Beech A60 incident near Boulder, Colorado, November 9, 1999
On November 9, 1999 at about 6:00 pm local time, a Beech A60, registered N457DA, suffered minor damage in an incident near Boulder, Colorado (Boulder Municipal Airport). It was a public-use flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fatigue failure of the #6 cylinder connecting rod cap.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- November 9, 1999 · about 6:00 pm local time
- Place
- Boulder, Colorado · Boulder Municipal Airport · map
- Type
- Incident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Beech A60 · all A60s on the register
- Registration
- N457DA · no longer on the register · serial P-166
- Damage
- Minor damage
- Flight
- Public-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot said that as he descended to 6,500 feet mean sea level, the left engine of the twin-engine airplane failed. The pilot landed the airplane without further incident. The engine had 23.5 hours on it since major overhaul. An engine teardown revealed that the #6 connecting rod had failed. Examination of the #6 cylinder parts found preexisting fractures on both the rod cap and the connecting rod. The fatigue features displayed on the rod cap are suggestive of lower stress propagation than those stress propagation marks on the connecting rod. It appeared that the engine failure-initiating event was the failure of the rod cap. Examination of the #6 connecting rod bolts indicated that they fractured as a result of overstress.
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: flight instructor, commercial pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 2,654 hours in all; 1,036 in this make and model; 43 in the last 90 days; 23 in the last 30 days; 2,600 as pilot in command; 245 on instruments
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 6,117 hours
- Last inspection: annual inspection, June 1, 1999
- Maximum gross weight: 6,500 lb
- Seats: 6
- Landing gear: retractable
- Engine: Lycoming TIO-541E1C4 (piston); 0 hours total
The flight
- Departed from: APA Englewood CO at 5:40 pm
- Destination: 1V5
- Flight plan: none
- Runway 26, 4,100 ft by 75 ft
Weather at the time
- Light: daylight
- Wind: from 270° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 64°F (18°C), dew point 30°F (-1°C)
- Altimeter: 29.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| 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.