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Going to link an aircrash investigation that found fake aircraft parts as the cause. May help with getting some extra context on where and how these things get

Going to link an aircrash investigation that found fake aircraft parts as the cause. May help with getting some extra context on where and how these things get into the system. https://admiralcloudberg.medium.com/riven-by-deceit-the-crash-of-partnair-flight-394-f8a752f663f8 https://admiralcloudberg.medium.com/riven-by-deceit-the-cras...

cfn 3y ago
Very long article but well worth the read. Scary stuff: "...a former drug trafficker from Colombia told South Florida detectives that she had switched to trafficking aircraft parts instead. After all, the money was almost as good — by some estimates, during the early 1990s, unapproved parts represented a $2 billion industry."
- bboygravity 3y ago
  So either unapproved parts are of very high quality or airlines have been extremely lucky so far?
  - hef19898 3y ago
    A combination of both, aerospace is so safe, the edge cases and tiniest margins matter. Good quality parts of the non-flying variety are often good enough, they just aren't good enough all the time. Nor are they traceable. So luck, that the parts don't fail in cataszrophic fashion. And even bad quality "flying" parts are usually reasonable high quality, after all the folks handling the real parts on a daily basis have to be fooled as well.
  - red-iron-pine 3y ago
    All of the above. Parts may be real / legit parts that exceeded their official lifespan, or "3rd shift" parts made at the same factory with mostly or entirely the same materials, just not run through QA to save money and given fake testing certifications. Could also just be a knockoff that's good enough most of the time. Large flag carriers like Delta also have real staff and processes, and it looks like they're doing inspections and sometimes catching bogus parts; smaller organizations may not do that.
  - matheusmoreira 3y ago
    The article discusses those possibilities. It seems this particular aircraft was so old and so extensively modified that the failures started adding up and combining in such unfathomable ways that they actually destroyed the plane. The worn out counterfeit bolts failed to destroy the plane. A shoddily made mount for a turbine generator literally broke but failed to destroy the plane. Both of them interacted at some points but failed to destroy the plane because the pilots turned off the generator in time. Only when they left the generator running for a long time did it interact long enough with the failures in the vertical stabilizer bolts to cause catastrophic aircraft destroying vibrations. > the FAA officials who played down the danger were not necessarily wrong either > unapproved parts cause annoying breakdowns and increase maintenance costs, but don’t directly cause crashes, simply because there are very few individual parts on an aircraft which could cause a crash if they fail > Redundancy in aircraft design largely shields us from the consequences, with the primary exception being very old aircraft like LN-PAA which predate many modern airworthiness requirements. > Even then, it took multiple unapproved parts in multiple locations, plus inadequate inspections and poor documentation, to actually bring down the plane. > So much was wrong with LN-PAA that its various faults started to interact in unpredictable ways, creating conditions which no one had foreseen, least of all the pilots, who probably went to their graves without any idea of what had befallen them.
Sebb767 3y ago
Just as a sidenote, the article ends with: > That being said, the probable continued existence of unapproved parts on the market should not really be cause for alarm to the flying public. [...] The fact is that Partnair flight 394 remains the only crash of a commercial airliner linked to unapproved parts, placing the issue rather far down the list of problems that cause the most crashes. It's worth a read, but the summary is that the problem is mostly under control and unlikely to cause a crash. > In general, this is because unapproved parts cause annoying breakdowns and increase maintenance costs, but don’t directly cause crashes, simply because there are very few individual parts on an aircraft which could cause a crash if they fail. Redundancy in aircraft design largely shields us from the consequences, with the primary exception being very old aircraft like LN-PAA which predate many modern airworthiness requirements. Even then, it took multiple unapproved parts in multiple locations, plus inadequate inspections and poor documentation, to actually bring down the plane.
- kayfox 3y ago
  Since that article was written in 2018, Lion Air Flight 610 crashed in part because of an unapproved replacement angle of attack sensor installed without proper testing. So there's at least one more crash associated with unapproved parts.
  - felixg3 3y ago
    How is lion air 610 related to that? The issue was not the single unapproved part but a whole series of malicious business decisions and corporate misconduct by a internally corrupt airplane manufacturer.
  - Prickle 3y ago
    Not really no. Lion Air 610, and the 23 other near miss incident reports all point to a fundamental design flaw in the Boeing 737 Max8 Primarily, that there is only one angle of attack sensor that feeds the MCAS system. There are two sensors, but the system just doesn't compare them. It just takes the result from one sensor and uses it regardless of errors. For comparison, Airbus A320 actually has a very similar system. But it is fed by 3 different angle of attack sensors. All 3 sensors are constantly compared against each other. I almost forgot! Below quotes are straight from Wikipedia MCAS page. > Boeing's own internal design guidelines related to the 737 MAX's development stated that the system should "not have any objectionable interaction with the piloting of the airplane" and "not interfere with dive recovery".[68] The operation of MCAS violated those.[69] > the specific failure modes that could lead to unintended MCAS activation (such as an erroneous high AOA input to the MCAS) were not simulated as part of these functional hazard assessment validation tests. As a result, additional flight deck effects (such as IAS DISAGREE and ALT DISAGREE alerts and stick shaker activation) resulting from the same underlying failure (for example, erroneous AOA) were not simulated and were not in the stabilizer trim safety assessment report reviewed by the NTSB."

