Hello all,

Today, Japan has ordered ANA and JAL to ground their fleets of 777 fitted with PW4000 engines following the UA328 incident.

https://www.japantimes.co.jp/news/2021/ ... ets-japan/
https://www.bloomberg.com/news/articles ... et-failure
https://japantoday.com/category/busines ... her-notice

Have any other countries or airlines grounded / planning to ground fleets fitted with PW4000 engines?

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

What would cause the failure of a turbine blade ? The composite material ? Or the EDM'ed cooling holes ? Or something else, perhaps ??

Timing wise, pretty easy for the airlines to ground these I would guess. So many other parked planes they can use.

Seems like an overreaction to me, the engine/airframe combination has significant history.

zeke wrote:

Seems like an overreaction to me, the engine/airframe combination has significant history.

True, especially with range of mission profiles - long, medium and short haul. The motors on the Japanese frames are doing three to six legs a day...or were before COVID.

Potentially silly question, but what is the model split? I presume most are 772s, but are there any 77Es and/or 773s as well?

Google fu is failing me.

UA has grounded 24 ships as well.

Man, PW4000 has given operators so much grief over the years on larger frames.... no wonder neither Boeing nor Airbus has allowed a PW-only powerplant on new widebody design, in 24yrs+

dik909 wrote:

What would cause the failure of a turbine blade ? The composite material ? Or the EDM'ed cooling holes ? Or something else, perhaps ??

IIRC the PW4077 engine uses hollow titanium blades, not composite. So it is possible that there is some metal fatigue or cracks in the blade. Bird strikes should also not be ruled out at this stage of the investigation.

TC957 wrote:

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

I know these motors are attached to Boeing product, but would it be considered more a P&W issue or are OEM's happy to remain relatively anonymous to the travelling public at large, in terms of how these incidents are reported in the media ?

In other words does Boeing deflect the flak (no pun intended) or roll with it ?

JannEejit wrote:

TC957 wrote:

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

I know these motors are attached to Boeing product, but would it be considered more a P&W issue or are OEM's happy to remain relatively anonymous to the travelling public at large, in terms of how these incidents are reported in the media ?

In other words does Boeing deflect the flak (no pun intended) or roll with it ?

Boeing is already actively involved (with the NTSB) in the investigation. I don't think they will wash their hands off the incident and leave PW to take all the responsibility. It is similar to when Airbus and PW had to deal with all the GTF engine issues in the past few years.

LAX772LR wrote:

UA has grounded 24 ships as well.

Man, PW4000 has given operators so much grief over the years on larger frames.... no wonder neither Boeing nor Airbus has allowed a PW-only powerplant on new widebody design, in 24yrs+

United had 24 flying and another 28 x PW powered B772 already parked. Looking at JAL, ANA and Asiana should be another 49 aircraft (B772/773).

After the first United incident, over the Pacific en route to Hawai in 2018, all the PW engines should be inspected for possible cracks in the fan blades. JAL incident happen in December 2020 and now this with United again in February 2021 and in all of them the blade that fails shows similar pattern (just saying this from looking at pictures from the different cases). The inspections should all already be done after the 2018 incident so they didn't catch the possible cracks?

How are the fan blades inspected? Is it done visually, using ultrasound, xrays or some other technique?

https://www.bbc.co.uk/news/world-us-canada-56149894 Says that Boeing recommended the grounding

"While [an] investigation is ongoing, we recommended suspending operations of the 69 in-service and 59 in-storage 777 aircraft powered by Pratt & Whitney 4000-112 engines," the company said in a statement.

Given the relatively low impact of the grounding and the PR situation, I don't think that's a surprising conclusion to make, makes it seem more likely that it wasn't a bird strike, or some other obvious "normal" flaw.

JibberJim wrote:

https://www.bbc.co.uk/news/world-us-canada-56149894 Says that Boeing recommended the grounding

"While [an] investigation is ongoing, we recommended suspending operations of the 69 in-service and 59 in-storage 777 aircraft powered by Pratt & Whitney 4000-112 engines," the company said in a statement.

