SARASOTA, FL, USA
N2994P
Lake LA-4-200
The pilot had just completed a touch-and-go landing on a lake. During the initial climb at an altitude of less than 500 feet, the airplane shuddered, then pitched nose down. The pilot reduced power and pulled the control column with negative results, then forcibly pushed and pulled the control column, which freed the elevator control. He maneuvered the airplane for an emergency water landing. Postaccident visual examination of the airplane revealed that the left horizontal stabilizer was displaced down about 12 degrees from the normally installed position. Further examination revealed that an attachment ear for the left horizontal stabilizer fitting beam had failed due to fatigue in an area of fretting wear. Fretting wear was also detected on the adjacent angle/top beam. For comparison, the right fitting/beam and angle/top beam were removed and examined. Fretting wear was detected on both components. A small crack was also detected on an attachment for the right fitting/beam, which had originated from fretting wear associated from the respective angle/top beam. An air worthiness directive (AD 98-10-12), effective 6/8/98, was issued to inspect the affected aircraft, to ensure proper clearance, and to correct if fretting, cracking, or corrosion were found.
On January 24, 1998, about 1430 eastern standard time, a Lake LA-4-200, N2994P, registered to Sylvan Educational Endeavors, was substantially damaged during takeoff from Lake Evers, near Sarasota, Florida. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal flight. The commercial-rated pilot and pilot-rated passenger were not injured. The flight originated about 1 minute earlier from the lake. The pilot stated that after takeoff from the Sarasota/ Bradenton International Airport, he flew to Lake Evers where he performed a touch-and-go landing. During the initial climb while over a river at an altitude less than 500 feet, he felt the airplane shudder and the airplane abruptly pitched nose down. He reduced power and pulled on the control column with no results. He then pushed and pulled the yoke, felt something give in the airframe, then recovered and maneuvered for landing on the river. The airplane touched down and bounced three times before coming to rest. Examination of the airplane revealed that the left horizontal stabilizer was angled down about 12 degrees from the normally installed position. Additionally, the fitting/beam attach (part number 2-2200-21) was failed. The failed fitting and non-failed associated angle/top beam (part number 2-2210-84) from the left horizontal stabilizer as well as the identical parts from the right horizontal stabilizer (part numbers 2-2200-21 and 2-2210-83) were submitted to the NTSB Metallurgy Laboratory for examination. Metallurgical examination of the failed fitting/beam attach for the left horizontal stabilizer revealed it failed due to fatigue caused by fretting wear. Additionally, a crack associated from fretting wear was detected on the right side fitting/beam attach part. Fretting wear was also detected on both the left and right angle/top beams. The airplane, minus the retained components was released to Mr. Harry Shannon, of Amphibians Plus, on April 2, 1998. The retained components were released as directed by the airplane owner, to Mr. Harry Shannon, on May 29, 1998.
inadequate clearance and fretting wear of the fitting/beam attachment to the angle/top beam, due to inadequate design, which resulted in fatigue and subsequent failure of the fitting/beam attachment ear.
Source: NTSB Aviation Accident Database
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