Debris Found in Undelivered 737MAx FUEL TANKS

[Longtimer]

737 Max: Debris found in planes' fuel tanks

The head of Boeing's 737 programme has told employees that the discovery was "absolutely unacceptable".

A Boeing spokesman said the company did not see the issue further delaying the jet's return to service.

It comes as the 737 Max remains grounded after two fatal crashes.

The US plane maker said it discovered so-called "Foreign Object Debris" left inside the wing fuel tanks of several undelivered 737 Maxs.

A company spokesman told the BBC: "While conducting maintenance we discovered Foreign Object Debris (FOD) in undelivered 737 Max airplanes currently in storage. That finding led to a robust internal investigation and immediate corrective actions in our production system."

Foreign Object Debris is an industrial term for rags, tools, metal shavings and other materials left behind by workers during the assembly process.

No timescale for 737 Max return, US regulator says (https://www.bbc.com/news/business-51407951)
Boeing reports its first loss in two decades (https://www.bbc.com/news/business-51292698)
Boeing delays 737 Max return date to July (https://www.bbc.com/news/business-51200118)

The revelation is the latest in a string of problems affecting what was once Boeing's best-selling plane.

The aircraft has been grounded by regulators around the world since March 2019.

It was banned from flying after two separate crashes killed 346 people.

737 Max timeline

29 October 2018: A 737 Max 8 operated by Lion Air crashes after leaving Indonesia, killing all 189 people on board
31 January 2019: Boeing reports an order of 5,011 Max planes from 79 customers
10 March 2019: A 737 Max 8 operated by Ethiopian Airlines crashes, killing all 157 people on board
14 March 2019: Boeing grounds entire 737 Max aircraft fleet


The US regulator, the Federal Aviation Administration (FAA), told the BBC that it was monitoring the plane maker's response to the new issue: "The FAA is aware that Boeing is conducting a voluntary inspection of undelivered aircraft for Foreign Object Debris (FOD) as part of the company's ongoing efforts to ensure manufacturing quality.

"The agency increased its surveillance based on initial inspection reports and will take further action based on the findings," it added.

Boeing said it didn't expect the issue to cause any fresh delays to the 737 Max's return to service, which the company said could happen by the middle of this year.

[John4321]

I’m not convinced that this issue would be limited to just the 737 Max production lines. Checks should cover all Boeing aircraft imho.

[Perrin]

I remember working in A/C major overhaul hanger and a customer found a bucking bar used for riveting in a fuel tank,here's the funny part the company told us to stamp our name on all our tools,do you think anyone did that.

[Tony Mabelis]

All newly built aircraft will have a certain amount of debris left behind at construction even after careful cleaning.
When I was being trained back in the 1960's we were told of a case where a loud clonking noise was heard while the integral fuel tanks in a wing were being 'shoshed' with liquid coating.
On investigation a vacuum cleaner was found, having been overlooked when the final skin was riveted in place.
FOD doesn't get much bigger than that!

[DaveReidUK]

All newly built aircraft will have a certain amount of debris left behind at construction even after careful cleaning.

I beg to differ.

[LessThanSte]

The 'absolutely unacceptable' comment did make me smile - that FOD was present, or that someone spotted it? :}

[Lordflasheart]

...
Nothing new for Boeing unfortunately. The problem has migrated from the KC-46. These from a year ago -

https://www.seattletimes.com/business/boeing-aerospace/boeing-tanker-jets-grounded-due-to-tools-and-debris-left-during-manufacturing/

See page 46 - post 906 by ORAC - https://www.pprune.org/military-aviation/550230-more-kc-46a-woes-46.html

...

[Superpilot]

An instructor at Oxford about 13 years ago claimed he was once tasked with investigating a fuel issue (random engine cutout) and found a large piece of carpet inside the wing of a mil jet transport plane.

[Krystal n chips]

Lordflasheart

10691149]..

Actually, it's something that has been going on for a lot longer than the above type.

