Aviation Accident Summaries

Aviation Accident Summary MIA08LA066

Tampa, FL, USA

Aircraft #1

N5489V

CESSNA 210L

Analysis

While inbound to land, the pilot lowered the landing gear using the normal system and the nose and left main landing gears went into the down and locked position; however, the right main landing gear did not due to a false down-and-locked indication caused by a malfunction of the right main landing gear down-and-locked switch. As such, the pilot observed a green light indicating that all landing gears were down and locked and continued the approach. During the landing roll the right main landing gear collapsed. Postaccident examination revealed that the malfunction of the right down-and-locked switch was caused by a bent plunger, which shut off the electrically-driven hydraulic pump before the right gear went into the down and locked position. Since 1992, the right main landing gear down-and-locked switch had been replaced six times, with the latest replacement occurring in October 2004. The airplane had been operated for 2,082 hours since the latest switch replacement. Additionally, the operator performs gear rigging testing every 300 hours. The latest rigging check occurred on November 15, 2007. The airplane had accumulated approximately 218 hours since then at the time of the accident.

Factual Information

On February 27, 2008, about 0141 eastern standard time, a Cessna 210L, N5489V, registered to and operated by Flight Express, Inc., as flight 805, experienced collapse of the right main landing gear during landing at Tampa International Airport (TPA), Tampa, Florida. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 135 non scheduled, domestic cargo flight from Columbia Metropolitan Airport (CAE), Columbia, South Carolina, to TPA. The airplane was substantially damaged and the certificated commercial pilot, the sole occupant, was not injured. The flight originated from CAE about 2243. The pilot stated that the flight departed and proceeded uneventfully to the destination airport where the flight was cleared to land on runway 27; the wind was from 300 degrees at 12 knots. When the flight was approximately 5 miles from his destination he performed the "TBGUMPS" flow which included to verify and vocalize: "Green light-On" pertaining to the landing gear being down and locked. He also visually verified that the left main landing gear was down and locked by looking outside his window. The flight continued and after the right main landing gear contacted the runway, the airplane momentarily became airborne. He further stated that he could tell the right main landing gear did not feel as solid as it should at the initial contact. The airplane touched down on the left main landing gear, and he held the nose landing gear off the runway as long as he could. The airplane veered to the right off the runway onto grass. The operator's director of maintenance (DOM) reported to an FAA airworthiness inspector that prior to raising the airplane, the landing gear green safe light illuminated when battery power was applied. The DOM also reported to the inspector that when the airplane was raised, the right main landing gear fell out of the wheel well and was moved to the down and locked position with no discrepancies noted. Postaccident examination of the airplane following recovery was performed by a Federal Aviation Administration (FAA) airworthiness inspector. The inspector reported that the entire horizontal and vertical stabilizer assembly was displaced 15 to 20 degrees to the right with extensive buckling to the left side fuselage skin. He also reported that the plunger of the right main landing gear down and locked switch was depressed and bent; physical effort was required to pull out the plunger of the switch. Additionally, the plunger was misaligned from its normally installed position. The down and locked switch was retained for further examination. Examination of the right main landing gear down and locked switch was performed at the airplane manufacturer's facility with FAA oversight. X-ray examination of the switch as received (plunger depressed) revealed the contacts were closed and electrical continuity through the attached electrical wires and switch was noted. X-ray examination of an exemplar switch with the plunger in the full up position (normal open position) revealed no electrical continuity through the wires and switch. Examination of the switch contacts and related mechanism of the accident down and locked switch revealed no damage or corrosion. By design, depressing of each plunger at all down and locked switches (indicating all gears are down and locked), builds up pressure in the hydraulic system and shuts off the electrically-driven hydraulic pump. Review of maintenance records revealed the right main landing gear down and locked switch had been replaced six times since 1992. The latest replacement occurred in October 2004. The entry for the latest replacement indicates the switch plunger was bent. At the time of the accident the airplane had accumulated approximately 2,082 hours since the latest switch replacement. Additionally, the operator performs gear rigging testing every 300 hours. The latest rigging check occurred on November 15, 2007. The airplane had accumulated approximately 218 hours since then at the time of the accident.

Probable Cause and Findings

The malfunction of the right main landing gear down-and-locked switch.

 

Source: NTSB Aviation Accident Database

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