ELBERT, CO, USA
N99HV
DUCI'S VANS RV-3
A witness said the pilot was performing aerobatics, and while maneuvering, the aircraft (acft) went into a nose high attitude as if it was coming to the top of a loop. He said one of the wings suddenly 'folded' up, and 'It looked as if it had bent at the connection between the wing and the fuselage. . . .' The acft then entered an uncontrolled descent & crashed. Metallurgical exam of the right wing revealed overload fractures in the lower & upper main spar caps, which were indicative of upward failure; initial fracture was in the lower cap area. Twisting & upward bending of the main upper spar cap was noted, as well as 'overstress separation.' Five bolt holes were found at the inboard portion of the upper & lower main spar caps with no respective bolts or remnants of such bolts. No deformation or distortion of any of the bolt holes was noted, but circular markings were noted on the forward side of both outboard holes, & similar indications were noted on the aft side of 2 other holes in the lower main spar cap. The investigation did not determine whether the missing bolts had failed & separated during the breakup, or if they had not been reinstalled during previous maintenance/modification. All rivets in both the upper & lower main spar caps were broken through the shanks 'consistent with direct shear separations. No evidence of cracking or breaking of rivet heads . . . was noted.' This was 1 of 3 RV-3s built by Tony Duci & the 2nd to structurally fail in flight. Acft had been modified as an RV-3A, but had not been re-certified as such. Aerobatic gross weight limit (1,050 lbs) had been exceeded by an estimated 120 lbs.
HISTORY OF FLIGHT On March 8, 1998, approximately 1510 mountain standard time, a Duci's Vans RV-3 (upgraded to an RV-3A), N99HV, was destroyed when it collided with terrain while maneuvering near Elbert, Colorado. The airline transport rated pilot, the sole occupant aboard, was fatally injured. Visual meteorological conditions prevailed, and no flight plan had been filed for the local personal flight conducted under Title 14 CFR Part 91. The flight originated at Elbert approximately 1445. The only witness to the accident, a U.S. Air Force Academy cadet, was watching the airplane from the south end of Kelly Airpark. The pilot "was performing aerobatics (loops, chandelles, rolls)." He then saw the airplane in a nose high attitude, "as if he were coming to the top of a loop." He said "one of his wings suddenly 'folded' up. It looked as if it had bent at the connection between the wing and the fuselage. It did not separate from the fuselage." The witness said the airplane nosed over, entered a "gentle spin," then stabilized and increased speed as it dove towards the ground. The witness estimated the time of the accident to be 1510, and he went to the nearest telephone and called 9-1-1. According to the Elbert County Sheriff's Office, the call was received at 1511. Two other witnesses submitted written statements, saying they had seen an airplane performing aerobatics over their homes. One witness said the airplane was 100 feet above the ground; the other said it was 65 feet. Their description of the airplane was similar to that of N99HV. The accident occurred during the hours of daylight at a location of 39 degrees, 13.732 minutes north latitude, and 104 degrees, 37.004 minutes west longitude. The wreckage was in a field in the rear of 2782 County Road 98, at an elevation of 6,939 feet msl. CREW INFORMATION The pilot, Christopher Keith Coffland, age 35, was born on January 7, 1963. He attended the United States Air Force Academy from August 1981 to June 1985, and was commissioned. He held Airline Transport Pilot Certificate No. 358625748, dated March 19, 1995, for multiengine land airplanes, with commercial privileges in single engine land airplanes and gliders (aero tow only). He also held a Flight Instructor Rating, dated February 9, 1996, for single and multiengine airplanes and instruments, and a Ground Instructor Rating, dated September 26, 1994, for advanced and instrument instruction. His first class airman medical certificate, dated June 23, 1997, contained no restrictions or limitations. Three master logbooks and eight smaller pilot logbooks were submitted for examination. It was discovered that the flight times contained in seven of the smaller logbooks (and part of the eighth) had been transferred to the three master logbooks. These master logbooks contained entries from May 22, 1984, to May 24, 1989; May 25, 1989, to July 23, 1993; July 24, 1993, to November 29, 1997, respectively. The eighth logbook contained RV-3 entries exclusively from June 2, 1997, to February 12, 1998. A summary of flight time contained in the three master and RV-3 logbooks, and a summary of flight time by aircraft type are attached to this report. Only one aerobatic entry was found in the RV-3 logbook. On June 13, 1997, the pilot flew the airplane for 0.6 hours and recorded the following: "Local-aerobatic-loop, slideback, split S, barrel roll, aileron roll." AIRCRAFT INFORMATION N99HV (formerly N67TD), s/n RV3-528, was one of three RV-3s built by Tony Duci (deceased). Construction was completed on November 11, 1979, and the airplane was issued an FAA Special Airworthiness Certificate in the Experimental Category on January 29, 1980. It was equipped with a Lycoming O-320 engine (s/n L-8663-27), rated at 150 horsepower, and an all wood, 2 blade, Great American propeller (m/n 68-66). The first RV-3 Mr. Duci constructed, N55F (formerly N55TD), broke up in flight on March 11, 1981, near Kennett, Missouri (see NTSB accident report MKC 81-F-A025). The accident airplane was his second creation. The third RV-3 he built, N81TD, was found to be registered to a private individual in Mullins, South Carolina. The following entry was made in the airplane's Performance Data: "11/20/81 - Delivered to Morgan, Mojave. 