Klaas Development INC LANCAIR IV P accident near Ooltewah, Tennessee, September 3, 2014
On September 3, 2014 at about 7:22 pm local time, a 2000 Klaas Development INC LANCAIR IV P, an amateur-built aircraft,, registered N541EM, was substantially damaged in an accident during enroute (cruise) near Ooltewah, Tennessee (Collegedale Muni airport). It was a business flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 3, 2014 · about 7:22 pm local time
- Place
- Ooltewah, Tennessee · Collegedale Muni · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Klaas Development INC LANCAIR IV P, built 2000, amateur-built
- Registration
- N541EM · no longer on the register · serial LIV-398
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
What happened, in order
- Aircraft maintenance event during prior to flight
- Part(s) separation from AC during enroute (cruise) defining event
- Off-field or emergency landing during emergency descent
- Collision with terrain or object (not controlled flight into terrain) during landing
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Propeller system › Prop/spinner section › Inadequate inspection
- cause Aircraft › Aircraft propeller/rotor › Propeller system › Prop/spinner section › Incorrect service/maintenance
- cause Personnel issues › Task performance › Inspection › Scheduled/routine inspection › Maintenance personnel
- cause Personnel issues › Task performance › Maintenance › Installation › Maintenance personnel
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 2,811.5 hours in all; 577 in this make and model
- Last flight review: April 28, 2014
- Medical certificate: Class 2 (without waivers/limitations)
- Seat: left
- Injury: fatal
The aircraft
- Airframe total time: 2,378 hours
- Last inspection: condition inspection, August 13, 2014
- Maximum gross weight: 3,200 lb
- Seats: 4
- Landing gear: retractable
- Engine: Continental Motors TSIO-550 E3B (piston); 2,378 hours total
- Operator: Empire Equipment LLC
The flight
- Departed from: TYS Knoxville TN at 6:51 pm
- Destination: JAN Jackson MS
- Flight plan: IFR
Weather at the time
- Light: daylight
- Wind: from 040° at 7 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 18,000 ft; a few clouds at 3,200 ft
- Temperature: 84°F (29°C), dew point 70°F (21°C)
- Altimeter: 30.03 inHg
- Observation at 7:27 pm from KCHA, 8 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.