Chance Vought F4U 5 N179PT

Summary

On 19 July 2016 at about 16:20 local time, a Chance Vought F4U 5 registered N179PT was involved in an accident near East Troy, Wisconsin, United States. One person was 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

19 July 2016 at 16:20

Classification

Accident

Location

East Troy, Wisconsin, United States

Nearest airport

East Troy Muni (57C)

Coordinates

42.7969, -88.3744

Aircraft

Chance Vought F4U 5

Registration

N179PT

Category

Airplane

Year built

1948

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

East Troy → East Troy

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN16LA274

Nobody was injured.

A failure of the O-ring in the left brake master cylinder for reasons that could not be determined, which resulted in a loss of directional control during landing.

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

Read the full NTSB narrative

Before the accident flight, the airplane's brakes were replaced with a custom brake system. Testing of the brake system after installation resulted in a failure of the right master cylinder. The cylinder was disassembled and the O-ring was found cut. The mechanic could not find any reason for the cut O-ring, so the O-rings on both master cylinders were replaced. The next brake test resulted in a brake fluid boil, and the brake builder informed the mechanic to change the type of hydraulic fluid. A subsequent ground brake test produced "no issues or hesitation with the brakes at all," to include "a full pressure pedal push to simulate a full locked brake to pressure test [the] system prior to taxi test." A maintenance flight was then conducted, and, during landing, the airplane began to drift to the right. The commercial pilot applied the left brake; however, the brake failed and the pedal "went to the floor." The airplane departed the runway and collided with a wind sock structure. Postaccident examination revealed that the left brake master cylinder O-ring was cut; however, the reason for the cut could not be determined. After the accident, the mechanic contacted the master cylinder manufacturer for guidance. The company replaced the master cylinders with an upgraded model. The new cylinders were installed on the airplane and the mechanic, with guidance from the custom brake manufacturer, conducted more testing. A second airplane flew with the newer brake system without issue.

Quoted verbatim from the NTSB record.