5/13/82 - Picked up plane with mods C-1 and new propeller." The following entry, dated May 13, 1982, was made in the airplane's Repairs Log: "Morgan Aviation - Completed modification CN-1. Copy appended this manual. This completes structural details - spar attachments - to qualify model change to RV-3A. To complete this qualification for acrobatics, flight demonstration remains as specified in CN-1." Upon learning of the accident, the airplane's previous owner, Henry Van Noy, submitted the following statement, dated March 12, 1998: "Mr. Coffland. . .received a placard and letters regarding the limit on acrobatics and the available main beam retrofit which had been reserved at the factory for his airplane. He said that he had discussed this with the staff at Van's Aircraft and did not plan to do acrobatics, and thus would defer the modification." Mr. Coffland's mechanic, John P. Sanders, submitted a statement, dated March 11, 1998, to wit: "I had no knowledge of any modification that was available to beef-up the spars on the RV-3. . .Chris (Coffland) never mentioned anything about a spar weakness or any concern about failure of his aircraft." In a note to Van's Aircraft, Inc., dated June 13, 1997, Mr. Coffland wrote: "Request that rights to the CN-2-I spar alteration kit be transferred to me and shipped as per request form." Van's Aircraft Invoice 116733 indicated "CN-301 CN2-I Spar Change" was shipped to Mr. Coffland on June 19, 1997. According to the maintenance records, the airplane was last inspected on March 1, 1998, "in accordance with the scope and detail of Appendix D of Part 43 and found to be in a condition for safe operation." At that time, the airframe had accumulated 755.1 hours. In the engine logbook, errors were noted in the interchangeable use of total, Hobbs meter, and tachometer times. Correcting for these errors, it was determined that the engine had accumulated 2,209:72 total hours, and 1,086.4 hours since major overhaul. WRECKAGE AND IMPACT INFORMATION The on scene examination disclosed a 15 foot long ground scar aligned on a magnetic heading of 268 degrees, terminating in a crater. From this point wreckage was distributed along a path aligned on a magnetic heading 230 degrees. The engine and propeller hub were 30 feet from the crater and slightly to the right of the wreckage path. The left wing and cockpit separated from the fuselage and were found 66 feet from the crater. The empennage and right wing were 164 feet and 196 feet beyond the crater, respectively. There were three creases across the top of the right wing, and the wing was bent up. The wing had pulled out from the spar, leaving about 6 inches of spar stub still attached to the wing. The majority of the spar remained with the left wing, and was also bent up and curled. Mr. Richard VanGrunsven, designer of the RV-3, examined the wreckage on March 16, 1998, and confirmed that the airplane had been modified and upgraded to an RV-3A in accordance with Change Notice CN-1. He also noted that some of the bolt holes in the spar immediately adjacent to (outboard) of the root rib showed little evidence (no elongation of the holes) of bolts having been installed. No bolt remnants were recovered and no torque marks were discernible (removal of bolts and nuts from the left wing revealed torque marks of the spar). MEDICAL AND PATHOLOGICAL INFORMATION An autopsy (#98A-093) and toxicological screen were performed by the El Paso County Coroner's Office County, Dr. David R. Bowerman, prosector. A toxicological screen was also performed by FAA's Civil Aeromedical Institute (CAMI). Both toxicology reports indicated negative findings for ethanol, cyanide, carbon monoxide, or drugs. The county coroner's report, however, indicated the presence of caffeine in the urine. TESTS AND RESEARCH The main and rear spars were shipped to NTSB's metallurgical laboratory for examination. According to the metallurgist's factual report, the twisting and upward bending of the right wing main spar upper cap was typical of "overstress separation." There was no evidence of deformation or distortion in any of the bolt holes. All rivets in both the upper and lower main spar caps were broken through the shanks, "consistent with direct shear separations. No evidence of cracking or breaking of rivet heads. . .was noted." The fractures of the right wing rear spar were typical of an overstress." The most recent weight and balance data for the airplane was dated June 25, 1987. It showed that the airplane's empty weight was increased to 796.3 pounds after the installation of a different propeller. The pilot's weight, based on his most recent airman medical certificate of June 23, 1997, was 215 pounds. A credit card receipt was later found in the pilot's wallet. He had purchased fuel at nearby Meadow Lake Airport in Peyton, Colorado, at 1436 on the afternoon of the accident. Based on this data, a weight and balance study was made and is attached to this report. At the time of the accident, it