# NTSB WPR18LA036: Doshier Wilbert A GT-500, N599RA, Willows, CA, November 25, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: November 25, 2017, 15:15 local (23:15 UTC) - Place: Willows, CA - Coordinates: 39.515834, -122.217224 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.5158&lon=-122.2172&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 96370 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR18LA036 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96370/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96370 - Page: https://openairdocs.org/ntsb/WPR18LA036 ## Probable cause A loss of engine power during takeoff due a coolant leak and the subsequent overheating of the engine, and the student pilot's failure to maintain airspeed and his exceedance of the airplane's critical angle of attack, which resulted in an aerodynamic stall and collision with terrain. Contributing to the accident was inadequate maintenance inspection and the flight instructors delayed remedial action. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng liquid cooling](https://openairdocs.org/ntsb-findings/01058570): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-findings/01058570/cases.md?model=056284S), [All aircraft, 17 cases](https://openairdocs.org/ntsb-findings/01058570/cases.md) - [Performance/control parameters: angle of attack](https://openairdocs.org/ntsb-findings/01062042): Aircraft › Aircraft oper/perf/capability · Capability exceeded (probable cause); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-findings/01062042/cases.md?model=056284S), [All aircraft, 990 cases](https://openairdocs.org/ntsb-findings/01062042/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Other (probable cause); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=056284S), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) - [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Student/instructed pilot (probable cause); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=056284S), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md) - [Attention/monitoring: monitoring other person](https://openairdocs.org/ntsb-findings/02021535): Personnel issues › Psychological · Instructor/check pilot (probable cause); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-findings/02021535/cases.md?model=056284S), [All aircraft, 200 cases](https://openairdocs.org/ntsb-findings/02021535/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=056284S), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=056284S), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Doshier Wilbert A GT-500, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=056284S), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The flight instructor and the student pilot, who was the pilot flying, departed for the third leg of the cross-country flight. The student pilot indicated that shortly after takeoff, when the airplane was about 70 ft above the runway, the engine sputtered and then lost power. He stated that he attempted to land straight ahead but did not maintain proper airspeed. The video from an onboard camera showed that after the engine lost power, the student pilot pulled back on the yoke, and the airplane rapidly descended toward the runway and impacted the ground likely following an aerodynamic stall. Postaccident examination of the engine revealed that the radiator coolant level was low enough that the fluid was not visible through the radiator cap. The examination revealed a coolant leak around the water pump housing nipple due to an improper seal of the hose to the nipple attachment. In addition, the radiator recovery and overflow bottle were improperly installed, which prevented the system from refilling coolant into the radiator during the engine cooling period in between flights. The intake port sides of the cylinders had antifreeze particles embedded into their surfaces consistent with overheating. The top portion of the No. 1 piston exhibited melted metal deposits from spark plug electrodes consistent with preignition and detonation, and the No. 2 piston exhibited discoloration and burnt-on carbon deposits consistent with the piston overheating for a period of time. It is likely that the airplane had lost a significant amount of coolant during the previous legs of the cross-country flight, which led to an overheated cylinder and subsequent engine failure. In addition, the student pilot failed to maintain airspeed after the partial loss of engine power. The airplane exceeded its critical angle of attack, which resulted in an aerodynamic stall at an altitude too low to recover. ## Factual narrative On November 25, 2017, about 1515 Pacific standard time, an amateur-built Quicksilver GT-500, N599RA, was substantially damaged when it was involved in an accident near Willows, California. The flight instructor and the student pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The student pilot, who was the pilot flying, reported that the accident flight was the third leg of a cross-country flight. He stated that after topping off both fuel tanks, the flight was departing from Willows-Glenn County Airport (WLW), Willows, California; when the airplane was about 70 ft above ground level and halfway down the runway, the engine momentarily sputtered and then experienced a total loss of power. He indicated that he attempted to land straight ahead but did not maintain proper airspeed, which, in his opinion, resulted in an aerodynamic stall and impact with terrain. Video from an onboard camera on the airplane’s left outboard wing showed the airplane lifting off about 4 minutes 25 seconds after the engine start. During the initial climb, the airplane was right of the runway centerline, and 22 seconds after liftoff, the engine lost power. The