Cessna 421B accident near Portland, Maine, July 2, 2004
On July 2, 2004 at about 11:36 pm local time, a Cessna 421B, registered N421KS, was substantially damaged in an accident near Portland, Maine (Portland International Jetport airport). It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
Failure of the right main landing gear down-lock mechanism resulting in the collapse of the right main landing gear.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 2, 2004 · about 11:36 pm local time
- Place
- Portland, Maine · Portland International Jetport · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 421B · all 421Bs on the register
- Registration
- N421KS · registry record · serial 421B-0507
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
Line personnel reported to the pilot that while the airplane had been parked on the ramp, heavy wind and rain "hydroplaned" the airplane across the ramp about 25 feet. After takeoff, the pilot retracted the landing gear and noticed an unfamiliar "clunking" noise during the retraction cycle. During the approach to the destination airport, he extended the landing gear and noted all three of the landing gear down and locked indicator lights were green. Sometime during the rollout he heard the "clunk" noise again, and the right wing began to settle lower than normal. The airplane then began to veer to the right and came to rest in the grass on the right side of runway. Examination of the right main landing gear revealed that two components of the down-lock mechanism had broken. The parts were submitted to the Safety Board Materials Laboratory. Metallurgical examination of the mating fractures revealed features typical of overstress separation. The fractures contained no evidence of fatigue.
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: private
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 4,312 hours in all; 294 in this make and model; 46 in the last 90 days; 9 in the last 30 days
- Last flight review: May 28, 2003
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 4,310.1 hours
- Last inspection: annual inspection, June 20, 2004; 8.5 hours since
- Maximum gross weight: 7,680 lb
- Seats: 7
- Landing gear: retractable
- Engine 1: Teledyne Continental GTSIO-520-H (piston); 0 hours total
- Engine 2: Teledyne Continental GTSIO-520-H (piston); 0 hours total
The flight
- Departed from: GON Groton CT at 10:30 pm
- Destination: PWM Portland ME
- Flight plan: IFR
- Runway 29, 6,800 ft by 150 ft
Weather at the time
- Light: daylight
- Wind: from 050° at 3 knots
- Visibility: 6 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 63°F (17°C)
- Altimeter: 29.90 inHg
- Observation at 11:51 pm from PWM
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 1 |
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.