Cessna 310I accident near Sunnyside, Washington, May 25, 2023
On May 25, 2023 at about 7:45 pm local time, a 1964 Cessna 310I, registered N6PK, was substantially damaged in an accident during landing (landing roll) near Sunnyside, Washington (Sunnyside Municipal 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
The failure of the side brace lock assembly of the right main landing gear due to overstress as a result of a hard landing.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 25, 2023 · about 7:45 pm local time
- Place
- Sunnyside, Washington · Sunnyside Municipal Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 310I, built 1964 · all 310Is on the register
- Registration
- N6PK · registry record · serial 310I0021
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that while on final approach he extended the gear, and a green light illuminated signifying that the gear was down. The landing was “firm” and, shortly after touchdown, the airplane’s right main landing gear slowly collapsed, causing the right wing to drop. The airplane veered to the right, exited the runway, and came to rest in a field about 100 ft from the runway centerline. During the accident sequence, the airplane sustained substantial damage to the right horizontal stabilizer and elevator. Postaccident examination of the right main landing gear fracture surface revealed that the side brace lock assembly likely fractured due to excessive axial compression loads that resulted in a ductile overstress fracture. Additionally, the bent side brace lock assembly attachment bolt at the lower end of the lock link also indicated that the loads associated with the failure of the attachment pin exceeded the design axial loads for the side brace lock assembly and were consistent with overload of the side brace lock assembly. The bearings and pin that attached the side brace lock to the lower end of the bellcrank, which were not recovered, were likely fractured as a result of the loads. The damage to the gear indicated that it likely failed as a result of the hard landing.
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
What happened, in order
- Landing gear collapse during landing (landing roll) defining event
- Runway excursion during landing (landing roll)
- Hard landing during landing
The NTSB's findings
- Aircraft › Aircraft systems › Landing gear system › Main landing gear › Failure
- Aircraft › Aircraft systems › Landing gear system › Main landing gear › Capability exceeded
- Personnel issues › Task performance › Use of equip/info › Aircraft control › Pilot
- Aircraft › Aircraft oper/perf/capability › Performance/control parameters › Landing flare › Not attained/maintained
Pilot
- Certificate: airline transport pilot, flight instructor
- Ratings: multi-engine land; multi-engine sea; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instrument: airplane
- Flight time: 12,628 hours in all; 250 in this make and model; 15 in the last 30 days; 745 on instruments
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: left
- Injury: no injuries
Passenger
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 5,695 hours
- Last inspection: annual inspection, September 1, 2022
- Maximum gross weight: 5,100 lb
- Landing gear: retractable
- Engine 1: Continental IO-520-E (piston); 1,725 hours total
- Engine 2: Continental IO-520-E (piston); 1,748 hours total
The flight
- Departed from: MWH Moses Lake WA at 8:30 pm
- Flight plan: none
- Runway 25, 3,425 ft by 60 ft
Weather at the time
- Light: daylight
- Wind: from 120° at 5 knots
- Visibility: 10 statute miles
- Sky: a few clouds at 7,500 ft
- Temperature: 73°F (23°C), dew point 43°F (6°C)
- Altimeter: 29.90 inHg
- Observation at 12:53 pm from KYKM, 27 miles away
Weather report (METAR): METAR KYKM 251953Z AUTO 12005KT 10SM FEW075 FEW090 23/06 A2990 RMK AO2 SLP120 T02330061
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
2 documents, released by the NTSB on November 14, 2024. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 11 pages | View Download |
| 2 | Materials Laboratory Factual Report 23-096 | PDF, 7 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.