Great Lakes 2T-1A-2 accident near Sonoma, California, May 14, 2005
On May 14, 2005 at about 5:30 pm local time, a Great Lakes 2T-1A-2, registered N765GL, was substantially damaged in an accident near Sonoma, California (Sonoma Valley Airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
a partial loss of engine power, which resulted from the fuel servo leaking and generating an excessively rich fuel/air mixture. A factor was the owner's failure to comply with a service bulletin.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 14, 2005 · about 5:30 pm local time
- Place
- Sonoma, California · Sonoma Valley Airport · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Great Lakes 2T-1A-2 · all 2T-1A-2s on the register
- Registration
- N765GL · registry record · serial 0765
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane collided with the runway during an aborted takeoff following a partial loss of engine power. Prior to departure the pilot completed an engine run-up, observing no anomalies with the engine gauges or the engine's performance. During the takeoff, as the pilot began to lift off of the runway surface, the engine began to surge and he noticed a subsequent degradation in climb performance. After reaching about 30 to 40 feet above ground level (agl), he realized the airplane would not be able to continue the departure and opted to perform an emergency landing on an alternate runway. The airplane collided with the runway in a 15-degree nose low attitude. A post accident examination of the engine found that the spark plugs, the cylinders, and piston heads were heavily sooted; signatures consistent with an excessively rich fuel mixture. No other anomalies were found that would have precluded the engine from normal operation. An examination of the fuel servo revealed that the unit had a black coloration in the throat section and blue staining present near the idle valve. These signatures were consistent with a rich fuel mixture and a continuous fuel leak. During the bench testing of the servo, several small fuel leaks were noted at the idle valve, fuel diaphragm, and center body seal. Flow tests at high power settings revealed that the fuel servo was running rich, well over the prescribed maximum flows for that unit. The unit was about 28 years old and did not appear to have ever been overhauled. A representative from the engine manufacturer stated that based on the fuel servo's tested flow, the engine would have been running very rich and most likely could not have produced normal power. The servo manufacturer issued a Service Bulletin in 1990 that recommends that the unit be overhauled at engine TBO or every 10 years.
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: private
- Ratings: single-engine land
- Flight time: 377 hours in all; 2 in the last 90 days; 1 in the last 30 days; 290 as pilot in command
- Last flight review: June 1, 2003
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: rear
- Injury: minor injuries
The aircraft
- Last inspection: annual inspection, November 1, 2004
- Maximum gross weight: 1,800 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming AEIO-360-BIG6 (piston); 0 hours total
The flight
- Departed from: 0Q3 Sonoma CA at 5:25 pm
- Flight plan: none
- Runway 25, 2,700 ft by 45 ft
Weather at the time
- Light: daylight
- Wind: from 210° at 8 knots
- Visibility: 10 statute miles
- Sky: broken clouds at 20,000 ft; clear
- Temperature: 72°F (22°C), dew point 59°F (15°C)
- Altimeter: 30.02 inHg
- Observation at 5:54 pm from APC, 8 miles away
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.