ATL03LA106 · Polstra Zodiac CH 601 HDS
Polstra Zodiac CH 601 HDS · Accident: total loss of engine power (mechanical failure) en route
From Cobb County International Airport-McCollum Field (RYY) to Thomson-McDuffie County Airport (HQU)
Event
- NTSB case
- ATL03LA106
- 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
Polstra Zodiac CH 601 HDS
- Aircraft type
- Polstra ZODIAC CH 601 HDS
- 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
- N721PT
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Cobb County International Airport-McCollum Field (RYY), Marietta, GATo Thomson-McDuffie County Airport (HQU), Thomson, GA
- Aircraft age
- Not recorded
- 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
- En route · cruise
- First occurrenceThe 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
- Total loss of engine power (mechanical failure)
- 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
- Engine assembly, valve, intake › Fatigue
- Engine assembly, valve, intake › Fractured
- Terrain condition › Rough/uneven
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
NTSB narrative
During cruise flight, the engine began to run rough and lose power, then it stopped completely. The pilot executed an emergency landing in a field, and the airplane collided with small trees and a tree stump. Examination of the engine revealed the intake valve on the No. 3 cylinder was fractured in the transition region between the stem and the head with no bending deformation. Metallurgical examination revealed the lock for the spring seat displayed fretting damage at the internal and external faces. Fretting damage was observed on the corresponding surface of the stem portion of the valve and on the corresponding bore face of the spring seat. The fretting damage was characteristic of higher than normal operating stresses or vibration and fatigue.
Probable cause
The total loss of engine power due to the fatigue fracture of the No. 3 cylinder intake valve, which resulted in a forced landing to rough terrain and subsequent collision with small trees and a tree stump.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ATL03LA106
- Event ID
- 20030620X00917
- Case number
- ATL03LA106
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
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, coordinates. 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: c7e1951f3589c84ab27348d56706160ee81a57524a3ae9da7bce0357742fab14; retrieved 2026-09-22T09:08:27.592Z.