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The 2 pilots, 3 cabin crewmembers, and 83 passengers on board were killed, is rhode island college free the airplane was destroyed by impact forces. Visual meteorological conditions prevailed for the flight, which operated on an instrument flight rules flight plan.

The National Transportation Safety Board determines that the probable cause of this accident was a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly’s acme nut threads. The thread failure was caused by excessive alaska airlines flight 261 resulting from Alaska Airlines.

Contributing to the accident were Alaska Airlines. Also contributing to the accident was the absence on the McDonnell Douglas MD of a fail-safe mechanism to prevent the alaska airlines flight 261 effects of total acme nut thread loss. The photo alaska airlines flight 261 shows the jackscrew from the horizontal stabilizer of Alaska Airlines alaska airlines flight 261 It is approximately 2 feet long and was recovered from main wreckage site on February 8, Download the full NTSB report.

I don’t think there’s anything beyond that we haven’t checked. I believe he’s talking about this CAM-2 oh. Oceanside right I just that’s something that oughta be in the computers, if they want it that bad they you guys oughta be able to pick up the phone CAM-3 mmm hmm. I gotta tell you, when I look at it from a safety point I think that something that lowers my groundspeed makes sense. I remember this is complicated, yea well, better start that now cause we are comin to you.

Los Angeles international airport information mike. I mean it was just I expect him to figure all that CAM-2 right. I need to get down about ten, change my configuration, make sure I can control the jet and I’d like to do that out here alaska airlines flight 261 the bay if I may. I don’t think we should Search the database. Search the database Search the site. Home Database 31 January – Alaska Airlines Back to top.

 
 

 

Alaska Air Flight Memorial Sundial | Port Hueneme, CA – Official Website

 

At this time, pilots from aircraft flying in the vicinity reported in, with one pilot saying, “and he’s just hit the water. He’s, ah, down. Both the horizontal stabilizer trim system jackscrew also referred to as ” acme screw ” and the corresponding acme nut, through which the jackscrew turns, were found.

The jackscrew was constructed from case-hardened steel and is 22 in 56 cm long and 1. The acme nut was constructed from a softer copper alloy containing aluminum, nickel, and bronze. As the jackscrew rotates, it moves up or down through the fixed acme nut, and this linear motion moves the horizontal stabilizer for the trim system.

Upon subsequent examination, the jackscrew was found to have metallic filaments wrapped around it, which were later determined to be the remains of the acme-nut thread. Once the thread had failed, the horizontal stabilizer assembly was subjected to aerodynamic forces that it was not designed to withstand, leading to the complete failure of the overstressed stabilizer assembly.

Based on the time since the last inspection of the jackscrew assembly, the NTSB determined that the acme-nut thread had deteriorated at 0. Over the course of the investigation, the NTSB considered a number of potential reasons for the substantial amount of deterioration of the nut thread on the jackscrew assembly, including the substitution by Alaska Airlines with the approval of the aircraft manufacturer McDonnell Douglas of Aeroshell 33 grease instead of the previously approved lubricant, Mobilgrease It was found that the use of Aeroshell 33 was not a factor in this accident.

Examination of the jackscrew and acme nut revealed that no effective lubrication was present on these components at the time of the accident. Both of these circumstances resulted from Alaska Airlines’ attempts to cut costs. Due to the extreme impact forces, only a few bodies were found intact, [5] and none were visually identifiable.

All passengers were identified using fingerprints, dental records, tattoos, personal items, and anthropological examination. The investigation then proceeded to examine why scheduled maintenance had failed to adequately lubricate the jackscrew assembly.

In interviews with the Alaska Airlines mechanic at SFO, who last performed the lubrication, the task was shown to take about one hour, whereas the aircraft manufacturer estimated the task should take four hours. This and other evidence suggested to the NTSB that “the SFO mechanic who was responsible for lubricating the jackscrew assembly in September did not adequately perform the task”.

