Cessna 150M N8135U

Summary

On 5 September 1999 at about 21:22 local time, a Cessna 150M registered N8135U was involved in an accident near Menlo Park, California, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

5 September 1999 at 21:22

Classification

Accident

Location

Menlo Park, California, United States

Coordinates

37.4504, -122.1702

Aircraft

Cessna 150M

Registration

N8135U

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Palo Alto → Oakland

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX99LA295

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.