Deadly Detail: How A Single Screw Caused An Airplane Crash

The use of incorrect screws and bolts in airplanes has been a contributing factor in several crashes and near-crashes. In one instance, a British Airways pilot was almost sucked out of a plane when a newly replaced windscreen was secured with the wrong-sized bolts. In another incident, a commuter airplane crashed, killing all 14 people on board, due to the absence of dozens of screws in its tail section following maintenance. Additionally, inadequate lubrication and improper maintenance of screws and bolts have been implicated in several aircraft accidents, including the crash of Alaska Airlines Flight 261, which resulted in the deaths of all 88 people on board. These incidents highlight the critical importance of ensuring proper screw and bolt usage and maintenance in airplane safety.

Maintenance crew's failure to notice loose screws

Maintenance Crews' Failure to Notice Loose Screws

The failure of maintenance crews to notice loose screws or other faulty fasteners can have dire consequences, as evidenced by several aircraft accidents and incidents caused by structural failures. In one tragic example, a commuter airplane crashed into a cornfield, killing all 14 people on board. It was later discovered that the plane was missing 43 screws in its tail section following maintenance the day before. This is far from an isolated incident, as improper maintenance is a common theme among aviation accidents.

To prevent such disasters, it is crucial for maintenance crews to conduct thorough inspections and address any issues with fasteners. Regular maintenance and simple procedures like checking for loose screws can prevent larger, more costly problems down the line. This is especially important in equipment that undergoes frequent use, as the constant motion can gradually work fasteners loose over time.

Temperature changes can also contribute to screws coming loose, as metal contracts in colder temperatures, pushing fasteners outwards. Additionally, equipment that bears significant weight, such as chairs, can experience issues with loose screws if not properly anchored. Rough maintenance practices, including over-tightening screws, can also lead to stripping at the top of the fastener, requiring replacement.

To mitigate these risks, maintenance crews should employ thread-locking products that are compatible with the materials of the fasteners and the items being fastened. For example, products like DAP Tank Bond Thread Stopper can be used on metal, wood, or plastic and prevent screws from unintentionally backing out. By following these practices and conducting diligent inspections, maintenance crews can help ensure the safety and integrity of aircraft and other equipment.

Lack of lubrication

On January 31, 2000, Alaska Airlines Flight 261 crashed into the Pacific Ocean near Anacapa Island, California, killing all 88 people on board. The cause of the crash was determined to be the failure of the horizontal stabilizer trim system jackscrew assembly's acme nut threads, resulting in a loss of pitch control. The absence of a fail-safe mechanism to prevent the catastrophic effects of total acme nut thread loss was a fundamental design flaw in the MD-83 aircraft.

Investigators found that the probable cause of the crash was a lack of lubrication, which led to excessive wear and the eventual failure of the jackscrew. The jackscrew mechanism jammed soon after takeoff, causing the stabilizer to break off and sending the plane into a roll before it plunged into the ocean.

The airline extended the lubrication interval, which contributed to the excessive wear of the acme nut threads due to inadequate lubrication. This was done to cut costs and keep the plane in the air longer, rather than having it undergo lengthier maintenance procedures. The type of grease used, which was recommended by Boeing Co., was also a factor, as it was not suitable for extended periods without re-lubrication.

The National Transportation Safety Board (NTSB) found that the airline had falsified records to meet scheduled departure times, as the jackscrew was already showing signs of wear and needed to be replaced. However, due to the pressure to adhere to departure schedules, the aircraft was cleared for takeoff despite the maintenance issues.

The Federal Aviation Administration (FAA) was criticized for inadequate oversight of airlines' maintenance programs, as problems with Alaska Airlines' maintenance program were overlooked. Following the crash, the FAA reviewed the maintenance programs of nine major airlines and reported improvements, but the Transportation Department's inspector general found that the FAA's inspectors were inadequately trained.

Inadequate maintenance

One striking example of inadequate maintenance leading to a near disaster occurred in June 1990 when a British Airways pilot was almost sucked out of a plane due to a newly replaced windscreen being secured with the wrong-sized bolts. This incident highlights the critical nature of proper maintenance procedures and the potential consequences of even small errors.

Another incident involving inadequate maintenance took place in 1991 when a commuter airplane crashed into a cornfield, resulting in the tragic loss of all 14 lives on board. An investigation revealed that the airplane was missing 43 screws in its tail section, specifically in the leading edge of its horizontal stabilizer, which is essential for maintaining the aircraft's horizontal stability during flight. This critical error caused a 9-foot-long piece of the stabilizer to detach in mid-flight, leading to a sudden and uncontrollable nosedive.

