Category: Feature

Screws Coming Loose on Jet Wing Mid-Air

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Tsamouris, the Fastener Specialists©

In March 2023, a video surfaced on social media showing three screws visibly shaking on the left wing of a
TAAG Angola Airlines Boeing 737-700 aircraft during flight.

The video, which quickly went viral, raised serious questions about the maintenance and safety standards of
the state-owned airline, which serves as the flag carrier of Angola. TAAG Angola Airlines, headquartered in
Luanda, operates domestic flights within Angola, as well as medium-haul services in Africa and long-haul
routes to Brazil, Cuba, and Portugal.

The incident highlighted the critical importance of proper maintenance and regular inspections of aircraft,
particularly in areas that are subject to high stress and vibration, such as the wings. Loose or missing
fasteners can potentially lead to structural issues, compromising the safety of passengers and crew.

How a Loose Bolt Led to China Airlines Boeing 737 Explosion

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In August 2007, a seemingly minor maintenance oversight led to a near-fatal accident during China Airlines
Flight 120. Fortunately, there were no casualties. The Boeing 737-800, carrying 157 passengers and 8 crew
members, caught fire and exploded at Naha Airport in Japan shortly after landing safely from Taipei and after
all passengers had evacuated.

The incident unfolded as the crew prepared for disembarkation, having taxied the aircraft to the gate and
shut off the engines. Suddenly, ground crew members noticed flames emanating from one of the engines
and promptly informed air traffic control. The captain, upon being alerted, ordered an emergency evacuation.
Miraculously, all passengers and crew managed to evacuate the aircraft through the four hatches using
slides, just moments before the plane exploded. The pilots, having ensured everyone’s safety, exited through
the cockpit window. Despite the harrowing experience, only minor injuries were reported.

The on-site investigation revealed that fuel had leaked from a puncture hole in a slat’s track. Further inquiry
uncovered that an incorrectly installed bolt in the right-wing of the aircraft’s slat down-stop had worked itself
loose. The bolt had been torqued without the requisite washer during scheduled maintenance six weeks
prior. Consequently, the nut came loose, causing the entire down-stop assembly to detach and fall onto the
slat-can assembly track during ground movement.

As the slat retracted, it pushed the detached assembly, eventually forcing the downstop bolt through the
slat-can wall, puncturing the fuel tank. The leaking fuel ignited upon contact with high-temperature areas on
the right engine, leading to the fire and explosions.

Shockingly, the cause of this near-disaster was traced back to a single missing washer, which was found
lying just below the opening in the wing forward spar.

In the aftermath of the incident, the Republic of China Civil Aeronautics Administration grounded the entire
fleet of Boeing 737-800s operated by China Airlines, Mandarin Airlines, and the Republic of China Air Force
for fuel system inspections. The Japanese Civil Aviation Bureau followed suit, requesting inspections of
aircraft of the same type operated by Japanese carriers.

Why it Takes Less Torque to Loosen a Bolt Than to Tighten It

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Have you ever struggled with a stubborn bolt, only to find that loosening it requires less effort than
tightening it? This phenomenon, which may seem counterintuitive at first, has a scientific explanation that
lies in the design of threaded fasteners.

YouTuber AvE delved into this topic (watch at YouTube), providing an in-depth demonstration and
explanation of why it takes less torque to loosen a bolt than to tighten it. Using an oscilloscope rigged as an
ad-hoc torque-strain gauge, AvE showcased that loosening a bolt requires approximately 10% less torque
than what was initially applied during tightening.

The key to understanding this difference lies in the pitched threads of the bolt, which act like an inclined
plane. When tightening a bolt, it’s akin to pushing an object uphill, requiring more effort to overcome the
incline. Conversely, loosening the bolt is like pulling an object downhill, which requires less force due to the
assistance of gravity.

This principle doesn’t account for external factors that may affect the bolt between installation and removal,
such as rust, corrosion, or seized threads. These issues can significantly increase the torque required to
remove a fastener, sometimes necessitating the use of additional tools or techniques.
By providing fasteners and torque tools from Bahco and Irimo that meet the highest standards of quality and
performance, at Tsamouris, we aim to support engineers and mechanics in their projects, whether they’re
tightening or loosening bolts.

Loose Wing Screw on Air China Boeing 737 Flight

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In July 2022, Air China found itself in the spotlight after a passenger on flight CA1921 from Beijing to
Hengyang noticed and recorded a loose wing screw on the Boeing 737NG aircraft. The video, which was
shared widely on Chinese social media platform Weibo, prompted the airline to take swift action and issue a
statement addressing the incident.

According to the statement, Air China “attached great importance” to the loose screw in the inboard canoe
fairing of the left flap and immediately inspected the relevant parts of the aircraft, repaired the loose screws,
and checked the entire fleet for similar issues.

