hold the elevator in the up position while the pilot applies full nose down control input.
HISTORY OF FLIGHT On April 14, 2001, at 1245 hours Pacific daylight time, a Schleicher ASW-20 glider, N47TR, was substantially damaged when it collided with the ground during initial climb after takeoff on an aero tow at the Williams Glider Port, Williams, California. The commercial pilot with a private pilot-glider rating was fatally injured. The glider was owned and operated by the pilot under 14 CFR Part 91. Visual flight rules prevailed for the local flight and no flight plan was filed. The flight was originating at the time of the accident. The glider's flight control system was equipped with Hotalier quick disconnect fittings at various locations to facilitate the disassembly of the glider for trailer transport. A witness, who is also the owner of the glider port, stated that he observed the pilot assembling the glider on April 14, 2001, between 1000 and 1100 in the morning. The pilot was the last departing member of a group of gliders, and was scheduled for a 1245 departure. It was observed that he was not in a hurry, and appeared to be taking his time in assembling the glider. The witness did not observe the pilot conduct a flight control check. He stated that the glider did not fly between the time it was assembled and the accident flight at 1245. A close friend and former partner in the glider was interviewed. He was present on the day of the accident and knew the pilot very well. He stated that he and the pilot had purchased the glider a little less than a year prior to the accident. The pilot had flown it over 50 times and had assembled it as many as 25 times. On the day of the accident, he and the pilot completed a control check while qued for the tow plane. He stated that he held the elevator while the pilot applied full up elevator control input. He felt the elevator move in the up position. He said neither the pilot nor he attempted to apply full nose down control input, as it was assumed the elevator was properly attached to the control rod fitting. He stated that in retrospect, the only way to positively check the connection is to hold the elevator in the up position while the pilot applies full nose down control input. It was also revealed that this particular glider was the first ever built in the ASW-20 series. The glider's designer had personally built and flown this glider for the purpose of exhibition and racing in the United States. The witness was airborne in a tow plane, on a right downwind leg at the glider port when he observed the glider's departure. He observed the glider liftoff and stated that it shot up rapidly at a 45-degree climb angle. The glider "kited" above the altitude of the tow airplane. The witness stated that he was becoming increasingly concerned for the safety of the tow plane as the glider began to force the tow plane's nose down. He observed the tow line break free of the tow plane. The glider then began a slow pitch down to level flight. He stated that he saw the wing flaps deploy and the glider slow to what he estimated to be stall speed. The glider then began to nose down into a 45-degree dive, and impacted the ground shortly thereafter. He landed immediately and went to the crash site within minutes of the accident. He inspected the empennage and noted that the elevator control push rod was not attached to the elevator. The tow plane pilot was also interviewed. He stated that the glider lifted off much faster than he was used to seeing, in his experience. He then began experiencing a strong pitch-down moment and was having difficulty controlling the tow plane. He attempted to maintain control for a few seconds, and when that became impossible, he triggered a cutting device, which separated him from the glider by severing the tow rope. As he turned away from the landing strip, he observed the glider begin a 45-degree dive and impact the ground. PERSONNEL INFORMATION A review of the Federal Aviation Administration (FAA) airman records revealed that the pilot held a commercial pilot certificate with airplane single engine, multiengine land and instrument airplane ratings. He held a private pilot certificate in gliders, limited to aero-tow only. The pilot held a first-class medical certificate issued September 9, 2000, with no limitations. According to his FAA medical application form, he was a professional pilot flying for a large regional airline. No personal pilot records have been provided, and the flight time appearing on page 3 of this report was obtained from the pilot's last FAA medical application. AIRCRAFT INFORMATION The aircraft was a Schleicher ASW-20 glider, serial number 20001. It was the first in a series of production gliders that were not offered for type certification in the United States. According to the airworthiness certificate, it was an experimental category for the purpose of exhibition and racing. A review of the maintenance logbooks revealed that the glider was first certified on April 2, 1979. An annual inspection was performed on March 24, 2001. The total airframe time at the last annual inspection was estimated to be 950 hours. A copy of the assembly instructions provided by the manufacturer for the ASW-20 were obtained from the Soaring Safety Association. Page 32, section 2.1 pertained to rigging the glider flight controls during the assembly process. It stated that the aileron and dive brake connections should be checked by trying to pull the push-pull rod away from the ball fitting. However, the instructions do not list this procedure for the elevator connection. The ailerons, dive brakes, and elevators are connected with the same type of fitting. Additionally, the instructions state that a "positive control check" should be performed prior to each flight. However, the instructions do not state how a positive control check should be performed. METEOROLOGICAL INFORMATION The Williams Glider Port is not equipped with a weather observing system. The weather was obtained from the Yuba City/Marysville Airport (MYV) automated weather observation system (AWOS). At 1253 on April 14, 2001, the MYV AWOS was reporting clear skies; visibility 9 miles; temperature 16 degrees Celsius; and calm winds. The MYV airport is 27 east of the Williams Glider Port on a magnetic bearing of 