Given the relatively low impact of the grounding and the PR situation, I don't think that's a surprising conclusion to make, makes it seem more likely that it wasn't a bird strike, or some other obvious "normal" flaw.

The most interesting thing about that BBC article about a Pratt and Witney engine failure is that it links to two stories about the 737 Max saga..

LAX772LR wrote:

UA has grounded 24 ships as well.

Man, PW4000 has given operators so much grief over the years on larger frames.... no wonder neither Boeing nor Airbus has allowed a PW-only powerplant on new widebody design, in 24yrs+

Their narrowbody engines hasn't been smooth sailing either. Who knows we may see the same thing on the GTF A320neos 20 years later?

journeyperson wrote:

The most interesting thing about that BBC article about a Pratt and Witney engine failure is that it links to two stories about the 737 Max saga..

That's purely down to an algorithm that links "similar" stories together.

JannEejit wrote:

journeyperson wrote:

The most interesting thing about that BBC article about a Pratt and Witney engine failure is that it links to two stories about the 737 Max saga..

That's purely down to an algorithm that links "similar" stories together.

No, that's in an editorially chosen part, the algorithm links are the original news report of the engine and the Indonesian crash, but the writer of the article did choose to put that bit about the 737 and the links in.

The Longtail 744 involved in the recent incident had PW4000-series engines. Did this play a part in the 777 PW4000 grounding?
https://www.theguardian.com/business/2021/feb/22/dutch-investigate-boeing-747-after-engine-parts-drop-after-takeoff-netherlands

hotelbravo wrote:

The Longtail 744 involved in the recent incident had PW4000-series engines. Did this play a part in the 777 PW4000 grounding?
https://www.theguardian.com/business/2021/feb/22/dutch-investigate-boeing-747-after-engine-parts-drop-after-takeoff-netherlands

No, the 777 uses the PW4000 112-inch fan, and the 747/767 use the 94-inch. Same family, different models.

flee wrote:

How are the fan blades inspected? Is it done visually, using ultrasound, xrays or some other technique?

P&W uses a fluorescent penetrant inspection, and thermal acoustic imaging inspection. The latter is proprietary.

Can read more about it in the UA 1175 NTSB report here:

https://data.ntsb.gov/Docket/?NTSBNumber=DCA18IA092

Looks like 3 blade failure incidents in 3 years (UA approaching HNL in 2018, JL leaving Okinawa in 2020, UA leaving DEN in 2021) from a fleet of 70 or so relevant 777s. That's about a 5% rate, I can understand the rationale for a grounding.

GCT64 wrote:

Looks like 3 blade failure incidents in 3 years (UA approaching HNL in 2018, JL leaving Okinawa in 2020, UA leaving DEN in 2021) from a fleet of 70 or so relevant 777s. That's about a 5% rate, I can understand the rationale for a grounding.

That’s only a ~5% rate if those 777s only flew a total of ~70 flights in the past 3 years.

GCT64 wrote:

Looks like 3 blade failure incidents in 3 years (UA approaching HNL in 2018, JL leaving Okinawa in 2020, UA leaving DEN in 2021) from a fleet of 70 or so relevant 777s. That's about a 5% rate, I can understand the rationale for a grounding.

How in the world did you arrive at that figure? Each frame is operating .33 times a year?

I clearly didn't mean 5% rate on each flight - obviously!! I'm not an idiot.
I meant 5% of the fleet have had a failure in the last 3 years.

Polot wrote:

GCT64 wrote:

Looks like 3 blade failure incidents in 3 years (UA approaching HNL in 2018, JL leaving Okinawa in 2020, UA leaving DEN in 2021) from a fleet of 70 or so relevant 777s. That's about a 5% rate, I can understand the rationale for a grounding.

That’s only a ~5% rate if those 777s only flew a total of ~70 flights in the past 3 years.

