McGrath, AK, USA
N4352F
PIPER PA 32R-300
The on-demand passenger flight was approaching its destination airport when the commercial pilot noted that the two main landing gear extended, but the nose landing gear did not extend and lock. The pilot diverted to a larger airport, where ground personnel verified that the nose landing gear was not down and locked even after the pilot completed the manual gear extension procedure. The pilot elected to land the airplane with the engine off, and he stated that the touchdown was uneventful. He held the airplane's nose off the runway for several hundred feet; the left main landing gear then collapsed and the nose wheel extended. The airplane slid about 200 ft before coming to rest. A witness reported that the touchdown was smooth and when the left main landing gear collapsed, the airplane gradually slowed to a stop on the runway. An examination of the airplane revealed that the alternator became inoperative during the flight, and, due to the cold temperatures, the battery was unable to accommodate the electrical load required by the system. In addition, the grease on the nosewheel was thick, which, combined with the cold temperatures, can increase its viscosity and reduce its effectiveness. Because the nose landing gear extends into the relative wind direction, it would be more difficult for it to extend and lock with the low battery power and increased viscosity of the grease. Further, because the landing gear was not in the "up" position when the emergency extension control was activated, the hydraulic fluid had already been released, thus rendering the emergency procedure ineffective. After landing and with a reduction in the relative wind, the gear was able to lock in place; however, the reason for the collapse of the left main landing gear could not be determined. When the alternator and battery were replaced, the airplane was placed on jacks and all three landing gear actuated as designed. A review of the passenger's injuries revealed that the fracture of the transverse process of L2 vertebrae was "age-indeterminate," which means that it could not be definitively determined when the injury occurred.
On November 20, 2016, about 1657 Alaska standard time, a Piper PA-32R-300 airplane, N4352F, sustained minor damage following a landing gear collapse during the landing roll on runway 16 at the McGrath Airport (PAMC), McGrath, Alaska. The commercial pilot and two of the passengers sustained no injuries. Fifteen days after the accident, the third passenger contacted the National Transportation Safety Board's (NTSB) Alaska regional office to report that she had sustained serious injuries as a result of the landing gear collapse event. The airplane was being operated by Bidzy Ta Hot Anna Corporation, dba Tanana Air Service, under the provisions of Title 14 Code of Federal Regulations Part 135 as an on-demand commercial flight. Visual meteorological conditions prevailed at PAMC and company flight following procedures were in effect for the visual flight rules flight. The flight departed Shageluk Airport (PAHX), Shageluk, Alaska, destined for Nikolai Airport (PAFS), Nikolai, Alaska, but elected to divert to PAMC following a landing gear malfunction when the airplane was approaching PAFS.On December 21, the pilot provided a written statement to the NTSB investigator-in-charge (IIC). The pilot reported that the airplane's electrical system began to malfunction as the airplane approached PAFS. As he prepared for landing, he placed the landing gear selector handle in the down position to extend the landing gear. The pilot said that both main landing gear extended, and cockpit indications confirmed the gear were down and locked, but the nose landing gear did not extend and the cockpit indicator warned of an unlocked/unsafe condition. He then attempted to retract the landing gear and divert to PAMC, but the landing gear did not retract. At PAMC, the pilot flew a number of low approaches over the runway and a mechanic confirmed that the nose landing gear was not down and locked. The pilot then completed the emergency landing gear extension checklist then flew another low approach over the runway, which confirmed that the nose landing gear was still retracted. The pilot continued to attempt to extend the landing gear to no avail. Unable to get the nose gear to extend, he elected to land the airplane; the mechanic reminded him to shut down the engine when the runway "was made" and to cut off the fuel. The pilot stated the touchdown was uneventful and he held the nose of the airplane off the runway for several hundred feet. The left main landing gear then collapsed, and the nose wheel subsequently locked; the left wing then contacted the runway surface as the airplane continued to slide about 200 feet before coming to rest on the centerline of the runway. The pilot reported that no luggage shifted during the landing. A witness confirmed that the touchdown was smooth and when the weight of the airplane got on the main gear, the left gear collapsed and the nose gear locked in place. The airplane continued to decelerate gradually and remained on the runway. The pilot reported that he and the front-seat passenger exited the airplane with the help of fire department personnel to ensure they didn't slip and the back-seat passengers exited the airplane on their own and quickly moved away from the airplane as instructed. The witness from the fire department stated that all three passengers exited the airplane on their own, that no one appeared injured or in pain, and that all refused medical treatment and said they were okay. A third witness, who was a first responder, stated that the rear-seat passenger retrieved her luggage, walked to an ambulance to get warm, and assured the first responder she was okay. The pilot reported that he saw this passenger walking through the snow later that evening. A review of photographs taken of the airplane show paint scraping on the bottom outboard edge of the left aileron, missing paint and an estimated 1-inch hole on the bottom outboard 6 inches of the left flap, evidence of scraping on the bottom of the left flap outboard control arm, a broken pitot mast, and scraping damage to the left main landing gear door. In a statement provided to the NTSB on December 11, the front-seat passenger stated that the airplane "hit the ground hard and began to slide." She said that, when the belly of the plane hit the ground, she felt her back "jar" and knew she was injured. She further stated that although she complained of neck and back pain, she received no medical attention that evening or the next day at the clinic. Three days later, in Seattle, she received medical attention that revealed that the right transverse process of the L2 vertebrae was fractured. The landing gear system in the PA-32 is electrically driven and hydraulically actuated. According to the maintenance manual, hydraulic fluid to the landing gear actuating cylinders is supplied by an electrically powered reversible pump. The airplane is also equipped with an emergency landing gear extension control. When activated, this system will release the hydraulic pressure that is holding the gear in the "up" position, allowing it to freefall and lock into place. While the main landing gear extends perpendicular to the relative wind, the nose gear, with assistance from a spring, extends opposite of the relative wind. Following the landing, the operator examined the airplane and determined that the alternator became inoperative during the flight, and, due to the cold external temperatures, the battery was unable to accommodate the electrical load required by the system. Also, the grease on the nosewheel was thick, which, when combined with the cold temperatures, can increase its viscosity and lower its effectiveness. When the alternator and battery were replaced, the aircraft was placed on jacks and the gear actuated as designed. At 1653, a METAR from PAMC reported, in part: wind calm, visibility 10 statute miles, sky condition clear, temperature -9 °F, dewpoint -17 °F, altimeter 29.64 inches of mercury.
The failure of the nose landing gear to extend and lock due to the failure of the alternator and reduced battery power due to the cold ambient temperature, which prohibited the electrically-driven hydraulic pump from supplying adequate hydraulic pressure to extend the nose landing gear. The cause of the left main landing gear collapse could not be determined, as there were no postaccident anomalies or malfunctions found when the landing gear was actuated following replacement of the alternator and battery.
Source: NTSB Aviation Accident Database
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