Laboratory tests indicated that the excessive wear of the jackscrew assembly could not have accumulated in just the four-month period between the September maintenance and the accident flight. Therefore, the NTSB concluded that “more than just the last lubrication was missed or inadequately performed”. A periodic maintenance inspection called an ” end-play check” was used to monitor wear on the jackscrew assembly.

The NTSB examined why the last end-play check on the accident aircraft in September did not uncover excessive wear. The investigation found that Alaska Airlines had fabricated tools to be used in the end-play check that did not meet the manufacturer’s requirements.

Testing revealed that the nonstandard tools “restraining fixtures” used by Alaska Airlines could result in inaccurate measurements and that if accurate measurements had been obtained at the time of the last inspection, these measurements possibly would have indicated the excessive wear and the need to replace the affected components. Between and , Alaska Airlines progressively increased the period between both jackscrew lubrication and end-play checks, with the approval of the Federal Aviation Administration FAA.

Since each lubrication or end-play check subsequently not conducted had represented an opportunity to adequately lubricate the jackscrew or detect excessive wear, the NTSB examined the justification of these extensions. In the case of extended lubrication intervals, the investigation could not determine what information, if any, was presented by Alaska Airlines to the FAA prior to Testimony from an FAA inspector regarding an extension granted in was that Alaska Airlines submitted documentation from McDonnell Douglas as justification for their extension.

Testimony from the director of reliability and maintenance programs of Alaska Airlines was that a data-analysis package based on the maintenance history of five sample aircraft was submitted to the FAA to justify the extended period between C-checks. Individual maintenance tasks such as the end-play check were not separately considered in this extension. The NTSB found, “Alaska Airlines’ end play check interval extension should have been, but was not, supported by adequate technical data to demonstrate that the extension would not present a potential hazard”.

The investigation concluded, “FAA surveillance of Alaska Airlines had been deficient for at least several years”. However, several factors led the board to question “the depth and effectiveness of Alaska Airlines corrective actions” and “the overall adequacy of Alaska Airlines’ maintenance program”. Systemic problems were identified by the investigation into the FAA’s oversight of maintenance programs, including inadequate staffing, its approval process of maintenance interval extensions, and the aircraft certification requirements.

The jackscrew assembly was designed with two independent threads, each of which was strong enough to withstand the forces placed on it. The aircraft designers assumed that at least one set of threads would always be present to carry the loads placed on it; therefore, the effects of catastrophic failure of this system were not considered, and no ” fail-safe ” provisions were needed.

For this design component to be approved ” certified ” by the FAA without any fail-safe provision, a failure had to be considered “extremely improbable”. The NTSB determined that the design of “the horizontal stabilizer jackscrew assembly did not account for the loss of the acme nut threads as a catastrophic single-point failure mode”.

An engineering fix developed by engineers of NASA and United Space Alliance promises to make progressive failures easy to see and thus complete failures of a jackscrew less likely. In , an Alaska Airlines mechanic named John Liotine, who worked in the Alaska Airlines maintenance center in Oakland, California , told the FAA that supervisors were approving records of maintenance that they were not allowed to approve or that indicated work had been completed when, in fact, it had not.

Liotine began working with federal investigators by secretly audio recording his supervisors. On December 22, , federal authorities raided an Alaska Airlines property and seized maintenance records. In August , Alaska Airlines put Liotine on paid leave, [28] and in , Liotine filed a libel suit against the airline. The crash of AS became a part of the federal investigation against Alaska Airlines, because, in , Liotine had recommended that the jackscrew and gimbal nut of the accident aircraft be replaced, but had been overruled by another supervisor.

In addition to the probable cause, the NTSB found these contributing factors: [6]. During the course of the investigation, and later in its final report, the NTSB issued 24 safety recommendations, covering maintenance, regulatory oversight, and aircraft design issues.

