Piper PA42-1000 incident near Lexington, Kentucky, February 5, 1999
On February 5, 1999 at about 2:00 pm local time, a Piper PA42-1000, registered N37KW, suffered minor damage in an incident near Lexington, Kentucky (Blue Grass airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Improper assembly of the engine gearcase by the manufacturer, which resulted in an uncontained failure of the 1st bull gear.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 5, 1999 · about 2:00 pm local time
- Place
- Lexington, Kentucky · Blue Grass
- Type
- Incident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA42-1000 · all PA42-1000s on the register
- Registration
- N37KW · registry record · serial 425527039
- Damage
- Minor damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The during descent for landing, the airplane's right engine, a TPE331-14B, experienced an uncontained gearcase failure. Disassembly of the engine revealed that the gearcase was ruptured in the 1st bull gear's plane of rotation and that the 1st bull gear had a 90 degree arc of the rim and gear teeth separated. Metallurgical examination of the 1st bull gear revealed a fatigue fracture that had originated in the gear's bore splines. The fatigue originated in area where the spline thickness was significantly reduced by indentations on the pressure surface of the splines. Review of the engine's overhaul manual revealed a tie-rod was used to provide a clamping force between the spur gear and 1st bull gear. The assembly procedures required that the tie-rod be stretched with a load of 22,000 pounds, and then secured with a nut that was hand-tightened. During disassembly of the gearcase, it was not possible to determine the amount of stretch on the tie-rod, or the breakaway torque on the retaining nut. Maintenance records revealed that the gearcase was disassembled, and reassembled during repairs, which were performed by engine manufacturer.
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
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane
- Flight time: 5,900 hours in all; 750 in this make and model; 95 in the last 90 days; 57 in the last 30 days; 4,500 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 3,694 hours
- Last inspection: 100-hour inspection, November 18, 1998; 90 hours since
- Maximum gross weight: 12,100 lb
- Seats: 7
- Landing gear: retractable
- Engine: Garrett TPE-331-14 (turboprop); 0 hours total
The flight
- Departed from: ILG Wilmington DE at 1:00 pm
- Destination: LEX
- Flight plan: IFR
- Runway 22, 7,003 ft by 153 ft
Weather at the time
- Light: daylight
- Wind: from 150° at 9 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 36°F (2°C), dew point 25°F (-4°C)
- Altimeter: 30.00 inHg
- Observation at 2:54 pm from LEX
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 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.