Reno, NV, USA
N501GP
BACKOVICH GEORGE C G P 5
The one-of-a-kind airplane designed specifically for air racing was participating in a practice air race session. Photographic and video evidence showed that the airplane entered the race course while accelerating and descending as the pilot was banking left around the back side of the race course. While passing one of the race pylons, the outboard portion of the right wing failed, and the airplane began rolling to the right followed by the empennage fragmenting and separating from the fuselage as the airplane descended into the ground. Based on the available evidence, the outboard right wing separation was the initiating failure and the empennage separation was a secondary failure. The outboard portion of right wing was reconstructed using the pieces found in the initial debris path. The reconstruction revealed that the right wing forward box spar fractured at the inboard end of a splice repair to the right wing spar in an area where the upper and lower spar caps transitioned from a singular rectangular cross section to two smaller rectangular finger sections. The scarf joints on each finger were also fractured through the adhesive with no evidence of wood grain failure on either side of the scarf areas. Typically, failure of a bonded wood joint should occur within the wood grain adjacent to the bond area if the adhesive has been properly prepared and applied. The accident airplane was involved in a landing accident about 30 months before the accident that substantially damaged the right wing. The wing was reportedly removed from the airplane and repaired by the original designer. No information existed on the repair, no logbook entry was made for the repair, and no requirement for documenting any repairs to the airplane existed in the operating limitations. It is likely that the right wing spar repair was not done in accordance with the approved methods in the Federal Aviation Administration Advisory Circular (AC) 43.13-1B, thus the strength of the wing in the area of the repair was reduced. Aircraft maintenance records contained entries related to cracking in the right and left wing lower skins. Personnel working on the airplane during the air races reported that the cracking was located in the area aft of the forward spar near the main landing gear trunnions, which was well inboard of the area where the right wing failed. The investigation determined that these cracks did not contribute to the accident. The morning of the accident, the pilot attempted a practice flight; however, he pulled off the course shortly after entering the course due to an excessive vibration. The race crew determined that the pilot had encountered the rev-limiting function on the engine control unit. The pilot reported to another pilot that he thought the airplane was going to shake itself apart during the event. It is possible that the airframe vibrations induced by the engine could have affected the spar repair on the right wing. Further, the airplane's high speed, high g-loads, and left bank produced wing loads sufficient to fail the right wing forward spar at the location of a previous repair. Even though the airplane was likely not being operated outside the original design envelope at the time of the right wing failure, the reduced strength of the repair led to the wing's failure.
HISTORY OF FLIGHTOn September 8, 2014, about 1516 Pacific daylight time, an experimental amateur built Backovich GP-5 airplane, N501GP, was destroyed when it impacted terrain following an in-flight breakup while conducting a practice race at the Reno-Stead Airport (RTS) Reno, Nevada. The airplane was registered to Lancair Northwest LLC, Portland, Oregon, and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The commercial pilot, sole occupant of the airplane, was fatally injured. Visual meteorological conditions prevailed and no flight plan was filed for the air race flight. The local flight originated from RTS about 5 minutes prior to the accident. Photographic and video evidence was obtained from spectators that captured the accident sequence. The evidence showed that the airplane was established in a left bank when a portion of the outboard right wing separated. The airplane began rolling to the right and descended to impact with the ground. The empennage fragmented and separated as the airplane was rolling and descending. Information provided by the Reno Air Race Association (RARA) revealed that the accident airplane had flown earlier in the day prior to the accident. During this flight, the pilot initiated a mayday call and landed due to a vibration, which he felt was due to reaching the engine rev limiter. PERSONNEL INFORMATIONThe pilot, age 63, held a commercial pilot certificate with an airplane single-engine land, airplane single-engine sea, airplane multi-engine land, and instrument airplane ratings. A second-class airman medical certificate was issued to the pilot on May 