Boeing 737 NG Pickle Fork issues

Irish Steve

In view of the increasing level of discussion about what is a separate issue to the MAX MCAS issues, I have split some messages out of the 737 MAX thread, and merged those messages into an earlier existing thread, and hope that all involved will use this thread to continue the discussion about the NG issue


The following link was posted earlier on AV Herald, and refers to an article that's been published about some unexpected cracking being found in 737NG family aircraft, which of course relates to the Ryanair Fleet.

I hope this is not going to cause even more problems than are already happening. I would have to admit to more than a little nervousness right now, given the issues that are already ongoing with the MAX issues, hopefully, this new issue will receive the attention that it needs to ensure ongoing safety.

https://komonews.com/news/local/exclusive-unexpected-cracking-found-on-critical-boeing-737ng-equipment

dogmatix

According to the BBC link, the FAA are implying it is only on "heavily used" NG's. Which probably would apply to Ryanair aircraft?

It never rains but it pours as they say. Hopefully this will just be an isolated incident with a few planes.

https://www.bbc.com/news/world-us-canada-49864964

Irish Steve

Heavily used in this respect is probably high cycles, which will be true for a lot of Ryanair frames. My own thoughts are that the problem may be being compounded by the requirement that seems to be SOP of firm landings, which are necessary on the 800 series in particular to avoid the tail strike problems, there's not much margin between the landing speed and the speed at which there is a risk of a tail strike due to increased flare, so the resolution I've heard suggested is to not be too concerned if the arrival is "positive", the important issue seems to be to make sure that the speed does not bleed off while trying to make it smooth.

goingnowhere

Ryanair tends to sell on its fleet after a few years so is unlikely to be in trouble (but those who bought those frames could be), its the carriers who buy new and use till the frame reaches end of its life, say Southwest and most mainline US carriers they may have a problem

Irish Steve

Seems that the affected first airframe has around 36,000 cycles, which is less than half of the expected life of a 737, based on the highest number recorded so far, and a quick check on the potential yearly cycles suggests that it would take a Ryanair aircraft about 18 years to reach that number, based on 6 sectors a day and 50 weeks a year flying. On that basis, they will probably have been moved on before the pickle fork issue becomes an issue, but until we have more details about exactly what's going on, we don't have enough to be get better clarity. We don't know if there have been any design changes over time to the affected component, it's altogether possible that there was some sort of change to the manufacturing process, or to the material quality that in theory didn't affect the projected life of the component, but maybe they missed something in those evaluations, which is now coming home to roost.

Either way, the one good thing to come out of this latest report is that Boeing have been up front about it, and are not looking to hide what's happening, which is good.

Irish Steve

Quote from a report carried this evening on AV Herald.

The FAA have issued Airworthiness Directive AD-2019-20-02 requiring repetitive inspections of the so called "pickle forks", a suspension system for wing-fuselage mounts, for all The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes.

The FAA reports: "In September 2019, the FAA received reports of cracking discovered in the left and right hand side outboard chords of the station (STA) 663.75 frame fittings and failsafe straps adjacent to the stringer S-18A straps on multiple Boeing Model 737-800 airplanes during a passenger-to-freighter conversion. The affected airplanes had accumulated between 35,578 and 37,329 total flight cycles. Cracking in the STA 663.75 frame fitting outboard chords and failsafe straps adjacent to the stringer S-18A straps, if not addressed, could result in failure of a Principal Structural Element (PSE) to sustain limit load. This condition could adversely affect the structural integrity of the airplane and result in loss of control of the airplane."

The FAA stated: "This AD requires repetitive inspections for cracking of the left and right hand side outboard chords of the STA 663.75 frame fittings and failsafe straps adjacent to the stringer S-18A straps. This AD also requires repair of all cracking using a method approved by the FAA or The Boeing Company Organization Designation Authorization (ODA). This AD also requires sending a report of all results of the initial inspection to Boeing."

