Aircraft Accident/Incident Report

Menlo Park, California 94025
Sunday, September 5, 1999 14:22 PDT

NTSB Narrative Summary Released at Completion of Accident

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.

NTSB Probable Cause Narrative

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.

Event Information

Type of Event Accident
Event Date 9/5/1999
Event Day of the Week Sunday
Time of Event 1422
Event Time Zone Pacific Daylight Time
Event City MENLO PARK
Event State CALIFORNIA
Event Country --
Zipcode of the event site 94025
Event Date Year 1999
Event Date Month 9
MidAir Collision Indicator No
On Ground Collision occurred ? No
Event Location Latitude
Event Location Longitude
Event Location Airport
Event Location Nearest Airport ID
Indicates whether the acc/inc occurred off or on an airport Off Airport/Airstrip
Distance from airport in statute miles --
Degrees magnetic from airport --
Airport Elevation --
Weather Briefing Completeness Unknown
Investigator's weather source Weather Observation Facility
Time of the weather observation 1430 Pacific Daylight Time
Direction of event from weather observation facility (degrees) 360
Weather Observation Facility ID PAO
Elevation of weather observation facility 3
Distance of event from weather observation facility (units?) 2
Time Zone of the weather observation PDT
Lighting Conditions Day
Lowest Ceiling Height 0
Lowest Non-Ceiling Height 0
Sky/Lowest/Cloud Conditions Clear
Sky Condition for Lowest Ceiling None
Visibility Runway Visual Range (Feet) 0
Visibility Runway Visual Value (Statute Miles) 0
Visibility (Statute Miles) 7
Air Temperature at event time (in degrees celsius) 27
Dew Point at event time (in degress fahrenheit) 11
Wind Direction (degrees magnetic) 350
Variable Wind Indicator Unknown
Wind Speed (knots) 10
Wind Velocity Indicator Unknown
Wind Gust Indicator Unknown
Wind Gust (knots) 0
Altimeter Setting at event time (in. Hg) 29
Density Altitude (feet) --
Intensity of Precipitation Unknown
METAR weather report --
Event Highest Injury None
On Ground, Fatal Injuries 0
On Ground, Minor Injuries 0
On Ground, Serious Injuries 0
Injury Total Fatal --
Injury Total Minor --
Injury Total None 1
Injury Total Serious --
Injury Total All --
Investigating Agency NTSB
NTSB Docket Number (internal use) 1729
NTSB Notification Source --
NTSB Notification Date Sep 5 1999 12:00AM
NTSB Notification Time 1435
Fiche Number and/or location -used to find docket information IMAGE
Date of most recent change to record Aug 14 2001 1:47PM
User who most recently changed record MONR
Basic weather conditions Visual Meteorological Cond
FAA District Office --

Aircraft Involved

Aircraft #1

Aircraft Registration Number N8135U
NTSB Number LAX99LA295
Missing Aircraft Indicator N
Federal Aviation Reg. Part Part 91: General Aviation
Type of Flight Plan filed None
Flight plan Was Activated? --
Damage Substantial
Aircraft Fire None
Aircraft Explosion None
Aircraft Manufacturer's Full Name Cessna
Aircraft Model 150M
Aircraft Series Identifier 150M
Aircraft Serial Number 15077898
Certified Max Gross Weight 1600
Aircraft Category Airplane
Aircraft Registration Class U.S. Registered/U.S. Soil
Aircraft is a homebuilt? No
Flight Crew Seats --
Cabin Crew Seats --
Passenger Seats --
Total number of seats on the aircraft 2
Number of Engines 1
Fixed gear or retractable gear Fixed
Aircraft, Type of Last Inspection 100 Hour
Date of Last Inspection Jul 26 1999 12:00AM
Airframe hours since last inspection 25
Airframe Hours 8000
ELT Installed Yes
ELT Activated Yes
ELT Aided Location of Event Site No
ELT Type --
Aircraft Owner Name I S B A, INC.
Aircraft Owner Street Address 8053 EARHART ROAD
Aircraft Owner City OAKLAND
Aircraft Owner State CA
Aircraft Owner Country
Aircraft Owner Zipcode 94621
Operator is an individual? --
Operator Name
Operator Same as Owner? Yes
Operator Is Doing Business As --
Operator Address Same as Owner? Yes
Operator Street Address
Operator City
Operator State
Operator Country
Operator Zip code
Operator Code
Owner has at least one certificate None
Other Operator of large aircraft? No
Certified for Part 133 or 137 Operation Unknown
Operator Certificate Number --
Indicates whether an air carrier operation was scheduled or not --
Indicates Domestic or International Flight --
Operator carrying Pax/Cargo/Mail --
Type of Flying (Per_Bus / Primary) Personal
Second Pilot on Board No
Departure Point Same as Event No
Departure Airport Code PAO
Departure City PALO ALTO
Departure State CA
Departure Country
Departure Time 1415
Departure Time Zone PDT
Destination Same as Local Flt --
Destination Airport Code OAK
Destination City OAKLAND
Destination State CA
Destination Country
Specific Phase of Flight Climb
Report sent to ICAO? --
Evacuation occurred --
Date of most recent change to record Jan 14 2001 10:25AM
User who most recently changed record dbo
Since inspection or accident --
Event Location Runway Number and Location 0
Runway Length --
Runway Width --
Sight Seeing flight No
Air Medical Flight No
Medical Flight --