The inboard canoe fairing, where the loose screw was located, is primarily used to regulate airflow, reduce
drag, and save fuel. The screws in question are responsible for fixing the flap track fairing tail cones, which
are a part of the inboard canoe fairing.

While there was no official explanation for the cause of the loose screw or its potential impact on flight
safety, aviation experts weighed in on the matter. Qiu Qing, an aviation blogger with over 300,000 followers
on Weibo, suggested that the issue could be attributed to either a broken supporting target in the fairing or
long-term vibration at the screw’s position.

According to the configuration deviation list (CDL) of the Boeing 737NG, it is acceptable for the aircraft to
take off without up to two flap track fairing tail cones. Veteran pilot Chen Jianguo told the Beijing Youth Daily
that one or two loose screws on the fairing would not affect safety, even if the fairing itself were missing.

Loose Screw Causes Gas Meter Leak

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In September 2022, a gas meter in the Kincaidston Ayr, Ayrshire, Scotland, was found to be ‘bubbling’ due to
a loose screw, raising concerns among residents still reeling from a devastating house explosion in the area
just months earlier.

Rikki Bell, a 34-year-old qualified plumber and heating engineer, captured shocking footage of the gas leak at
his parents’ home on Sorrel Drive. Bell’s parents had noticed the smell of gas near their front door and porch,
prompting their son to investigate.

Using leak detector fluid, Bell discovered that a nut on the meter, which had been installed just nine months
earlier as part of major replacement works following the Gorse Park explosion, had not been properly
tightened. “It was basically tightened by hand,” Bell explained, adding that it took about four full turns with a
spanner to stop the leak.

Rikki’s mum, Tracy Bell, contacted SGN, the gas network operator, but was disappointed by their response.
She felt that the customer service agent and engineer downplayed the severity of the issue, stating, “To be
told it is just a loose screw is not good enough… It does not fill you with confidence — I do not understand
how it could have happened, and it is gas, it is dangerous and it is not a water tap. Things like this should be
checked and checked again.”

This incident emphasizes the critical importance of properly installed and maintained gas fittings and the
potential consequences of even seemingly minor issues like loose screws.

Loose Screw from Air Canada Propeller Smashes into Passenger’s Window Mid-Flight

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In December 2017, an Air Canada passenger experienced a terrifying moment when a screw from the
plane’s propeller came loose mid-flight and smashed into the window by his seat. The passenger shared
images on Reddit of the alarming incident, which occurred on a flight to Vancouver.

He described hearing a loud “pop” and then noticing that a screw had embedded itself in the outer pane of
the window. The noise caused concern among passengers, and the flight attendant promptly notified the
pilot. The pilot, who had over 25 years of flying experience, stated that he had never encountered such an
incident before.

Upon landing, the pilot spoke with the “lucky” passenger at length, revealing that even the aircraft
manufacturer, Bombardier, had never seen a case of a screw coming loose and embedding itself in a
window.

An Air Canada spokesperson confirmed the incident, stating that one of the twelve one-inch bolts on the
“prop spinner” had come loose during the descent into Vancouver. The bolt struck the exterior pane of the
two acrylic window panes, resulting in a small hole. Fortunately, the interior pane was not impacted, and the
aircraft landed safely without further incident.

Events like these highlight the critical importance of proper maintenance and the use of high-quality
fasteners in the aviation industry.

Tesla’s USD 100,000 Cybertruck Needs a Rivet Drilled through the Pedal for Safety

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In April 2024, Tesla faced a significant setback when a viral video revealed that the accelerator pedal pad on
its highly anticipated Cybertruck could slip off and get stuck in the interior trim, causing the vehicle to
accelerate uncontrollably. In response, the company temporarily halted deliveries and issued a recall for
every Cybertruck on the road.

The solution to this potentially dangerous issue turned out to be surprisingly simple: a single rivet installed to
secure the pedal pad in place. At a “Cyber Takeover” event in Long Beach, California, Tesla demonstrated the
quick fix, which takes just 35 seconds to complete once the required drilling jig is in place.

The process, as outlined in Tesla’s Service Bulletin, involves measuring the distance between the bottom of
the aluminum accelerator pedal pad and the bottom of the pedal backing before beginning the work. If the
bottom of the pad is 5mm or further from the bottom of the pedal, the entire pedal assembly must be
replaced.

Once the measurement is confirmed to be within the acceptable range, a hole is drilled using the jig, and a
rivet is installed to secure the pedal pad, preventing it from coming off due to an “unapproved change”
during manufacturing that made it slipperier than intended.

