Cessna 150M accident near Menlo Park, California, September 5, 1999
On September 5, 1999 at about 9:22 pm local time, a Cessna 150M, registered N8135U, was substantially damaged in an accident near Menlo Park, California. It was a personal 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 left muffler rear wall, which resulted in hot exhaust gasses being ported onto, and shorting, the magneto p-lead wires. The failure of maintenance personnel to detect the impending failure of the muffler during the recent engine maintenance activity is also causal.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 5, 1999 · about 9:22 pm local time
- Place
- Menlo Park, California · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 150M · all 150Ms on the register
- Registration
- N8135U · no longer on the register · serial 15077898
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot had just departed the airport and was over the San Francisco Bay when the engine suddenly lost power. He attempted to make an emergency landing on a nearby bridge but had insufficient altitude and landed in the water on the shore short of the area. The airplane nosed over when the nose wheel plowed into the mud. Postaccident examination of the engine revealed that the spark plugs were not producing any spark. The 'P-leads' were grounded at a short in a tie-wrapped wire bundle under a grommet at the firewall. The insulation was melted and the inside conductor was contacting the radio shielding of the wire where it was attached to the airframe. Additional examination of the engine found that the rear wall section of the left muffler was missing, with the remaining edges eroded. With the muffler wall missing, hot exhaust gases were directed towards the firewall where the shorted section of the 'P-leads' were located. Maintenance actions had been performed in the engine compartment three times in the past 2 months, with the last maintenance activity 3 days prior to the accident when a cylinder was replaced. The loss of power event occurred on the first flight following return of the airplane to service.
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: 72 hours in all; 70 in this make and model; 30 in the last 90 days; 7 in the last 30 days; 15 as pilot in command
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 8,000 hours
- Last inspection: 100-hour inspection, July 26, 1999; 25 hours since
- Maximum gross weight: 1,600 lb
- Seats: 2
- Landing gear: fixed
- Engine: Continental O-200-A48B (piston); 0 hours total
The flight
- Departed from: PAO Palo Alto CA at 9:15 pm
- Destination: OAK Oakland CA
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 350° at 10 knots
- Visibility: 7 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 52°F (11°C)
- Altimeter: 29.00 inHg
- Observation at 9:30 pm from PAO, 2 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.