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Debris Found in Undelivered 737MAx FUEL TANKS

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Debris Found in Undelivered 737MAx FUEL TANKS

Old 19th Feb 2020, 16:06
  #21 (permalink)  
 
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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 .
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Old 19th Feb 2020, 16:31
  #22 (permalink)  
 
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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?
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Old 19th Feb 2020, 16:32
  #23 (permalink)  
 
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Originally Posted by BDAttitude View Post
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...
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Old 19th Feb 2020, 16:46
  #24 (permalink)  
 
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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.
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Old 19th Feb 2020, 17:56
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Originally Posted by old,not bold View Post
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.
Do you have any more details on that? I've only found mention of "during maintenance".

PS
From: https://www.flightglobal.com/air-tra...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.
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Old 19th Feb 2020, 18:27
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On an early 747s first major overhaul, I found nice large chrome Crow bar in the air conditioning bay.
Some things dont change.
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Old 19th Feb 2020, 21:27
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Red face

Originally Posted by threep View Post
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.
... or a pretty big disincentive to account for all tools so everyone can go home and feed the cat.
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Old 19th Feb 2020, 22:23
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Originally Posted by stormin norman View Post
On an early 747s first major overhaul, I found nice large chrome Crow bar in the air conditioning bay.
A number of large black birds drinking beer in a gaudy dive somewhere in the belly then?
Did you report a birdstrike?
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Old 19th Feb 2020, 22:54
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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.
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Old 20th Feb 2020, 05:35
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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.
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Old 20th Feb 2020, 06:52
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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/b...-problems.html

This story also says the FAA were not very active in resolving the problems.
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Old 20th Feb 2020, 08:32
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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.
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Old 20th Feb 2020, 08:36
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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.
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Old 20th Feb 2020, 10:20
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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.
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Old 20th Feb 2020, 10:56
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Originally Posted by Peter H View Post
.........
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.

Last edited by old,not bold; 20th Feb 2020 at 11:07.
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Old 20th Feb 2020, 11:40
  #36 (permalink)  
 
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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.
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Old 20th Feb 2020, 11:51
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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.
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Old 20th Feb 2020, 12:09
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Originally Posted by old,not bold View Post
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.
Thanks for the reassurance. The term "during maintenance" sparked thoughts of FOD found on a fuel filter triggering a fuller inspection of the tanks.
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Old 20th Feb 2020, 14:37
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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.
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Old 20th Feb 2020, 14:59
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Originally Posted by discorules View Post
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.
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.
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