The initial deliveries of the 767 resulted in a lot of fuel pump failures until the problem was traced to swarf in the fuel tanks notably the centre tank. The Boeing reps we worked with at the time, both a credit to Boeing and themselves, really nice people and very professional engineers, were " somewhat scathing " as to the calibre of those recently hired to build the aircraft.

To be fair, Boeing subsequently imposed a far more intensive QC and inspection regime after which, no more fuel pump failures,

[kontrolor]

Boeing managment should be fired. All of them. And then put on trial. Volkswagen was forced to pay billions of $ becaues of the dieselgate, and Boeing still dodges any kind of formal punishment.

[BDAttitude]

An instructor at Oxford about 13 years ago claimed he was once tasked with investigating a fuel issue (random engine cutout) and found a large piece of carpet inside the wing of a mil jet transport plane.
Sounds more versatile than an issued kneepad. Though unfortuneately not strapped to the owner.

[Perrin]

They should fire the ones who paid airlines to buy their junk.

[possel]

An instructor at Oxford about 13 years ago claimed he was once tasked with investigating a fuel issue (random engine cutout) and found a large piece of carpet inside the wing of a mil jet transport plane.
...On investigation a vacuum cleaner was found, having been overlooked when the final skin was riveted in place. FOD doesn't get much bigger than that!
Yes it does: when I was working on Vulcans many years ago, there was a story that a wooden chair had been found inside a Vulcan wing fuel tank once!

[Twitter]

I remember working in A/C major overhaul hanger and a customer found a bucking bar used for riveting in a fuel tank,here's the funny part the company told us to stamp our name on all our tools,do you think anyone did that.

What is funny about that?

[threep]

It should be impossible for a tool to be left behind. The usual process at the end of a shift change is to make sure that every fitter accounts for every one of their tools. If something is missing, the whole shift has to stay and look for it, and they won't be too thrilled. That's a pretty big incentive to diligently account for all your tools!

That should be the culture when working on aircraft.

[Compton3fox]

Yes it does: when I was working on Vulcans many years ago, there was a story that a wooden chair had been found inside a Vulcan wing fuel tank once!
Thank you possel! I remembered reading that story but had forgotten the details. Made me smile!

[Perrin]

What is funny about that?
I did not mean it to be funny,the company should have had produced safeguards

[anson harris]

The military have something called "tool control". It could refer to people, although I've always assumed it referred to spanners etc.

[V12]

threes

Just as in the med/surgical world: none of us would take too kindly for the scalpel to be left inside after the op. In the past, the medical world has benefited from aviation's practice of confidential reporting. Time for the aviation world to learn from the medical one. Given the potential seriousness of the most minor error, one wonders that any management who didn't enforce accountability of tools, and thorough disposal of FOD, should be able to stay in post. A raft of senior sackings would perhaps go a long way to sorting the problem.

[Maninthebar]

Not at all clear that the world of surgery has this issue locked down. Wikipedia (https://en.wikipedia.org/wiki/Retained_surgical_instruments) (I know, I know) reports that
According to the U.S. Department of Health and Human Services (https://en.wikipedia.org/wiki/U.S._Department_of_Health_and_Human_Services), [the rate of leaving FOD in patients] is anywhere between 1 in 100 to 1 in 5000.[1] (https://en.wikipedia.org/wiki/Retained_surgical_instruments#cite_note-Gibbs-1) However a study done in 2008 reported to the Annals of Surgery (https://en.wikipedia.org/wiki/Annals_of_Surgery) that mistakes in tool and sponge counts happened in 12.5% of surgeries.[8] (https://en.wikipedia.org/wiki/Retained_surgical_instruments#cite_note-Gamble-8) Additionally, the Patient Safety Monitor Alert, announced in 2003 that 1,500 tools were stitched into patients each year.[9] (https://en.wikipedia.org/wiki/Retained_surgical_instruments#cite_note-9) Khaled Sakhel, part of the Department of Obstetrics and Gynecology at the Eastern Virginia Medical School, reported that it is expected to occur at least once “in every 1,000–1,500”[6] (https://en.wikipedia.org/wiki/Retained_surgical_instruments#cite_note-Sakhel-6) stomach surgeries.

