what is going wrong with our industry ? 2

[rb1957]

from Flight today ...

P&W geared turbofan issue will ground hundreds of A320neos through 2026

What is going on in our industry that we're seeing such actions against delivered aircraft ? And not just P&W, several engines, OEMs have been suffering "recalls" of late ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[btrueblood]

Rolled out of Singapore airport last week, and was surprised to see row upon row of parked A320's with empty engine fairings parked along taxiways.

Now we apparently had a bunch of repair parts sourced in the UK which were fraudulent?

 

[3DDave]

It may be a good sign - being willing to ground aircraft over an issue that did not start with an accident investigation. There is also the increased expansion into more sophisticated materials and manufacturing methods. Example, powdered metal alloys and putting gear trains as power components into huge turbofans.

Overall the industry has decreased fatal accident rates due to mechanical issues at an amazing rate.

 

[rb1957]

sorry, I don't see this as anything "good". At best this is bolting the barn door after the horse has bolted.

how did the production QA get defeated so badly (in so many different areas) ?

Discovering a problem with a new material or process ... that's different. But still a "failure" ... how did such things get out into the world ?

Sure there are plenty of examples. A favourite of mine is 7079 ... AIUI the only alloy to corrode worse in the field than under the lab tests.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[3DDave]

How? Lack of infinite time and infinite money to perform infinite tests and to squeeze all that into the required time to make a salable product.

 

[rb1957]

I guess it's still early days.

is it new processes being pushed beyond what testing was thought to be enough ? "Surely" engines are tested for so much durability that we're not seeing this ??

is it bogus parts (again) ? have we (mistakenly, again) placed our trust in certificates, and are now seeing the problems this creates ?

Is there something in the production that's been "overlooked" ??

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[SWComposites]

Simple - TOO MANY MBA types who are only focused on short term cost reductions and this quarter’s earnings and share price. QA is seen as a cost to be reduced. Constant focus on reducing cycle times and beating up on suppliers to reduce their cost and price.

And the regulators are captured by the corporations and pressured to look the other way and not come down hard when defects are found.

 

[rb1957]

and now those issues are coming home to roost !

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[SWComposites]

Info on P&W GTF engine powder metal contamination effect:

https://airinsight.com/pratt-whitney-gtf-update/

Apparently "microscopic iron particles" got into the powder resulting in small inclusions in the parts.

 

[enginesrus]

PM is great for parts that need to be cracked. Why consider it for the disk? If I read that correctly.

 

[Sparweb]

Broad question, so probably as many answers as people who want to answer...

Two suggestions, if I were to answer your question directly:

1)
Decreasing use of experience and increasing use of computerized models for judgement. Computers are tools for design, which is not judgement. "It looks good on screen so it should be good". Design is being done by people with less hands-on experience than ever, therefore are unable to exercise clear judgement. And it doesn't have to be experience in an aircraft factory or MRO hands-on time. Young engineers used to be steered to the industry by working with machines, not just high-school test scores. This is the "guys changing the oil in their own cars" argument, and I believe there's a nugget of truth in there. It doesn't help when the managers have even less technical knowledge than the designers.

I've fabricated parts that were subsequently put on an aircraft and flown away. Have you? Have your colleagues?

2)
Victim of our own success, the time has quietly passed that regulators will merely respond to an accident with investigation and corrective action. Today, corrective action can be initiated by the simple prediction of an accident. This is actually a victory, but in disguise. We developed this vast and insightful safety system based on thousands of smoking holes. Then applied the lessons to the design. We are now solving problems that typically take 10,000 hours to break. Now that hundreds of planes don't pile themselves into the ground every year, and we can go half a decade between times an airliner does this (in the continental North America, mind you) then fewer and fewer people in industry and government actually know what an accident looks like.

I've touched and examined the wreckage of several crashed aircraft. Have you? Have your colleagues?

Those of you who said yes to my questions above, check your birth certificate because it's probably printed before 1980.

The subject engines won't ground all the NEO's until 2026. The engines will just be rotated out of service with others that presumably don't have the problem. Each plane will be grounded for a weekend - some airliners can have an engine swap done in one shift! (I don't know if the Neos are like this).