After the installation, Tesla’s workers inspect the work with a mirror and clean up any debris left in the
customer’s USD 100,000 (EUR 90,000) plus truck, ensuring that the vehicle is returned in pristine condition.
At Tsamouris, we recognize the importance of fasteners in preventing potentially life-threatening accidents.

When Montrealers Flocked to Collect Rivets from Old Champlain Bridge

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In September 2023, thousands of Montrealers lined up in Brossard and on Nuns’ Island to receive a piece of
history — a souvenir rivet from the old Champlain Bridge. The bridge, which connected Montreal and its
suburbs for nearly 60 years, was decommissioned in 2019 and replaced by a new USD 4.4 billion (EUR 4
billion) span.

Despite the pouring rain, people eagerly waited to get their hands on one of the 4,000 rivets being given
away as keepsakes. The giveaway proved immensely popular, with some individuals lining up as early as 7
a.m. on the previous day in Brossard.

The original Champlain Bridge, opened in 1962, was the most-travelled bridge in Canada, with 50 million
trips per year. It played a significant role in the economic development of both Montreal and its surrounding
areas. However, the bridge was also plagued with problems, including a lack of drainage that led to rapid
corrosion, ultimately leading to the decision to replace it when it was less than 50 years old.

Nathalie Lessard, a spokeswoman for Jacques Cartier and Champlain Bridges Inc., the federal Crown
corporation managing the old bridge, emphasized the importance of the rivets: ”Rivets are not used to build
bridges anymore; now they use nuts and bolts,” she explained, highlighting the historical significance of
these fasteners.

The rivets were removed as part of a USD 400 million (EUR 370 million), multi-year effort to dismantle the old
bridge, which is on schedule to be completed in early 2024. The giveaway is part of the corporation’s effort to
recycle some 90% of all the bridge materials, including 25,000 tonnes of steel. Other pieces of the bridge
have been repurposed into various projects, such as a bicycle, a footbridge for a scout camp, school
furniture, and even watches.

Tsamouris is a leading supplier of high-quality bolts, committed to providing fasteners that ensure the safety
and longevity of the public infrastructure they are used in.

Boeing Finds Missdrilled Rivet Holes on 50 Undelivered 737 Max

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Back in February 2024, Boeing announced that it has discovered incorrectly drilled holes in the fuselages of
approximately 50 undelivered 737 Max jets. This setback was expected to cause rework and potentially delay
the delivery of these planes, raising further concerns about quality control at the manufacturer and its
suppliers.

Stan Deal, the CEO of Boeing’s commercial plane unit, stated in a memo to employees that a supplier had
identified two holes that may not have been drilled according to the company’s requirements. While Deal
emphasized that this issue is not an immediate flight safety concern and that the 737s currently in use can
continue flying, it underscores the ongoing challenges faced by Boeing and its suppliers in maintaining high
standards of quality and safety.

The latest problems come on the heels of a January 5th, 2024, incident involving a 737 Max 9 jet operated by
Alaska Airlines, in which a panel blew out mid-flight due to missing bolts, forcing an emergency landing and
the grounding of some Max 9s in the United States. Reports have suggested that Boeing workers had
previously opened and reinstalled the panel that blew off the Alaska Airlines plane, raising further questions
about quality control practices.

In response to these issues, the Federal Aviation Administration (FAA) has stated that it will limit Boeing’s
output until it is confident in the company’s quality control processes. The regulator is also investigating
Boeing’s manufacturing practices and production lines, including those involving Spirit AeroSystems,
Boeing’s fuselage supplier.

At Tsamouris, we understand the critical importance of quality control and precision in the manufacturing
process, particularly when it comes to fasteners and components that play a vital role in ensuring the safety
and reliability of aircrafts.

Why Jeans Have Rivets

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In the late 1800s, the American West was a hive of activity, with men toiling on farms, ranches, railroads, and
gold mines in harsh and dirty conditions. The grueling work often led to “blowouts” — the splitting of pants
at pockets and other stress points. J.W. Davis, a Latvian tailor and inventor based in Reno, Nevada, who
specialized in making tents and wagon covers, devised a solution: placing rivets on work pants at these
points of strain, including the crotch.

He reached out to his fabric supplier, Levi Strauss in San Francisco, proposing a patent partnership. On May
20th, 1873, Jacob Davis and Levi Strauss & Co. obtained U.S. patent No. 139,121 for “an Improvement in
Fastening Pocket Openings,” marking the birth of the riveted blue jean. The near-indestructibility of Levi’s®
made them the go-to choice for the diverse, rugged individuals — workers, outcasts, entrepreneurs, and
outlaws — who were shaping America’s future.

Over a century later, these tiny rivets continue to serve their original purpose, ensuring that your jeans’
pockets remain securely attached and ready to handle whatever you throw their way.