[BDAttitude]

One could argue though that human bowels are slightly more cluttered than your average aluminum cavitiy in aviation. Maybe we do also have some surgeons on the forum who can comment ;).

[old,not bold]

Before we all over-fulminate about the debris being found, let's all remember that it was found, and moreover it was found in the course of an inspection made specifically to ensure that any debris would be found.

Having found it, it would be equally a matter of good routine and practice to report it with a view to pre-delivery prevention of debris in fuel tanks in the future. (Boeing MEDA process, for those who know, as copied throughout the industry).

The inspection was/is a capture point designed to make sure that no debris is present, and as such it worked perfectly.

End of story. A more sensational story would have been "Debris not found in B737 fuel tanks before delivery".

Boring, eh?

[Maninthebar]

One could argue though that human bowels are slightly more cluttered than your average aluminum cavitiy in aviation. Maybe we do also have some surgeons on the forum who can comment ;).

The again the size of the FOD relative to the cavity...

[MechEngr]

Keeping the tanks clean from the factory is not enough.
Humorous anecdote - an airplane was being refueled. Got all done and time to unlatch the hose. The handle on the hose shut-off valve would not return to the shut-off position. Because of a mechanical interlock to keep the fuel from pouring out of the hose when it was not coupled to a supply tank or an aircraft, the hose could not be uncoupled without first closing the valve, which could not be done.

Break out the metal cutting saw to slice through the valve, but not before the panicked ground crew tried to pry the hose end from the aircraft, damaging the aircraft severely.

For some reason, known to no one, a meter stick had made its way into that valve when it had been opened, blocking the valve from closing again. Apparently, at some time, the meter stick had been stowed into the hose.

So, on the contract I was working, the requirement was to use fuel connectors that had integral fuel strainers.

[Peter H]

old,not bold

Do you have any more details on that? I've only found mention of "during maintenance".

PS
From: https://www.flightglobal.com/air-transport/boeing-orders-737-max-inspections-after-fuel-tank-fod/136819.article

Boeing has ordered the inspection of all undelivered 737 Maxes, after it found debris in the wing fuel tanks of some of the grounded narrowbodies.

The airframer states that it has also recommended 737 Max customers globally with aircraft in active storage for more than a year to inspect the fuel tank for foreign object debris (FOD).

The company states it first discovered FOD while conducting maintenance on undelivered 737 Maxes in storage at its Renton facility.

That finding led to a robust internal investigation and immediate corrective actions in our production system. We are also inspecting all stored 737 Max airplanes at Boeing to ensure there is no FOD,” the airframer states.

That isn't giving me a warm feeling that the FOD was found by a regular check made on all planes as part of pre-delivery.
I would like to be reassured.

[stormin norman]

On an early 747s first major overhaul, I found nice large chrome Crow bar in the air conditioning bay.
Some things dont change.

[glob99]

threep

... or a pretty big disincentive to account for all tools so everyone can go home and feed the cat.

[meleagertoo]

A number of large black birds drinking beer in a gaudy dive somewhere in the belly then?
Did you report a birdstrike?

[MechEngr]

My wife's former job was civilian US Army helicopter support. One ongoing problem was that tools went missing all the time. To ensure the right tools were used, they were supplied to the mechanics, who had lessened motive to keep track of them. There were repeated efforts to make tool-box inserts with individual recesses for the tools so an inventory at a glance could be done, but it always worked out that there was too much variety and therefore too much cost to manufacture them. So they tried to find a pour-in liquid that would either cool or cure. The best one was a promising proposal that went really well into a number of presentations, until the supplier mentioned that the fumes produced during the process were highly toxic. Yup - no one was going to ship this to thousands of Army mechanics to apply on their own.

The main loss of tools seemed to be simple theft, but you cannot necessarily be sure the mechanic missing the tool is the one stealing the tool.