More than half of these were directly related to jackscrew lubrication and end-play measurement. Also included was a recommendation that pilots were to be instructed that in the event of a flight control system malfunction, they should not attempt corrective procedures beyond those specified in the checklist procedures, and in particular, in the event of a horizontal stabilizer trim control system malfunction, the primary and alternate trim motors should not be activated, and if unable to correct the problem through the checklists, they should land at the nearest suitable airport.

Goglia’s statement for the final report, with which the other three board members concurred, he wrote:. This is a maintenance accident. Alaska Airlines’ maintenance and inspection of its horizontal stabilizer activation system were poorly conceived and woefully executed. The failure was compounded by poor oversight Had any of the managers, mechanics, inspectors, supervisors, or FAA overseers whose job it was to protect this mechanism done their job conscientiously, this accident cannot happen NTSB has made several specific maintenance recommendations, some already accomplished, that will, if followed, prevent the recurrence of this particular accident.

But maintenance, poorly done, will find a way to bite somewhere else. After the crash, Alaska Airlines management said that it hoped to handle the aftermath in a manner similar to that conducted by Swissair after the Swissair Flight accident.

They wished to avoid the mistakes made by Trans World Airlines in the aftermath of the TWA Flight accident, in other words, TWA’s failure to provide timely information and compassion to the families of the victims. The victims’ families approved the construction of a memorial sundial , designed by Santa Barbara artist James “Bud” Bottoms, which was placed at Port Hueneme on the California coast. The names of each of the victims are engraved on individual bronze plates mounted on the perimeter of the dial.

This is the only time the award has ever been given posthumously. Both McDonnell Douglas and Alaska Airlines eventually accepted liability for the crash, and all but one of the lawsuits brought by surviving family members were settled out of court before going to trial.

Steve Miletich of The Seattle Times wrote that the western portion of Washington “had never before experienced such a loss from a plane crash”. As part of a memorial vigil in , a column of light was beamed from the top of the Space Needle.

The park’s playground was named “Rachel’s Playground”, in memory of six-year-old Rachel Pearson, who was on board the MD [18] and who was often seen playing at the park. Two victims were falsely named in paternity suits as the fathers of children in Guatemala in an attempt to gain insurance and settlement money. Subsequent DNA testing proved these claims to be false. The crash has appeared in various advance fee fraud “” email scams , in which a scammer uses the name of someone who died in the crash to lure unsuspecting victims into sending money to the scammer by claiming the crash victim left huge amounts of unclaimed funds in a foreign bank account.

From Wikipedia, the free encyclopedia. Aviation accident over the Pacific Ocean in Puerto Vallarta. San Francisco. Crash site. California portal Aviation portal s portal. Yahoo Movies. Retrieved January 7, Archived from the original on January 31, Retrieved February 3, CNN International. February 1, Retrieved February 16, The MD was manufactured in and had more than 26, of hours in flight.

The Spokesman-Review. Associated Press. National Transportation Safety Board. December 30, Archived PDF from the original on June 15, Retrieved September 9, The Seattle Times. The New York Times. February 3, ISSN Archived from the original on November 11, Retrieved May 22, Las Vegas Sun. Archived from the original on February 8, Retrieved February 7, Archived from the original on September 18, Retrieved May 31, Fairbanks Daily News-Miner.

Archived from the original on February 4, Retrieved February 4, Alaska Airlines. March 24, Archived from the original on February 12, Retrieved May 29, Seattle Post-Intelligencer. Archived from the original on September 4, Retrieved November 23, Archived from the original on May 30, Los Angeles Times.

Archived from the original on July 15, Minerva Press. ISBN OCLC School counselors said she and her friend, Rachel Janosik, were funny, enjoyable, mature young women. Don Shaw , 63, Shelton—Affable tour guide, Mr. Shaw was a fixture in the halls of the Legislature. Before that, he was a principal at two elementary schools in the Snohomish School District. He is survived by his wife, Earlene Shaw, who works at the state Senate cafeteria. Harry Stasinos , 54, Brier—Mr. Stasinos was a longtime Seattle insurance agent and an active member of the Seattle-area Greek community.