engine can be heard detonating about 15 seconds after full throttle application, and it started to seize until it completely lost power. The student pilot pulled back on the control yoke, and the airplane rapidly descended toward the runway and impacted the ground hard, which resulted in substantial damage to the fuselage and left-wing strut. A postaccident engine examination revealed that the radiator coolant level was low enough that the fluid was not visible through the radiator cap. Draining the remaining coolant from the system allowed investigators to estimate that about 1/4 of the antifreeze was missing from the cooling system before the accident. The radiator overflow and recovery bottle had fluid in it. However, the hose leading from the radiator to the recovery bottle was improperly attached at the top of the bottle instead of the bottom. The 90° fitting installed into the top of the recovery bottle extended into the bottle less than 1 inch (in), so the system could not replenish any lost coolant in between flights during the cool-down cycle. The normal hose connection nipple used for installation was plugged. A small leak was found on the water pump inlet hose, water pump housing, case halves, and motor mount plate on the exhaust side of the engine where the water pump and coolant hoses are mounted on. The hose that was attached to the water pump housing nipple measured 1 inch (in) in diameter, while the water pump housing nipple measured between 0.904 in and 0.978 in. Examination of both cylinders showed signs of lack of coolant. The intake port sides of the cylinders had antifreeze particles embedded in their surfaces consistent with overheating. Both spark plug electrodes on the No.1 cylinder were melted, indicative ofpreignition and subsequent detonation within that cylinder, and both spark plug electrodes on the No.2 cylinder showed signs of overheating. Black carbon deposits were observed around the perimeter on the spark plugs which indicated that the engine ran rich. The top portion of the No. 1 piston exhibited melted metal deposits (from the spark plug electrodes), indicative of preignition and detonation. In addition, the outside surface of the piston around the pin and the ring gap exhibited black burn marks consistent with preignition/detonation high-pressure/temperature gases escaping between the ring end gap and burning away the aluminum portion of the piston. The carbon build-up and the aluminum discoloration on the bottom side of the piston were consistent with exposure to excessive temperatures for a long period of time. The No. 2 piston exhibited discoloration and burnt-on carbon deposits consistent with the piston overheating for a period of time. Two vertical striations noted on the intake side of No. 2 piston indicated an area of high pressure consistent with a piston that overheated and expanded, reducing the cylinder-to-piston wall clearance to below tolerance. Both carburetors' needle jets, jet needles, and all the moving parts within the carburetor showed signs of significant wear. Inspection of the crankshaft, main bearings, and connecting rod bearings showed no anomalies. ## Aircraft - Registration: [N599RA](https://openairdocs.org/deregistered/N599RA-2018-06-11), registration cancelled 2018-06-11, S/N 0151, built 2009 (OpenAirDocs) - Reported make and model: DOSHIER WILBERT A GT-500 (NO SERIES) - Registry model: [Doshier Wilbert A GT-500](https://openairdocs.org/model/doshier-wilbert-a-gt-500) (registry code 056284S) (OpenAirDocs) - Registry engine: [Rotax 582UL-99](https://openairdocs.org/engine/rotax-582ul-99) (registry code 55559, 2 cycle) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 0151 - Year built: 2009 - Airframe hours: 1451.3 - Engines: ROTAX 582UL-99 reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, December 9, 2016 - Departed: WLW, Willows, CA - Destination: 0O4, Corning, CA - Airport: WLW, Willows-Glenn County, runway 16, 4,125 × 100 ft, asphalt - Equipment: Airframe parachute, Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 49; injuries: minor; student; last flight review November 18, 2017; seat: front; restraint: 3-point; flight hours: 200 total, 145 in this make and model - Flight instructor; age 80; injuries: minor; flight instructor; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review June 7, 2017; seat: rear; restraint: 3-point; flight hours: 2,835 total, 4 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 5 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 55 °F - Altimeter: 29.98 inHg - Observed at: KOVE, 28 nm away ## 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 20171125024359A](https://openairdocs.org/incident/20171125024359A), Nov 25, 2017: Doshier Wilbert A GT-500, Willows, CA, Destroyed. On 11/25/2017 at approximately 1450 hours aircraft N599RA an experimental GT-500 light sport aircraft during a VFR training flight experienced engine failure… ## Docket (4 files) The files NTSB released with the investigation on December 31, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96370. 32.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 7.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8050047&FileExtension=pdf&FileName=6120%20REPORT_Redacted-Rel.pdf - Record of conversation (item 2, PDF, 1 page, 66 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=10093719&FileExtension=pdf&FileName=RECORD%20OF%20CONVERSATION%20-%20Pilot-Rel.pdf - Engine exam (item 3, PDF, 21 pages, 25.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8050153&FileExtension=pdf&FileName=Investigation%20Summary%20Report-Rel.pdf - Photo of the wreckage (item 4, PDF, 1 page, 156 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=8050191&FileExtension=pdf&FileName=Photo%201-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.