14, 2014, with the limitation stated "must have corrective lenses for distant and near vision." The pilot reported on his air races entry packet, dated July 18, 2014, that he had accumulated over 9,000 hours of total flight time, 35 hours within the previous 90 days, and 120 hours in the accident make/model airplane. AIRCRAFT INFORMATIONThe experimental amateur-built single-seat, low-wing, retractable-gear, tailwheel equipped airplane, serial number (S/N) 001, was completed in 2002. It was powered by a Chevrolet V8 engine, rated at 625 horse power. The airplane was also equipped with a three bladed adjustable pitch propeller. The Backovich GP-5 airplane was designed by a private individual specifically for air racing and was completed in 2011 in its current configuration. The one-of-a-kind airplane was 24 feet, 2 inches long with a wing span of 22 feet, 2 inches. The airplane was manufactured with wood primary structure and had a fiberglass overwrap layer on the exterior surfaces. No design drawings or engineering documents exist for the airplane. The airplane was originally completed in 2002 and received a special airworthiness certificate on December 30, 2002, in the experimental category with registration number N153GB. The accident pilot flew the airplane in the 2010 National Championship Air Races (NCAR) and subsequently purchased the airplane on behalf of Lancair Northwest, LLC, on October 6, 2010. The airplane registration number was changed to N501GP on November 12, 2011. The airplane received a new special airworthiness certificate on July 10, 2012, in the experimental category with experimental operating limitations for phase 1 and phase 2. The airplane was entered and raced in the 2012 NCAR where it placed fourth. It was not entered in the 2011 or 2013 NCAR. The airframe logbook had numerous entries from its beginning on November 28, 2002, through September 15, 2010, when the last entry was made before the sale. The airframe had accrued 41.5 hours time in service (TIS) by this date. The entries detailed ongoing issues with the engine and numerous test flights. An entry on August 7, 2010, certified that the flight testing was complete at 40.25 hours TIS. The first entry after the sale was made on January 26, 2012, in which a new electrical system, engine mount, engine, and avionics was installed at 42.5 hours TIS. A condition inspection was also completed at this time. Four additional logbook entries were made before the accident date. On February 5, 2013, work was documented on the landing gear and a condition inspection was signed off at 98.0 hours TIS. On March 18, 2014, work was documented to repair cracks in the left wing lower skin and repair the elevator bellcrank bulkhead. A condition inspection was signed off at 128.2 hours TIS. On September 2, 2014, work was documented to repair cracks in the right wing lower skin and to tighten and re-safety a bolt on the right aileron bellcrank. The condition inspection was signed off at 128.2 hours TIS. On September 3, 2014, work was documented on the tail wheel at an unknown TIS. The engine logbook documented the installation of the engine on January 26, 2012, with a tach time of 0.0 hours. A total of 4 entries in the engine logbook documented minor maintenance and condition inspections of the engine that matched dates on 4 of the entries in the airframe logbook. Three of the engine entries contained tach times that matched with the tach time reported in the airframe logbook but the corresponding increase in airframe time did not correlate. The propeller logbook documented the installation of the propeller on January 2, 2012, with a total time of 0.0 hours. Three additional entries in the propeller logbook documented condition inspections of the propeller that matched dated entries in the airframe and engine logbooks. The propeller total time entered on February 5, 2013, did not correlate with either the airframe or engine times. METEOROLOGICAL INFORMATIONA review of recorded data from the Reno-Tahoe International Airport automated weather observation station, located about 14 miles south of the accident site, revealed at 1455, conditions were wind from 200 degrees at 13 knots, gusting to 21 knots, visibility 10 statute miles, a scattered cloud layer at 10,000 feet, temperature 30 degrees Celsius, dew point -2 degrees Celsius, and an altimeter setting of 29.91 inches of mercury. AIRPORT INFORMATIONThe experimental amateur-built single-seat, low-wing, retractable-gear, tailwheel equipped airplane, serial number (S/N) 001, was completed in 2002. It was powered by a Chevrolet V8 engine, rated at 625 horse power. The airplane was also equipped with a three bladed adjustable pitch propeller. The Backovich GP-5 airplane was designed by a private individual specifically for air racing and was completed in 2011 in its current configuration. The one-of-a-kind airplane was 24 feet, 2 inches long with a wing span of 22 feet, 2 inches. The