He also served for a time with the Federal Emergency Management Agency. He lived in Brier with his partner, Charlene Sipe. Sipe was also a longtime insurance agent. The two worked together several years at the Roy Potter Insurance Agency. The couple was considering starting their own insurance agency. Morris Thompson , 62, Fairbanks, Alaska—An advocate for Alaska natives, he was celebrating his retirement after 12 years as president of Doyon, Ltd.

He was traveling with his wife, Thelma, and daughter Sheryl. Thelma Thompson , 56, Fairbanks, Alaska—Mrs. Thompson was traveling with her husband, Morris Thompson, and daughter, Sheryl Thompson. Thompson was an important figure in extreme skiing in Valdez, helping organize annual events.

Described by friends as a soft-spoken, caring person, Ms. Thompson is survived by two sisters. Branson was vacationing with his fiancee, Janice Stokes. His mother said he was a sweet, handsome man who loved his job and loved people. Janice Stokes , 48, Ketchikan, Alaska—Ms. Stokes had three college-age children, as well as a brother in Seattle and a sister in Alaska. She was traveling with her fiance, Malcolm Branson. William Bryant , 45, San Francisco—Mr. Bryant was a travel agent who was excited when he received free tickets for a trip to Mexico.

Luque had worked at Taste Catering in San Francisco since One of six children born to Jovanna Luque of Olympia, Mr. Luque is the second child she has lost. He was traveling with William Bryant, his best friend. Robert Ost , 39, San Bruno, Calif. He was with his wife, Ileana, their 4-month-old daughter, Emily, and his mother and her longtime companion.

Ileana Ost , 30, San Bruno, Calif. She had gone with her family to Mexico to celebrate the birthday of her mother, Jean Permison. Emily Ost , 4 months, San Bruno, Calif. Jean Permison , 73, Scotts Valley, Calif. She was also accompanied by her longtime companion, Charles Russell. Charles Russell , 65, Scotts Valley, Calif. Russell was traveling with his companion, Jean Permison, and her family.

Russell and Permison lived in a retirement community where they were beloved for their lively parties and volunteer work. Jean Gandesbery , 66, Davis, Calif. Robert Gandesbery , 69, Davis, Calif. Gandesbery was retired from a career with child-welfare services. He was remembered for being a friendly neighbor and loving owner of two golden retrievers, Casey and Emma, and he loved to play the clarinet. Cynthia Oti , 43, Oakland, Calif. She had treated herself to a weekend getaway in Puerto Vallarta and was scheduled to go on the air two hours after the flight was expected to land in San Francisco.

Bradley Long , 39, Sacramento—A successful real estate broker, Mr. Long was flying home from visiting the bed-and-breakfast inn he owned in Puerto Vallarta with his partner, William Knudson. Knudson was known for his love of boating and restoring old cars with his partner, Bradley Long. Ellen Masland Salyer , 51, Sebastopol, Calif. She is survived by her husband of 13 years, Phil Salyer.

Joyce Lake , 62, Corte Madera, Calif. Ronald Lake , 59, Corte Madera, Calif. Retired from a career at the U. Treasury, he collected miniature trains and loved to take his wife on rail trips.

He worked for a San Francisco wholesale ice-cream manufacturer. Jerri Fosmire , 48, Eugene, Ore. Her husband, Lee, 41, and children, 5-year-old Barbara and year-old Daniel, stayed behind in Mexico. She was a treasured volunteer at a Eugene elementary school. Barbara Hatleberg , 64, Eugene, Ore. Glenn Hatleberg , 65, Eugene, Ore.

Hatleberg was beloved at his Lutheran church in Eugene, where he served as an usher during services. Karl Karlsson , 51, Petaluma, Calif. The rec room at the Karlsson home featured a jukebox, a pinball machine and a bumper-pool table. He was coming home with his wife, Carol. Carol Karlsson , 42, Petaluma, Calif. She used to drive a riding lawn mower around their yard, and relax in the family swimming pool. He moved to San Francisco last year.

