# NTSB WPR21LA219: Stoddard Hamilton Glasair II, N8176J, Darby, MT, May 29, 2021

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Class 3 · Limited · Final report
- Date: May 29, 2021, 11:06 local (17:06 UTC)
- Place: Darby, MT · North bound lane on West Fork Road
- Coordinates: 45.953056, -114.14222 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=45.9531&lon=-114.1422&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach-VFR go-around: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: FSDO
- NTSB case key (mKey): 103195
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA219
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103195/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103195
- Page: https://openairdocs.org/ntsb/WPR21LA219

## Probable cause

The pilot’s impact with terrain during a go-around following an attempted precautionary landing due to a low oil pressure indication. The reason for the low oil pressure indication could not be determined based on the available information.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Performance/control parameters: descent/approach/glide path](https://openairdocs.org/ntsb-findings/01062040): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Weston James GLASAIR II S FT, 1 case](https://openairdocs.org/ntsb-findings/01062040/cases.md?model=05606WD), [All aircraft, 809 cases](https://openairdocs.org/ntsb-findings/01062040/cases.md)
- [Engine (reciprocating): recip eng oil sys](https://openairdocs.org/ntsb-findings/01058550): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Weston James GLASAIR II S FT, 1 case](https://openairdocs.org/ntsb-findings/01058550/cases.md?model=05606WD), [All aircraft, 130 cases](https://openairdocs.org/ntsb-findings/01058550/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Enroute: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340); cases with it: [Weston James GLASAIR II S FT, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=05606WD), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md)
- [Approach-VFR go-around: Collision during takeoff/land](https://openairdocs.org/ntsb-events/490) (defining event); cases with it: [Weston James GLASAIR II S FT, 1 case](https://openairdocs.org/ntsb-events/490/sequence.md?model=05606WD), [All aircraft, 1,309 cases](https://openairdocs.org/ntsb-events/490/sequence.md)

## Analysis

The pilot was conducting a local flight with a passenger when he received a low oil pressure warning, and he decided to perform a precautionary landing to a nearby grass runway. While on final approach for landing, the pilot determined that the airplane was high and fast, and he attempted to slip to slow the airplane and descend quickly, but about halfway down the runway, chose to go around and began a turn to land in the other direction. About three-quarters of the way through the turn, the pilot “felt the airplane begin to stall.” He pushed the nose down and the airplane contacted the ground in a left-wing-low, nose-down attitude. The automotive conversion engine was rotated by hand after removal of the flywheel dampener plate. About 2 quarts of oil was drained from the engine. Examination of the crankshaft and connecting rods revealed no anomalies. The oil filter and adapter were removed, and black RTV sealant was noted around the base of the filter adapter. The oil filter element was inspected and found to contain a sliver of black RTV material; however, based on the available information, the reason for the low oil pressure indication could not be determined.

## Factual narrative

On May 29, 2021, about 1015 mountain daylight time, an experimental, amateur-built Glasair II S FT airplane, N8176J, was substantially damaged when it was involved in an accident near Darby, Montana. The pilot and the passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that, during the flight, while at an altitude of about 6,800 ft, the engine monitor alerted him to a low oil pressure indication. The oil pressure continued to drop, and the pilot began a descent toward a nearby private grass strip for a precautionary landing. During the final approach, the pilot determined that the airplane was high and fast, and he attempted a slip to slow the airplane and descend quickly. About halfway down the runway, the pilot elected to go around and added engine power before he started a turn. About three quarters of the way through the turn, the pilot “felt the airplane begin to stall.” To avoid powerlines, the pilot pushed the nose down and the airplane contacted the ground in a left-wing-low, nose-down attitude. The airplane was substantially damaged and both occupants were transported to the hospital with serious injuries. Postaccident examination of the experimental, Eggenfellner Subaru engine revealed that the engine crankshaft would not rotate until the dampener off the fly wheel was removed. The crankshaft then rotated through several complete cycles. No binding or abnormal noise was noted, and compression was developed in each cylinder. All six sparkplugs displayed normal operating signatures. About 2 quarts of engine oil was drained out of the engine. The oil sump was removed with no abnormalities noted. The oil filter and oil filter adapter were removed and RTV sealant was noted around the base of the oil filter adapter. The O-ring was nicked and deteriorated. The open oil filter had about an inch long sliver of RTV sealant around the base of the oil filter adapter. Due to engine design and lack of specialized tooling, no further examination or testing were accomplished.

## Aircraft

- Registration: [N8176J](https://openairdocs.org/aircraft/N8176J), registered now, S/N 2123, built 1999 (OpenAirDocs)
- Reported make and model: STODDARD HAMILTON GLASAIR II (FT)
- Registry model: [Weston James GLASAIR II S FT](https://openairdocs.org/model/weston-james-glasair-ii-s-ft) (registry code 05606WD) (OpenAirDocs)
- Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 2123
- Year built: 1999
- Engines: Eggenfellner E6 3.6 Liter 250 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Departed: K32S, Stevensville, MT
- Destination: Same as departure
- Airport: K4U7, West Fork Lodge Airport, runway 2 / 20, 2,600 × 65 ft, grass/turf
- Equipment: Unknown

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 63; injuries: serious; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review April 30, 2021; seat: left; restraint: 4-point; flight hours: 363.3 total, 290 in this make and model, 341.1 as pilot in command, 5.4 in the last 90 days, 5.4 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 57 °F, dew point 36 °F
- Altimeter: 30.20 inHg
- Observed at: KMSO, 58 nm away
- METAR: KMSO 291753Z VRB03KT 10SM CLR 14/02 A3020

## 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 20210529007059A](https://openairdocs.org/incident/20210529007059A), May 29, 2021: Weston James GLASAIR II S FT, Darby, MT, Destroyed. Pilot reported loss of oil pressure, attempted landing on a private grass strip. Approach speed was excessive, mid field without touching down, powered up to…

## Docket (5 files)

The files NTSB released with the investigation on November 22, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103195. 13.2 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 7 pages, 6.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13330478&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf
- Witness statement (item 2, PDF, 2 pages, 966 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13330461&FileExtension=pdf&FileName=Witness%20statement_Redacted-Rel.pdf
- FAA engine exam (item 3, PDF, 7 pages, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=13330880&FileExtension=pdf&FileName=FAA%20engine%20exam_Redacted-Rel.pdf
- Release of aircraft wreckage, NTSB form 6120.15 (item 4, PDF, 1 page, 43 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14599504&FileExtension=pdf&FileName=NTSB%20Release%20Choice%20Aviation%20signed-Rel.pdf
- Photos (item 5, PDF, 3 pages, 2.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14012939&FileExtension=pdf&FileName=Photos%20WPR21LA219-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.

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