Russia's leased planes may be worthless

[kschachn]

Why would another plane be able to fly with parts from these planes aren't they suspect as well? If the plane as an aggregate of these parts cant fly what is the reasoning for letting individual parts fly. Not trying to be a wiseguy just trying to understand. If they are willing to certify these suspect parts to fly why cant they just break the plane down and recertify it. They have been rebuilding B-52's forever. I understand that it would get expensive but wouldnt it be cheaper than buying a new plane.

Also because many if not most of the parts on an aircraft are not time-controlled. As to recertification that is not usually possible. The Airworthiness Limitations Section of an aircraft maintenance manual is absolute and must be followed for life-limited components. There's no legal means to recertify an engine disk for example, it has a life limit and that's that. Metal fatigue, corrosion, cracking etc. can't be undone so all you could do is melt it down and forge a new one. An overhaul does not reset the life limit.

The other thing is that some of this can get weird when taken to the extreme. Many airframes have a structural life limit and it doesn't list which part(s) of that airframe are the critical components that actually determine the limit. It's a joke that you could take an airplane that is one cycle away from the airframe limit and disassemble it to use those structural parts in other airplanes. Since the parts were airworthy when removed they can be installed elsewhere on an aircraft that hasn't reached its airframe limit. On the face of that it is legal. Similarly you could put a brand new structural component on that same "one cycle away" airplane and the next cycle it is now reached the limit. Nobody does this of course.

As you mention for the B-52 there are schemes to either extend the life of an airframe or even reset it to back to zero. Douglas did some of this for the MD-10 conversions, in the beginning it was going to be a total reset of the airframe life but in the end that became too expensive so it was just something else which I can't remember right now. But as has already been mentioned you can extend airframe life basically forever if you are willing to spend the money on engineering, labor, parts and regulatory recertification. Replacing a main spar for example is not for the faint of heart.

 

[Kuato]

From a Google search,

Perhaps unique among prewar aircraft, the DC-3 continues to fly in active commercial and military service as of 2021, eighty-six years after the type's first flight in 1935.

Dude, you are obviously not getting it.

There is a huge difference between pulling your car with a broken suspension off the higway and calling AAA, and having a critical wing component fail at 35,000 feet. One is inconvenient. The other kills everyone on board.

THAT is why all mx history is required. The DC3s in your link DO in fact have all mx records dating back to date of manufacture. So the owners KNOW exactly when each part on the plane was replaced.

If you can't understand that, go get smarter somewhere.

 

[ArrestMeRedZ]

There is a significant difference between a military aircraft like the B-52 and a commercial airliner. Often times when a military aircraft is flown well beyond it's originally planned lifespan, problems surface during nondestructive testing. Those problems are then fixed fleetwide, or if the fix is too expensive, the fleet is retired.
Other times problems are masked until they appear in flight. After the loss of one or more aircraft of a certain type, a safety board determines the cause. The fleet may be grounded until inspection and/or repairs are complete.
As bad as it sounds, we accept a reasonable loss rate of military aircraft. If the need exists, we will use them until we can't use them any more. We don't accept the same with commercial aircraft. Passengers don't get paid to take the same risks as military aircrew, and they don't have ejection seats to get out of an aircraft coming apart around them.

 

[kschachn]

More dead horse beating--

As far as airframe structural life limits go some airplanes never had one as part of their type certificate. The DC-9 for example had no limit. But later on the subject of aging aircraft became a hot topic and the FAA issued a series of Airworthiness Directives mandating the accomplishment of specific manufacturer service bulletins in order to operate aircraft beyond a published limit. For that DC-9 the limit was 110,000 cycles which is a large limit. Some Northwest Airlines DC-9s came close to that limit before being scrapped. I do not believe there were any operators that complied with the Service Bulletins to extend the life beyond the 110,000 cycle limit however as the requirements of the bulletin were extensive. Stuff like aft pressure bulkhead replacement and other complicated and expensive repairs.

