Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf
Docket And Docket Items - National Transportation Safety Board: https://dms.ntsb.gov/pubdms
Aviation Accident Data Summary - National Transportation Safety Board: https://app.ntsb.gov/pdf
NTSB Identification: DCA16CA197
14 CFR Part 91: General Aviation
Accident occurred Tuesday, June 28, 2016 in Yuma, AZ
Probable Cause Approval Date: 12/16/2016
Aircraft: FACEBOOK UK LTD AQUILA, registration: N565AQ
Injuries: Unavailable
NTSB investigators used data provided by various entities, including, but not limited to, the Federal Aviation Administration and/or the operator and did not travel in support of this investigation to prepare this aircraft accident report.
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 highest drag configuration available to the autopilot.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
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.
Facebook’s Drone Crash Prompts Safety Investigation: Giant drone, called Aquila, experienced a “structural failure” during a test flight on June 28, according to the National Transportation Safety Board
The Wall Street Journal
By DEEPA SEETHARAMAN
November 21, 2016 8:59 p.m. ET
A U.S. air-safety watchdog is investigating an accident during the first flight of a Facebook Inc. drone designed to extend internet access.
The giant drone, called Aquila, experienced a “structural failure” while approaching Yuma, Ariz. during a test flight on June 28, according to a spokesman for the National Transportation Safety Board. There were no injuries, but the drone was “substantially damaged” and the damage “compromised the airworthiness of the aircraft,” the spokesman said.
A Facebook spokeswoman declined to share details about the damage or cause of the failure ahead of the NTSB’s report. A spokeswoman said Facebook viewed the Aquila test flight a success. “We have already learned a lot from the results of this flight test and will continue to learn from all the future flight tests we plan to run,” she said.
The NTSB, whose primary function is to probe accidents, plans to release a more detailed report on the accident within the next two months. Bloomberg first reported on the accident Monday.
The incident is the latest snag in Facebook’s broader push to boost global internet availability through its Internet.org initiative.
In September, a Facebook satellite was destroyed on the launchpad during a t est of the Falcon 9 rocket designed by Elon Musk’s Space Exploration Technologies Corp., or SpaceX. In February, India’s telecommunications regulator banned a Facebook service that offered unlimited access to a limited number of websites.
Eventually, Facebook hopes to build a fleet of high-altitude, solar-powered Aquila drones that can beam broadband access to the 1.6 billion people that live in areas that don’t have access to a mobile network today. The Aquila drone weighs less than a 1,000 pounds and has a 138-foot wingspan, larger than a Boeing 737 single-aisle plane. Facebook expects the drone to stay aloft for 90 days at a time.
Facebook previously said that Aquila’s flight lasted 96 minutes, more than an hour longer than planned. The accident occurred at 7:43 a.m. local time, according to the NTSB.
Facebook previously flagged the structural failure in a July 21 blog post. It said engineers were analyzing the results of the test, including “a structural failure we experienced just before landing.”
The Federal Aviation Administration authorizes such experimental drones to fly only in specific designated areas, isolated from manned aircraft.
The agency is currently working on regulations addressing commercial uses of small drones, 55 pounds or less, at altitudes below 400 feet. Rules covering larger drones weighing hundreds of pounds or more -- and designed to operate at much higher altitudes -- are years away despite strong industry pressure for faster federal action.
—Andy Pasztor contributed to this article.
Original article and comments can be found here: http://www.wsj.com
No comments:
Post a Comment