Cessna 185F accident near Bozeman, Montana, June 24, 2004
On June 24, 2004 at about 9:10 pm local time, a Cessna 185F, registered N4585F, was substantially damaged in an accident near Bozeman, Montana (Gallatin Field). 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 right main gear brake disk attach flange during the landing roll, due to fatigue cracks emanating from numerous corrosion pits present on the surface of the disk, leading to the right brake becoming totally inoperative, and resulting in a rapid inadvertent ground-loop. Factors include hard braking applied by the pilot in order to turn off the active runway at an early taxiway, and considerable corrosion on the surface of the brake disk flange.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 24, 2004 · about 9:10 pm local time
- Place
- Bozeman, Montana · Gallatin Field · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 185F · all 185Fs on the register
- Registration
- N4585F · no longer on the register · serial 1851092
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
During the landing roll, the pilot was applying heavy braking in order to turn off the runway at taxiway Echo, when the aircraft suddenly and rapidly ground-looped to the left. An initial post-accident inspection of the aircraft revealed that the right main gear brake rotor assembly had torn lose from the wheel itself, rendering the right wheel brake totally inoperative. The wheel hub and brake disk assembly were shipped to the NTSB Materials Laboratory, where it was determined that the brake disk attachment flange failed in fatigue in the bend around the attachment flange. The brake disk showed a substantial amount of general corrosion, and although the attachment flange met the minimum thickness requirements, most of its surface was covered by corrosion and corrosion pitting. The fatigue crack propagation that eventually lead to the failure had originated in one of these corrosion pits.
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: single-engine land
- Flight time: 2,450 hours in all
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Maximum gross weight: 3,350 lb
- Seats: 6
- Landing gear: fixed
- Engine: Continental IO-520-D (piston); 0 hours total
The flight
- Destination: BZN Bozeman MT
- Flight plan: none
- Runway 30, 9,003 ft by 150 ft
Weather at the time
- Light: daylight
- Visibility: 20 statute miles
- Sky: clear
- Temperature: 75°F (24°C), dew point 0°F (-18°C)
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.
Other NTSB records under N4585F the same tail number, which may have belonged to a different aircraft at the time
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.