airplane was manufactured with wood primary structure and had a fiberglass overwrap layer on the exterior surfaces. No design drawings or engineering documents exist for the airplane. The airplane was originally completed in 2002 and received a special airworthiness certificate on December 30, 2002, in the experimental category with registration number N153GB. The accident pilot flew the airplane in the 2010 National Championship Air Races (NCAR) and subsequently purchased the airplane on behalf of Lancair Northwest, LLC, on October 6, 2010. The airplane registration number was changed to N501GP on November 12, 2011. The airplane received a new special airworthiness certificate on July 10, 2012, in the experimental category with experimental operating limitations for phase 1 and phase 2. The airplane was entered and raced in the 2012 NCAR where it placed fourth. It was not entered in the 2011 or 2013 NCAR. The airframe logbook had numerous entries from its beginning on November 28, 2002, through September 15, 2010, when the last entry was made before the sale. The airframe had accrued 41.5 hours time in service (TIS) by this date. The entries detailed ongoing issues with the engine and numerous test flights. An entry on August 7, 2010, certified that the flight testing was complete at 40.25 hours TIS. The first entry after the sale was made on January 26, 2012, in which a new electrical system, engine mount, engine, and avionics was installed at 42.5 hours TIS. A condition inspection was also completed at this time. Four additional logbook entries were made before the accident date. On February 5, 2013, work was documented on the landing gear and a condition inspection was signed off at 98.0 hours TIS. On March 18, 2014, work was documented to repair cracks in the left wing lower skin and repair the elevator bellcrank bulkhead. A condition inspection was signed off at 128.2 hours TIS. On September 2, 2014, work was documented to repair cracks in the right wing lower skin and to tighten and re-safety a bolt on the right aileron bellcrank. The condition inspection was signed off at 128.2 hours TIS. On September 3, 2014, work was documented on the tail wheel at an unknown TIS. The engine logbook documented the installation of the engine on January 26, 2012, with a tach time of 0.0 hours. A total of 4 entries in the engine logbook documented minor maintenance and condition inspections of the engine that matched dates on 4 of the entries in the airframe logbook. Three of the engine entries contained tach times that matched with the tach time reported in the airframe logbook but the corresponding increase in airframe time did not correlate. The propeller logbook documented the installation of the propeller on January 2, 2012, with a total time of 0.0 hours. Three additional entries in the propeller logbook documented condition inspections of the propeller that matched dated entries in the airframe and engine logbooks. The propeller total time entered on February 5, 2013, did not correlate with either the airframe or engine times. WRECKAGE AND IMPACT INFORMATIONExamination of the accident site by representatives from the National Transportation Safety Board (NTSB) revealed that wreckage debris was scatted between race pylons 5 and 6 of the outer race course. All major structural components of the airplane were located within the approximate 4,000 foot long debris path. All debris remained within the predetermined safety areas for the outer race course. There were three distinct debris fields located in the sagebrush covered terrain. The first debris field along the route of flight contained the outboard portion of the right wing, fragmented portions of the right aileron, the aileron bellcrank, and numerous pieces of wing skin and internal wing structure. The second debris field along the route of flight contained the right and left horizontal stabilizers, right and left elevators, the fragmented vertical stabilizer and rudder, pieces of the empennage structure, and several pieces of the acrylic canopy. The third debris field along the route of flight contained the initial impact crater and the highly fragmented remains of the airplane, engine and propeller. There was no evidence of a post-crash fire. The entire airplane was accounted for in the three debris fields. The debris from the first and second debris fields was collected separately for further examination. The g-meter was found in the third debris field. One pointer was situated just above zero, one was situated at -4.5 and one was situated at -4.0. The Advanced Flight Systems AF-4500 multifunction display (MFD) screen and main body were recovered separated in the third debris field. The Pectel SQ6 Engine Control Unit (ECU) was also recovered in the third debris field. The MFD and ECU were sent to the NTSB Vehicle Reorders Laboratory for download and analysis. See the NTSB Onboard Electronic Devices Specialist's Factual Report in the public