Beechcraft J35 N4932B

Summary

On 17 August 1999 at about 18:31 local time, a Beechcraft J35 registered N4932B was involved in an accident near Marysville, California, United States. 2 people were on board and 2 were seriously injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

17 August 1999 at 18:31

Classification

Accident

Location

Marysville, California, United States

Nearest airport

Yuba County (MYV)

Coordinates

39.1495, -121.4694

Aircraft

Beechcraft J35

Registration

N4932B

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

San Rafael → Caldwell

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX99FA270

2 people were seriously injured.

A loss of engine power due to improperly torque cylinder base nuts by maintenance personnel during a top overhaul.

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

Read the full NTSB narrative

The pilot radioed that the aircraft's engine was failing and he was altering his course to land at the nearest airport. While on left base leg for landing, the cowling flew open, oil filled the windshield, and the engine ceased delivering power. The aircraft impacted a tree and came to rest in a city park. At the scene, the No. 6 engine cylinder was separated from the crankcase and engine components associated with that cylinder were found over a 40-foot radius around the aircraft. The engine crankcase where the No. 6 cylinder attached was broken away at the 12 o'clock position; the upper forward, upper rear, and lower rear mounting studs were broken; and the lower forward stud and the two lower center studs were present. The skirt of the No. 6 cylinder exhibited a pattern of longitudinal striations where it mated into the crankcase opening. At the lower left of the cylinder mount location was a small ledge of material, which approximated the shape of the circumference of the cylinder base flange. Opposite this location, on the upper right of the cylinder mounting location, was a brightly polished wear area. The engine received a top overhaul 7 months, 41.8 hours prior to the accident. Breakaway torque was measured on the remaining cylinder base nuts and found to range between 25 and 40 foot-pounds; the specification torque values are between 40.8 and 42.5.

Quoted verbatim from the NTSB record.