As a side note, when moving helicopters by ship, they would frequently arrive with various knobs missing from control panels. The initial user claim was that shipping vibration was responsible, but they did some cases with full stretch wrap of the entire helicopter. I guess plastic wrap magically damped those high levels of vibration on the ships because the knobs of those helicopters arrived in place and secure. Sigh.

[SMT Member]

Visited the shop floor of a well-known producer of engine nacelles not long ago, at their final assembly plant where the nacelles are installed on the engines. They had some rather fancy tool cabinets with internal scanners, which meant the assembly workers had to use their electronic badge to "scan out" every single piece of tool they used. When they closed the cabinets up, it would scan the contents and in case a tool was missing, would sound an alarm advising exactly which tool was missing. Until it was located and put back in its correct place, the employee would be unable to badge out from work. They never had a tool go missing after introducing these cabinets.

[nicolai]

There is also this report from April 2019 of debris from fastening swarf up to the size of work lights and ladders being left in 787s made in Charleston:
https://www.nytimes.com/2019/04/20/business/boeing-dreamliner-production-problems.html

This story also says the FAA were not very active in resolving the problems.

[JohnFTEng]

Early 70's on Jaguar flight test one prototype had recurring issues with low fuel pressure and collector box warnings, Eventually traced to a packet of safety matches stuck in pump intake. Centre fuselage was a French section and they were French matches. Quality overall was very good though.

[Mr @ Spotty M]

This is nothing new with the B737, l can recall finding Fod outside of the fuel tanks on the B737-200 series of the B737.

[WOTME?]

When I was at Bruggen in the RAF a Jaguar on a post maintenance test flight went inverted and a 6" 3/8 drive socket extension floated in front of the pilots face.

[old,not bold]

.........
That isn't giving me a warm feeling that the FOD was found by a regular check made on all planes as part of pre-delivery.
I would like to be reassured. Yes, well, it's a point of view; but we can be fairly certain that a mechanic checked the tanks because that task was on a worksheet given to him or her. In other words it was a pre-planned systemic check; whether it was technically "maintenance" is a matter of semantics. The aircraft are in storage, if I understood it correctly, and there will be a maintenance regime in force for that storage, plus another set of tasks to prepare for removal from storage into service. Somewhere in either or both of those regimes there will be a visual internal inspection of fuel tanks. I see that as a capture of something that has gone wrong, which should be reported and put right once the root cause has been established. The important point is that the capture did its job.

We could speculate that two things actually went wrong, and that each one needs its root cause analysis; firstly the debris should never have got into the tank, and secondly I would have thought that as the aircraft left the factory into storage the debris should have been looked for and found in the course of a final quality inspection. After all, in other circumstances it might have gone to a customer and not into storage. To that extent I share your misgivings.

Boeing is probably ahead of us all; see #1 above; "That finding led to a robust internal investigation and immediate corrective actions in our production system." I'd like to think they used the MEDA template, since they've given it to the world, but who knows.

[Ancient Observer]

Concorde fuel tanks

I wonder what happened to all that Kevlar that they put in to Concorde fuel tanks after the Paris crash??

At the time, there was a great video of the fitting, but I can't find it now.

[BDAttitude]

Yep that "Team, ... FOD is absolutely unacceptable ... (no greets) Mark" letter sounded like good kick in the crotch, the stand downs mentioned were for sure fun and more check lists and signage will certainly improve shop floor morale to be more forward looking and proactive.

[Peter H]

old,not bold

Thanks for the reassurance. The term "during maintenance" sparked thoughts of FOD found on a fuel filter triggering a fuller inspection of the tanks.

[discorules]

I recall a certain number of small items being found in the fuel tanks of BA38 the T7 which crashed at LHR in 2008.

Although these were not deemed to have attributed to the cause of the crash, it's certainly an undesirable situation, regardless of whether they were there from delivery or introduced at a subsequent time.