Here is an older Boeing Aero magazine article that describes some of the provisions of the aging aircraft regulations. Note how high the cycle limits were in general for Douglas airframes and especially the DC-9 and MD-80. Structurally those were very robust aircraft. Douglas did a series of pressurization life-cycle tests in their Long Beach parking lot and somewhere I have a great picture of an MD-80 airframe surrounded by a chain mail fence, where the fuselage was repeatedly pressurized and depressurized over several years. Ultimately after more than 200,000 cycles the airframe was disassembled to look for cracks or other defects that would indicate impending failure of the airframe. Even after all those cycles there was nothing that would indicate failure in the test article.

https://www.boeing.com/commercial/aeromagazine/articles/2012_q4/pdfs/AERO_2012q4_article2.pdf

 

[andyd]

When I first moved to my house, the Boston- Hyannis Air flew a daily DC3 overhead . That lasted until the mid 90s. The plane is parked at the Barnstable Airport. The Concorde used to drop to sub-sonic every morning about 8:15.

 

[Wolf359]

As bad as it sounds, we accept a reasonable loss rate of military aircraft. If the need exists, we will use them until we can't use them any more. We don't accept the same with commercial aircraft. Passengers don't get paid to take the same risks as military aircrew, and they don't have ejection seats to get out of an aircraft coming apart around them.

What? You mean you don't agree with this guy? "You pays your money and you takes your chances."

 

[TCL]

They'll fly them as cheap bombs.

 

[bullwinkle]

Russia will likely just keep flying them until they fall out of the sky-the value they place on human life is demonstrably lower than hours-bombing civilians, sending their army out with no real training, etc. I feel a little sorry for the airplane leasing companies, though, they're taking a bath on this one. Them and all the Russian pilots, passengers, and people underneath the flight path!

 

[nthach]

, there is no limit to how long a company can keep an aircraft flying. The structure has a design life but this can be extended through inspections, updates, engineering overrides, etc. A non-pressurized vessel such as the DC-3 doesn't suffer from the cyclic fatigue that a modern jet suffers from.

From what I also understand besides records keeping, tracking of LLPs(such as engine parts and life support equipment like oxygen generators) and the logbook, the type certificate is also important to how long a plane can legally fly - no type certificate, no fly. Isn’t the revocation of the Concorde’s flight certificate by Airbus the main reason besides economics for the reason it’s no longer flying? And if Boeing pulls the TC of the old McDonnell-Douglas era jets(DC-8/9/10, MD-11) and their “classic” planes, no one can legally fly them?

 

[nthach]

Russia will likely just keep flying them until they fall out of the sky-the value they place on human life is demonstrably lower than hours-bombing civilians, sending their army out with no real training, etc. I feel a little sorry for the airplane leasing companies, though, they're taking a bath on this one. Them and all the Russian pilots, passengers, and people underneath the flight path!

AFAIK, Russia isn’t part of the JAA and NATO has a naming convention for Russian and Chinese planes? Correct me if I’m wrong.

I know Russia was able to fly their planes into European and Carribean airspace but didn’t the JAA and FAA have to grant Aeroflot and Cubana permission to fly Russian-made aircraft into their airspace? I know the An-225 has made appearances into the US but that operator was Ukrainian.

 

[kschachn]

From what I also understand besides records keeping, tracking of LLPs(such as engine parts and life support equipment like oxygen generators) and the logbook, the type certificate is also important to how long a plane can legally fly - no type certificate, no fly. Isn’t the revocation of the Concorde’s flight certificate by Airbus the main reason besides economics for the reason it’s no longer flying? And if Boeing pulls the TC of the old McDonnell-Douglas era jets(DC-8/9/10, MD-11) and their “classic” planes, no one can legally fly them?

You can legally fly an aircraft without a type certificate, the manufacturers do that all the time during initial certification. Likewise you can also fly without a standard airworthiness certificate but you need a special airworthiness certificate. Such as for an experimental category aircraft.

 

[kschachn]

From what I also understand besides records keeping, tracking of LLPs(such as engine parts and life support equipment like oxygen generators) and the logbook, the type certificate is also important to how long a plane can legally fly - no type certificate, no fly. Isn’t the revocation of the Concorde’s flight certificate by Airbus the main reason besides economics for the reason it’s no longer flying? And if Boeing pulls the TC of the old McDonnell-Douglas era jets(DC-8/9/10, MD-11) and their “classic” planes, no one can legally fly them?

