Wednesday, July 20, 2016

Chance Vought F4U-5 Corsair, N179PT: Accident occurred July 19, 2016 at East Troy Municipal Airport (57C), Walworth County, Wisconsin

Aviation Accident Final Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

NTSB Identification: CEN16LA274 
14 CFR Part 91: General Aviation
Accident occurred Tuesday, July 19, 2016 in East Troy, WI
Probable Cause Approval Date: 09/06/2017
Aircraft: CHANCE VOUGHT F4U 5, registration: N179PT
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

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.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
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.

The National Transportation Safety Board did not travel to the scene of this accident.

Additional Participating Entity:
Federal Aviation Administration / Flight Standards District Office; Milwaukee, Wisconsin

Aviation Accident Factual Report - National Transportation Safety Board: https://app.ntsb.gov/pdf

Investigation Docket - National Transportation Safety Board: https://dms.ntsb.gov/pubdms

Fighters & Legends LLC: http://registry.faa.gov/N179PT

NTSB Identification: CEN16LA274
14 CFR Part 91: General Aviation
Accident occurred Tuesday, July 19, 2016 in East Troy, WI
Aircraft: CHANCE VOUGHT F4U 5, registration: N179PT
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On July 19, 2016, about 1120 central daylight time, a Vought F4U-5 Corsair airplane, N179PT, departed the runway surface after landing at the East Troy Municipal Airport (57C), East Troy, Wisconsin. The pilot was not injured and the airplane was substantially damaged. The airplane was registered to Fighters & Legends LLC and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight. The local flight departed 57C about 1115.

The pilot departed from 57C on a maintenance flight, in order to test the airplane brakes. He reported that the brake tested normal during the taxi. He applied the brakes several times in flight, and received positive pressure of the brake pedals. On the full stop landing to runway 8, the pilot applied the brakes and received normal braking action. As the airplane slowed, it slowly drifted to the right. The pilot applied a small amount of left brake to correct the drift and the pedal went to the floor; pumping the pedal did not correct the problem. In order to avoid a ditch, the pilot applied the right brake; however, the airplane's wing collided with the airfield's windsock. Substantial damage was sustained to the airplane's right wing.

Prior to the accident, the airplane's brakes were replaced with a custom brake system using Grove master cylinders. 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 with Viton O-rings and care was given to carefully place them into the cylinders. The next brake test resulted in a brake fluid boil, so the brake builder informed the mechanic to change the hydraulic fluid from MIL-PRF 5606 to MIL-PRF-83282. 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."

After the accident, the mechanic contacted the master cylinder manufacturer (not the brake builder) for guidance. The company replaced the master cylinders with an upgraded model. The new cylinders were installed on the accident airplane and the mechanic, with guidance from the custom brake manufacturer, conducted more testing.


On February 6, 2017, a second Corsair flew with the newer brake system without issue.

NTSB Identification: CEN16LA274
14 CFR Part 91: General Aviation
Accident occurred Tuesday, July 19, 2016 in East Troy, WI
Aircraft: CHANCE VOUGHT F4U 5, registration: N179PT
Injuries: 1 Uninjured.

This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

On July 19, 2016, about 1050 central daylight time, a Vought F4U-5 Corsair airplane, N179PT, was substantially damage while landing at the East Troy Municipal Airport (57C), East Troy, Wisconsin. The pilot was not injured. The airplane was registered to Fighters & Legends LLC and operated by a private individual under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight which operated without a flight plan. The local flight departed 57C about 1030.

Preliminary information obtained by the Federal Aviation Administration indicated that during the landing roll, the airplane began drifting to the right. The pilot corrected with left brake, but was unable to command any braking with the left pedal and was unable to stop the drift. The airplane exited the right side of the runway and collided with a windsock. The airplane's right wing was substantially damaged.

The airplane had recently completed an annual inspection when components of its brake system were replaced. The accident flight was the first flight since the annual inspection.

AIRCRAFT, EXPERIMENTAL EXHIBITION CHANCE VOUGHT F4U-5, ON LANDING WENT OFF THE RUNWAY AND STRUCK THE WINDSOCK, EAST TROY, WISCONSIN. 

NTSB Identification: CHI99FA266C
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
Accident occurred Thursday, July 29, 1999 in OSHKOSH, WI
Probable Cause Approval Date: 06/22/2000
Aircraft: Chance Vought F4U-5, registration: N179PT
Injuries: 1 Serious, 1 Minor, 1 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The three airplanes were part of a formation demonstration flight of eight World War II Navy fighters, divided into four sections of two airplanes each, that had been cleared to takeoff from runway 18 at Wittman Regional Airport, Oshkosh, Wisconsin, during the annual Experimental Aircraft Association (EAA) convention, 'AirVenture 99'. Air traffic control clearance for the departing aircraft had been relinquished from the FAA tower to a local 'air boss'. The air boss had cleared all of the airplanes to takeoff as a flight. Witnesses saw the lead airplane, a Bearcat, N14HP, and his wingman, taxi down runway 18 approximately 1,400 feet, turn toward the southwest and stop. Approximately 4 seconds later, the lead airplane in the second section, a Corsair, N712RD, collided into N14HP severing the Corsair's left wing, and the Bearcat's right wing. The Corsair continued down the runway, rolling over on it's left side, came apart, and burst into flames. The remains of the Corsair came to rest in a field east of the runway, approximately 2,000 feet down. The Bearcat was turned approximately 180 degrees and came to rest on the runway's east edge. A second Corsair, the wingman of N712RD, veered off of the west side of runway 18, sustaining substantial damage to it's left wing. Examination of all three airplanes revealed no anomalies.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
The pilot of the other airplane not following the instructions briefed by the formation leader, and the pilot's maneuvering his airplane to avoid the airplane in front of him.

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