cfn 3y ago

Very long article but well worth the read. Scary stuff: "...a former drug trafficker from Colombia told South Florida detectives that she had switched to trafficking aircraft parts instead. After all, the money was almost as good — by some estimates, during the early 1990s, unapproved parts represented a $2 billion industry."

bboygravity 3y ago
So either unapproved parts are of very high quality or airlines have been extremely lucky so far?
- hef19898 3y ago
  A combination of both, aerospace is so safe, the edge cases and tiniest margins matter. Good quality parts of the non-flying variety are often good enough, they just aren't good enough all the time. Nor are they traceable. So luck, that the parts don't fail in cataszrophic fashion. And even bad quality "flying" parts are usually reasonable high quality, after all the folks handling the real parts on a daily basis have to be fooled as well.
- red-iron-pine 3y ago
  All of the above. Parts may be real / legit parts that exceeded their official lifespan, or "3rd shift" parts made at the same factory with mostly or entirely the same materials, just not run through QA to save money and given fake testing certifications. Could also just be a knockoff that's good enough most of the time. Large flag carriers like Delta also have real staff and processes, and it looks like they're doing inspections and sometimes catching bogus parts; smaller organizations may not do that.
- matheusmoreira 3y ago
  The article discusses those possibilities. It seems this particular aircraft was so old and so extensively modified that the failures started adding up and combining in such unfathomable ways that they actually destroyed the plane. The worn out counterfeit bolts failed to destroy the plane. A shoddily made mount for a turbine generator literally broke but failed to destroy the plane. Both of them interacted at some points but failed to destroy the plane because the pilots turned off the generator in time. Only when they left the generator running for a long time did it interact long enough with the failures in the vertical stabilizer bolts to cause catastrophic aircraft destroying vibrations. > the FAA officials who played down the danger were not necessarily wrong either > unapproved parts cause annoying breakdowns and increase maintenance costs, but don’t directly cause crashes, simply because there are very few individual parts on an aircraft which could cause a crash if they fail > Redundancy in aircraft design largely shields us from the consequences, with the primary exception being very old aircraft like LN-PAA which predate many modern airworthiness requirements. > Even then, it took multiple unapproved parts in multiple locations, plus inadequate inspections and poor documentation, to actually bring down the plane. > So much was wrong with LN-PAA that its various faults started to interact in unpredictable ways, creating conditions which no one had foreseen, least of all the pilots, who probably went to their graves without any idea of what had befallen them.

Sebb767 3y ago

Just as a sidenote, the article ends with: > That being said, the probable continued existence of unapproved parts on the market should not really be cause for alarm to the flying public. [...] The fact is that Partnair flight 394 remains the only crash of a commercial airliner linked to unapproved parts, placing the issue rather far down the list of problems that cause the most crashes. It's worth a read, but the summary is that the problem is mostly under control and unlikely to cause a crash. > In general, this is because unapproved parts cause annoying breakdowns and increase maintenance costs, but don’t directly cause crashes, simply because there are very few individual parts on an aircraft which could cause a crash if they fail. Redundancy in aircraft design largely shields us from the consequences, with the primary exception being very old aircraft like LN-PAA which predate many modern airworthiness requirements. Even then, it took multiple unapproved parts in multiple locations, plus inadequate inspections and poor documentation, to actually bring down the plane.

kayfox 3y ago
Since that article was written in 2018, Lion Air Flight 610 crashed in part because of an unapproved replacement angle of attack sensor installed without proper testing. So there's at least one more crash associated with unapproved parts.
- felixg3 3y ago
  How is lion air 610 related to that? The issue was not the single unapproved part but a whole series of malicious business decisions and corporate misconduct by a internally corrupt airplane manufacturer.
- Prickle 3y ago
  Not really no. Lion Air 610, and the 23 other near miss incident reports all point to a fundamental design flaw in the Boeing 737 Max8 Primarily, that there is only one angle of attack sensor that feeds the MCAS system. There are two sensors, but the system just doesn't compare them. It just takes the result from one sensor and uses it regardless of errors. For comparison, Airbus A320 actually has a very similar system. But it is fed by 3 different angle of attack sensors. All 3 sensors are constantly compared against each other. I almost forgot! Below quotes are straight from Wikipedia MCAS page. > Boeing's own internal design guidelines related to the 737 MAX's development stated that the system should "not have any objectionable interaction with the piloting of the airplane" and "not interfere with dive recovery".[68] The operation of MCAS violated those.[69] > the specific failure modes that could lead to unintended MCAS activation (such as an erroneous high AOA input to the MCAS) were not simulated as part of these functional hazard assessment validation tests. As a result, additional flight deck effects (such as IAS DISAGREE and ALT DISAGREE alerts and stick shaker activation) resulting from the same underlying failure (for example, erroneous AOA) were not simulated and were not in the stabilizer trim safety assessment report reviewed by the NTSB."