MIA98FA025

History of flight

On November 7, 1997, about 1017 eastern standard time, a Fokker F100, N865US, flight 479, registered to and operated by US Airways, as 14 CFR Part 121 scheduled domestic passenger flight, from Milwaukee, Wisconsin, to Charlotte, North Carolina, experienced a failure and separation of the right main landing gear on landing rollout at the Charlotte-Douglas International Airport. Visual meteorological conditions prevailed and an IFR flight plan was filed. The airplane sustained substantial damage. The airline transport-rated pilot-in-command, first officer, 3 flight attendants, and 99 passengers reported no injuries. The flight originated 1 hour 57 minutes before the accident.

The PIC stated the first officer made the approach and landing to runway 36 left. On landing rollout the airplane experienced a slight vibration which increased in intensity rapidly. The PIC effected a positive change of controls and instructed the first officer to notify the control tower that they would stop on the runway and to dispatch the emergency vehicles. The airplane started to veer to the right. Differential braking, rudder pedal steering, and nose wheel steering was used to keep the airplane aligned with the centerline of the runway. The airplane came to a complete stop. The first officer informed the PIC that the right wing was resting on the runway. The emergency passenger evacuation checklist was initiated and an evacuation of the airplane was commanded. All passengers and crew evacuated the airplane utilizing the forward galley service door, down the emergency escape chute, or through the right over wing emergency exits. The flight attendants stated the evacuation was calm and orderly except for passengers delaying evacuation while trying to retrieve carry-on bags. A left main landing gear brake fire was extinguished by company maintenance personnel.

Personnel information

All pertinent aviation regulations, 14 CFR Part 121, airman competency and proficiency checks, had been recorded as conducted. Further information pertaining to the pilot-in-command is contained in this report on page 3 First Pilot Information, NTSB Form 6120.4 Supplement U, CFR 121 Training and Flight Checks, and NTSB Form 6120.1/2 Pilot Information.

All pertinent aviation regulations, 14 CFR Part 121, airman competency and proficiency checks have been recorded as conducted. Further information pertaining to the first officer is contained in NTSB Form 6120.1/2, Second Pilot Information, and NTSB Form 6120.4, Supplement E, Second Pilot Information, and Supplement U, 121 Training and Flight Checks.

All pertinent aviation regulations, 14 CFR Part 121 flight attendant competency and proficiency checks have been recorded as conducted. Further information pertaining to the flight attendants is contained in NTSB Form 6120.4, Supplement U, Flight Attendant Information.

Aircraft information

Review of maintenance records revealed the right main landing gear (RMLG) had 13,890.5 hours and 13,108 cycles at the time of the accident, and had never been overhauled, only repaired. The heavy check (overhaul) on the RMLG was not due until 18,500 hours. The shimmy damper installed on this aircraft is MAL-095. The RMLG was initially installed on N883US. It was declared unserviceable on July 18, 1996, due to a reported gear vibration and worn bushings in the torque link. The RMLG was sent to a U.S. Airways landing gear shop at Winston-Salem for repair. The upper torque link, torque link pin, torque link apex pin, and shimmy damper unit were replaced. The main fitting torque link bore dimensions were found to be within the original size of 2.1562 to 2.1580 inches inside diameter per the component maintenance manual 32-10-62 repair #6; however, there was no record of the dimensions in the repair document, and replacement bushings were fabricated. The inside diameter of the bushings were honed to ensure the upper torque link pin would be installed with the required interference fit. The RMLG was declared serviceable on July 18, 1996, and placed in the Pittsburgh (PIT) inventory. The RMLG was declared unserviceable on January 27, 1997, after the upper torque link, torque link pin, shimmy damper, and apex pin were robbed, and placed on another airplane. The RMLG was returned to Winston-Salem to have the robbed parts replaced. A visual check of the main fitting upper torque link attach lug bushings revealed the inner diameter of a lug bushing and two antirotation pin bushings had been scored when the component was robbed. The main fitting torque link lug dimensions were within limits, and replacement bushings were fabricated. The RMLG was placed back in serviceable condition on January 29, 1997, and installed on N865US on February 5, 1997. For additional information see NTSB Maintenance Records Group Chairman Factual Report and Aircraft Information contained in NTSB Form 6120.4.

A review of logbook pages concerning the RMLG from September 22, 1997, and 1 week before the accident revealed the following write ups and corrective action:

October 8, 1997 Hydraulic fluid was dripping between the wheels of the right gear.

Action Found brake line inboard "B" nut loose. Tightened "B" nut on the # 3 brake shuttle valve. Cycled brakes several times.

October 9, 1997 The # 2 RMLG shimmy damper is leaking.

Action Serviced shimmy damper in accordance with Maintenance Manual task 12-12-02-610-813A.

October 10, 1997 The RMLG shimmy damper requires servicing frequently.

Action The shimmy damper was serviced per U.S. Airways Job Card 532-11-0. Note: the damper was programmed for replacement at the next overnight Transit Check.

October 14, 1997 The RMLG shimmy damper checked normal. No leaks were noted, and there was no history listed in the maintenance data computer system.

Action None.

October 28, 1997 Nose gear strut bumps, grinds, and bottoms-out during taxi.

Action Serviced strut per J5-90-0007C-001 procedures.

Meteorological information

Visual meteorological conditions prevailed at the time of the accident. For additional information see pages 3 and 4 of this report, Weather Information.

Flight recorders

N865US was equipped with a Fairchild model A100 cockpit voice recorder. The recorder was forwarded to the NTSB laboratory for analysis. The cockpit voice recorder was recorded clearly. The recording indicated no abnormal operations by the flight crew. No transcript of recorded communications was made.

N865US was equipped with a Loral model F800 digital flight data recorder (DFDR). The recorder was forwarded to the NTSB laboratory for analysis and a successful readout was performed. The DFDR indicates the airplane made a normal descent and landing to runway 36 left at an airspeed of 133 knots. The vertical acceleration shows increased activity after touchdown and the data indicates a change in roll from 0 degrees to 2 degrees. The roll registers 2 degrees for 3 seconds, at which point the maximum vertical acceleration of 1.41gs is measured. Immediately following, the roll increases to almost 12 degrees, and the airplane comes to rest on a heading of 016 degrees. (For additional information see NTSB Flight Data Recorder Specialist's Factual Report of Investigation.)

Wreckage and impact information

N865US was located on runway 36 left, 5,903 feet from the landing threshold on a heading of 016 degrees magnetic.

Examination of the runway revealed evidence of faint shimmying of the No. 3 right main landing gear wheel 2, 750 feet from the landing threshold. Additional shimmying indications (tire marks) from the Nos. 3 and 4 main wheel assemblies were noted 2,920 feet from the threshold.

The first indication of hydraulic fluid was noted on the runway 3,274 feet from the threshold. A consistent heavy accumulation of hydraulic fluid extended in a straight line masking the tire marks on the runway for an additional 500 feet.

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