# NTSB WPR21LA108: Abbett Gerry Lancair Evolution, N7569A, Saratoga, WY, February 8, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: February 7, 2021, 18:44 local (Feb 8, 2021, 01:44 UTC) - Place: Saratoga, WY - Coordinates: 42.1, -107.58 - Nearby events: https://openairdocs.org/map.md?lat=42.1000&lon=-107.5800&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) - Highest injury: No injuries - Injuries: 3 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FSDO - NTSB case key (mKey): 102614 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA108 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102614/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102614 - Page: https://openairdocs.org/ntsb/WPR21LA108 ## Probable cause A windshield failure during cruise flight due to stress concentrations in the bond area as a result of improper assembly of the windshield. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Windows-windshield system: flight compartment windows](https://openairdocs.org/ntsb-findings/01035610): Aircraft › Aircraft structures · Fatigue/wear/corrosion (probable cause); cases with it: [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/01035610/cases.md) - [Windows-windshield system: flight compartment windows](https://openairdocs.org/ntsb-findings/01035610): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [All aircraft, 42 cases](https://openairdocs.org/ntsb-findings/01035610/cases.md) - [Maintenance: fabrication](https://openairdocs.org/ntsb-findings/02062025): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [All aircraft, 30 cases](https://openairdocs.org/ntsb-findings/02062025/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338) (defining event); cases with it: [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) - [Enroute-cruise: Emergency descent initiated](https://openairdocs.org/ntsb-events/130); cases with it: [All aircraft, 42 cases](https://openairdocs.org/ntsb-events/130/sequence.md) ## Analysis While in cruise flight at 27,000 ft mean sea level, the experimental, amateur-built airplane’s windshield shattered, followed immediately by a rapid decompression of the cabin. The pilot performed an emergency descent and landed uneventfully. The windshield was substantially damaged. Examination revealed that the fracture originated from a small crack located at the exterior surface of the windshield within the bonded edge. The presence of parallel linear scratches near the fracture origin and on the windshield edge suggests that the bonded area was not sanded in accordance with the build instructions. The evidence also suggests that the in-service stresses in the as-manufactured windshield were high enough to cause fractures from scratches that deviated from the build instructions; therefore, it is likely that the windshield failure was the result of stress concentrations in the bond area due to scratches made with methods inconsistent with the build instructions. ## Factual narrative On February 7, 2021, about 1844 mountain standard time, an experimental, amateur-built Lancair Evolution airplane, N7569A, was substantially damaged when it was involved in an accident near Saratoga, Wyoming. The pilot and the two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, while diverting to an airport to assess a landing gear issue and during cruise flight at 27,000 ft mean sea level (msl), he heard an “explosion” that knocked the headsets off the airplane occupants’ heads immediately followed by a rapid depressurization of the cabin. The pilot reduced power to idle, deployed the landing gear, and entered a rapid descent. Once the airplane was in an established descent, the pilot activated the autopilot and configured it to level off at 12,500 ft msl in the event they lost consciousness. The pilot stated that he did not don the oxygen mask or headset because he did not feel comfortable removing his hands from the controls given the operational and environmental conditions at the time. After leveling the airplane at 12,500 ft msl, the pilot searched for the closest airport and subsequently landed without incident. Postaccident photographs showed substantial damaged to the windshield. According to the pilot, the airplane received annual inspections from a maintenance facility in Redmond, Oregon, from its construction to the date of the accident. The maintenance facility that built the airplane in 2016 and performed condition inspections in the years that followed reported that they did not perform any work on the windshield. The windshield was manufactured from 3/8-inch-thick cast polymethyl methacrylate, commonly referred to as acrylic. According to the manufacturer’s build instructions, once the outer edges of the windshield are cut and smoothed to fit within a joggle around the windshield, the interior and exterior bond surfaces are sanded first with 80 grit abrasive paper along the edge of a reference tape. The entire bond area is then sanded with 40-grit paper using a dual action (DA) sander. Once the sanding is complete, the bond areas are cleaned using alcohol and the exterior bond surface is bonded to the frame using a Hysol 9360 epoxy. The interior bond surface is bonded with a wet layup of carbon fabric and Rhino 1307-LV epoxy resin and hardener. The manufacturer reported that the sanding would have taken place at the airplane kit manufacturer’s facility. Examination at the NTSB materials laboratory identified the primary crack origin at the lower right side of the windshield at the exterior surface of the windshield and a fracture that emanated from that origin area. Elliptical scratches were observed across most of the bond surface, consistent with the use of a DA sander; however, many edges around the circumference of the windshield exhibited a flat chamfer with linear grinding marks on the flat portion along with deep parallelgrooves. According to the build instructions, the edge of the windshield required the use of a DA grinder for a rounded (bull nose) edge profile. The windshield also contained cracks emanating from elliptical scratches in bond areas on the exterior surface near the origin and the interior surface near the upper edge. The windshield edge was similar to the edge of a windshield that was analyzed as part of a separate accident investigation (NTSB accident number WPR17LA104), where cracks were observed emanating from grooves at the flat chamfered edge. ## Aircraft - Registration: N7569A (not matched to a registry record) - Reported make and model: ABBETT GERRY LANCAIR EVOLUTION - Category: Airplane, amateur-built - Serial number: 067 - Year built: 2016 - Airframe hours: 387 - Engines: P&W CANADA PT6A-42A 850 horsepower turbo prop - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 2, 2020, 0 hours before - Departed: AFO, Afton, WY - Destination: VPZ, Valparaiso, IN - Flight plan: IFR - Equipment: Electronic primary flight display, Onboard weather, Stall warning system, ADS-B, Angle of attack indicator, Auto-pilot, Electronic multifunction display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, without waivers/limitations; last flight review March 12, 2020; seat: left; restraint: 3-point; flight hours: 1,323 total, 314 in this make and model, 1,257 as pilot in command, 21 in the last 90 days, 11 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 28 knots, gusting 42 - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 28 °F, dew point 7 °F - Altimeter: 29.65 inHg - Observed at: KRWL, 25 nm away - METAR: METAR KRWL 080153Z AUTO 27028G42KT 9SM -SN CLR M02/M14 A2965 RMK AO2 PK WND 27044/0055 SLP054 P0000 T10171139= ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Accident 20210207001729A](https://openairdocs.org/incident/20210207001729A), Feb 7, 2021: Abbett Gerry LANCAIR EVOLUTION, Saratoga, WY, Substantial damage. N7569A, a Lancair Evolution, was in cruise flight on February 7th 2021 over central Wyoming when the aircraft experienced a windscreen separation at flight… ## Docket (6 files) The files NTSB released with the investigation on November 8, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102614. 14.5 MB in all. - Materials laboratory factual report 22-008 (item 1, PDF, 19 pages, 30 photos, 7.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14288988&FileExtension=pdf&FileName=22-008-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 11 pages, 5.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13320334&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Email correspondence (item 3, PDF, 8 pages, 214 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14566191&FileExtension=pdf&FileName=email%20correspondence_Redacted-Rel.pdf - Manufacturer's window installation procedures (item 4, PDF, 2 pages, 219 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14616894&FileExtension=pdf&FileName=Excerpt%20from%20window%20installation%20procedure-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 5, PDF, 2 pages, 615 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14536908&FileExtension=pdf&FileName=NTSB%20Release%20of%20Wreckage_Redacted-Rel.pdf - Accident photographs (item 6, PDF, 4 pages, 926 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14530075&FileExtension=pdf&FileName=Accident%20Photographs-Rel.pdf From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.