NTSB Factual Report

On February 16, 2006, at 1647 eastern standard time, a Cessna 525A, N701TF, registered to and operated by Zinc Acquisitions LLC, and piloted by an airline transport-certificated pilot, experienced a loss of directional control and subsequent collapse of the nose landing gear during the landing roll at Tampa International Airport, Tampa, Florida. Visual meteorological conditions prevailed at the time of the accident. The executive/corporate flight was being conducted under the provisions of Title 14 CFR Part 91, and an instrument flight rules (IFR) flight plan had been filed and activated. The pilot and four passengers were not injured. The cross-country flight originated approximately 1600 from Marco Island Airport, Marco Island, Florida, and was en route to Tampa.

The pilot stated that the flight to the destination airport was uneventful until landing. He landed on runway 18L, and after touchdown on all landing gears, he placed the flap selector handle to the ground flap position and applied the brakes. The airplane "swerved" to the right which he corrected back to the runway centerline. He applied the normal brakes again and the airplane again "swerved" to the right. He again corrected back to the runway centerline and applied the normal brakes the third time. The airplane again "swerved" to the right and he applied the emergency brake. The airplane departed the right side of the runway, and the nose landing gear contacted the concrete pad of a runway marker sign, causing separation of the nose landing gear. The airplane came to rest and all occupants exited the airplane.

FAA inspector reported finding hydraulic fluid covering the left main landing gear. He said the main and auxiliary left brake lines were both fractured, and the right main landing gear tire was "shredded off the wheel."

According to NTSB's Materials Laboratory Factual Report, "The [left] brake line transmits hydraulic fluid and the auxiliary brake line transmits compressed nitrogen between two bulkheads under the wing. The left hand brake line was fractured near its mid point and the auxiliary brake line was fractured adjacent to the flared inboard end. Microscopic examination of the left brake line revealed "the fracture mode over most of the break was fatigue cracking." Microscopic examination of the left auxiliary brake line revealed a fracture plane "perpendicular to the length of the line, and no overall deformation was noted in the tube adjacent to the fracture, features consistent with fatigue cracking that propagated most of the way through the tube before final separation."

According to a statement submitted by an FAA airworthiness inspector, he reviewed the airplane's maintenance records back to its date of manufacture, and "did not locate any removal or replacement of left main landing gear brake line part numbers 6317013 or 6317014-13."

NTSB Probable Cause

Failure of both the left main and auxiliary brake lines due to fatigue cracking, rendering directional control impossible. A contributing factor in this accident was the airport sign concrete pad.