Sunday, November 15, 2020

Runway Excursion: General Atomics MQ-9, N341HK; accident occurred November 25, 2019 in Palmdale, Los Angeles County, California

Additional Participating Entity: 
Federal Aviation Administration / Flight Standards District Office; Van Nuys, California  

Investigation Docket - National Transportation Safety Board:


Location: Palmdale, California 
Accident Number: DCA20CA028
Date & Time: November 25, 2019, 10:52 Local 
Registration: N341HK
Aircraft: General Atomics MQ-9 
Aircraft Damage: Substantial
Defining Event: Runway excursion
Injuries: N/A
Flight Conducted Under: Part 91: General aviation - Instructional

Analysis

On November 25, 2019, at 1052 Pacific standard time (PST), N341HK a General Atomics Aeronautical Systems (GA-ASI) MQ-9 unmanned aircraft system (UAS), sustained substantial damage after departing runway 26 when landing during a training flight at the Gray Butte airport, Palmdale, California. The flight was operated by GA-ASI as a routine pilot and sensor operator training flight. The flight departed Gray Butte, and was conducted under the provisions of 14 CFR Part 91 and an FAA Certificate of Authorization (COA). There were no injuries or other damage.

At 1058 PST, the automated surface observation system at Gray Butte reported clear skies with wind from 260 at 18 knots, variable from 220 degrees to 290 degrees, with a peak wind of 270 degrees at 28 knots.

According to the operator/manufacturer, the student pilot was pilot-flying and the aircraft touched down at 79 knots indicated airspeed (KIAS) crabbed to the left approximately 5 degrees, consistent with a 7 knot crosswind component from the left. Upon touchdown, the aircraft began drifting to the left with the nose wheel off the ground. Over approximately the next 15 seconds, increasing right rudder was applied as the aircraft continued to drift left. Pitch stick position was +9 degrees (with pitch trim set to -5 degrees, pitch command was +4 degrees, 2 degrees above recommended pitch in the Flight Manual). The throttle was not moved to ground idle or reverse. A go-around was initiated, but the aircraft departed the runway before the engine could respond.

Operator/manufacturer examination of data logs systems information revealed that since the autopilot prioritizes pitch control over yaw control for movement of the ruddervators, the atypically high pitch command limited the ruddervator authority available for yaw control. With the ruddervators saturated in pitch, yaw authority from the ventral rudder alone was insufficient to effect a right yaw.

The flight manual did not have any information about the possibility of pitch control prioritization resulting in limited yaw authority.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be:
Incorrect control inputs by the student pilot during a crosswind landing, resulting in control saturation and a runway excursion.

Findings

Personnel issues Aircraft control - Student/instructed pilot
Environmental issues Crosswind - Response/compensation
Aircraft Crosswind correction - Incorrect use/operation

Factual Information

History of Flight

Landing Runway excursion (Defining event)

Student pilot Information

Certificate: Commercial 
Age: 28
Airplane Rating(s): Single-engine land 
Seat Occupied: Left
Other Aircraft Rating(s): None 
Restraint Used:
Instrument Rating(s): Airplane 
Second Pilot Present:
Instructor Rating(s): None 
Toxicology Performed: No
Medical Certification: Class 2 Without waivers/limitations
Last FAA Medical Exam: August 8, 2019
Occupational Pilot: Yes 
Last Flight Review or Equivalent: September 19, 2018
Flight Time: 987.7 hours (Total, all aircraft), 315 hours (Total, this make and model) 

Flight instructor Information

Certificate: Commercial; Flight instructor
Age:
Airplane Rating(s):
Seat Occupied: Rear
Other Aircraft Rating(s):
Restraint Used: None
Instrument Rating(s): 
Second Pilot Present:
Instructor Rating(s): 
Toxicology Performed: No
Medical Certification: 
Last FAA Medical Exam:
Occupational Pilot: 
Last Flight Review or Equivalent:
Flight Time: 2906 hours (Total, all aircraft)

Aircraft and Owner/Operator Information

Aircraft Make: General Atomics 
Registration: N341HK
Model/Series: MQ-9 5 
Aircraft Category: Airplane
Year of Manufacture: 2014
Amateur Built: No
Airworthiness Certificate: Certificate of authorization or waiver (COA)
Serial Number: FC341
Landing Gear Type: Retractable - Tricycle
Seats: 0
Date/Type of Last Inspection: October 22, 2019 
Certified Max Gross Wt.: 10500 lbs
Time Since Last Inspection: 
Engines: 1 Turbo prop
Airframe Total Time: 1979.9 Hrs at time of accident
Engine Manufacturer: Honeywell International Inc.
ELT: Not installed
Engine Model/Series:
Registered Owner: 
Rated Power:
Operator: 
Operating Certificate(s) Held: Certificate of authorization or waiver (COA)

Meteorological Information and Flight Plan

Conditions at Accident Site: Visual (VMC)
Condition of Light: Day
Observation Facility, Elevation: KGXA,3028 ft msl
Distance from Accident Site: 0 Nautical Miles
Observation Time: 10:58 Local 
Direction from Accident Site: 0°
Lowest Cloud Condition: Clear 
Visibility: 10 miles
Lowest Ceiling: 
Visibility (RVR):
Wind Speed/Gusts: 18 knots /
Turbulence Type Forecast/Actual: /
Wind Direction: 
Turbulence Severity Forecast/Actual: /
Altimeter Setting: 29.85 inches Hg 
Temperature/Dew Point:
Precipitation and Obscuration:
Departure Point: Palmdale, CA (04CA)
Type of Flight Plan Filed: None
Destination: Palmdale, CA (04CA)
Type of Clearance: None
Departure Time: 08:44 Local
Type of Airspace: Class G

Airport Information

Airport: Gray Butte 04CA 
Runway Surface Type: Asphalt
Airport Elevation: 3028 ft msl 
Runway Surface Condition: Dry
Runway Used: 26 
IFR Approach: None
Runway Length/Width: 8000 ft / 150 ft
VFR Approach/Landing: Full stop;Traffic pattern

Wreckage and Impact Information

Crew Injuries: N/A
Aircraft Damage: Substantial
Passenger Injuries:
Aircraft Fire: None
Ground Injuries: N/A 
Aircraft Explosion: None
Total Injuries: N/A
Latitude, Longitude: 34.571109,-117.668891

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