The AD is currently considered interim action.

L1011

If this is widespread it'll push down resale / later lease values due to the further inspections and potential repair costs and that will impact on airlines that only have younger ones

Irish Steve

Just looked at the AD, the work to do it is minor, one hour inspection, and one hour for the paperwork, but the sting in the tail is that if cracking is found, the aircraft is grounded until repaired, and if I read it correctly, there is not yet a repair scheme in place to deal with the issue. Depending on the outcome of the inspections, this could hurt some operators.

An aircraft with more than 30,000 cycles has to be inspected within 7 days, if above 22600 cycles, within the next 1000 cycles, so the higher time airframes are being looked at with a significant degree of urgency, and if cracks are found, they're on the ground. The inspection is to be repeated every 3500 cycles, so not massively onerous there.

I wonder how many of them will be grounded, the implication of the initial report is that several examples have been found already, there are nearly 2000 US aircraft that have to be inspected, and the AD applies to all 737 600, 700, 800, and 900 series airframes.

L1011

Leeham saying 5% of inspected frames have the issue. That's sufficient that inspection is going to have to be retained as a regular event.

Irish Steve

From a friend who's doing one of these inspections this week, the actual inspection, while tedious, as it needs a boroscope to see the affected area, is the easy bit. Getting the necessary repair parts designed, manufactured and approved will be a challenge, but the real issue will be the procedure for fitting the new parts, it's going to need some complex jigs to keep everything in position while the old parts are removed and the new ones fitted, it will very definitely not be a "quick" fix in terms of time and cost.

5% of the US fleet of 2000 means that there are 100 frames to be dealt with there, and at present, the AD requires them to be grounded if above 30K cycles, so that is going to have a significant effect on schedules, utilisation and second hand values. The worldwide fleet is just over 7000 frames, so there's going to be a lot of work to be done if the numbers stay at that percentage.

Irish Steve

Rawr wrote: »

True. Makes you wonder though if operators like these guys have started to consider any kind of "Plan B".

Considering a possible nightmare situation where the Max has to be scrapped (unlikely, but you never know); could they ever consider swapping to A320s or would the plan be to run the NGs longer than they normally would until Boeing come up with some kind of 737 successor?

The possibly worse scenario is that the operators may not be able to continue using the NG's as a result of the pickle fork issue that's also been reported, and affecting higher usage frames, and at present, that issue is at present unresolved, and results in the grounding of affected airframes.

Depending on the cost, complexity and timescale of the eventual fix for the NG's, a number of airlines could find themselves with increasingly reduced NG fleets, with no replacement available from Boeing as a result of the other issues with the NG.

The NG issues may well take a lot longer to resolve, and if the pickle fork issue is also likely to affect the MAX airframe, that could result in a massive redesign of the MAX to design it out of the product.

The Boeing problems are far from resolved, and there is no quick or easy resolution available from any other manufacturer, not in the short term, or even in the medium term, as the logistics of gearing up production of any line is not even close to quick.

I suspect that there are a lot of very worried people all over Boeing right now.

Hotblack Desiato

Southwest are in a tricky situation if the pickle fork issue gets bad and there's no return of the Mac Max on the horizon.

Ryanair Group have Airbus fleets so in theory can expand them with leases, but lease prices will be going up across the board!

Storm 10

Hotblack Desiato wrote: »

Southwest are in a tricky situation if the pickle fork issue gets bad and there's no return of the Mac Max on the horizon.

Ryanair Group have Airbus fleets so in theory can expand them with leases, but lease prices will be going up across the board!

On the radio this morning they said Ryanair could not go for Airbus as all their maintenance is Boeing, how could they manage if aircraft suffer technical issues and only Boeing trained people available .

Hotblack Desiato

Ryanair != Ryanair Group

cnocbui

Storm 10 wrote: »

On the radio this morning they said Ryanair could not go for Airbus as all their maintenance is Boeing, how could they manage if aircraft suffer technical issues and only Boeing trained people available .

