Aviation Accident Summaries

Aviation Accident Summary WPR09LA029

Mesa, AZ, USA

Aircraft #1

N421PC

CESSNA 421C

Analysis

At the conclusion of the business flight, the pilot placed the landing gear selector in the down position. The gear did not extend. Then, the pilot attempted to extend the gear using the emergency procedure, and he was similarly unsuccessful. The pilot landed with the gear partially extended. The airplane swerved off the runway and was substantially damaged. An examination of the landing gear system revealed that an aluminum hydraulic line had ruptured at a 45-degree bend near the location of an Adel clamp. The subsequent loss of fluid rendered the primary and emergency gear extension systems inoperative.

Factual Information

On October 29, 2008, about 1959 mountain standard time, a Cessna 421C, N421PC, experienced the collapse of its landing gear during rollout at the Falcon Field, Mesa, Arizona. The airplane was owned and operated by Dry Force, Inc., Mesa. The airplane was substantially damaged, and neither the commercial certificated pilot nor four passengers were injured. Visual meteorological conditions prevailed at the time of the business flight, and an instrument flight rules flight plan was filed. The flight was performed under the provisions of 14 Code of Federal Regulations Part 91, and it originated from San Diego, California, about 1737 Pacific daylight time. The pilot reported to the National Transportation Safety Board investigator that, at the conclusion of the flight on approach to Falcon Field, he placed the landing gear selector in the down position. Thereafter, he observed that the landing gear's green position light failed to illuminate for the left gear. The pilot attempted to lower the gear several times and finally attempted to extend the gear using the emergency "blow down" procedure. None of the procedures worked. The pilot landed on runway 22 with a partially extended landing gear. The airplane touched down softly on the runway, but substantial structural damage occurred as the airplane swerved off the runway and slid to a stop. Belly skin was punctured, and several ribs were bent upward. The pilot reported that he smelled a strong odor of hydraulic fluid in the cabin. An examination of the landing gear system revealed that an aluminum hydraulic line associated with the gear's operation had ruptured beneath an Adel clamp. There was a crack in the line at a 45-degree bend near this location. The pilot also reported that the emergency gear extension system was rendered inoperative when the hydraulic leak occurred. The total time on the airframe and broken line was about 4,113 hours.

Probable Cause and Findings

The failure of the hydraulic landing gear extension systems due to a ruptured line.

 

Source: NTSB Aviation Accident Database

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