Debris Found in Undelivered 737MAx FUEL TANKS
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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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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?
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?
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.
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,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-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.
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.
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.
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.
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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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.
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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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.
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.
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.
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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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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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.
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.
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.