Translation: 'could not' = we would have to spend some money.

banie01

Hotblack Desiato wrote: »

Southwest are in a tricky situation if the pickle fork issue gets bad and there's no return of the Mac Max on the horizon.

Ryanair Group have Airbus fleets so in theory can expand them with leases, but lease prices will be going up across the board!

There's also the issue of either hiring Airbus certified pilots and letting go the current Boeing only ratings.
Or retraining and certifying all their current pilots with the concurrent knock on in pilot availability and scheduling.
On retraining Maintenance techs or negotiating new service providers.

The Max's main selling point to many airlines was minimal training cost or downtime to retrain NG rated pilots.

The airframe itself is not fit for purpose and is certification is attempted without its being grandfathered under a 737 designation.

Boeing could possibly ramp up NG production and hope cheap lease or deep discounting will offset Airlines shifting supplier.
But, couple fuel cost with the public perception of the older design being less Green and it becomes another way for Boeing to burn cash.

That there is no real capacity for new or urgent orders available at Airbus is a godsend for Boeing IMO.

L1011

NG production has officially ended, only the KLM mistake frame (and some military varients) is left to be made. Would be slightly embarrassing to resume sales and production

banie01

L1011 wrote: »

NG production has officially ended, only the KLM mistake frame (and some military varients) is left to be made. Would be slightly embarrassing to resume sales and production

Oh I know the civil production has ended.
I was merely musing on a likely contingency that Boeing may consider to ensure that they can keep customers flying.

TomSweeney

https://www.bbc.com/news/world-australia-50244699
Qantas grounding one of it's 737 NG planes, are the NG 737-800s ?

Or is it another name for the MAX?

Inquitus

TomSweeney wrote: »

https://www.bbc.com/news/world-australia-50244699
Qantas grounding one of it's 737 NG planes, are the NG 737-800s ?

Or is it another name for the MAX?

No its the previous version and it had the cracks at 27,000 cycles when boeing only recommends checking after 30,000 cycles.

Rawr

TomSweeney wrote: »

https://www.bbc.com/news/world-australia-50244699
Qantas grounding one of it's 737 NG planes, are the NG 737-800s ?

Or is it another name for the MAX?

NG or Next Generation is a whole sub-set of 737s.

I think thery started with the 737-600, then introduced the 737-700 & 737-800 (The Ryanair workhorse) and finally the longer 737-900.

Anything earlier than NG might be referred to as 737 Classic, and the MAX is the newest 737 variant but is not part of the NG family.

TomSweeney

Do Ryanair have any NGs?
Or are they still using -800s only ?

Inquitus

TomSweeney wrote: »

Do Ryanair have any NGs?
Or are they still using -800s only ?

From here

Ryanair operates a fleet of over 450 Boeing 737-800 series aircraft, with orders of up to 210 new Boeing 737 aircraft, this includes 135 new Boeing 737 MAX 200s, and options for 75 more MAX 200s, which will enable Ryanair to grow its fleet to 585 by 2024, further lower its fares and grow traffic from 142m customers last year to 200m p.a. in 2024. The average age of the Ryanair fleet is approximately 6.5 years, and is set to get younger with the latest aircraft order.

Aircraft In service Orders Passengers Notes
Boeing 737-700 1 — 149 Used for training and as a replacement aircraft.
Boeing 737-800 418 — 189 Largest Boeing 737-800 operator
Boeing 737 MAX 200 — 135 197
Total 419 135

Captain_Crash

TomSweeney wrote: »

Do Ryanair have any NGs?
Or are they still using -800s only ?

The 737-600/700/800/900 series is the 737NG, so all of Ryanair's fleet including the sole 700 they have are NG's

cnocbui

Qantas have found a couple cracked 737s and there are calls by some suggesting they ground the whole fleet.

STB.

