FORT PIERCE, FL, USA
N37BA
Southwest Florida Aviation SW204
According to the pilot, at 50 feet, agl and 35 mph over an orange grove, he felt a shudder and heard cracking noises from the rear of the helicopter. He tried to put the rotorcraft down between rows of trees, but lost all control during his landing attempt, started spinning, and rolled over. The tail rotor assembly was located 400 feet from the wreckage with one rotor blade tip weight missing. Factory examination revealed the cause of the separation of the tip weight was corrosion of the adhesive bond between the blade skin, the blade spar, and the tip weight. The blade's data plate was missing and the data plate recess was smoothed over. The blade part and serial number provided by the operator did not match factory assembly records, and the factory was encouraged by the FAA to file a 'Suspected Unapproved Parts' report.
On May 24, 2000, about 0820 eastern daylight time, a Southwest Florida Aviation SW-204, N37BA, registered to and operated by Colony Services Inc. as a Title 14 CFR Part 137 agricultural aerial application flight, crashed in a citrus grove in the vicinity of Fort Pierce, Florida. Instrumental meteorological conditions prevailed, and no flight plan was filed. The helicopter received substantial damage and the commercially-rated pilot, the sole occupant, was not injured. The flight originated from a remote field about 5 minutes before the accident. According to the pilot, he was at 50 feet agl, and about 35 mph forward flight over an orange grove when he felt a shudder, heard loud cracking noises, and lost directional control. He attempted a forced landing between tree rows, touched down, and lost all control. According to an FAA inspector, examination of the wreckage site revealed the rotorcraft collided with orange trees and made several rotations and collisions with the terrain before coming to rest on its left side. The tail rotor assembly was found about 400 yards from the wreckage. Inspection of the assembly revealed one of the tail rotor blade tip weights had torn loose, causing an imbalance and separation of the tail rotor assembly from the tail boom at the 90-degree gearbox. The blade data plate was missing and the area where the plate had been factory mounted was raised and painted over. The tail rotor blade and the tip weight, found later by a ground crewman, were boxed and shipped to Bell Helicopter Textron for failure analysis with FAA oversight. According to the examination report, the cause for the blade tip weight separation was corrosion of the bond-line between the adhesive and the blade skin and corrosion of the bond-line between tip weight and the adhesive around the spar on the lead side of the blade. Screws used for a secondary means of fastening were still attached to the tip weight, and the countersunk screw holes in the blade skin revealed inward dimpling and elongation. A comparison of the reported blade part and serial numbers with the actual features of the blade did not match the Bell Helicopter assembly records. It was revealed that the reported blade and serial number was assembled in 1972 using a Narmco 1113 adhesive, (yellow). The adhesive found on the submitted blade was Narmco 123, (purple), and was used during the time frame, 1966 to 1968. The Bell Helicopter Textron Report No. 20400R-019 is an attachment to this report. According to the FAA inspector who oversaw the blade examination, the apparent inconsistency between the blade serial number and the color of the tip cap adhesive caused him to request that Bell Helicopter Textron file a "Suspected Unapproved Part" report. This was accomplished on September 15, 2000.
An in-flight separation of a tail rotor blade tip weight resulting in tail rotor assembly imbalance and separation due to the installation of an unapproved rotor blade by company maintenance personnel, and the subsequent collision with trees during an emergency landing.
Source: NTSB Aviation Accident Database
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