[Maninthebar]

From page 5 of the Final Report



Foreign Object Debris (FOD)

Five loose articles were discovered in the fuel tanks, which otherwise were clean. It was likely that the plastic scraper had been in the aircraft since the aircraft was constructed and as it was trapped beneath the right tank suction inlet, it would not have compromised the fuel feed from this tank. The two pieces of plastic tape and the brown backing paper might have compromised the left main tank water scavenge system; however there is no evidence that this contributed to the accident. Likewise, it was assessed that the small piece of fabric/paper in the guillotine valve of the right OJ pump would have had no effect on the fuel flow from the centre tank.

[tonytales]

tank contamination, whether from swarf from structural repairs, tools or equipment is an old, old story. Back in the fifties they were retrofitting L-1049 Connies with tip tanks. This required strctural rework in the fuel tanks. One of our customer European airlines, noted for their thoroughness in workmanship did the mods. They used to criticize us if they rfound so much as a washer or snip of safety wire in the engine accessory section.
The first conversion was completed and on its first Atlantic crossing it suffered considerable engine problems. We pulled the fuel strainers and found handfuls of swarf including drill shavings, hi-lock collars, etc. We heard much less criticism from them
Yeas later at Eastern I was told of an errant paper cup in a fuel tank. It had been used to carry hi-loc collars into the tank for a plank repair. The cup migrated to the fuel vent outlet and o refueler was surprised when when a wing plank popped its rivets and burst upward. Considering the large exposed area, it doesn't take much internal tank pressure to pop things.
I found, over my career bucking bars for instance years after the aircraft was built. And then there is the general debris left behind in years of service. I put a company inspector on board a test flight of a customer DC8-63 cargo conversion. In the course of the flight the Captain put her into a full stall. During recovery two engines on one side stalled while the others spooled up. They did recover from the inverted spin that time but the inspector most remembered the cloud of debris that filled the cockpit when she inverted.
As DQC (Chief Inspector) at several airlines I always required an RII (Required Inspection) for an Okay to Close a fuel tank. Holding Quality Control's feet to the fire is the only was to minimize FOD in the tanks.

[cashash]

I have found wrenches and flashlights in fuel tanks - a friend in the RAF whilst working on the Vulcan heavy maintenance found a stool!. Yes, people should be more careful but people are what people are and I cant see you ever eliminating the issue.

[gums]

Besides the FOD, there's also the opposite. Another reason for accounting for all parts and tools. Missing components after maintenance or even construction have likely caused many crashes or close calls. You know, "Hey, Joe! what's this bolt for?".
And that's what happened to me on the infamous leading edge flap failure. Thru the grace of God and that FBW system, it would have been a lawn dart when right LEF folded up about 200 - 300 feet in the air on takeoff.
https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/333x240/rightwing_d8c47dc7434e6b9fb5555def185f89008058e47b.jpg

The folks working on the flap system failed to insert and secure a "keeper bolt" that kept the drive motor shaft inserted into the flap drive tube that ran the length of the wing. So the "spline gear" connection worked itself loose on the way to the runway and came disconnected a few second after gear up. No procedure for the failure, as this was early in the plane's history.

[Super Cecil]

A number of large black birds drinking beer in a gaudy dive somewhere in the belly then?
Did you report a birdstrike?
:}:}:8
Made my day

[cattletruck]

This Friday morning I caught the 6am train to work. In it were lots of tradies and most of them were half asleep in their seats. Immediately I thought of this thread and wondered what cockups they would unintentionally create for the day.

You can't stop humans being humans.

The folks working on the flap system failed to insert and secure a "keeper bolt"

In Chuck Yaegers autobiography he describes how they liked to do an aileron flick roll on short finals in their jets. He lost one of his friends in one such manoeuvre and the investigation revealed a bolt had been fitted the wrong way around and had jammed the aileron.

All in the name of preserving astronomical executive salaries.

[Geosync]

as a mechanic we’d find all kind of crap from the factory on small jets, tools left in the belly, FOD of all sizes, outflow valves incorrectly wired.

saw the inside of a bearing race closed off to the rest of the engine shot peened over the years due to a piece of tooling that had broken off during assembly and closed off without being noticed.

did a stint building comm satellites, there are all sorts of tools forever lodged inside those things flying through space. The once constant is that QC will never catch everything.

