# NTSB WPR22LA334: Buxbaum Mark Edward Long EZ, N444MR, Medicine Bow, WY, September 5, 2022

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Class 3 · Limited · Final report
- Date: September 5, 2022, 10:30 local (16:30 UTC)
- Place: Medicine Bow, WY · Highway 30 between Hanna and Medicine Bow, WY.
- Coordinates: 41.8984, -106.4389 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.8984&lon=-106.4389&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Defining event: [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Western Pacific Region
- Parties: FAA
- NTSB case key (mKey): 105867
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR22LA334
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105867/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105867
- Page: https://openairdocs.org/ntsb/WPR22LA334

## Probable cause

A partial loss of engine power due to the fatigue fracture of the No. 4 exhaust valve head.

## Findings

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

- [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Buxbaum Mark Edward LONG EZ, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=056905H), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md)
- [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Buxbaum Mark Edward LONG EZ, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=056905H), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md)
- [Object/animal/substance: fence/fence post](https://openairdocs.org/ntsb-findings/03022047): Environmental issues › Physical environment · Effect on equipment; cases with it: [Buxbaum Mark Edward LONG EZ, 1 case](https://openairdocs.org/ntsb-findings/03022047/cases.md?model=056905H), [All aircraft, 313 cases](https://openairdocs.org/ntsb-findings/03022047/cases.md)

## Sequence of events

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

- [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Buxbaum Mark Edward LONG EZ, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=056905H), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Buxbaum Mark Edward LONG EZ, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=056905H), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

According to the pilot, he and a passenger were on a cross-country flight when, at approximately 7,500 feet above mean sea level (msl), the aircraft began aggressively shaking. The pilot initially flew toward a nearby airport but decided to land on a highway. The airplane landed hard, veered off the road, and impacted terrain. Subsequently, the airplane nosed over onto a fence and sustained substantial damage to the fuselage and wings. During the postaccident examination of the engine, excessive oil and carbon were discovered on the No. 4 cylinder valve springs, guide, stem, and retainers, which is consistent with exhaust blow-by. In addition, approximately 0.8 inches of the No. 4 exhaust valve stem and valve head were not recovered from the cylinder and engine. The remaining valve stem had excessive play within the valve guide. The fracture of the stem portion of the exhaust valve was the result of a fatigue crack that emanated from severe corrosion pits at the outer surface of the stem, which resulted in a loss of engine power. The engine's logbook entries revealed that it was last overhauled 41 years before the accident, exceeding Lycoming's recommendation of 12 years. It is likely that the No. 4 exhaust valve deteriorated from age and likely fractured from a fatigue crack.

