November-December 2022 - 33

Besides factors like fuel prices and seat types, the main consideration
is safety. Usually, a plane's life span isn't measured
in years but rather in pressurization cycles. Every time a plane
takes flight, it is pressurized, which puts stress on the fuselage
and the wings. This is called metal fatigue. Short-haul planes,
which undergo multiple takeoffs and landings each day, will have
a shorter life span than long-haul flights.
A plane that undergoes too many pressurization cycles without
being replaced has the potential to suffer damage to the metal.
If you bend a paperclip over and over again until it snaps, you'll
understand the dangers of metal fatigue. When you put pressure
on the same parts of the metal shell of the plane over and over
again, this can cause pieces of the plane to break off mid-flight.
One of the most famous and tragic occurrences of this happened
in 1988, when Aloha Airlines Flight 243 suffered explosive decompression
due to too many pressurization cycles. This particular
aircraft had over 90,000 flight cycles - well over double the safety
limit. The plane experienced widespread metal fatigue cracks,
causing a portion of the roof to come completely off the aircraft.
There was one fatality and passengers were injured.
How Can You Tell How " Old " a Plane Is?
The Aloha Airlines flight had one positive outcome: it completely
revamped aviation safety policies and procedures. You
can read about some of the changes in the report the National
Transportation Safety Board released after the incident. But
one of the biggest causes of the failure was a failure to assess or
maintain the plane.
Today, we have comprehensive safety measures in place to make
sure that sort of incident can't happen again. Safety-critical guidelines
like DO 178C helped put more benchmarks into place. Ways
to evaluate planes without taking them apart have become more
accessible. Today, ultrasonic phased-array testing is a common
non-destructive evaluation method which looks for imperfections
by analyzing the echoes from ultrasonic waves to find cracks or
welds. It's kind of like giving a plane an ultrasound - you scan
the outside to see what's inside.
Although it is possible to maintain a plane beyond its pressurization
limit, as the plane gets older, it becomes less costeffective
to maintain an old plane, and more cost-effective to
simply buy a new one.
Factors To Consider
There are many factors to consider when deciding
how long to keep a plane flying. They include:
* the plane's age,
* pressurization cycles,
* flight hours and
* whether there are more cost-efficient
models to replace the plane with.
What Happens To
Retired Planes?
Retired planes are headed to one of two
places: another buyer or the scrapyard.
If the plane is still safe to fly, or if a buyer
is more willing to pay for maintaining an
old plane than buying a new plane, a plane
might be resold to another fleet. It's worth
noting that different countries have different
plane safety requirements. What's no longer
thought of as safe in one country might still
be considered safe in another.
When there are no buyers for old planes,
Vance Hilderman
is an aviation
expert, author and
CEO of AFuzion.
they are typically sent to scrapyards where they're disassembled
for parts. This is an important consideration when deciding when
to retire a plane. Besides safety or economic factors like fuel efficiency
or seat type, it's important to retire the plane early enough
to be able to reuse certain parts, which can help recoup much
of the cost.
IATA reports that when a plane is decommissioned at the right
time, 90 percent of the parts can be reused or recycled. And there's
a huge market for those spare parts. GM Insights reported that
the aircraft recycling market size was over $4 billion in 2020.
However, the secondhand plane-part market changes quite
quickly, so many airplane owners will send their retired planes
to plane graveyards to be kept until the owner judges the time
is right to harvest and resell the part. These graveyards are typically
in dry, spacious areas like Arizona and southern California.
Even with the most conscientious maintenance, most airplanes
will eventually need to be retired. All in all, most experts say the
average lifespan of a plane is about 22.8 years. As with any average,
your mileage may vary.
There are many factors to consider when deciding how long
to keep a plane flying: its age, pressurization cycles and flight
hours. Another factor is whether there are more cost-efficient
models to replace the plane with. And when planes do retire, it's
worth looking at the secondhand parts market to see how much
you can recoup the cost of getting a replacement plane.
PHOTO: © ANDREISTANESCU | DREAMSTIME.COM | 165627565
www.AviationPros.com 33
http://www.DREAMSTIME.COM http://www.AviationPros.com
November-December 2022

Table of Contents for the Digital Edition of November-December 2022
