Aviation Accident Summaries

Aviation Accident Summary ERA20LA053

Louisville, KY, USA

Aircraft #1

N9097W

PIPER PA28

Analysis

The commercial pilot was on the return leg of a two-leg flight. While on final approach of the airport traffic pattern for runway 24 with the reported wind from 280° at 7 knots, the pilot descended using the visual approach slope indicator for reference with no "irregular indications of plane operation." He continued the approach maintaining 85 knots to the threshold, then, after crossing the threshold, he began to slow to 70 knots. When in ground effect with no stall speed annunciation, the flaps set to 25°, and pitch trim set to neutral, he began to flare the airplane, when suddenly the nose “jerked down” and he was unable to physically manipulate the control yoke. The airplane impacted the runway causing collapse of the nose landing gear and down displacement of the right wing, consistent with a hard landing. Based on automatic dependent surveillance-broadcast data, the average calculated groundspeed was 81 knots for the last 30 seconds of the flight, which was well above the published stall speed with flaps extended. Postaccident examination of the airplane revealed impact damage to the lower portion of the control column which caused binding of the stabilator flight control system with a flight instrument. Although the stabilator flight control cable tension was 2 pounds less than the specified value, that likely would not have resulted in an uncommanded nose-down pitch. Despite the pilot’s claim that he was unable to manipulate the control yoke, no pre-impact anomalies were noted during the examination that would have contributed to a hard landing. The accident is consistent with the pilot improperly flaring the airplane, which resulted in a hard landing.

Factual Information

On December 10, 2019, about 1303 eastern standard time, a Piper PA-28-235, N9097W, was substantially damaged when it was involved in an accident near Louisville, Kentucky. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that he was on the return leg of a round-trip flight when he contacted the Bowman Field Airport (LOU) air traffic control tower and reported a 3-mile left base position for runway 24. He was cleared for a visual approach to runway 24 and began descending to traffic pattern altitude while he performed before landing procedures and reduced speed. He turned onto the final leg of the airport traffic pattern for runway 24 and descended using the visual approach slope indicator with no "irregular indications of plane operation." Automated terminal information service "Zulu" was current and included wind from 280° at 7 knots. He maintained approach speed with a slight crosswind, the flaps set to the second notch or 25°, and pitch trim set to neutral. He maintained 85 knots to the threshold, and after crossing the threshold he began to slow to 70 knots. When in ground effect with no stall annunciation, he began to flare the airplane. Suddenly the nose "jerked down" and he was unable to physically manipulate the control yoke. The airplane impacted the pavement of runway 24 with the nose gear, causing it to collapse. The airplane came to rest on left of the runway 24 centerline about 30 ft from the end of the aiming point marking, with the nose and left main landing gear in the grass, and the right main landing gear wheel still on the runway. The pilot secured the electrical system, turned off the fuel selector, and exited the airplane. Examination of the airplane at the accident site before recovery by a Federal Aviation Administration (FAA) inspector revealed the right wing was displaced downward outboard of the inboard fuel tank and the nose landing gear was collapsed aft. Gouges were noted on the runway centerline about 120 ft from the displaced threshold; the gouges were consistent with being made by the propeller. Marks on the runway from the displaced right wing and collapsed nose landing gear continued from the initial impact to the resting position of the airplane. Initial examination of the airplane at the accident site revealed only slight movement of the stabilator. Examination of the airplane following recovery by representatives of the Federal Aviation Administration (FAA) revealed impact damage to the flight control pulleys near the control yoke lower mount area caused by a portion of the collapsed nose landing gear assembly. The vertical portion of the control column was displaced enough to cause the pilot's control yoke slide tube to contact the bottom of the directional gyro (DG). After the DG was placed back into the instrument panel and pressure applied to the control yoke opposite the direction of displacement, the stabilator control moved freely to the stops in both directions. Testing of the stabilator control cables also with FAA oversight revealed they were 2 pounds below the appropriate reading correlated to the temperature. The stabilator trim actuator was found positioned slight airplane nose-up, which corresponded to the cockpit setting. A review of automatic dependent surveillance-broadcast data for the flight revealed that between 1302:54 and 1303:24 (last target), the airplane traveled about 4,070 ft in about 30 seconds, which correlated to an average calculated groundspeed of about 81 knots. The airplane flight manual specified the stall speed range at gross weight for clean configuration (no flaps extended) and flaps extended are 61 and 53 knots, respectively. According to NTSB personnel, the wind reported by LOU ATCT was consistent with the surface observations. The wind of 20+ knots did not occur until about 2,500 ft mean sea level, which did not meet the low level windshear criteria.

Probable Cause and Findings

The pilot’s improper flare to land, which resulted in a hard landing and the nose landing gear collapsing.

 

Source: NTSB Aviation Accident Database

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