And just to be clear Airbus did not revoke the TC, they can surrender it but only the regulatory agency can revoke or suspend it. Which means they no longer hold the certificate either, so someone else could - in theory.

 

[MolaKule]

When I worked on the Boeing 737 Next Generation series and the Boeing 777 in the Stress Analysis and Fatigue group we used FEA software but verified the results with hand calculations (meaning the Scientific Calculator and paper/pencil).

Each and every part was analyzed for fatigue life with accompanying inspection data which described the part, where it was located, the inspections schedule, and replacement criteria.

There is no automotive equivalent to aircraft stress and fatigue analysis, and any attempt to compare is a False Analogy.

 

[George Bynum]

When I worked on the Boeing 737 Next Generation series and the Boeing 777 in the Stress Analysis and Fatigue group we used FEA software but verified the results with hand calculations (meaning the Scientific Calculator and paper/pencil).

When I worked on the Boeing 737 Next Generation series and the Boeing 777 in the Stress Analysis and Fatigue group we used FEA software but verified the results with hand calculations (meaning the Scientific Calculator and paper/pencil).

Mola, just curious; how often did your hand calculations find the FEA results different? Similar kinda work, when I got differing results it was ALWAYS a GIGO situation ... the G may be hand or software inputs. I (so far) never found a software error.

 

[sk_pete]

If I get a 100,000 mile car with no service records, I do the timing belt and water pump in addition to the spark plugs, wires, filters, fluids, etc. to bring the maintenance up to date. Also do an inspection of the brakes, suspension, tires, body and frame while I'm at it.

Broken car, no problem you can call taxi
Try that with plane at high altitude

 

[MolaKule]

Mola, just curious; how often did your hand calculations find the FEA results different? Similar kinda work, when I got differing results it was ALWAYS a GIGO situation ... the G may be hand or software inputs. I (so far) never found a software error.

I had exactly the same experience. If there was a difference, myself or someone else had entered something into the software incorrectly, or had made a differing assumption of the conditions. Software errors were uncommon.

Both analyses went to our Chief Structural/Stress engineer before documentation and if there were any differences, we had a group conference on why there were differences and how to determine what the proper values should be. The conferences were very helpful and instructive as we all realized the seriousness of our task, because we had to get it right as there were many lives at stake. The theory was: If you can do it by hand then you have an understanding of Structural/Stress/Fatigue analysis.

Structural/Stress analysis is an iterative process and in some rare cases, the Materials Group had not given us updated materials' data. But all of this was clarified before the design went to the FAA and subsequently to assembly.

Later on, I actually wrote improvements to FEA software.

 

[97prizm]

Add into the fact that no only must everything be documented, you have to use certified parts that the FAA or EASA has checked off. Second if you want to change the way Boeing or Airbus recommends repairing or a procedure you have to show that it's safe and complies with all rules.

 

[Dave Hess]

So basically Russia will cannibalize aircraft or get black market parts to keep them flying ?

 

[y_p_w]

So basically Russia will cannibalize aircraft or get black market parts to keep them flying ?

Sure they could try to keep them flying by cannibalizing parts, but then there's the issue of where they can fly, since they wouldn't be certified to fly in many countries. The flying public in Russia might not necessarily trust that they're safe either.

This was just throwing a wrench in the works. It wasn't a long term strategy, but just revenge. And in the long term it's going to be nuts how this all works, as who would trust them in the future after pulling off something like this?

 

[Jetronic]

I don't think it

Sure they could try to keep them flying by cannibalizing parts, but then there's the issue of where they can fly, since they wouldn't be certified to fly in many countries. The flying public in Russia might not necessarily trust that they're safe either.

This was just throwing a wrench in the works. It wasn't a long term strategy, but just revenge. And in the long term it's going to be nuts how this all works, as who would trust them in the future after pulling off something like this?

I don't think it matters, they won't trust leasing airplanes from western firms either.