[radiosutch]

You're going to get severe corrosion if the right combination of metals are in contact for a long period. Galvanic coorosion if you care to Google it. Could be serious over time if on a structural element and not noticed.

[ARealTimTuffy]

https://time.com/5789295/fuel-tank-debris-boeing-737/

[Longtimer]

It would be of interest to learn the extent, makeup and of course size of the debris.

[Twitter]

When I rebuilt my kitchen, I was horrified to find the junk hidden behind and under those original cabinets. Same discovery when under the bath.
The motto seems to be “What the eye don’t see, the heart don’t grieve about”
Pretty piss poor, when a home is the most expensive item many people will own.
This is aviation however, where all of us work on a daily basis to keep it safe, think up and learn improved procedures and undergo almost continuous training. Some folk here seem to think it funny to find strange things in a fuel tank or a wiring environment.
Time to wake up methinks.

[ATC Watcher]

I had the chance to take delivery of a new 757 in Renton a few decades back , It had h only a few seats fitted , the rest was empty and I was surprised to find all kind of small junk left over on the cabin , with nothing better to do at 40.000 ft for 10 hours we filled 2 duty-free size plastic bags.. Debris included , rivets heads, gaskets, cables , insulation bits ..etc.. Strange that for 100 M$ no-one had bothered to make a visual tour and clean the aircraft before delivery.. On mechanic on board said that it was current to take a week " finishing" the aircraft before installing the interior. OK this was over 30 years ago .
Looks like old habits die hard..

[BDAttitude]

Twitter

I can assure you that sweeping the construction waste beneath the bathtub before bricking up is still SOP. As house builder you may want to do the FOD inspection before any cavity is closed.

I think I have read here or somewhere else that B stopped accounting for tools sometime ago. Any details available to confirm or discard that?

[NWA SLF]

Keeping track of this thread, I do see people reporting FOD discovered in tanks of planes other than Boeings, but nothing said about Airbus. Are Airbus planes really 100% free of any debris left in tanks? Having been an engineer in mobile equipment other than airplanes for 44 years, FOD in fuel tanks much less complex than those of an airplane was a constant problem. I remember requirements like after completion and final production cleaning, audits performed on a random basis using a chemical spray to release adherence to the tank surfaces with the discharge filtered and weighed. Debris measuring beyond a certain mass (limit based on the particular tank) required corrective action, more frequent audits, etc. There was no such thing as a 100% clean tank. Static electricity, airborne contamination, manufacturing swarf, corrosion, material scale, bacteria (fuel being organic promotes life of, well in technical terms, really icky organisms). Sealant over applied can squeeze out and cause grief. Then despite all efforts to clean up, the first fuel load could introduce new crud despite requirements for final filters. Now being a old retired guy, I have a lot of toys around my place. I buy clean fuel, keep it clean, and still despite all that care I end up with plugged fuel filters - like 4 filters having finer filtration down the chain on my largest engine and now my FADEC reporting low pressure due to plugged filters but not yet at the prescribed replacement interval. So what is the Airbus secret to having perfection? As an engineering manager in France, I lost one of my employees to Airbus. He can't tell me of any secret but then again maybe he is sworn to secrecy.

[golfyankeesierra]

So what is the Airbus secret to having perfection? As an engineering manager in France, I lost one of my employees to Airbus. He can't tell me of any secret but then again maybe he is sworn to secrecy.

Plastic fuel tanks? 😏

[redparrot]

Hello from Mississauga Ontario Canada

When I started work for a large Canadian airline I was told to help a fuel tank sealer I was told to sit on the wing and act as a safety guard to watch the tank sealer working inside the wing fuel tank. The team leader told me not to let the tank sealer out of my sight and warned me that I could get fired if I left my post.

