ERA15LA311 · Thomas A Siminski ZENITH CH 750
Thomas A Siminski ZENITH CH 750 · Accident: loss of engine power (partial) during initial climb
From Allentown Queen City Municipal Airport (XLL) to Allentown Queen City Municipal Airport (XLL)
Event
- NTSB case
- ERA15LA311
- 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
- Unknown
- 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
Thomas A Siminski ZENITH CH 750
- Aircraft type
- Thomas A Siminski ZENITH CH 750
- 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
- N1750Z
- Operator
- Siminski Thomas A
- Onboard fatalities
- Unknown
- Route
- From Allentown Queen City Municipal Airport (XLL), Allentown, PATo Allentown Queen City Municipal Airport (XLL), Allentown, PA
- Aircraft age
- About 3 years (built 2012)
- 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 (partial)
- 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 pilot reported that, after takeoff, the airplane's engine lost partial power about 100 ft above ground level and that he then attempted to return to the airport. The pilot further stated that "the engine would not keep me flying and the airplane just fell into the forest."
During the on-scene examination, the No. 1 spark plug was found missing from the cylinder head but still attached to the ignition lead. The threads were stripped out of the cylinder head. It is likely that the No. 1 spark plug was liberated from the cylinder head due to the stripped threads, which led to the partial loss of engine power.
Probable cause
A partial loss of engine power due to the No. 1 spark plug being liberated from the cylinder head due to the stripped threads in the cylinder head. Contributing to the accident was the pilot’s decision to attempt to return to the airport while at a low altitude.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA15LA311
- Event ID
- 20150814X40417
- Case number
- ERA15LA311
- 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: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 6d2cd215df72f2dd29b339f25688a796727bc2679a3117b98f1ca4eb984088a8; retrieved 2026-09-16T02:40:22.518Z.