He was vacationing with his daughter, Jacquelyn Choate. Jacquelyn Choate , 17, Santa Cruz, Calif. She grew up in Sacramento. Rodrigo Laigo , 53, Fairfield, Calif.

They had just moved to the Bay Area from Los Angeles, where they had raised three sons. Naomi Laigo , 53, Fairfield, Calif. She loved golf as much as her husband, Rodrigo. Dean Forshee , 47, Benicia, Calif—The professional musician was a skilled pedal steel, acoustic and electric guitar player who taught lessons and devoted his life to music, especially country and rockabilly. He is survived by his wife of five years, Susan da Silva.

Larry Baldridge Jr. He was a vice president of business development for Creditland, Inc. He was coming home from Mexico with his girlfriend, Nina Voronoff. Renato Bermudez , 39, San Francisco—Mr. Bermudez was a firefighter who helped save the life of a person trapped inside a burning building in He won commendations from a booster group for the action. Aloysius Han , 65, Oakland, Calif. Han often traveled to Mexico, where he owned a condominium and other property.

He lived with his mother in Oakland and spent much of his time caring for exotic birds, his koi pond and a garden. Juan Marquez , 34, San Francisco—An adult-education book salesman, he owned two condos in Puerto Vallarta with his partner, Dale Rettinger, and went there often to relax.

Marquez was flying home alone while Mr. Rettinger stayed behind for a longer vacation.

 
 

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The airline was convinced that Aeroshell 33 was causing corrosion. But Boeing refuted the claim and inferred that it was more likely the airline did not properly lubricate or check the jackscrew. The tests also simulated the acme nut wear process by using blocks milled from a scrap acme nut and rings turned from a jackscrew forging.

At this contact, the ring slowly wore a divot into the surface of the block. By carefully measuring the divot, we could accurately determine the wear rates for each type of grease and also the rate from using no grease. After months of constant movement back and forth, the tests showed normal wear rates with both grease types.

However, only the specimens with no grease mirrored the severe wear rate of the accident airplane. Over the course of a year I dragged the Systems Group all over the country to observe different maintenance shops perform jackscrew lubrications and end-play checks. We noticed a lot of differences.

Many did not apply grease to the entire length of the jackscrew as per the procedure. Like the end play check intervals, Alaska Airlines received FAA permission to extend their jackscrew lubrication intervals four times from to with no supporting data.

The original interval was flight hours graphic In July , the criteria was changed to 8 calendar months which equated to 2, flight hours. It is clear is that the events of January 31, , forever changed Alaska Airlines, making it a different airline than the one that existed on that day. It aggressively took action to improve itself by hiring a new vice president VP of safety who reported directly to the CEO, filling executive vacancies in safety and maintenance, creating a large safety office, hiring new mechanics, revising its general maintenance manual and reviewing every C-check aircraft in the fleet to ensure that all work was properly performed.

The airline continued to assess its own safety culture and leadership through the years in what became an obsession to improve safety. This past January, to honor the victims of flight on its 20th anniversary, hundreds of family members, friends and loved ones came together in Ventura around the Memorial Sundial constructed after the crash. Woltjer, R. Other Psychiatry and Psychology Commons.

Advanced Search Search Help. Privacy Copyright. A few seconds before UTC , Flight impacted the Pacific Ocean at high speed about 14 miles 23 kilometers; 12 nautical miles offshore, between the coastal city of Port Hueneme, California, and Anacapa Island. At this time, pilots from aircraft flying in the same area reported in, with one SkyWest Airlines pilot saying: “and he’s just hit the water”.

Another reported: “Ah, yes sir he ah, he ah, hit the water. He’s ah down. The aircraft was destroyed by the impact forces, and all occupants on board were killed by blunt force trauma. Recovered jackscrew — the spiral “wire” wrapped around the threaded portion is the remnants of the internal screw thread stripped from the acme nut.

