Cessna 185F N4585F

Summary

On 24 June 2004 at about 21:10 local time, a Cessna 185F registered N4585F was involved in an accident near Bozeman, Montana, United States. 2 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

24 June 2004 at 21:10

Classification

Accident

Location

Bozeman, Montana, United States

Nearest airport

Gallatin Field (KBZN)

Coordinates

45.7781, -111.1575

Aircraft

Cessna 185F

Registration

N4585F

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Unknown → Bozeman

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA04LA117

Nobody was injured.

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.

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

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.