ERA17LA182 · Stinson 108 2
Stinson 108 2 · Accident: loss of engine power (total) during initial climb
From Eagles Nest Airport (31E) to Frederick Municipal Airport (FDK)
Event
- NTSB case
- ERA17LA182
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 0 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Stinson 108 2
- Aircraft type
- Stinson 108
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N9366K
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Eagles Nest Airport (31E), West Creek, NJTo Frederick Municipal Airport (FDK), Frederick, MD
- Aircraft age
- About 70 years (built 1947)
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- Initial climb
- Defining eventThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Loss of engine power (total)
- Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
- Tree(s)
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Aircraft › Aircraft power plant
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
The private pilot reported that, while en route on a cross-country flight, the engine began to "shake." The pilot attempted to return to the airport; however, the engine experienced a total loss of power. The pilot subsequently initiated an emergency descent; however, the airplane struck trees and terrain about 1 mile from the approach end of the runway.
The crankshaft and remaining cylinders remained intact, and the engine crankshaft rotated smoothly when the propeller was turned by hand. The No. 4 cylinder's exhaust pushrod shroud and exhaust pushrod were both bent. An examination of the engine revealed that the No. 4 cylinder was fracture-separated from the crankcase. The piston, sections of the No. 4 cylinder, and sections of the crankcase were missing. The No. 4 exhaust valve stem was fractured about halfway along its length, and the fracture surface was consistent with reverse bending fatigue crack propagation, which typically results from a stuck valve. The lower half of the stem and face were missing. The No. 4 exhaust valve guide clearance was excessive, and the valve's guide and tip area contained carbon deposits. The cylinder walls contained circular gouges consistent with the exhaust valve face diameter. It is likely that the carbon deposits on the valve stem resulted in the valve getting stuck, which initiated the reverse bending fatigue crack and led to the exhaust valve face stem fracturing and dropping into the cylinder and the subsequent catastrophic engine failure. The engine maintenance records were incomplete and prevented a determination of when the last clearance check of the No. 4 cylinder was performed or when it was last overhauled/replaced.
Probable cause
A total loss of engine power due to the No. 4 cylinder’s exhaust valve getting stuck and the subsequent fracturing of the valve face stem.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA17LA182
- Event ID
- 20170517X04530
- Case number
- ERA17LA182
- Dataset
- full-current
- Source SHA-256
- 5cf380f0061817c0331a6b2d8cc7e0ee3a79bea469a1001dc5c10e56f35f5ab3
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2017-05-17.
- API snapshot SHA-256: 712d5ac9c2c58931fb337697b167fa83fa9b6bc69816ffe49d9c30586608fc77; retrieved 2026-09-16T05:17:32.273Z.