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Debris Found in Undelivered 737MAx FUEL TANKS

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Debris Found in Undelivered 737MAx FUEL TANKS

Old 20th Feb 2020, 20:14
  #41 (permalink)  
 
Join Date: Aug 2001
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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.

Last edited by tonytales; 20th Feb 2020 at 20:16. Reason: spelling correction
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Old 20th Feb 2020, 22:13
  #42 (permalink)  
 
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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.
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Old 20th Feb 2020, 22:34
  #43 (permalink)  
 
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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.


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.
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Old 20th Feb 2020, 22:37
  #44 (permalink)  
 
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Smile

Originally Posted by meleagertoo View Post
A number of large black birds drinking beer in a gaudy dive somewhere in the belly then?
Did you report a birdstrike?

Made my day
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Old 21st Feb 2020, 08:39
  #45 (permalink)  
 
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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.
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Old 21st Feb 2020, 15:12
  #46 (permalink)  
 
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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.
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Old 22nd Feb 2020, 08:17
  #47 (permalink)  
 
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FOD

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.
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Old 23rd Feb 2020, 00:49
  #48 (permalink)  
 
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https://time.com/5789295/fuel-tank-debris-boeing-737/
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Old 23rd Feb 2020, 02:31
  #49 (permalink)  
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It would be of interest to learn the extent, makeup and of course size of the debris.
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Old 23rd Feb 2020, 07:28
  #50 (permalink)  
 
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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.
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Old 23rd Feb 2020, 08:58
  #51 (permalink)  
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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..
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Old 23rd Feb 2020, 14:43
  #52 (permalink)  
 
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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?
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Old 23rd Feb 2020, 17:40
  #53 (permalink)  
 
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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.
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Old 23rd Feb 2020, 19:24
  #54 (permalink)  
 
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Originally Posted by NWA SLF View Post
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? 😏
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Old 24th Feb 2020, 13:22
  #55 (permalink)  
 
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Devil man left in aircraft fuel tank !!!

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
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Old 24th Feb 2020, 13:52
  #56 (permalink)  
 
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According to CNBC 2/3 of undelivered MAX carry FOD in the fuel tanks. https://www.cnbc.com/2020/02/21/boei...urces-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.
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Old 24th Feb 2020, 18:24
  #57 (permalink)  
 
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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.
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Old 24th Feb 2020, 20:56
  #58 (permalink)  
 
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Originally Posted by clearedtocross View Post
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.
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Old 24th Feb 2020, 22:19
  #59 (permalink)  
 
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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.
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Old 25th Feb 2020, 00:50
  #60 (permalink)  
 
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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.
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