If these three accident are related (all are fanblade failures) than the ifsd rate is unacceptable high
Seen the presently very low usage of this engine/aircaft combination I can understand a temporally grounding

Opus99 wrote:

TC957 wrote:

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

Is it really trouble for them?
In cases like this what are they supposed to do. I understand liaise with the OEM. But they stopped building this jet almost 20 years ago so I’m not sure if this will add to the pile of problems

It's not trouble at all. Other than just bad press and that will die out.

PW on the other hand...

Antarius wrote:

Opus99 wrote:

TC957 wrote:

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

Is it really trouble for them?
In cases like this what are they supposed to do. I understand liaise with the OEM. But they stopped building this jet almost 20 years ago so I’m not sure if this will add to the pile of problems

It's not trouble at all. Other than just bad press and that will die out.

PW on the other hand...

I assume 20 year old engines are not under any warranty by now. Would be interesting to see hours/major rebuilds data on these engines, especially fan blades.
End-of-life fatigue is not a totally unexpected problem...

kalvado wrote:

Antarius wrote:

Opus99 wrote:

Is it really trouble for them?
In cases like this what are they supposed to do. I understand liaise with the OEM. But they stopped building this jet almost 20 years ago so I’m not sure if this will add to the pile of problems

It's not trouble at all. Other than just bad press and that will die out.

PW on the other hand...

I assume 20 year old engines are not under any warranty by now. Would be interesting to see hours/major rebuilds data on these engines, especially fan blades.
End-of-life fatigue is not a totally unexpected problem...

Not necessarily warranty, but it will use PW's time and resources to investigate and mitigate. Additionally, these engines must be under the expected service life.

Antarius wrote:

kalvado wrote:

Antarius wrote:

It's not trouble at all. Other than just bad press and that will die out.

PW on the other hand...

I assume 20 year old engines are not under any warranty by now. Would be interesting to see hours/major rebuilds data on these engines, especially fan blades.
End-of-life fatigue is not a totally unexpected problem...

Not necessarily warranty, but it will use PW's time and resources to investigate and mitigate. Additionally, these engines must be under the expected service life.

Plus PW would probably want to look at the other PW4000 series engines on 747s and A330s, especially since there was a 744 that had an engine blade fall from the sky on the same day.

UK grounds them too.
https://www-standard-co-uk.cdn.ampproje ... m=referral

That's the beauty about traceability! Each engine has/had an inspection. Some would of been rebuilt with new blades, each blade should have a service start date technically so you can track the no. of days vs flight hours.

My question is, did all 3 failures happen at the same stage of a flight? 2 happened just after take off correct? What about the third?

wrt to PW4K on 777s, they're pushing the limits of the core anyway (i heard that they're smaller than a JT9), so eventually this things is gonna happen sometime.

pugman211 wrote:

That's the beauty about traceability! Each engine has/had an inspection. Some would of been rebuilt with new blades, each blade should have a service start date technically so you can track the no. of days vs flight hours.

My question is, did all 3 failures happen at the same stage of a flight? 2 happened just after take off correct? What about the third?

UA328 in 2018 was cruising at FL360
JA8978 in 2020 was climbing and stopped at FL190
UA1175 in 2021 was climbing and stopped at FL130

pugman211 wrote:

That's the beauty about traceability! Each engine has/had an inspection. Some would of been rebuilt with new blades, each blade should have a service start date technically so you can track the no. of days vs flight hours.

My question is, did all 3 failures happen at the same stage of a flight? 2 happened just after take off correct? What about the third?

The JAL incident was 40 minutes after takeoff I believe. So different stage

TC957 wrote:

Yet more trouble for Boeing. I'm surprise there are ( were ) as many as 69 of these elderly 772's still in service.

How is this more trouble for Boeing? I would think PW is more in trouble than Boeing.

