History of Flight
On October 4, 2009, about 1240 eastern daylight time, a Cessna 210, registration N9443T, was substantially damaged during landing at Bowman Field Airport (LOU) in Louisville, Kentucky. The flight, a review and instrument competency check for a commercial pilot, was conducted under 14 Code of Federal Regulations Part 91. The certificated flight instructor and the commercial pilot were not injured. Visual meteorological conditions prevailed, and no flight plan had been filed.
According to the flight instructor, the takeoff was uneventful. During the flight, which included holding, instrument approaches, and landings at nearby airports, the hydraulically actuated landing gear and flaps were cycled several times without incident. After returning to LOU and being cleared for landing on runway 24, the commercial pilot attempted to lower the landing gear. The gear-up light extinguished, but the gear-down light did not illuminate, and no wheels were observed from the side windows.
The flight instructor advised the tower of the problem and was directed to orbit south of the airport while troubleshooting. The landing gear circuit breaker checked OK, and the flaps would not extend. The flight instructor manually pumped the gear extension lever for several minutes without result.
After several attempts to lower the gear, the flight instructor declared an emergency and requested fire trucks and EMS. He took over control while the commercial pilot stowed loose items. The instructor flew a no-flaps approach and touched down at minimum safe speed. The commercial pilot then pulled the mixture control, shut off the magnetos, used the starter to move the propeller to prevent damage, turned off the master switch, and shut off the fuel to reduce fire risk. As the airplane scraped down the runway, it veered left, departed the paved surface, tilted left, and came to rest with the left horizontal stabilizer and left wingtip contacting the ground.
Personnel Information
The flight instructor held a commercial pilot certificate with ratings for airplane single-engine land and instrument airplane. He reported 2,878.7 total hours of flight experience. His most recent third-class medical certificate application was dated July 23, 2008. The commercial pilot held ratings for airplane single-engine land and instrument airplane; his most recent third-class medical certificate application was dated April 1, 2009.
Aircraft Information
The Cessna 210 was manufactured in 1960. Its most recent annual inspection was completed on December 12, 2008, at which time the airplane had accrued 4,354.4 total hours. During that inspection, a new high-pressure electrical fuel pump was installed in the nose wheel well.
Meteorological and Airport Information
The reported weather at LOU at 1253 included winds from 220 degrees at 3 knots, visibility 10 miles, few clouds at 3,800 feet, temperature 16°C, dew point 6°C, and an altimeter setting of 30.11 inches of mercury. LOU had two runways (6/24 and 15/33); runway 24 was asphalt in fair condition, 4,326 feet long and 75 feet wide.
Wreckage and Examination
Post-accident examination by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the horizontal stabilizer. In the nose landing gear wheel well, a considerable amount of hydraulic fluid was present on visible surfaces. The right side of the nose wheel tire and the strut assembly were wet with hydraulic fluid. The hydraulic lines in the nose gear well were made of aluminum. The right-side nose gear door actuator line had separated at the ferrule and flare of the line; the B nut remained attached to the actuator, and the line was dripping hydraulic fluid. No other leaks or breaks were found in that wheel well. The main landing gear wheel wells showed no signs of leakage.
Hydraulic Line Analysis
Examination of the failed hydraulic line by Safety Board investigators revealed no aluminum tubing identification markings. The line was fractured at the flared end that attached to the nose landing gear actuator port. Straight sections of the line had slight bends. Features consistent with fatigue were observed, including multiple origins on the lower surface, covering approximately one-third of the fracture surface. Beyond the fatigue region, features indicated overstress fracture. A portion of the hydraulic line was covered with a longitudinally-split black flexible tube wrapped with black electrical tape; a contact mark was found where the tape and tube were worn away. After removal, two additional contact marks were discovered on the opposite side of the plastic sleeve, and the underlying tubing exhibited two wear marks, one of which had a groove approximately 50 percent of the wall thickness deep.
FAA photographs showed that the high-pressure electrical fuel pump installed during the annual inspection was mounted above and in close proximity to the failed hydraulic line. The contact marks were also near the fuel line fitting attached to the pump. Advisory Circular AC 43-13-1B provides guidance on inspecting hydraulic systems for leaks, worn tubing, and other conditions, and recommends that damaged lines be replaced or repaired with tubing of the same size and material.