263 degrees. WRECKAGE AND IMPACT INFORMATION The wreckage was located 130 feet from the initial ground scar in tall grass on the left side of the departure end of runway 34, on a magnetic bearing of 340 degrees. Two additional scars were located on a magnetic bearing of 250 degrees and 070 degrees on either side of, and 30 feet from the first scar noted. The left winglet was found adjacent to the ground scar to the left of the center scar. The wing span of this glider is approximately 60 feet. The glider was resting upright with the fuselage pointing approximately 320 degrees. The cockpit area was crushed aft and folded under the fuselage. The canopy had shattered and separated from the cockpit. The fuselage aft of the cockpit was undamaged. The tail boom section of the fuselage was fractured in two places just forward of the empennage. The empennage was attached, but was resting at a 45-degree angle to the left of the vertical axis of the fuselage. The vertical and horizontal stabilizers were undamaged. The left wing was attached to the fuselage. It had a spanwise tear in the leading edge running from the wing root approximately 2/3 of the wingspan. The upper and lower surfaces of the wing were undamaged. The left winglet was not attached to the wing tip. The right wing was attached to the fuselage. There were two fractures noted on the outboard wing area. The first fracture was 8 feet outboard of the fuselage, and ran from the leading edge to the trailing edge at a 30-degree angle, sloping outboard, and terminating at the outboard edge of the right wing flap. The second fracture paralleled the first and was outboard of the first by approximately 8 feet, terminating at the midpoint of the right aileron. The right winglet was attached and undamaged. MEDICAL AND PATHOLOGICAL INFORMATION The Colusa County Sheriff/Coroner's office performed a postmortem examination of the pilot. Toxicological examinations of the pilot were conducted by the FAA Toxicology and Accident Research Laboratory, Oklahoma City, Oklahoma. Negative results for all screened substances were reported. TESTS AND RESEARCH A postaccident examination of the flight control system disclosed that the elevator control push rod was disconnected from the elevator at a quick disconnect fitting in the vertical stabilizer. There was no damage noted to the elevator bell crank or the terminal end of the elevator control push rod. No damage was noted in the control push rod tunnel or on the elevator ball pip fitting. The wings were laid out in their appropriate positions next to the attach points in the fuselage. The ailerons, flaps, and spoilers were connected by push rod tubes located in the wing structure. The terminal ends of each control push rod protruded from the wing root of each wing and were completely accessible for examination. Control continuity was established for the ailerons, flaps, and spoilers by activating the associated control rods. The glider had a control stick, which was broken in half. The elevator and aileron control tubes were still attached to their respective hardware, which was attached to the control stick. The cables were intact and were hooked up with the control stick and attaching hardware. Control continuity was established from the control stick to the corresponding terminal ends located in the fuselage/wing root joint. The rudder cables were found attached to the rudder pedals, however the cables had been cut aft of the seat area to facilitate the removal of the pilot. The remaining cables within the fuselage activated the rudder when moved. The spoiler and flap push rods and cables were also attached and continuity was established to the wing attach point on the fuselage. An operational ASW-20 of the same type was examined at the Tehachapi Mountain Glider port on May 19, 2001. The elevator control attachment was examined and photographed for inclusion in this report. The attaching hardware on the example glider has a receiver and sliding lock pin that, according to the owner, provides a secure attachment when properly installed. A witness hole in the sliding lock device allows the assembler to positively confirm that the elevator control has been captured. The accident glider was equipped with the same elevator control device, but had the additional security of a locking sleeve that covered the entire mechanism to prevent the sliding capture pin from backing out. However, the pilot and owner of the example glider stated that this was unnecessary, as he has never seen nor heard of this attachment failing once it was properly secured. The attached control rod end can be observed by looking at the top of the rudder without moving the elevator. However, moving the elevator up exposes the entire connection, which was clearly visible from all directions. The owner stated that although the weight and balance information was in German, the checklists and manuals for his glider were provided in English when he purchased it. ADDITIONAL INFORMATION The wreckage was released to, and accepted by, the owner's representative on April 17, 2001. The Soaring Society of America (SSA) provides a supplement detailing assembly procedures for gliders and sailplanes. Appendix D of the SSA's Soaring Safety Foundation (SSF) Safety Advisory is attached to this report. The SSA and SSF have encouraged manufacturers to provide automatic hookups for critical components such as ailerons, flaps, glide path control devices, and elevators. The report states, "Many of the gliders and sailplanes today have these automatic attachments." Additionally, the SSA has produced a series of videotapes discussing glider safety. Volume one of the series discusses in detail the proper assembly and positive control checks to be used. The FAA practical test standards for the issuance of a private pilot certificate with a glider rating specifically states that a positive control check must be accomplished, however, no reference is made as to how the check should be completed.
The failure of the pilot to attach the elevator control rod to the elevator, resulting in a loss of pitch control and subsequent ground impact. Additional factors were the failure to complete a positive control check and the lack of clear guidance in the assembly procedures.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