Boeing has called for the ground of all PW powered 777.
https://www.msn.com/en-us/news/us/boein ... li=BBorjTa

Gees guys do you remember the RR Trent issues on the 787 and the hell that RR went through on this channel over the past three years? And PW with the GTF? Those discussions were over new engine technology. Are we in for a repeat with PW on this one? I hope not. Don't we - surely - need to keep in mind history, and the big picture? These 777 birds are hardly young; indeed among the first off the block 1995/96 indeed! Don't know about the age/cycles on the engines though which obviously will be younger than the airframes. But this is proven tech that has been in service for 24 years. Fatigue is always an issue at some point and as we have become increasingly aware - manufacturing faults too. If I am not mistaken this has affected all 3 big manufacturers?

Who remembers just 2 months ago. https://www.flightglobal.com/safety/jal ... 74.article

Was Boeing /FAA take initiative to ground this sub fleet, or did they after the Japanse authorities did so?

keesje wrote:

Who remembers just 2 months ago. https://www.flightglobal.com/safety/jal ... 74.article

Was Boeing /FAA take initiative to ground this sub fleet, or did they after the Japanese authorities did so?

This is more the question in my opinion - hence the Japan groundings....

Just as BA didn't choose P&W.

Could this problem extend to other planes fitted with the PW4000? (767, 744, A330, A340, MD-11)?

Antarius wrote:

kalvado wrote:

Antarius wrote:

It's not trouble at all. Other than just bad press and that will die out.

PW on the other hand...

I assume 20 year old engines are not under any warranty by now. Would be interesting to see hours/major rebuilds data on these engines, especially fan blades.
End-of-life fatigue is not a totally unexpected problem...

Not necessarily warranty, but it will use PW's time and resources to investigate and mitigate. Additionally, these engines must be under the expected service life.

Yep, and given how few and old these aircraft are coupled with the crappy resale market post-COVID, I'd expect that any fix that is more than additional/different inspections of the engine will be shelved in favor of PW and/or buying back the planes at fair market value (the price the airline would get for the frames if there wasn't an issue), potentially structured as part of a larger Boeing order for some carriers.

Total guess on my part, but I'm betting the inability to douse that fire (and pending investigations as to what may have prevented it), is playing a big part in this sudden rush to ground.

....imagine if that had occurred in an ETOPS diversion, and they'd had to fly like that for 2.5hrs+

AECM wrote:

pugman211 wrote:

That's the beauty about traceability! Each engine has/had an inspection. Some would of been rebuilt with new blades, each blade should have a service start date technically so you can track the no. of days vs flight hours.

My question is, did all 3 failures happen at the same stage of a flight? 2 happened just after take off correct? What about the third?

UA328 in 2018 was cruising at FL360
JA8978 in 2020 was climbing and stopped at FL190
UA1175 in 2021 was climbing and stopped at FL130

Other way around, United 1175 was in 2018 and United 328 was this recent one.

unless I overlooked above, who is operating these right now:

United
ANA
JAL

others? (stored or active)

KAL have 772 & 773 with PW4000

French CAC40 today : -0.03%

Airbus : +4.39%
Safran : +2.45%

LAX772LR wrote:

Total guess on my part, but I'm betting the inability to douse that fire (and pending investigations as to what may have prevented it), is playing a big part in this sudden rush to ground.

....imagine if that had occurred in an ETOPS diversion, and they'd had to fly like that for 2.5hrs+

I'd say that because whatever the actual failure was uncontained is the main reason for the grounding/inspection. When engines are designed, you design them to contain "normal" failures such as blade loss, bird strike, small FOD ingestion, etc. to protect the airframe. The fire was a symptom of the failed containment.

Since we are seeing uncontained failures, it likely means one of two things (assuming design issues):
- The containment is insufficient (though this is tested)
- something is failing that is "not allowed to fail", disk failure, shaft failure, etc. This could also be because the parts aren't lifing as well as expected.

This of course does not cover in possible in service issues with maintenance and/or undetected damage.

The grounding, IMO, is a good call until the investigation finds a smoking gun and puts in place a repair or inspection requirement to mitigate the risk of this same failure happening. The fact that the planes landed safely with the engines mostly intact should make the investigation a bit easier.

The airlines being less busy due to COVID also lessens the blow of the grounding.