Nasa Ames Research Center SIERRA UNREG

Summary

On 27 July 2013 at about 02:15 local time, a Nasa Ames Research Center SIERRA registered UNREG, operated by NASA Ames Research Center, was involved in an accident near Beaufort Sea, Alaska, United States. Nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

27 July 2013 at 02:15

Classification

Accident

Location

Beaufort Sea, Alaska, United States

Coordinates

71.4744, -149.6364

Aircraft

Nasa Ames Research Center SIERRA

Registration

UNREG

Category

Airplane

Year built

2013

Engines

1

Operator

NASA Ames Research Center

Operating rule

Public Use

Purpose of flight

Aerial Observation

Phase of flight

Not recorded

Route

Oliktok Point → Oliktok Point

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

DCA13CA172

Nobody was injured.

continued operation into engine intake system icing conditions resulting in a loss of power; due to schedule pressure and an insufficient risk management process.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

On July 26, 2013, approximately 18:50 Alaska Daylight Time, a National Aeronautics and Space Administration (NASA) Sensor Integration Evaluation Remote Research Aircraft (SIERRA) single-engine fixed wing unmanned aircraft system (UAS) was substantially damaged following an engine power loss and uncontrolled descent into the Beaufort Sea, 65 nautical miles north of Oliktok Point, Alaska.  The flight was conducted as a non-military public aircraft operation under the provisions of Title 49 of the United States Code (U.S.C.) Sections 40102 and 40125, and a Federal Aviation Administration (FAA) Certificate of Authorization (COA). There were no injuries.   The UAS was on it's maiden science flight for the Marginal Ice Zone Observations and Processes Experiment (MIZOPEX) and lost engine power 4.5 hours into the 6 hour scheduled flight.  The UAS was powered by a 26 horsepower Herbrandson Dyad 290B 2-cycle carbureted engine with a belt driven pusher fixed pitch propeller.  The flight crew noted a loss of engine RPM and electrical bus voltage on the CloudCap Piccolo Autopilot (AP) system display that was part of the ground control system (GCS).  The UAS was beyond the range of the hand held radio and under the control of the Piccolo AP, upon losing power the GCS operator was unable to issue any commands to the aircraft.  Telemetry data revealed that for a period of about 60 minutes prior to the accident, RPM and altitude fluctuated, and throttle demand increased, indicating the possibility of engine intake icing. Weather conditions at the time of the accident were included relative humidity (RH) from 85% to 95%, at 4 degrees C. The nearest observation sites to the accident were Deadhorse (62 km) and Nuiqsut (52 km). Both of these stations reported temperatures ranging from 9 to 14 degrees Celsius during the flight time.  The National Center for Atmospheric Research examined the weather conditions and concluded a high risk for carburetor ice existed. The MIZOPEX Project was under significant time and budget constraints due to a change in project plan from a larger UAS platform requiring payload bay changes within the original funding timeline. A full NASA Mishap Investigation Team report of this accident is available in the public docket for this case.

Quoted verbatim from the NTSB record.