Later the tank sealer told me that a tank sealer had been found dead inside a DC-8 fuel tank upon arrival at an airport in the UK. When the DC-8 arrived it had a snag for an inboard wing fuel pump fail and when they went to change the pump it was very hard to remove and they found the pump jammed with white coverall cloth It was from the coveralls of the tank sealer. They speculated he had passed out in the tank, went unnoticed , and the next shift closed up the aircraft and it left for the flight to the UK. Only then was it discovered that they had a man missing in YUL.

A very sad story and I never found out if the story was true but several coworkers told me to drop any questions about the sad death

[clearedtocross]

According to CNBC 2/3 of undelivered MAX carry FOD in the fuel tanks. https://www.cnbc.com/2020/02/21/boeing-to-expand-737-max-inspections-sources-say.html. Pretty grim!
And why should all those MAX already delivered (grounded all over the world) as well as any other plane that left a B factory in the last few years be safe? And fuel tanks are not the only place where you could leave FOD.

[tdracer]

It sort of depends on how you define FOD. It's very difficult to go into a fuel tank that has held fuel, and not leave any residue behind.
When we were doing the 747-8 flight testing, they needed to go into the number 3 tank of one of the flight test aircraft for some reason. A few flights later, we got an impending bypass on the #3 engine fuel filter. After the filter was removed and inspected, it was discovered that filter was filled with fibers from the protective garments that were used when entering the fuel tank.

[ST Dog]

And why should all those MAX already delivered (grounded all over the world) as well as any other plane that left a B factory in the last few years be safe?
Safe or FOD free?

There can be FOD present and still be safe. It's not the desired state, but the mere presence of FOD does not inherently make them unsafe.


The problem with the reporting on this is the implication that any FOD could bring down the plan.
And the complete absence of any info on what sort of FOD was found or what quantity.

[tonytales]

There can be no question that FODc in a fuel tank is an undesired condition. As seen in most accidents, it is not a single failure or condition that causes an aircraft to go down. It is the combination of conditions, the proverbial, when "the holes line up in the Swiss Cheese".
Tank entry is a serious business, particularly on an aircraft that has been in service. It can be a life threatening occupation and the atmosphere inside a used fuel tank is not pleasant. Strict procedure are needed to purge and render the tank safe for entry and a dependable breathing system and protective clothing are required for a wet tank. One expert I knew was Eddie Oakes who was known as a tank sealing expert back when I was working. He told me of participating in tank rescues where a sealer was wedged in a tank. They had called in the local Fire Rescue people who were preparing to used a Rescue Sawzal to actually cut the wing open to get the man out. Eddie swore that panicked people, lodged in a tank, actually swell up. He went in, calmed and talked and assisted the man out.
Getting around inside a tank with its structural members and sharp edges and tight spots is a hard task. Still, the tank sealers and Quality Control must do what is needed to at least minimize the FOD in any tank that has been entered.

[ARealTimTuffy]

As mentioned, it is important what the FOD is. Some fibres from workers garments or even some residual bits of something is different than a major tool or large piece of debris left behind because it was forgotten.

At this point we don’t know. But 35 out of 50 as reported a day or so ago certainly isn’t good.

[clearedtocross]

ST Dog

Safe or FOD free?

I am sorry to disagree. A production process or maintenance procedure that does not care to remove FOD is not safe, regardless of the type of FOD. I once nearly got killed because some guy left a screwdriver in a wing of a Cessna 182. Surprise surprise when I raised the flaps after a training touchandgo and only the starboard flap retracted.

[Dog Star]

All aerospace workers must have tools marked, bonuses long term tied to success of their assembly line efforts

[ST Dog]

A screwdriver is quite different than some wire insulation or drilling swarf

When we did FOD walkdowns on the airfield not every little bit was of concern. Only things that could be picked up by an engine and do damage.

Not all FOD is equal in all situations.

That's why we need more detail about what was found to determine the seriousness.

Could it have caused a crash? Just an early landing? Or just short fuel filter life.

