ERA14FA421 · Klaas Development Inc LANCAIR IV P
Empire Equipment Klaas Development Inc LANCAIR IV P · Accident: part(s) separation from aircraft en route
From McGhee Tyson Airport (TYS) to Jackson-Medgar Wiley Evers International Airport (JAN)
Event
- NTSB case
- ERA14FA421
- 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
- 1 · 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
Klaas Development Inc LANCAIR IV P
- Aircraft type
- Klaas Development LANCAIR
- 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
- N541EM
- Operator
- Empire Equipment
- Onboard fatalities
- Unknown
- Route
- From McGhee Tyson Airport (TYS), Knoxville, TNTo Jackson-Medgar Wiley Evers International Airport (JAN), Jackson, MS
- Aircraft age
- About 14 years (built 2000)
- 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
- 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
- Part(s) separation from aircraft
- 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 propeller/rotor
- Personnel issues › Task performance
Approximate · Coordinates from the NTSB case API, not marked as estimated; no uncertainty radius is established.
NTSB narrative
Shortly after departing on a personal cross-country flight and leveling off at the filed cruise altitude, the commercial pilot reported trouble maintaining altitude and descended to a lower altitude. He then reported both engine and instrument problems and requested to divert to a nearby airport. Subsequently, the pilot reported that the engine had lost power, oil was all over the windshield, and that there was no visibility due to the oil. Shortly thereafter, he stated that a forced landing was imminent; the last radar return for the flight was about 2 miles from a nearby airport and in the vicinity of the accident location.
On-scene examination of the wreckage revealed that the propeller hub and propeller blades were missing and that oil was noted covering the airplane and windshield fragments. The propeller blades and hub were later located about 8 miles from the accident location.
Five of the six propeller mounting bolts were found inside their bores. The sixth bolt was not located. Metallurgical examination determined that the remaining five mounting bolts failed due to reverse bending fatigue. The witness marks on the aft face of the propeller hub were consistent with marks from bolts or bolt fragments while the propeller hub was still partially attached. This would likely occur when the bolt or dowel was still intact before total separation of the propeller assembly. The reverse bending failure of the hub mounting bolts were likely indicative of a loose connection between the hub and the crankshaft.
Maintenance records revealed that the propeller was overhauled about 35 flight hours before the accident and was inspected about 15 flight hours before the accident; however, the records did not note, nor were they required to, the torque setting that was achieved. Considering the extensive damage to the propeller flange in conjunction with the limited number of flight hours, it is likely that at least one of the propeller mounting bolts was not torqued sufficiently at the time of installation and gradually loosened during the subsequent flights.
Probable cause
The inadequate torque of the propeller mounting bolts and inspection of the propeller, which resulted in the fatigue fracture of the bolts and a subsequent in-flight separation of the propeller assembly.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record ERA14FA421
- Event ID
- 20140903X63615
- Case number
- ERA14FA421
- 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, 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: 559f517eab226743c580a80926d3c7c5ca995205c2af222b52f8a073e6726f64; retrieved 2026-09-14T17:25:21.223Z.