docket for the details of the investigation. Further examination of the right wing was conducted by the Airworthiness Group. The group reconstructed the outboard right wing using the pieces recovered in the first debris field. The largest intact piece of right wing included the forward portion of rib 9, rib 10, rib 11, the wingtip outboard of rib 11, the forward spar outboard of rib 10, and portions of the upper and lower skins. Most of the outboard 50 inches of right wing was conclusively identified in the recovered debris from the inboard end of the aileron to the wing tip. The outboard 50 inches of upper wing skin was identified and reconstructed between the forward and rear spars. The leading edge structure forward of the forward spar and inboard of rib 9 (about 32 inches inboard of the wing tip) was not conclusively identified. The forward portion of rib 9 was intact forward of the forward spar. The aft portion of rib 9 between the forward and rear spars was reconstructed. The nose of the leading edge between rib 9 and about 9 inches inboard of the wing tip was not conclusively identified. Most of the lower wing skin from rib 9 outboard was identified and reconstructed between the forward end of the nose ribs and the rear spar. A triangular section between ribs 9 and 10 and forward of the forward spar was not conclusively identified. Rib 10 was intact and located about 10 inches outboard of rib 9 or 22 inches inboard of the wing tip. There was a rectangular section of lower wing skin missing just outboard of rib 10 that extended from the rear spar location forward about 4 inches. The area was consistent with the location of the outboard aileron balance weight. The forward spar was a box structure. The forward spar upper spar cap transitioned from a solid rectangular cap to two finger caps about 7 inches inboard of rib 9. Examination of the wreckage revealed a spliced section of forward spar upper spar cap about 18.5 inches long that spanned from about 10.5 inches inboard of rib 9 to about 8 inches outboard of rib 9. The spliced section contained the transition area with a single scarf joint at the inboard end in the rectangular area and two scarf joints at the outboard end in the finger area. The spliced section of forward spar upper spar cap remained attached to a section of the wing upper skin. The upper spar cap was fractured through the grain of the splice piece at the inboard scarf joint. The bond line and remaining portion of the scarf were not identified. The upper spar cap fingers were fractured through the grain of the splice piece from about rib 9 outboard. The forward finger scarf was intact. The aft finger was also fractured at the scarf with both adhesive and wood grain failure in the scarf area. The outboard ends of the finger scarfs also had thin wood doublers installed on the lower surface of the upper spar cap. There was no evidence of doublers installed at the inboard scarf joint on the upper spar cap. The identified portions of the forward spar lower spar cap only consisted of the two fingers, there was no transition area. Each finger had a spliced section between about 7 inches inboard of rib 9 to about 6 inches outboard of rib 10. The inboard scarfs were fractured through the adhesive with no fracture of the wood in the scarf areas. Each of the fingers was also fractured about 10 inches inboard of rib 9 (inboard of the end of the scarf joints) with features consistent with positive bending overload. The outboard scarf joints were intact and each had a thin wood doubler installed on the upper surface of the lower spar cap. There was no evidence of doublers installed at the inboard scarf joints on the lower spar cap. There was significant excessive dried adhesive present throughout the area of the spliced section of spar. The aileron bellcrank was recovered separated from the wing structure but still remained attached to a section of the forward spar aft web just inboard of rib 9. The section of aft web extended from about 8 inches inboard of rib 9 to about 3 inches outboard of rib 9. The section of aft web from about 3 inches outboard of rib 9 to rib 10 was separated from the wing. The aileron push-pull tube was fractured about 7.5 inches inboard of the bellcrank attach point with features consistent with bending overload. The aileron control link was fractured in the threaded portion at the aft end about 10 inches aft of the bellcrank attach point. The forward spar forward web was fractured about 10 inches inboard of rib 9 and intact from the fracture to the wing tip. Most of the rear spar was reconstructed from the inboard aileron hinge to the outboard aileron hinge. This portion of rear spar wa
The failure of the right wing under normal race loads due to an improper repair of the right wing spar that reduced its structural strength following a previous landing accident.
Source: NTSB Aviation Accident Database
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