So to the OP, I answered your question, but I don't think a pro-active correction to a manufacturing defect is a sign of something "wrong with our industry". The OEM's of aircraft and engines publish MANY MANY service bulletins every year for problematic things in their products. Singling out one issue is like finding one sick tree in a forest and condemning the whole forest.

 

[MintJulep]

The subject engines won't ground all the NEO's until 2026. The engines will just be rotated out of service with others that presumably don't have the problem. Each plane will be grounded for a weekend - some airliners can have an engine swap done in one shift! (I don't know if the Neos are like this).

It's possible to change an engine in a shift. But only if there is a new engine to install, and at the moment it seems that there will be a shortage of known-good engines to install.

Remember that a big selling point of the GTW was its reliability. As a result, the population of spare engines is small as compared to other engines. Oh by the way, the spare population is also at risk.

According to this article

https://www.reuters.com/business/ae...3-pratt-whitney-gtf-engine-issues-2023-09-11/

RTX is now saying that the repair of a confirmed bad engine will take 300 days!

The same article states "An average of 350 jets could be grounded per year through 2026, with as many as 650 jets sitting idle in the first half of 2024."

I suspect that a part of how this happened will be "paper mitigations" of process risks that were not implemented, or not implementable, or never passed down to the people that would implement them.

Recall thread815-498902

 

[rb1957]

"I suspect that a part of how this happened will be "paper mitigations" of process risks that were not implemented, or not implementable, or never passed down to the people that would implement them." ... I guess I was foolish (at least naive) in thinking that all these SSAs and FHAs and FMEAs helped the situation ?


"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[IRstuff]

They only help if someone bothers to read. Typically, TLDR

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[rb1957]

Sure the SSA is typically WTL ! but the resulting actions should be presented to the operator in an MMS (or ICA) so that it is a simple maintenance action.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

[MintJulep]

I guess I was foolish (at least naive) in thinking that all these SSAs and FHAs and FMEAs helped the situation ?

Don't take me wrong. They do help, as evidenced by the successes cited by Sparweb earlier. But there is always room for improvement.

@rb1957: earlier in this thread you asked: "how did the production QA get defeated so badly (in so many different areas) ?"

The following is my speculation, based on fragments gathered from various public sources:

The defects of concern are detectable. RTX is confident that current production is unaffected; presumably because they now know what to look for and how to look for it. They have an inspection plan for the population in the field that can find defective parts.

But during the production period where the suspect parts were released, the defects were not found. Because they were not using the correct technology or scan parameters during final inspection.

Possibly the process FMECA identified the need for UT of the finished hubs, but was not specific enough to identify the types of defects to look for, or the technology and parameters necessary to find them.

The QA/QC team looked and said "yeah, yeah, we'll do UT" and checked the box. The "closure checkers" possibly don't know enough about NDT to ask "what type of UT?", and checked the box.

That's how production QA gets defeated. "Paper mitigations".

See the reference to "angled scan" in this article

https://airinsight.com/pratt-whitney-gtf-update/

I'd guess this means phased array UT vs single-scan UT.

 

[3DDave]

Or the nature of the defect is as a nucleation site 0.0001 inches or less across and is only a problem because it is the wrong alloy, remaining undetectible until after a significant amount of time and temperature. Imagine dealing with passivization of stainless steel by finding and removing individual iron particles.

 

[RoarkS]

As I'm literally reading about iron inclusions in SLS HP turbine blades on ALL 777 engine options.

how did the production QA get defeated so badly (in so many different areas) ?
--My answer: Sapa Aluminum Portland Oregon.

TOO MANY MBA types... OMG yes. I just quit what will probably be my last Aerospace engineering job... at least for the foreseeable future. I'm happy teaching for the time being... Health and retirement benefits are stunning. Literally our engineering progress meetings went from discussing how to handle various engineering hurdles to EBITDA margins and how late we were paying vendors because nobody could sign a check. I care about Alloys, bolts. rivets, Coatings. Bearings. O-ring grooves. Testing. Manufacturability. That is how to make me not care. I wish I cared. I really do. I'd do almost anything to care... but it might as well have been a brick wall.

 

[rb1957]

RoarkS ... you and Will must get on like a house on fire !

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.