Rockwell 690B accident near Monterey, California, June 17, 1999
On June 17, 1999 at about 5:00 am local time, a Rockwell 690B, registered N480K, was substantially damaged in an accident near Monterey, California (Monterey Peninsula airport). It was a business flight under general aviation rules (Part 91). No one was hurt; 5 people were on board or involved. The weather was instrument conditions (cloud, fog or low visibility).
The NTSB's probable cause their words, unchanged
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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 17, 1999 · about 5:00 am local time
- Place
- Monterey, California · Monterey Peninsula · map
- Type
- Accident
- Injuries
- No one was hurt; 5 people were on board or involved.
- Weather
- instrument conditions (cloud, fog or low visibility)
- Aircraft
- Rockwell 690B
- Registration
- N480K · registry record · serial 11543
- Damage
- Substantial damage
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
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: commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 5,650 hours in all; 950 in this make and model; 8 in the last 90 days; 5 in the last 30 days; 5,500 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 4,687 hours
- Last inspection: 100-hour inspection, November 3, 1998; 34 hours since
- Maximum gross weight: 10,325 lb
- Seats: 8
- Landing gear: retractable
- Engine: Garrett TPE331-5-252K (turboprop); 0 hours total
The flight
- Departed from: 48V Tri-County CO at 1:00 am
- Destination: MRY
- Flight plan: IFR
- Runway 10R, 7,600 ft by 150 ft
- A second pilot was aboard
Weather at the time
- Light: night, dark
- Wind: from 230° at 9 knots
- Visibility: 9 statute miles
- Sky: overcast at 400 ft; not recorded
- Temperature: 54°F (12°C), dew point 52°F (11°C)
- Altimeter: 29.00 inHg
- Observation at 4:54 am from MRY, 1 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 2 | |||
| Passengers | 3 |
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.