FAA 737 inspection AD covers 175 jets

Note: Dominic Gates of The Seattle Times has a particularly thorough piece looking at this incident. The Wall Street Journal also has a good story on the topic. The New York Times has this story.

Update, April 5: Flightblogger has this story about how the 737s subject to the AD were identified. As Jon Ostrower closes his piece, he asks what the design changes were. KIRO TV (Seattle) told us that Boeing told it design changes were made to strengthen that area of the airplane.

Original Post:

The FAA said late April 4 that it will issue an airworthiness directive April 5 requiring immediate inspections of 175 Boeing 737-300/400/500 aircraft, following the Southwest Airlines in-flight decompression April 1. Eighty of the aircraft are in the US. Only those with more than 30,000 cycles are affected.

The FAA press release is here.

Other countries with reciprocity airworthiness agreements with the US–such as Germany, for example–will follow the FAA’s AD. Countries without airworthiness agreements with the US aren’t required to follow the FAA AD, and it’s unclear how many aircraft are involved.

KIRO TV in Seattle reports that “hundreds” of aircraft, but fewer than 500, may be subject to inspections globally.

In another development, The Daily Record near Baltimore reported (with the Associated Press) that Southwest is pointing a finger at Boeing for the problem. Whether the tone and intent by Southwest is as severe as The Record suggests is up for debate.

By end of business on April 4, most of the 79 jets Southwest grounded for inspection had been passed and were back in service. Three jets were found to have cracks and inspections continued on the remaining aircraft.

12 Comments on “FAA 737 inspection AD covers 175 jets

  1. lap-shear joints have been a perpetual problem for most aircraft, whether by corrosion, fatigue, or material flaws or manufacturing issues. putting coatings around fasteners or at the faying surface usually reduce fatigue life. Usually, automated systems like Gemcor ,etc are used to drill csk and squeeze most of the rivets into place along a lap jpint. It doesn’t take much of a change in clamping pressure, hole size, or squeeze forces to make a joint somewhat less than desired. Qual;ity control via samples helps, but it takes a very careful examination to notice the small changes that can cause long term problems. Especially at high rate production.

    AS I had postulated earlier, it was likely that ALL such body sections ( made/assembled at company x ) between dates y and z ( or K cycles )would have to undergo some sort of extra inspection .

  2. I assume that even though the initial, additional inspections only affect 80 of Southwest’s aircraft, it would continue to affect more and more as they climb above the 30, 000 cycle level.

    Could this have an impact on Southwest’s fleet replenishment plans? (earlier than expected, buying/replacing more than planned, does Boeing have a disadvantage).

    Perhaps the line from the Southwest spokesperson is an early negotiating tactic? Or maybe they who spoke without thinking and might be performing other duties soon?

    • Was the design life ( cycles, hours ) ever proven on a specimen or
      is this another Boeing Grandfathered Property (TM)?

      The high design life tends to be brought forward as a distinct
      Boeing point of excellence .

  3. I’m going to get clobbered for the following comment- but here goes

    1) its a good bet that the manufacturing process in that area of the skin lap joint is a prime suspect

    2) its probable that the same vendor/manufacturer ( Boeing Wichita – now spirit ?? ) made not only 737 sections but 757 body sections ( I’m NOT sure about this )

    3) as a result ALL 737 and 757 Prior to perhaps a change in process – when they reach 30K cycles or so will require extra inspections ( MY SWAG )

    4) It could also be a material glitch with a skin supplier, not usually noticeable until way late

    AS far as design life- someone should be able to verify when full scale fatigue tests were run on that section or the complete airplane. The tests may not have been done on any derivitive since the -200 – I DONT know. But they may have been done for 757 which probably uses the same basic body section and assembly technigue- and MAY have resulted in a change in process about that time – mid 90’s

    • Are the subcontractors allowed the freedom to vary manufacturing in
      a significant way on their own?

      • To be blunt, no! But who knows if they have or not? Same for the fatigue frame. Who knows how much care and attention was put into assembling that airframe by rather experienced hands? Can one say the same about all the airframes since then?
        Perhaps some would be surprised to read this but quality control does not mean inspecting every square inch of every aircraft. What actually gets inspected and how often can be a shock to some.

  4. UWE- it depends on the issue- they must meet the specifications and general parameters in all cases, The problem is always how to define or write specs that cover all possible knowns and unknowns. The inspection criteria are usually well defined, and the production process must in varying degrees meet FAA certification standards.

    Even so, the day to day settings and adjustments on a ‘ machine’ process such as automated riveting are usually well controlled and documented IF everyone follows the rules. When it comes to riveting, unless there is obvious malformed rivets or gaps under head or high countersinks, it is difficult and or time consuming to verify each rivet installation. Thus process control parameters must be carefully set and adhered to. And once a rivet is installed, the correction is difficult.

  5. I suspect the aircraft with less than 30,000 cycles are going to take a serious hit in terms of residual/resale value, which could potentially be very damaging to some airlines balance sheets and credit lines.
    Lessors also could be hit.

  6. Aero Ninja :
    Perhaps some would be surprised to read this but quality control does not mean inspecting every square inch of every aircraft. What actually gets inspected and how often can be a shock to some.

    That would jibe with Boeing having a pronounced lack of process control
    and fits in with the issues that surfaced during 747-8 design and the
    problematic Dreamliner design and manufacture.
    Additionally the 737 maintance cost advantage may well be due to just not
    enough maintance being required by the manufacturer ( nothing ever happened
    and lets grandfather another spec ).

    • I wasn’t talking about Boeing and I am pretty certain it is not unique to them.

      z.B. Aircraft being put together in China by former farming hands, or something of that nature.

      • IMHO this specific item seems to be Boeing centric.
        Inexpirience is not the relevant point.
        You can fix that with better/tighter inspection.
        My myopic vision was set on insufficient
        process control. i.e. you don’t know what your workforce does.
        Management’s bliss from ingnorance: It used to work, we never checked.
        The US union model to me looks like a variation on outsourcing.

        Porting the 747 (paper)design to CAD and the resultant problems exposed that a lot of production detail done on the shopfloor had no complementary paper trail in the production documentation.

      • well – A lot of SW (LUV) airframe maintenance is / or has been done in . . . El salvador and outsourced Domestic
        at least according to Transport Union Workers of America . . in a March 3 2011 report – bitch

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