was estimated the airplane weighed 1,170.1 pounds. The utility category gross weight of the RV-3 is 1,100 pounds, and pilots are urged to limit the wing loading to 4.4 Gs factor. When operated in the aerobatic category, however, the RV-3A gross weight is reduced to 1,050 pounds. ADDITIONAL INFORMATION The following includes information was provided by Mr. Richard VanGrunsven, President of Van's Aircraft, Inc. Approximately 230 RV-3s have been built, and between 150 to 180 of these airplanes are active. NTSB's accident data base indicates there have been five RV-3 inflight structural failures. Mr. VanGrunsven said another RV-3 structural failure had occurred in Canada in 1979. After examining the spars and accident report findings from the first four accidents in Canada, Washington, Streator, Illinois, and Kennett, Missouri, the company concluded that construction deficiencies, particularly in spar construction and rear spar attach were probable contributing factors in three of these accidents. The RV-3 wing utilizes a NACA 23012 airfoil. The original wing spar (referred to as Type I, circa 1973-1983) was mathematically stress analyzed to design and ultimate load limits of 6.0 and 9.0 Gs, respectively, at an aerobatic gross weight of 1,050 pounds (non-aerobatic gross weight is 1,100 pounds). The spar consisted of .040 aluminum channel web with a build up of seven 1/8" x 1-1/4" bars held together with 1/8" AN470 rivets to form the upper and lower caps. As an assembly option, an epoxy adhesive could be used to bond the seven aluminum bars together to form a single unit to facilitate drilling and riveting the unit to the spar web. (It was later discovered that the adhesive provided some interbar shear and column strength, but the bonding process can deteriorate, so was not considered as contributing to spar strength. In 1982, the company conducted a static load test on a Type I spar and found that it met the 9.0 G ultimate load criteria. On March 16, 1981, FAA issued GENOT (General Notice) TWA 1/40 SVCB, prohibiting aerobatics in the RV-3. The action was permanent, and could not be rescinded. Following this action, the company issued Change Notice 1 (CN-1) to RV-3 owners and builders. Briefly, CN-1 modified the wing by reinforcing the rear spar attach point and strengthening the wing root rib. FAA and Canadian MOT (Ministry of Transport) reports on the RV-3 accidents suggested that these areas could have been the primary failure points. When CN-1 was drafted, it appeared that the only means of regaining aerobatic operating authorization would be for individual RV-3 owners to change their designation to RV-3A or something else. Soon thereafter, FAA issued another letter stating that RV-3 owners showing compliance with CN-1 could reapply for aerobatic operating limitations. Thus, the RV-3A designation was adopted by some builders, but does not signify any definite structural distinction. Records show that although N99HV had been modified in accordance with CN-1, it was never re-certificated as an RV-3A. In 1984, the wing spar was redesigned (referred to as the Type II spar). It incorporated five bars of 3/16" x 1-1/4" aluminum bar held together with 3/16" AN470 rivets. Though the primary purpose was to simplify construction and minimize the possibility of construction errors, a slight increase in calculated bending strength was achieved. Two additional ribs were added in the root rib area to increase torsional stiffness, and the rear spar attach was strengthened. Suggested airspeed limitations have remained relatively unchanged. Vne (Never Exceed speed) is 210 mph. Va (Maneuvering speed) is 127 mph (down from 132 mph). Vs (Stall speed, clean) is 54 mph. Because of the high ratio between Vne and Vs, the RV-3 is more susceptible to pilot-induced overstress than most contemporary light airplanes. Three other accidents followed involving inflight wing failures (Carmel, California, 1986; Antioch, California, 1988; Forest Grove, Oregon, 1995). All involved RV-3s with the original Type I wing. In 1996, an RV-3 wing with a Type I spar was again static load tested with failure occurring below the 9.0 G load level. A review of test data revealed that the 1982 test had been performed on a wing whose spar had been assembled with the optional epoxy bonding process. The 1996 test wing used a spar constructed without the epoxy adhesive. While the epoxy adhesive had not been calculated to add any spar bending strength, it appeared to have added compression buckling strength. As a result of further static load testing on both Type I and Type II wing spars, the company issued Change Notice II (CN-II), specifying a wing spar modification it deemed necessary for aerobatic strength. CN-II included a detailed history, explanation, and recommendations, and was sent to all known RV-3 and RV-3A owners and builders. In addition to the Federal Aviation Administration, parties to the investigation included Van's Aircraft, Inc., and Textron Lycoming. With the exception of the right wing main and aft spars, the wreckage was released to a representative of the pilot's insurance company on March 17, 1998. The spars were released to the representative on May 4, 1998.
in-flight failure of the right wing spar (for an undetermined reason) as the pilot was performing aerobatic flight. The airplane's excessive gross weight (for aerobatics) was a related factor.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