Both the horizontal stabilizer trim system jackscrew also referred to as “acme screw” and the corresponding acme nut, which the jackscrew turns through, were found. The jackscrew was constructed from case-hardened steel and is 22 inches 56 cm long and 1.

The acme nut was constructed from a softer copper alloy containing aluminum, nickel, and bronze. As the jackscrew rotates, it moves up or down through the fixed acme nut, and this linear motion moves the horizontal stabilizer for the trim system.

Upon subsequent examination, the jackscrew was found to have metallic filaments wrapped around it, which were later determined to be the remains of the acme-nut thread. Once the thread had failed, the horizontal stabilizer assembly was then subjected to aerodynamic forces that it was not designed to withstand, leading to complete failure of the overstressed stabilizer assembly.

Based on the time since the last inspection of the jackscrew assembly, the NTSB determined that the acme-nut thread had deteriorated at 0. The plane dropped from about 31, ft 9, m to between 23, and 24, ft 7, and 7, m in around 80 seconds. Alaska informed air traffic control ATC of their control problems. After the flight crew stated their intention to land at LAX, ATC asked whether they wanted to proceed to a lower altitude in preparation for the approach.

They descended to a lower altitude and started to configure the aircraft for landing at LAX. Beginning at UTC , the CVR recorded the sounds of at least four distinct “thumps”, followed 17 seconds later by an “extremely loud noise”, as the overstrained jackscrew assembly failed completely and the jackscrew separated from the acme nut holding it in place.

These aircraft immediately contacted the controller. He is, uh, definitely in a nose down, uh, position, descending quite rapidly.

The crew of a SkyWest airliner reported, “He’s, uh, definitely out of control. The CVR transcript reveals the pilots’ constant attempts for the duration of the dive to regain control of the aircraft. After the jackscrew failed, the plane pitched down degrees and was rolling over to the left. Performing an upset recovery maneuver, the captain commanded to “push and roll, push and roll,” managing to increase the pitch to degrees, he stated, “ok, we are inverted Despite the attempt to fly the plane inverted, which almost entirely arrested its descent, the aircraft had lost too much altitude in the dive and was far beyond recovery.

At this time, pilots from aircraft flying in the vicinity reported in, with one pilot saying, “and he’s just hit the water. He’s, ah, down. Both the horizontal stabilizer trim system jackscrew also referred to as ” acme screw ” and the corresponding acme nut, through which the jackscrew turns, were found. The jackscrew was constructed from case-hardened steel and is 22 in 56 cm long and 1. The acme nut was constructed from a softer copper alloy containing aluminum, nickel, and bronze.

As the jackscrew rotates, it moves up or down through the fixed acme nut, and this linear motion moves the horizontal stabilizer for the trim system. Upon subsequent examination, the jackscrew was found to have metallic filaments wrapped around it, which were later determined to be the remains of the acme-nut thread.

Once the thread had failed, the horizontal stabilizer assembly was subjected to aerodynamic forces that it was not designed to withstand, leading to the complete failure of the overstressed stabilizer assembly. Based on the time since the last inspection of the jackscrew assembly, the NTSB determined that the acme-nut thread had deteriorated at 0.

Over the course of the investigation, the NTSB considered a number of potential reasons for the substantial amount of deterioration of the nut thread on the jackscrew assembly, including the substitution by Alaska Airlines with the approval of the aircraft manufacturer McDonnell Douglas of Aeroshell 33 grease instead of the previously approved lubricant, Mobilgrease It was found that the use of Aeroshell 33 was not a factor in this accident.

Examination of the jackscrew and acme nut revealed that no effective lubrication was present on these components at the time of the accident. Both of these circumstances resulted from Alaska Airlines’ attempts to cut costs. Due to the extreme impact forces, only a few bodies were found intact, [5] and none were visually identifiable.

All passengers were identified using fingerprints, dental records, tattoos, personal items, and anthropological examination. The investigation then proceeded to examine why scheduled maintenance had failed to adequately lubricate the jackscrew assembly. In interviews with the Alaska Airlines mechanic at SFO, who last performed the lubrication, the task was shown to take about one hour, whereas the aircraft manufacturer estimated the task should take four hours.