[DaveReidUK]

Most definitions of FOD describe it only in terms of the sadly inevitable objects and material that are to be found on the manoeuvring area of an airport, left there by anonymous persons whom it's impossible to control.

There's no mention of debris left on an aircraft by AMEs as a consequence of manufacture or maintenance - that's neither expected nor acceptable.

That should give you a clue.

Skybrary: Foreign Object Debris (FOD) (https://www.skybrary.aero/index.php/Foreign_Object_Debris_(FOD))

[FlexibleResponse]

History tells us that it is pretty hard to justify any aviation manufacturing process in which FOD ends up inside the finished product. Especially in fuel tanks, control runs, electrical circuits, hydraulic systems, pitot/static systems, all other aircraft systems, components and structures (did I miss anything?).

The concept of "good" FOD as opposed to the classically defined and accepted "bad" FOD is new to me, and begs the question of what is "good" FOD and how is it objectively defined?

[Jackjones1]

I did a fair bit of fuel tank work on early 747’s ... modifications repairs etc & you would be surprised where swarf/removed sealant can get too & even the most vigilant person would not get it all, the smaller the tank the harder it was to remove...... I think a fuel filter change was called for within 100 hours.

[Jackjones1]

Brand new aircraft coming in from Boeing’s torches in flap track boat fairings & hammers found on shelving the list was endless & before I retired toolboxes came in with named/identified person but as anyone who has worked in the aircraft industry you always purchased other tools to help do certain tasks & did you identify them .... of course not as if they needed to be replaced if worn out or broken manufacturer would not replace as damage had occurred on identifying tool!!!

[Vendee]

DaveReidUK

Of course older engineers will know that FOD originally stood for Foreign Object Damage but the acronym has been redefined in recent years. On a less pedantic note, people who have never been inside an aircraft fuel tank are unlikely to understand how complex a structure it is with so many places for foreign objects to hide. Even a clean tank can sometimes become "infected" as small bits of the PRC sealant can detach over time and accumulate in the various nooks and crannies. That's not an excuse for poor engineering practice and quality control but sometimes it can be a challenging task.

[Bend alot]

clearedtocross

I am surprised the starboard flap retracted - must have had loose cables!

[ST Dog]

The concept of "good" FOD as opposed to the classically defined and accepted "bad" FOD is new to me, and begs the question of what is "good" FOD and how is it objectively defined?

Who, other than you, said anything about "good" FOD?

But not all FOD is equally BAD, some is much worse and far more serious.

The whole reason you have fuel filters is because the fuel may contain non fuel particles, be it bits of rust, water, or biologic matter.

My suspicion is the is something that the filters would catch (and have on the AC while in service) leading to a clogged filter but reduced pressure would signal it before it was dangerous vs something like a rag that could suddenly block the fuel pickup.

But again, we don't know because no reporting has covered what was found (material, size, etc)

[ST Dog]

Of course older engineers will know that FOD originally stood for Foreign Object Damage but the acronym has been redefined in recent years.

This thread was the first time I had heard it refer to this new definition.

[tdracer]

I think it changed about 10 years ago to make it more generic. Never cared much for the new definition.
We also used to talk about "DOD" - Domestic Object Damage - usually referring to down stream engine damage that resulted from liberated engine bits such as broken blades on the like.

[Fris B. Fairing]

I believe the original term was Foreign Object Damage. The things that caused it were just foreign objects.

[Hugo1980]

Tony Mabelis

I've heard various versions of this story from Australia to UK. But I've never been able to confirm any of them.
I'm sure large objects have been found in fuel tanks but everyone who tells the story swears they were there.😂

[Big Pistons Forever]

Quality construction on a production line takes time and costs money. When you have a Boeing company culture that from the very top prioritized build speed and cost reduction over build quality, I find it amazing that anybody is surprised at the continuing steady parade of news outlining QA failures at Boeing.

Sadly I think the rot is too deep and all pervasive to fix absent a total reboot of the company. Boeing is one crash away from oblivion and clueless MBA bean counters in the C suite are still rearranging the deck chairs on the Titanic....