TomSweeney wrote: »

Do Ryanair have any NGs?
Or are they still using -800s only ?

RyanAir have about 420 NG's. Average age is 8 years. Thought I saw something about 2 recently returned to Seattle by them for this reason.

This issue now with the NG series is what the expose on Boeing broadcast many years ago warned of.

The main structural parts (bear straps and chords) were meant to be computer designed and assembled using ATA (and were accordingly certified for higher gross weight and alt). Following problems reported by Boeing assemblers, they went into the people contracted to make these parts (Ducommun) and discovered lads with angle grinders. Boeing management buried the whole thing. Its posted earlier in this thread. The QA mannager left and they took a court case. That was also buried when heard ten years later. There is a documentary on it (here). Tip of the iceberg stuff.

Here is the email sent to all its customers at the end of September by Boeing, with pictures of the problems etc

Interesting that Ryanair claim that it wont affect them. How can they be so sure ? Quantas are looking at anything over 22k cycles. Anyone got an idea of average cycles per year on FR?

Here is Ryanair's fleet in detail including year of delivery. Whilst they say the average is 8 years. There are are a lot of planes in the fleet that are 17 years old.

https://www.airfleets.net/flottecie/Ryanair-active-b737ng.htm

Blut2

Google is telling me the average for an airline airframe is approx 1200 cycles per year. I'd assume FR work their aircraft significantly harder than "average" though, given their more efficient routes/timings/general operations. Someone with more knowledge than me can probably answer - given that, would 1600~ cycles p.a. be a reasonable estimation for FR?

If so, and anything over 22k is a problem, they're probably going to have to do some checking on their older planes.

STB.

@Blut if that is the case, at the rates you have quoted and adopting what Qantas has implemented in investigating those with a lifetime over 22k cycles (apx 13.75 years @ 1600 cycle pa) then RyanAir need to be looking least at apx 70 of their planes (or one sixth of their fleet using 2006 as a cut off).

These ones.

