# NTSB DCA16CA197: Facebook UK Aquila, N565AQ, Yuma, AZ, June 28, 2016 - Type: NTSB accident investigation - Classification: Accident · No injuries · Data collection · Final report - Date: June 28, 2016, 07:43 local (14:43 UTC) - Place: Yuma, AZ - Coordinates: 33.099998, -114.400001 - Nearby events: https://openairdocs.org/map.md?lat=33.1000&lon=-114.4000&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: No injuries - Status: Completed, report December 16, 2016 - Report: Approved by Office Director - NTSB office: Major Investigations Division - NTSB case key (mKey): 93514 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DCA16CA197 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/93514/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=93514 - Page: https://openairdocs.org/ntsb/DCA16CA197 ## Probable cause a structural failure of the wing as a result of exceeding the airspeed envelope due to wind gusts which were beyond the capabilities of the autopilot. Contributing to the accident was an insufficient amount of drag to track the glideslope in the presence of atmospheric disturbances. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Wing structure: main frame (on wing)](https://openairdocs.org/ntsb-findings/01035710): Aircraft › Aircraft structures · Failure (probable cause); cases with it: [Facebook UK AQUILA 1A, 1 case](https://openairdocs.org/ntsb-findings/01035710/cases.md?model=06101L5), [All aircraft, 8 cases](https://openairdocs.org/ntsb-findings/01035710/cases.md) - [Turbulence: convective turbulence](https://openairdocs.org/ntsb-findings/03032020): Environmental issues › Conditions/weather/phenomena · Effect on equipment (probable cause); cases with it: [Facebook UK AQUILA 1A, 1 case](https://openairdocs.org/ntsb-findings/03032020/cases.md?model=06101L5), [All aircraft, 145 cases](https://openairdocs.org/ntsb-findings/03032020/cases.md) - [Auto flight system: autopilot computer](https://openairdocs.org/ntsb-findings/01022211): Aircraft › Aircraft systems · Capability exceeded (probable cause); cases with it: [Facebook UK AQUILA 1A, 1 case](https://openairdocs.org/ntsb-findings/01022211/cases.md?model=06101L5), [All aircraft, 1 case](https://openairdocs.org/ntsb-findings/01022211/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Approach: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Facebook UK AQUILA 1A, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=06101L5), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Approach: Turbulence encounter](https://openairdocs.org/ntsb-events/360); cases with it: [Facebook UK AQUILA 1A, 1 case](https://openairdocs.org/ntsb-events/360/sequence.md?model=06101L5), [All aircraft, 423 cases](https://openairdocs.org/ntsb-events/360/sequence.md) ## Analysis On June 28, 2016, at 0743 mountain standard time, the Facebook Aquila unmanned aircraft, N565AQ, experienced an inflight structural failure on final approach near Yuma, Arizona. The aircraft was substantially damaged. There were no injuries and no ground damage. The flight was conducted under 14 Code of Federal Regulations Part 91 as a test flight, the aircraft did not hold an FAA certificate of airworthiness. This was the first flight of the full-scale aircraft. The flight launched in restricted airspace from Yuma Proving Ground's (YPG) Site 8 UAV runway. There were no anomalies noted during the 90-minute flight. According to the operator, at 0704, a simulated landing at 1,250 feet above sea level was performed to test the autoland feature of the autopilot. Autoland is the normal, and only, landing maneuver of the aircraft. The maneuver was executed normally, tracking the centerline and glidepath, and obeying the wave-off command. At the time of the simulated landing, the crew noted that the wind had increased above the intended test limit of 7 knots at flight altitude. At 0737, the crew commanded a landing to the designated landing site. During the final approach, the aircraft encountered an increasing amount of turbulence and wind speeds of up to 10 knots at the surface and 12 to 18 knots, as measured by the aircraft at flight altitude. The operators post-flight telemetry analysis showed that the aircraft experienced significant deviations in pitch, roll, and airspeed, consistent with turbulence during the final approach. At 0743, while on final approach at 20 feet above the ground, the right outboard wing experienced a structural failure with a downward deflection. Four seconds later, the aircraft impacted the ground at a groundspeed of 25 knots in an approximately wings-level attitude. The aircraft sustained substantial damage as a result of the impact and wing failure. As a result of the aircrafts design (skid landing gear, low-slung engines and propellers), the operator expected some damage during normal landings. The operators analysis of available data indicates that the structural failure was likely initiated by a wind gust that lofted the aircraft above the glidepath about 5 seconds prior to failure. The autopilot responded to this gust by lowering the nose of the aircraft to reestablish itself on the glidepath. The airspeed then increased to 28 KIAS from the normal 24 KIAS. As the aircraft descended back onto the glidepath, the autopilot started to deflect the elevons upwards. The operator determined that the combination of high airspeed, up elevon, and low angle of attack, resulted in increased downward lift (and torsion) on the outer wing panels. This loading exceeded its structural limit and resulted in a downward deformation and failure of the right wing. At the time of the last gust (5 seconds prior to touchdown) the aircraft was near idle power and the inboard propellers were commanded to the windmilling state - the highestdrag configuration available to the autopilot. ## Factual narrative On June 28, 2016, at 0743 mountain standard time, the Facebook Aquila unmanned aircraft, N565AQ, experienced an inflight structural failure on final approach near Yuma, Arizona. The aircraft was substantially damaged. There were no injuries and no ground damage. The flight was conducted under 14 Code of Federal Regulations Part 91 as a test flight, the aircraft did not hold an FAA certificate of airworthiness. This was the first flight of the full-scale aircraft. The flight launched in restricted airspace from Yuma Proving Ground's (YPG) Site 8 UAV runway. There were no anomalies noted during the 90-minute flight. According to the operator, at 0704, a simulated landing at 1,250 feet above sea level was performed to test the autoland feature of the autopilot. Autoland is the normal, and only, landing maneuver of the aircraft. The maneuver was executed normally, tracking the centerline and glidepath, and obeying the wave-off command. At the time of the simulated landing, the crew noted that the wind had increased above the intended test limit of 7 knots at flight altitude. At 0737, the crew commanded a landing to the designated landing site. During the final approach, the aircraft encountered an increasing amount of turbulence and wind speeds of up to 10 knots at the surface and 12 to 18 knots, as measured by the aircraft at flight altitude. The operators post-flight telemetry analysis showed that the aircraft experienced significant deviations in pitch, roll, and airspeed, consistent with turbulence during the final approach. At 0743, while on final approach at 20 feet above the ground, the right outboard wing experienced a structural failure with a downward deflection. Four seconds later, the aircraft impacted the ground at a groundspeed of 25 knots in an approximately wings-level attitude. The aircraft sustained substantial damage as a result of the impact and wing failure. As a result of the aircrafts design (skid landing gear, low-slung engines and propellers), the operator expected some damage during normal landings. The operators analysis of available data indicates that the structural failure was likely initiated by a wind gust that lofted the aircraft above the glidepath about 5 seconds prior to failure. The autopilot responded to this gust by lowering the nose of the aircraft to reestablish itself on the glidepath. The airspeed then increased to 28 KIAS from the normal 24 KIAS. As the aircraft descended back onto the glidepath, the autopilot started to deflect the elevons upwards. The operator determined that the combination of high airspeed, up elevon, and low angle of attack, resulted in increased downward lift (and torsion) on the outer wing panels. This loading exceeded its structural limit and resulted in a downward deformation and failure of the right wing. At the time of the last gust (5 seconds prior to touchdown) the aircraft was near idle power and the inboard propellers were commanded to the windmilling state - the highestdrag configuration available to the autopilot. ## Aircraft - Registration: [N565AQ](https://openairdocs.org/deregistered/N565AQ-2019-01-15), registration cancelled 2019-01-15, S/N F1501 (OpenAirDocs) - Reported make and model: FACEBOOK UK LTD AQUILA (1A) - Registry model: [Facebook UK AQUILA 1A](https://openairdocs.org/model/facebook-uk-aquila-1a) (registry code 06101L5) (OpenAirDocs) - Category: Airplane, unmanned - Serial number: F1501 - Year built: 2015 - Airframe hours: 1.5 - Engines: Joby Motor electric; Joby Motor electric; Joby Motor DSRF250 CW-02 electric; Joby Motor DSRF250 CW-02 electric - Damage: Substantial damage - Flight: Flight test, Part 91 - Operator: Facebook, Inc. - Registered owner: FCL Tech - Airworthiness certificate: None - Last inspection: June 27, 2016 - Departed: N/A, Yuma, AZ - Destination: None, Yuma, AZ - Airport: None, Site 8 YPG, runway 8, 500 × 500 ft, gravel - Equipment: Auto-pilot, Data recorder, Satellite tracking device, Video recording device, ADS-B, Airframe parachute, Angle of attack indicator ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 29; injuries: none; private; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review April 4, 2015; seat: left; flight hours: 1,688 total, 2 in this make and model, 1,609 as pilot in command, 13 in the last 90 days, 2 in the last 30 days - Co-pilot; age 37; injuries: none; private; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review March 15, 2016; seat: right; flight hours: 2,263 total, 28 in this make and model, 624 as pilot in command, 17 in the last 90 days, 3 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 180° at 10 knots - Temperature: 91 °F - Altimeter: 29.79 inHg - Turbulence: Moderate - Observed at: N/A ## Docket (1 files) The files NTSB released with the investigation on December 16, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=93514. 2.1 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40447661&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.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.