Incident Description
A pilot reported that while flying approximately 5 miles north of Fort Lauderdale Executive Airport (FXE) at about 4,000 feet mean sea level, the airplane experienced a sharp nose-down pitch accompanied by uncontrollable back-and-forth oscillation of the control yoke lasting about 5 seconds. A loud shearing noise was heard from the right rear of the aircraft before pitch control was regained. The pilot looked toward the right rear and observed sheet metal flapping in the wind near the elevator section. He declared an emergency and was cleared for an immediate landing at FXE; the landing was uneventful.
Damage Details
An examination by the National Transportation Safety Board (NTSB) revealed that a section approximately 16 inches was missing from the right elevator's outboard area. The remaining outboard portion of the elevator, up to the inboard attaching hinge, was peeled upward and aft. The attaching hardware that connects the elevator trim tab horn to the elevator trim actuator push-rod was missing. No abnormality was observed on the surfaces of the trim tab horn or the push-rod attaching area.
Maintenance History
The accident airplane had undergone inspections and maintenance on February 21, 2005, which included an overhaul of the elevator trim tab actuator. The mechanic who performed the tasks stated that after installing the actuator, he attached the push-rod to the elevator trim horn using a new bolt, washer, nut, and cotter pin from shop stock, in accordance with the maintenance manual. Another mechanic stated he was present and handed the cotter pin to the installing mechanic.
An FAA inspector examined the maintenance facility and interviewed the mechanics involved. The inspector reported no discrepancy with the bins of cotter pins. The installing mechanic stated he remembered installing the cotter pin but could not recall the exact pin used, adding that it was given to him by the other mechanic. The FAA inspector instructed the second mechanic to demonstrate where he obtained the cotter pin. The mechanic went to the bin area and opened two bins, one of which contained the proper cotter pin. He stated he believed he took the correct pin.
Preflight Inspections
The pilot who test flew the accident airplane after maintenance stated that a preflight inspection was accomplished and no irregularities were noted. He personally completed two test flights. The airplane owner's pilot also performed a preflight inspection in the facility's hangar prior to signing the delivery receipt and at least two more times before and during the en route flight to Florida.
Investigation
During the investigation, the pilot of the accident flight was asked to demonstrate the preflight steps and specify what type of nut was securing the trim tab horn to the push-rod—a self-locking nut or one using a cotter pin. He recalled a nut but could not recall observing a cotter pin.