Rockwell 690B N480K

Summary

On 17 June 1999 at about 05:00 local time, a Rockwell 690B registered N480K was involved in an accident near Monterey, California, United States. 5 people were 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

17 June 1999 at 05:00

Classification

Accident

Location

Monterey, California, United States

Nearest airport

Monterey Peninsula (KMRY)

Coordinates

36.6009, -121.8800

Aircraft

Rockwell 690B

Registration

N480K

Category

Airplane

Engines

2

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Tri-County → Unknown

Aircraft damage

Substantial

Weather

IMC

Light

Night/Dark

NTSB number

LAX99LA241

Nobody was injured.

The failure of maintenance personnel to properly adjust the drag brace preload during recent landing gear maintenance, which resulted in the overload failure and separation of the hydraulic cylinder attach boss.

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

Read the full NTSB narrative

The pilot and copilot reported that they were on approach and as they passed the outer marker, they observed three green lights indicating the landing gear was extended. They observed hydraulic pressure of about 1,000 psi during the landing checks. The pilot said he landed the airplane with a slight tailwind, observed two beta lights, and he pulled the power levers into ground idle/reverse. Shortly thereafter, he felt the left landing gear collapse and he observed one red unsafe light and two green landing gear lights, with a corresponding gear warning horn. Postaccident examination of the left main gear revealed that a piece was fractured from the inboard gear-forging boss, which houses a clevis for the attachment of the hydraulic cylinder. The clevis remained attached to the hydraulic cylinder, which in the fully extended position is consistent with gear down. Metallurgical examination of the fracture faces revealed features typical of overstress separation. No pre-existing cracks or other defects were found on the fracture. A review of the Commander maintenance manual indicates that an adjustment must be made to the cylinder over travel following gear maintenance to obtain the proper drag brace preload. The left hand hydraulic cylinder, main landing gear aft wheel well door, and hydraulic components were replaced about 34 hours before the accident.

Quoted verbatim from the NTSB record.