How much more bad news can Boeing (NYSE: BA) bear?

Earlier this week, we learned that China's C919 airplane -- the "737 killer" -- is starting to gain traction with plane buyers. Boeing rival Comac has already managed to book 100 orders for the new plane; mainly captive-audience Chinese airlines, granted, but the plane has also won orders from the aircraft leasing arm at General Electric (NYSE: GE). This news followed last week's in-flight fire aboard one of Boeing's six 787 Dreamliners undergoing Federal Aviation Administration certification testing. And now comes the really bad news.

That fire may have been more serious than feared. According to a report just out from Morgan Stanley, initial reports of the fire are beginning to suggest a need to revamp the 787's software and electrical systems from the ground up. This is "bigger than a simple, single component failure," said Morgan Stanley. If a redesign is required, it could take as long as a year to complete, delaying deliveries to long-suffering customers like United Continental (NYSE: UAL) and AMR Corp. (NYSE: AMR). Morgan Stanley surmises that initial deliveries to Japan's All Nippon Airways may be pushed back to 2012.

Yes, a whole year. If you were hoping this problem would blow over quickly (as I was), that Boeing would open up the power panel and find some crispy critter in there, fried after gnawing through the insulation on some wiring -- no such luck.

And yes, it could conceivably take a year to fix. Consider, for example, the problem Ford (NYSE: F) has had with fixing a significantly simpler electrical problem on its cars' cruise control system. That one's been going on since the first recall was issued in 2005 -- five years ago. Granted, Ford has the larger problem of wrangling up millions of old cars while Boeing can fix this before production, but enacting a change across its far-flung supply chain this late in the game is serious stuff.

So if you've been viewing the recent weakness at Boeing, and at key 787 suppliers like Precision Castparts (NYSE: PCP) and Spirit AeroSystems (NYSE: SPR) as a "buying opportunity," and planning to pile into the stocks in hopes of a quick rebound, I've got one word of advice for you: Don't.

Ford Motor and Precision Castparts are Motley Fool Stock Advisor recommendations, while Spirit AeroSystems Holdings is a Motley Fool Hidden Gems selection, but Fool contributor Rich Smith does not own shares of any company named above. The Motley Fool has a disclosure policy.

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