This and other evidence suggested to the NTSB that “the SFO mechanic who was responsible for lubricating the jackscrew assembly in September did not adequately perform the task”. Laboratory tests indicated that the excessive wear of the jackscrew assembly could not have accumulated in just the four-month period between the September maintenance and the accident flight. Therefore, the NTSB concluded that “more than just the last lubrication was missed or inadequately performed”.

A periodic maintenance inspection called an ” end-play check” was used to monitor wear on the jackscrew assembly. The NTSB examined why the last end-play check on the accident aircraft in September did not uncover excessive wear. The investigation found that Alaska Airlines had fabricated tools to be used in the end-play check that did not meet the manufacturer’s requirements.

Testing revealed that the nonstandard tools “restraining fixtures” used by Alaska Airlines could result in inaccurate measurements and that if accurate measurements had been obtained at the time of the last inspection, these measurements possibly would have indicated the excessive wear and the need to replace the affected components.

Between and , Alaska Airlines progressively increased the period between both jackscrew lubrication and end-play checks, with the approval of the Federal Aviation Administration FAA. Since each lubrication or end-play check subsequently not conducted had represented an opportunity to adequately lubricate the jackscrew or detect excessive wear, the NTSB examined the justification of these extensions.

In the case of extended lubrication intervals, the investigation could not determine what information, if any, was presented by Alaska Airlines to the FAA prior to Testimony from an FAA inspector regarding an extension granted in was that Alaska Airlines submitted documentation from McDonnell Douglas as justification for their extension. Testimony from the director of reliability and maintenance programs of Alaska Airlines was that a data-analysis package based on the maintenance history of five sample aircraft was submitted to the FAA to justify the extended period between C-checks.

Individual maintenance tasks such as the end-play check were not separately considered in this extension. The NTSB found, “Alaska Airlines’ end play check interval extension should have been, but was not, supported by adequate technical data to demonstrate that the extension would not present a potential hazard”.

The investigation concluded, “FAA surveillance of Alaska Airlines had been deficient for at least several years”. However, several factors led the board to question “the depth and effectiveness of Alaska Airlines corrective actions” and “the overall adequacy of Alaska Airlines’ maintenance program”.

Systemic problems were identified by the investigation into the FAA’s oversight of maintenance programs, including inadequate staffing, its approval process of maintenance interval extensions, and the aircraft certification requirements.

The jackscrew assembly was designed with two independent threads, each of which was strong enough to withstand the forces placed on it. The aircraft designers assumed that at least one set of threads would always be present to carry the loads placed on it; therefore, the effects of catastrophic failure of this system were not considered, and no ” fail-safe ” provisions were needed.

For this design component to be approved ” certified ” by the FAA without any fail-safe provision, a failure had to be considered “extremely improbable”. The NTSB determined that the design of “the horizontal stabilizer jackscrew assembly did not account for the loss of the acme nut threads as a catastrophic single-point failure mode”. An engineering fix developed by engineers of NASA and United Space Alliance promises to make progressive failures easy to see and thus complete failures of a jackscrew less likely.

In , an Alaska Airlines mechanic named John Liotine, who worked in the Alaska Airlines maintenance center in Oakland, California , told the FAA that supervisors were approving records of maintenance that they were not allowed to approve or that indicated work had been completed when, in fact, it had not.

Liotine began working with federal investigators by secretly audio recording his supervisors. On December 22, , federal authorities raided an Alaska Airlines property and seized maintenance records. In August , Alaska Airlines put Liotine on paid leave, [28] and in , Liotine filed a libel suit against the airline. The crash of AS became a part of the federal investigation against Alaska Airlines, because, in , Liotine had recommended that the jackscrew and gimbal nut of the accident aircraft be replaced, but had been overruled by another supervisor.

In addition to the probable cause, the NTSB found these contributing factors: [6].

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