## Factual narrative

On September 5, 2022, about 1033 mountain daylight time, an Edward Long EZ, N444MR, was substantially damaged when it was involved in an accident near Medicine Bow, Wyoming. The pilot and passenger sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, he and a passenger were on a cross-country flight from Kanab Municipal Airport (KKNB) Kanab, Utah, to Chadron Municipal Airport (KCDR), Chadron, Nebraska. While enroute, about 20 miles east of Rawlings, WY and about 7,500 ft msl, the airplane started to violently shake. The pilot initially maneuvered towards a local airport but decided to land the airplane on a highway. The airplane touched down hard, veered off the road, and impacted terrain. Subsequently, the airplane nosed over onto a fence and sustained substantial damage to the fuselage and wings (see Figure 1). Figure 1. View of airplane wreckage (courtesy of local law enforcement) A postaccident examination of the engine revealed oil and carbon buildup on the valve rockers, springs, and keys. It also revealed that the No. 4 engine exhaust valve head separated from its stem. The remaining valve stem had excessive play while situated in the valve guide (see Figure 2). Lycoming Service Bulletin No. 338C, Procedure to Determine Exhaust Valve and Guide Condition, was issued on November 22, 2004. It states: To insure positive and trouble free valve train operation, the inspection procedure described in this publication should be accomplished as recommended in the Time of Compliance section of this publication. Failure to comply with the provisions of this publication could result in engine failure due to excessive carbon build up between the valve guide and valve stem resulting in sticking valves or; broken exhaust valves which result from excessive wear (bell-mouthing) of the exhaust valve guide. This inspection was to occur every 400 hours, but no engine maintenance log entries documenting compliance with the Service Bulletin were found. No remnants of the No. 4 exhaust valve head were discovered within the cylinder or engine. The remaining exhaust valve stem measured approximately 3.5 inches in length, as opposed to the standard length of 4.3 inches. The face of the No. 4 piston and cylinder wall exhibited mechanical damage consistent with valve head separation. Figure 2. Five photos showing the No. 4 cylinder spring and rocker, piston, cylinder wall and exhaust valve seat. The recovered exhaust valve that fractured at the stem, rocker arm, inner and outer valve springs from the No. 4 cylinder were sent to the National Transportation Safety Board (NTSB) Materials Laboratory. The examination revealed that the fracture of the stem portion of the exhaust valve was the result of a fatigue crack that emanated from severe corrosion pits at the outer surface of the stem. The engine logbook entries revealed that Lycoming rebuilt the engine on November 24, 1981.No additional entries indicated that the engine had since been overhauled. The No. 1 cylinder was replaced on June 27, 2017. According to the Hobbs meter, the engine had accumulated a total of 898.1 hours. However, the engine's 41 years of service since its last overhaul exceeded the manufacturer's recommendations. According to Lycoming Service Instruction No. 1009BE, Time Between Overhaul (TBO) Schedules: All engine models are to be overhauled within twelve (12) calendar years of the date they first entered service or of last overhaul. This calendar year time period TBO is to mitigate engine deterioration that occurs with age, including corrosion of metallic components and degradation of non-metallic components such as gaskets, seals, flexible hoses and fuel pump diaphragms.

## Aircraft

- Registration: [N444MR](https://openairdocs.org/aircraft/N444MR), registered now, S/N 563, built 1995 (OpenAirDocs)
- Reported make and model: BUXBAUM MARK EDWARD LONG EZ
- Registry model: [Buxbaum Mark Edward LONG EZ](https://openairdocs.org/model/buxbaum-mark-edward-long-ez) (registry code 056905H) (OpenAirDocs)
- Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 563
- Year built: 1995
- Airframe hours: 302.1
- Engines: LYCOMING O-235 SERIES 115 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, May 10, 2022
- Departed: KNB, Kanab, UT
- Destination: HSR, Hot Springs, SD
- Equipment: ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 65; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; seat: front

## Weather

- Conditions: Visual (VMC), Day
- Wind: 260° at 9 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point -6 °F
- Altimeter: 30.31 inHg
- Observed at: KEHY, 10 nm away
- METAR: KEHY 051615Z AUTO 26009KT 10SM CLR 26/M21 A3031 RMK AO2 PWINO

## Docket (7 files)

The files NTSB released with the investigation on September 18, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105867. 25.9 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 473 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15116727&FileExtension=pdf&FileName=n444mr%206120_Redacted-Rel.pdf
- Passenger 6120 (item 2, PDF, 11 pages, 4.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15117275&FileExtension=pdf&FileName=6120%20Passenger%20N444MR-Rel.pdf
- Engine exam notes (item 3, PDF, 8 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16044125&FileExtension=pdf&FileName=WPR22LA334%20Engine%20Examinaiton-Rel.pdf
- Personal electronic device - specialist's factual report_WPR22LA334 (item 4, PDF, 3 pages, 315 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15435638&FileExtension=pdf&FileName=Personal%20Electronic%20Device%20-%20Specialist%27s%20Factual%20Report_WPR22LA334-Rel.pdf
- Materials laboratory factual report 23-106 (item 5, PDF, 8 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16625870&FileExtension=pdf&FileName=23-106%20cylinder%20valve%20stem-Rel.pdf
- Supporting documents (item 6, PDF, 3 pages, 13.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=17497470&FileExtension=pdf&FileName=Supporting%20Documents_Redacted-Rel.pdf
- Wreckage release form (item 7, PDF, 1 page, 5.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15116737&FileExtension=pdf&FileName=revised%20Signed%20NTSB%20wreckage%20release_Redacted-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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