Aviation Accident Summaries

Aviation Accident Summary CHI96LA274

YANKTON, SD, USA

Aircraft #1

N3392V

BEECH 35

Analysis

The airplane's nose landing gear would not extend. During the attempts to extend the nose gear the pilot said he pitched the airplane up and down. The propeller began cavitating during these attempts. The pilot reported loosing oil pressure as he approached the runway. When he felt he would be able to land the pilot said he stopped the engine. He said the airplane '...just quit flying....' The airplane collided with the ground about 150 yards short of the runway threshold. Inspection of the airplane revealed an open oil sump quick-drain fitting and a broken nose gear retracting actuator arm (arm). The bottom of the airplane was covered with oil. About 50 percent of the arm's fracture surfaces were corroded. Representatives from the airframe stated the failed arm will allow the landing gear to be free in the nosegear well. The oil quick-drain finger-holds can be contacted by the nosegear when the airplane is pitched up and down. The propeller manufacturer stated the propeller will go into a high blade angle when the oil supply is stopped. He said the rotating propeller will cause a considerable amount of drag if it is still rotating.

Factual Information

On August 3, 1996, at 1635 central daylight time (cdt), a Beech 35, N3392V, piloted by a private pilot, was substantially damaged when it landed short of runway 19 (3,500' X 75' dry asphalt) at the Chan Gurney Municipal Airport, Yankton, South Dakota. Visual meteorological conditions prevailed at the time of the accident. The personal CFR Part 91 Flight was not operating on a flight plan. The pilot and 2 passengers reported no injuries. A third passenger reported minor injuries. The flight departed Fairmont, Minnesota, at 1340 cdt. According to the pilot's written statement on NTSB Form 6120.1/2, the airplane's nose landing gear (nose gear) failed to fully extend while enroute to its destination airport traffic pattern. The pilot said he made "...numerous attempts to extend and retract [the nose gear]. [He also tried to] dive and climb, none of which was successful... ." While attempting to extend the nose gear, the pilot said the airplane's propeller began "...cavitating, causing wildly fluctuating RPM manifold pressure indicating a loss of oil pressure." The pilot said he had "...lined up for Runway 19... ." He said he "...had the plane 'on the numbers' (airport made, speed 80 MPH) when I turned off the engine & electrics. We were on glide & the plane just quit flying." N3392V collided with the ground about 150 yards short of Runway 19's threshold. The on-scene investigation by a Federal Aviation Administration (FAA) principal maintenance inspector (PMI). The PMI said the nose gear's retracting actuator arm had separated from the actuator drive shaft. This caused the nose gear's extension and retraction linkages to become unsecured. Examination of the arm revealed its fracture surfaces were corroded over 17/32" of its 2-inch surface. He said the engine had an external oil sump and reservoir. The PMI said he looked into the oil reservoir and did not see any oil. He said he dip-sticked the reservoir and observed a trace of oil on the end of the stick. The oil sump's quick-drain valve was located in the nosewheel well. The bottom of the fuselage was oil covered. The quick-drain valve was open. The pilot said the quick-drain valve was the older style. It had "butterfly" wings finger holds attached to it for opening and closing the valve. According to an American Bonanza Society (ABS) representative, the nose gear actuating linkage arms are not tight when the actuator arm is broken. He said the quick drain valve butterfly wings can be contacted by the unsecured nose gear assembly causing it to open. The ABS representative said this would be particularly true if the pilot was pitching the airplane up and down trying to extend the nose gear. N3392V's nose gear's retracting actuator arm was an older style that had been superseded by a larger assembly. However, the larger assembly was not required to be changed by a Beech service bulletin or an FAA Airworthiness Directive. N3392V's airframe logbook showed it did not have an annual inspection for about 8 years. The annual inspection completed on December 6, 1995, was at the end of the 8 year period. This date's logbook entry states, in part, that the mechanic "...replaced retract rod from gear box forward. Replaced nose gear cylinder, 'O' rings, gasket set, adjusted nose gear strut... ." The maintenance record entries following this date did not show replacement of the older style actuating arm with the newer version. The propeller manufacturer was contacted regarding N3392V's propeller operation. A representative from the manufacturer said the propeller blades will go into high pitch angle, low RPM, when the oil supply has been lost. He said the 26.5 degree blade angle will create considerable drag while the propeller is rotating.

Probable Cause and Findings

an improper in-flight decision by the pilot when he shut the engine off as the airplane approached the landing runway. Factors associated with this accident were an inadequate maintenance inspection by the mechanic when the actuating arm fracture was not identified during the annual inspection occurring 5 months before the accident, and the pilot not maintaining a proper glidepath and descent rate on final approach after shutting his engine off.

 

Source: NTSB Aviation Accident Database

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