29938 1240 737-8AS 02/12/2002 EI-DAC
33544 1249 737-8AS 03/12/2002 EI-DAD Stored 10/2010 to 11/2010
33545 1252 737-8AS 09/12/2002 EI-DAE Stored 10/2010 to 11/2010
29939 1262 737-8AS 09/01/2003 EI-DAF
29940 1265 737-8AS 17/01/2003 EI-DAG
33546 1269 737-8AS 22/01/2003 EI-DAH
33547 1271 737-8AS 03/02/2003 EI-DAI
33548 1274 737-8AS 04/02/2003 EI-DAJ
33717 1310 737-8AS 18/04/2003 EI-DAK
33718 1311 737-8AS 22/04/2003 EI-DAL
33719 1312 737-8AS 23/04/2003 EI-DAM
33549 1361 737-8AS 02/09/2003 EI-DAN
33550 1366 737-8AS 06/09/2003 EI-DAO
33553 1372 737-8AS 12/09/2003 EI-DAS
33552 1371 737-8AS 13/09/2003 EI-DAR
33551 1368 737-8AS 19/09/2003 EI-DAP
33804 1529 737-8AS 01/07/2004 EI-DCF
33805 1530 737-8AS 02/07/2004 EI-DCG
33566 1546 737-8AS 03/08/2004 EI-DCH
33567 1547 737-8AS 03/08/2004 EI-DCI
33564 1562 737-8AS 01/09/2004 EI-DCJ
33565 1563 737-8AS 01/09/2004 EI-DCK
33807 1578 737-8AS 02/10/2004 EI-DCM
33808 1590 737-8AS 01/11/2004 EI-DCN
33809 1592 737-8AS 01/11/2004 EI-DCO
33810 1595 737-8AS 01/11/2004 EI-DCP
33811 1613 737-8AS 02/12/2004 EI-DCR
33568 1631 737-8AS 14/01/2005 EI-DCW
33569 1635 737-8AS 21/01/2005 EI-DCX
33570 1637 737-8AS 26/01/2005 EI-DCY
33815 1639 737-8AS 26/01/2005 EI-DCZ
33571 1642 737-8AS 02/02/2005 EI-DHA
33573 1655 737-8AS 17/02/2005 EI-DHC
33572 1652 737-8AS 23/02/2005 EI-DHB
33816 1657 737-8AS 26/02/2005 EI-DHD 23/12/09 : Skidded off icy taxiway at Glasgow Preswick airport, United Kingdom.
33574 1658 737-8AS 03/03/2005 EI-DHE
33575 1660 737-8AS 06/03/2005 EI-DHF
33576 1670 737-8AS 18/03/2005 EI-DHG
33817 1677 737-8AS 15/04/2005 EI-DHH
33577 1782 737-8AS 01/09/2005 EI-DHN
33578 1792 737-8AS 14/10/2005 EI-DHO
33579 1794 737-8AS 21/10/2005 EI-DHP
33822 1798 737-8AS 25/10/2005 EI-DHR
33580 1807 737-8AS 07/11/2005 EI-DHS
33581 1809 737-8AS 14/11/2005 EI-DHT
33582 1811 737-8AS 14/11/2005 EI-DHV
33823 1819 737-8AS 26/11/2005 EI-DHW
33585 1824 737-8AS 06/12/2005 EI-DHX
33824 1826 737-8AS 08/12/2005 EI-DHY
33583 1834 737-8AS 19/12/2005 EI-DHZ
33584 1836 737-8AS 19/12/2005 EI-DLB
33586 1844 737-8AS 13/01/2006 EI-DLC
33825 1847 737-8AS 13/01/2006 EI-DLD
33587 1864 737-8AS 09/02/2006 EI-DLE
33589 1869 737-8AS 14/02/2006 EI-DLG
33588 1867 737-8AS 14/02/2006 EI-DLF
33590 1886 737-8AS 06/03/2006 EI-DLH
33591 1894 737-8AS 22/03/2006 EI-DLI
34177 1899 737-8AS 28/03/2006 EI-DLJ
33592 1904 737-8AS 29/03/2006 EI-DLK
33595 1926 737-8AS 24/04/2006 EI-DLN
34178 1929 737-8AS 25/04/2006 EI-DLO
33596 2057 737-8AS 25/09/2006 EI-DLR
33598 2063 737-8AS 01/10/2006 EI-DLV
33599 2078 737-8AS 17/10/2006 EI-DLW
33600 2082 737-8AS 18/10/2006 EI-DLX
33601 2088 737-8AS 26/10/2006 EI-DLY
33603 2112 737-8AS 21/11/2006 EI-DPB
33623 2123 737-8AS 06/12/2006 EI-DPD
33604 2120 737-8AS 06/12/2006 EI-DPC

STB.

Interestingly, two ryanair planes went to Boeing in Seattle on 26th October and remain there. One 15, the other 16 years old.

https://planefinder.net/data/aircraft/EI-DAL

https://planefinder.net/data/aircraft/EI-DCL


That seems to be where the repairs are being carried out in the US for affected planes.


Are RyanAir playing down possible disruptions ?

Hotblack Desiato

Would it be correct to presume that Boeing are going to have to contribute towards the cost of replacing a major structural part this far in advance of its design life?

STB.

Hotblack Desiato wrote: »

Would it be correct to presume that Boeing are going to have to contribute towards the cost of replacing a major structural part this far in advance of its design life?

275,000 dollars per plane......

2/3 weeks to repair one......

Can you see where this is going ?

I think Boeing know they are going to have to set up a European repair centre. I just hope that Ryan Air do the right thing here. Assuming the cycle calcs above are correct - Are they willing to inspect that many planes, and how long would they be out of commission for these inspections ? And what if they discover its prevalent more in their fleet ???

Everyday those planes are in the air, the more stress can be put on what is meant to be a practicably indestructible part.