In addition to these incidents, there have been numerous other instances where inadequate maintenance has been identified as a contributing factor to airplane crashes. For example, the crash of Continental Express Flight 2574 was attributed to improper maintenance, specifically a failure of the horizontal stabilizer during flight due to a misunderstanding during maintenance. Similarly, the crash of American Airlines Flight 191 was linked to improper maintenance, where the number one engine broke off due to a faulty maintenance procedure.

To prevent such devastating consequences, it is imperative that maintenance crews adhere to strict protocols and undergo comprehensive training. Additionally, effective quality assurance systems and improved human factor considerations, such as addressing the "Dirty Dozen" human errors, are vital to enhancing aviation safety and reducing the occurrence of maintenance-related incidents.

Poor oversight

• In 1990, a British Airways pilot was almost sucked out of a plane when a newly replaced windscreen was secured with the wrong-sized bolts. The storekeeper pointed out the error, but the maintenance manager decided to replace the old bolts with the same size as the ones he had taken out.
• In 1991, a Continental Express airplane plunged into a cornfield, killing all 14 people aboard. It was later discovered that the plane was missing dozens of screws in its tail section after undergoing maintenance the day before the crash.
• In 1996, a ValuJet DC-9 crashed into the Everglades after a fire in the cargo hold. The fire was caused by improperly stored oxygen canisters.
• In 2002, a China Airlines 747 crashed into the Taiwan Strait after a pilot accidentally activated the thrust reverser on takeoff.
• In 2009, a Turkish Airlines 737 crashed near Amsterdam after a faulty altimeter reading.
• In 2010, a UPS Airlines 747-400F crashed near Dubai after an in-flight fire.
• In 2013, a UPS Airlines DC-8-700F crashed near Birmingham, Alabama, after a fire in the cockpit.
• In 2014, an Air Algérie plane crashed in Mali after the crew lost control of the aircraft.
• In 2015, a TransAsia Airways plane crashed in Taiwan after an engine failure.
• In 2016, an EgyptAir plane crashed into the Mediterranean Sea after a fire in the cockpit.
• In 2017, a United Airlines plane suffered an engine failure and landed in the ocean near Hawaii.
• In 2018, a Southwest Airlines plane suffered an engine failure and landed in Philadelphia.
• In 2019, a Boeing 737 MAX 8 crashed into the Java Sea after a malfunction of the Maneuvering Characteristics Augmentation System (MCAS).
• In 2020, a Pakistan International Airlines plane crashed into a residential area in Karachi after an engine failure.
• In 2021, a Sriwijaya Air plane crashed into the Java Sea after takeoff.
• In 2022, a China Eastern Airlines plane crashed in Guangxi, China, after a sudden descent.
• In 2023, a Boeing 737 MAX 9 suffered rapid decompression after a door plug blew out mid-flight.

Use of counterfeit aircraft parts

The use of counterfeit aircraft parts poses a significant threat to the aviation industry, compromising safety, reliability, and airworthiness. This issue is not limited to a specific type of aircraft, affecting commercial airliners, military jets, and major airlines such as American Airlines, Delta, and Southwest Airlines. The discovery of counterfeit components has led to the grounding of more than 100 planes to remove these parts.

Counterfeit parts are often accompanied by forged documentation, making it challenging to ensure the integrity of the supply chain and quality management. The procurement process is particularly vulnerable, with unapproved suppliers, inadequate authentication procedures, and a lack of rigorous inventory control. This allows counterfeit parts to infiltrate the supply chain, leading to potential disasters.

The consequences of using counterfeit parts can be catastrophic and have resulted in engine failures, mid-air emergencies, and accidents. For example, the crash of Partner Flight 394 in 1989 was caused by counterfeit bolts and brackets, resulting in the death of all 55 people on board. Another incident involving American Airlines flight 587, an Airbus A300-605R, in 2001 is also suspected to be linked to counterfeit parts.

To combat this issue, robust documentation procedures, strict safety management, and comprehensive back-to-birth traceability are essential. The aviation industry has adopted standards such as SAE, ISO, and AS9100 to mitigate the risks. Additionally, regulatory bodies and industry giants have formed coalitions to reinforce the integrity of the aviation supply chain and prevent unauthorized components from entering the global market. These efforts aim to protect passenger safety and ensure the airworthiness of aircraft.

The use of counterfeit aircraft parts is a serious matter that requires a multifaceted approach, including regulatory compliance, technological advancements, and collaboration among stakeholders. By implementing stringent measures, the industry strives to safeguard against the fatal consequences of counterfeit parts and maintain the highest standards of safety and reliability.

Frequently asked questions